package vm

import (
	"bytes"
	"encoding/binary"
	"encoding/hex"
	"errors"
	"fmt"
	"math"
	"math/big"
	"math/rand"
	"strings"
	"testing"

	"github.com/nspcc-dev/neo-go/internal/random"
	"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
	"github.com/nspcc-dev/neo-go/pkg/io"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func fooInteropHandler(v *VM, id uint32) error {
	if id == interopnames.ToID([]byte("foo")) {
		if !v.AddGas(1) {
			return errors.New("invalid gas amount")
		}
		v.Estack().PushVal(1)
		return nil
	}
	return errors.New("syscall not found")
}

func TestInteropHook(t *testing.T) {
	v := newTestVM()
	v.SyscallHandler = fooInteropHandler

	buf := io.NewBufBinWriter()
	emit.Syscall(buf.BinWriter, "foo")
	emit.Opcodes(buf.BinWriter, opcode.RET)
	v.Load(buf.Bytes())
	runVM(t, v)
	assert.Equal(t, 1, v.estack.Len())
	assert.Equal(t, big.NewInt(1), v.estack.Pop().value.Value())
}

func TestVM_SetPriceGetter(t *testing.T) {
	v := newTestVM()
	prog := []byte{
		byte(opcode.PUSH4), byte(opcode.PUSH2),
		byte(opcode.PUSHDATA1), 0x01, 0x01,
		byte(opcode.PUSHDATA1), 0x02, 0xCA, 0xFE,
		byte(opcode.PUSH4), byte(opcode.RET),
	}

	t.Run("no price getter", func(t *testing.T) {
		v.Load(prog)
		runVM(t, v)

		require.EqualValues(t, 0, v.GasConsumed())
	})

	v.SetPriceGetter(func(op opcode.Opcode, p []byte) int64 {
		if op == opcode.PUSH4 {
			return 1
		} else if op == opcode.PUSHDATA1 && bytes.Equal(p, []byte{0xCA, 0xFE}) {
			return 7
		}

		return 0
	})

	t.Run("with price getter", func(t *testing.T) {
		v.Load(prog)
		runVM(t, v)

		require.EqualValues(t, 9, v.GasConsumed())
	})

	t.Run("with sufficient gas limit", func(t *testing.T) {
		v.Load(prog)
		v.GasLimit = 9
		runVM(t, v)

		require.EqualValues(t, 9, v.GasConsumed())
	})

	t.Run("with small gas limit", func(t *testing.T) {
		v.Load(prog)
		v.GasLimit = 8
		checkVMFailed(t, v)
	})
}

func TestAddGas(t *testing.T) {
	v := newTestVM()
	v.GasLimit = 10
	require.True(t, v.AddGas(5))
	require.True(t, v.AddGas(5))
	require.False(t, v.AddGas(5))
}

func TestPushBytes1to75(t *testing.T) {
	buf := io.NewBufBinWriter()
	for i := 1; i <= 75; i++ {
		b := randomBytes(i)
		emit.Bytes(buf.BinWriter, b)
		vm := load(buf.Bytes())
		err := vm.Step()
		require.NoError(t, err)

		assert.Equal(t, 1, vm.estack.Len())

		elem := vm.estack.Pop()
		assert.IsType(t, &stackitem.ByteArray{}, elem.value)
		assert.IsType(t, elem.Bytes(), b)
		assert.Equal(t, 0, vm.estack.Len())

		errExec := vm.execute(nil, opcode.RET, nil)
		require.NoError(t, errExec)

		assert.Equal(t, 0, vm.istack.Len())
		buf.Reset()
	}
}

func runVM(t *testing.T, vm *VM) {
	err := vm.Run()
	require.NoError(t, err)
	assert.Equal(t, false, vm.HasFailed())
}

func checkVMFailed(t *testing.T, vm *VM) {
	err := vm.Run()
	require.Error(t, err)
	assert.Equal(t, true, vm.HasFailed())
}

func TestStackLimitPUSH1Good(t *testing.T) {
	prog := make([]byte, MaxStackSize*2)
	for i := 0; i < MaxStackSize; i++ {
		prog[i] = byte(opcode.PUSH1)
	}
	for i := MaxStackSize; i < MaxStackSize*2; i++ {
		prog[i] = byte(opcode.DROP)
	}

	v := load(prog)
	runVM(t, v)
}

func TestStackLimitPUSH1Bad(t *testing.T) {
	prog := make([]byte, MaxStackSize+1)
	for i := range prog {
		prog[i] = byte(opcode.PUSH1)
	}
	v := load(prog)
	checkVMFailed(t, v)
}

func TestPUSHINT(t *testing.T) {
	for i := byte(0); i < 5; i++ {
		op := opcode.PUSHINT8 + opcode.Opcode(i)
		t.Run(op.String(), func(t *testing.T) {
			buf := random.Bytes((8 << i) / 8)
			prog := append([]byte{byte(op)}, buf...)
			runWithArgs(t, prog, bigint.FromBytes(buf))
		})
	}
}

func TestPUSHNULL(t *testing.T) {
	prog := makeProgram(opcode.PUSHNULL, opcode.PUSHNULL, opcode.EQUAL)
	v := load(prog)
	require.NoError(t, v.Step())
	require.Equal(t, 1, v.estack.Len())
	runVM(t, v)
	require.True(t, v.estack.Pop().Bool())
}

func TestISNULL(t *testing.T) {
	prog := makeProgram(opcode.ISNULL)
	t.Run("Integer", getTestFuncForVM(prog, false, 1))
	t.Run("Null", getTestFuncForVM(prog, true, stackitem.Null{}))
}

func testISTYPE(t *testing.T, result bool, typ stackitem.Type, item stackitem.Item) {
	prog := []byte{byte(opcode.ISTYPE), byte(typ)}
	runWithArgs(t, prog, result, item)
}

func TestISTYPE(t *testing.T) {
	t.Run("Integer", func(t *testing.T) {
		testISTYPE(t, true, stackitem.IntegerT, stackitem.NewBigInteger(big.NewInt(42)))
		testISTYPE(t, false, stackitem.IntegerT, stackitem.NewByteArray([]byte{}))
	})
	t.Run("Boolean", func(t *testing.T) {
		testISTYPE(t, true, stackitem.BooleanT, stackitem.NewBool(true))
		testISTYPE(t, false, stackitem.BooleanT, stackitem.NewByteArray([]byte{}))
	})
	t.Run("ByteArray", func(t *testing.T) {
		testISTYPE(t, true, stackitem.ByteArrayT, stackitem.NewByteArray([]byte{}))
		testISTYPE(t, false, stackitem.ByteArrayT, stackitem.NewBigInteger(big.NewInt(42)))
	})
	t.Run("Array", func(t *testing.T) {
		testISTYPE(t, true, stackitem.ArrayT, stackitem.NewArray([]stackitem.Item{}))
		testISTYPE(t, false, stackitem.ArrayT, stackitem.NewByteArray([]byte{}))
	})
	t.Run("Struct", func(t *testing.T) {
		testISTYPE(t, true, stackitem.StructT, stackitem.NewStruct([]stackitem.Item{}))
		testISTYPE(t, false, stackitem.StructT, stackitem.NewByteArray([]byte{}))
	})
	t.Run("Map", func(t *testing.T) {
		testISTYPE(t, true, stackitem.MapT, stackitem.NewMap())
		testISTYPE(t, false, stackitem.MapT, stackitem.NewByteArray([]byte{}))
	})
	t.Run("Interop", func(t *testing.T) {
		testISTYPE(t, true, stackitem.InteropT, stackitem.NewInterop(42))
		testISTYPE(t, false, stackitem.InteropT, stackitem.NewByteArray([]byte{}))
	})
}

func testCONVERT(to stackitem.Type, item, res stackitem.Item) func(t *testing.T) {
	return func(t *testing.T) {
		prog := []byte{byte(opcode.CONVERT), byte(to)}
		runWithArgs(t, prog, res, item)
	}
}

func TestCONVERT(t *testing.T) {
	type convertTC struct {
		item, res stackitem.Item
	}
	arr := []stackitem.Item{
		stackitem.NewBigInteger(big.NewInt(7)),
		stackitem.NewByteArray([]byte{4, 8, 15}),
	}
	m := stackitem.NewMap()
	m.Add(stackitem.NewByteArray([]byte{1}), stackitem.NewByteArray([]byte{2}))

	getName := func(item stackitem.Item, typ stackitem.Type) string {
		return fmt.Sprintf("%s->%s", item, typ)
	}

	t.Run("->Bool", func(t *testing.T) {
		testBool := func(a, b stackitem.Item) func(t *testing.T) {
			return testCONVERT(stackitem.BooleanT, a, b)
		}

		trueCases := []stackitem.Item{
			stackitem.NewBool(true), stackitem.NewBigInteger(big.NewInt(11)), stackitem.NewByteArray([]byte{1, 2, 3}),
			stackitem.NewArray(arr), stackitem.NewArray(nil),
			stackitem.NewStruct(arr), stackitem.NewStruct(nil),
			stackitem.NewMap(), m, stackitem.NewInterop(struct{}{}),
			stackitem.NewPointer(0, []byte{}),
		}
		for i := range trueCases {
			t.Run(getName(trueCases[i], stackitem.BooleanT), testBool(trueCases[i], stackitem.NewBool(true)))
		}

		falseCases := []stackitem.Item{
			stackitem.NewBigInteger(big.NewInt(0)), stackitem.NewByteArray([]byte{0, 0}), stackitem.NewBool(false),
		}
		for i := range falseCases {
			testBool(falseCases[i], stackitem.NewBool(false))
		}
	})

	t.Run("compound/interop -> basic", func(t *testing.T) {
		types := []stackitem.Type{stackitem.IntegerT, stackitem.ByteArrayT}
		items := []stackitem.Item{stackitem.NewArray(nil), stackitem.NewStruct(nil), stackitem.NewMap(), stackitem.NewInterop(struct{}{})}
		for _, typ := range types {
			for j := range items {
				t.Run(getName(items[j], typ), testCONVERT(typ, items[j], nil))
			}
		}
	})

	t.Run("primitive -> Integer/ByteArray", func(t *testing.T) {
		n := big.NewInt(42)
		b := bigint.ToBytes(n)

		itemInt := stackitem.NewBigInteger(n)
		itemBytes := stackitem.NewByteArray(b)

		trueCases := map[stackitem.Type][]convertTC{
			stackitem.IntegerT: {
				{itemInt, itemInt},
				{itemBytes, itemInt},
				{stackitem.NewBool(true), stackitem.NewBigInteger(big.NewInt(1))},
				{stackitem.NewBool(false), stackitem.NewBigInteger(big.NewInt(0))},
			},
			stackitem.ByteArrayT: {
				{itemInt, itemBytes},
				{itemBytes, itemBytes},
				{stackitem.NewBool(true), stackitem.NewByteArray([]byte{1})},
				{stackitem.NewBool(false), stackitem.NewByteArray([]byte{0})},
			},
		}

		for typ := range trueCases {
			for _, tc := range trueCases[typ] {
				t.Run(getName(tc.item, typ), testCONVERT(typ, tc.item, tc.res))
			}
		}
	})

	t.Run("Struct<->Array", func(t *testing.T) {
		arrayItem := stackitem.NewArray(arr)
		structItem := stackitem.NewStruct(arr)
		t.Run("Array->Array", testCONVERT(stackitem.ArrayT, arrayItem, arrayItem))
		t.Run("Array->Struct", testCONVERT(stackitem.StructT, arrayItem, structItem))
		t.Run("Struct->Array", testCONVERT(stackitem.ArrayT, structItem, arrayItem))
		t.Run("Struct->Struct", testCONVERT(stackitem.StructT, structItem, structItem))
	})

	t.Run("Map->Map", testCONVERT(stackitem.MapT, m, m))

	ptr := stackitem.NewPointer(1, []byte{1})
	t.Run("Pointer->Pointer", testCONVERT(stackitem.PointerT, ptr, ptr))

	t.Run("Null->", func(t *testing.T) {
		types := []stackitem.Type{
			stackitem.BooleanT, stackitem.ByteArrayT, stackitem.IntegerT, stackitem.ArrayT, stackitem.StructT, stackitem.MapT, stackitem.InteropT, stackitem.PointerT,
		}
		for i := range types {
			t.Run(types[i].String(), testCONVERT(types[i], stackitem.Null{}, stackitem.Null{}))
		}
	})

	t.Run("->Any", func(t *testing.T) {
		items := []stackitem.Item{
			stackitem.NewBigInteger(big.NewInt(1)), stackitem.NewByteArray([]byte{1}), stackitem.NewBool(true),
			stackitem.NewArray(arr), stackitem.NewStruct(arr), m, stackitem.NewInterop(struct{}{}),
		}

		for i := range items {
			t.Run(items[i].String(), testCONVERT(stackitem.AnyT, items[i], nil))
		}
	})
}

// appendBigStruct returns a program which:
// 1. pushes size Structs on stack
// 2. packs them into a new struct
// 3. appends them to a zero-length array
// Resulting stack size consists of:
// - struct (size+1)
// - array (1) of struct (size+1)
// which equals to size*2+3 elements in total.
func appendBigStruct(size uint16) []opcode.Opcode {
	prog := make([]opcode.Opcode, size*2)
	for i := uint16(0); i < size; i++ {
		prog[i*2] = opcode.PUSH0
		prog[i*2+1] = opcode.NEWSTRUCT
	}

	return append(prog,
		opcode.INITSSLOT, 1,
		opcode.PUSHINT16, opcode.Opcode(size), opcode.Opcode(size>>8), // LE
		opcode.PACK, opcode.CONVERT, opcode.Opcode(stackitem.StructT),
		opcode.STSFLD0, opcode.LDSFLD0,
		opcode.DUP,
		opcode.PUSH0, opcode.NEWARRAY,
		opcode.SWAP,
		opcode.APPEND, opcode.RET)
}

func TestStackLimitAPPENDStructGood(t *testing.T) {
	prog := makeProgram(appendBigStruct(MaxStackSize/2 - 2)...)
	v := load(prog)
	runVM(t, v) // size = 2047 = (Max/2-2)*2+3 = Max-1
}

func TestStackLimitAPPENDStructBad(t *testing.T) {
	prog := makeProgram(appendBigStruct(MaxStackSize/2 - 1)...)
	v := load(prog)
	checkVMFailed(t, v) // size = 2049 = (Max/2-1)*2+3 = Max+1
}

func TestStackLimit(t *testing.T) {
	expected := []struct {
		inst opcode.Opcode
		size int
	}{
		{opcode.PUSH2, 2},    // 1 from INITSSLOT and 1 for integer 2
		{opcode.NEWARRAY, 4}, // array + 2 items
		{opcode.STSFLD0, 3},
		{opcode.LDSFLD0, 4},
		{opcode.NEWMAP, 5},
		{opcode.DUP, 6},
		{opcode.PUSH2, 7},
		{opcode.LDSFLD0, 8},
		{opcode.SETITEM, 7}, // -3 items and 1 new kv pair in map
		{opcode.DUP, 8},
		{opcode.PUSH2, 9},
		{opcode.LDSFLD0, 10},
		{opcode.SETITEM, 7}, // -3 items and no new elements in map
		{opcode.DUP, 8},
		{opcode.PUSH2, 9},
		{opcode.REMOVE, 5}, // as we have right after NEWMAP
		{opcode.DROP, 4},   // DROP map with no elements
	}

	prog := make([]opcode.Opcode, len(expected)+2)
	prog[0] = opcode.INITSSLOT
	prog[1] = 1
	for i := range expected {
		prog[i+2] = expected[i].inst
	}

	vm := load(makeProgram(prog...))
	require.NoError(t, vm.Step(), "failed to initialize static slot")
	for i := range expected {
		require.NoError(t, vm.Step())
		require.Equal(t, expected[i].size, int(vm.refs), "i: %d", i)
	}
}

func TestPushm1to16(t *testing.T) {
	var prog []byte
	for i := int(opcode.PUSHM1); i <= int(opcode.PUSH16); i++ {
		if i == 80 {
			continue // opcode layout we got here.
		}
		prog = append(prog, byte(i))
	}

	vm := load(prog)
	for i := int(opcode.PUSHM1); i <= int(opcode.PUSH16); i++ {
		err := vm.Step()
		require.NoError(t, err)

		elem := vm.estack.Pop()
		val := i - int(opcode.PUSH1) + 1
		assert.Equal(t, elem.BigInt().Int64(), int64(val))
	}
}

func TestPUSHDATA1(t *testing.T) {
	t.Run("Good", getTestFuncForVM([]byte{byte(opcode.PUSHDATA1), 3, 1, 2, 3}, []byte{1, 2, 3}))
	t.Run("NoN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA1)}, nil))
	t.Run("BadN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA1), 1}, nil))
}

func TestPUSHDATA2(t *testing.T) {
	t.Run("Good", getTestFuncForVM([]byte{byte(opcode.PUSHDATA2), 3, 0, 1, 2, 3}, []byte{1, 2, 3}))
	t.Run("NoN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA2)}, nil))
	t.Run("ShortN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA2), 0}, nil))
	t.Run("BadN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA2), 1, 0}, nil))
}

func TestPUSHDATA4(t *testing.T) {
	t.Run("Good", getTestFuncForVM([]byte{byte(opcode.PUSHDATA4), 3, 0, 0, 0, 1, 2, 3}, []byte{1, 2, 3}))
	t.Run("NoN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA4)}, nil))
	t.Run("BadN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA4), 1, 0, 0, 0}, nil))
	t.Run("ShortN", getTestFuncForVM([]byte{byte(opcode.PUSHDATA4), 0, 0, 0}, nil))
}

func TestPushData4BigN(t *testing.T) {
	prog := make([]byte, 1+4+stackitem.MaxSize+1)
	prog[0] = byte(opcode.PUSHDATA4)
	binary.LittleEndian.PutUint32(prog[1:], stackitem.MaxSize+1)

	vm := load(prog)
	checkVMFailed(t, vm)
}

func getTestCallFlagsFunc(syscall []byte, flags callflag.CallFlag, result interface{}) func(t *testing.T) {
	return func(t *testing.T) {
		script := append([]byte{byte(opcode.SYSCALL)}, syscall...)
		v := newTestVM()
		v.SyscallHandler = testSyscallHandler
		v.LoadScriptWithFlags(script, flags)
		if result == nil {
			checkVMFailed(t, v)
			return
		}
		runVM(t, v)
		require.Equal(t, result, v.PopResult())
	}
}

func TestCallFlags(t *testing.T) {
	noFlags := []byte{0x77, 0x77, 0x77, 0x77}
	readOnly := []byte{0x66, 0x66, 0x66, 0x66}
	t.Run("NoFlagsNoRequired", getTestCallFlagsFunc(noFlags, callflag.NoneFlag, new(int)))
	t.Run("ProvideFlagsNoRequired", getTestCallFlagsFunc(noFlags, callflag.AllowCall, new(int)))
	t.Run("NoFlagsSomeRequired", getTestCallFlagsFunc(readOnly, callflag.NoneFlag, nil))
	t.Run("OnlyOneProvided", getTestCallFlagsFunc(readOnly, callflag.AllowCall, nil))
	t.Run("AllFlagsProvided", getTestCallFlagsFunc(readOnly, callflag.ReadOnly, new(int)))
}

func callNTimes(n uint16) []byte {
	return makeProgram(
		opcode.PUSHINT16, opcode.Opcode(n), opcode.Opcode(n>>8), // little-endian
		opcode.INITSSLOT, 1,
		opcode.STSFLD0, opcode.LDSFLD0,
		opcode.JMPIF, 0x3, opcode.RET,
		opcode.LDSFLD0, opcode.DEC,
		opcode.CALL, 0xF9) // -7 -> JMP to TOALTSTACK)
}

func TestInvocationLimitGood(t *testing.T) {
	prog := callNTimes(MaxInvocationStackSize - 1)
	v := load(prog)
	runVM(t, v)
}

func TestInvocationLimitBad(t *testing.T) {
	prog := callNTimes(MaxInvocationStackSize)
	v := load(prog)
	checkVMFailed(t, v)
}

func isLongJMP(op opcode.Opcode) bool {
	return op == opcode.JMPL || op == opcode.JMPIFL || op == opcode.JMPIFNOTL ||
		op == opcode.JMPEQL || op == opcode.JMPNEL ||
		op == opcode.JMPGEL || op == opcode.JMPGTL ||
		op == opcode.JMPLEL || op == opcode.JMPLTL
}

func getJMPProgram(op opcode.Opcode) []byte {
	prog := []byte{byte(op)}
	if isLongJMP(op) {
		prog = append(prog, 0x07, 0x00, 0x00, 0x00)
	} else {
		prog = append(prog, 0x04)
	}
	return append(prog, byte(opcode.PUSH1), byte(opcode.RET), byte(opcode.PUSH2), byte(opcode.RET))
}

func testJMP(t *testing.T, op opcode.Opcode, res interface{}, items ...interface{}) {
	prog := getJMPProgram(op)
	v := load(prog)
	for i := range items {
		v.estack.PushVal(items[i])
	}
	if res == nil {
		checkVMFailed(t, v)
		return
	}
	runVM(t, v)
	require.EqualValues(t, res, v.estack.Pop().BigInt().Int64())
}

func TestJMPs(t *testing.T) {
	testCases := []struct {
		name  string
		items []interface{}
	}{
		{
			name: "no condition",
		},
		{
			name:  "single item (true)",
			items: []interface{}{true},
		},
		{
			name:  "single item (false)",
			items: []interface{}{false},
		},
		{
			name:  "24 and 42",
			items: []interface{}{24, 42},
		},
		{
			name:  "42 and 24",
			items: []interface{}{42, 24},
		},
		{
			name:  "42 and 42",
			items: []interface{}{42, 42},
		},
	}

	// 2 is true, 1 is false
	results := map[opcode.Opcode][]interface{}{
		opcode.JMP:      {2, 2, 2, 2, 2, 2},
		opcode.JMPIF:    {nil, 2, 1, 2, 2, 2},
		opcode.JMPIFNOT: {nil, 1, 2, 1, 1, 1},
		opcode.JMPEQ:    {nil, nil, nil, 1, 1, 2},
		opcode.JMPNE:    {nil, nil, nil, 2, 2, 1},
		opcode.JMPGE:    {nil, nil, nil, 1, 2, 2},
		opcode.JMPGT:    {nil, nil, nil, 1, 2, 1},
		opcode.JMPLE:    {nil, nil, nil, 2, 1, 2},
		opcode.JMPLT:    {nil, nil, nil, 2, 1, 1},
	}

	for i, tc := range testCases {
		i := i
		t.Run(tc.name, func(t *testing.T) {
			for op := opcode.JMP; op < opcode.JMPLEL; op++ {
				resOp := op
				if isLongJMP(op) {
					resOp--
				}
				t.Run(op.String(), func(t *testing.T) {
					testJMP(t, op, results[resOp][i], tc.items...)
				})
			}
		})
	}
}

func TestPUSHA(t *testing.T) {
	t.Run("Negative", getTestFuncForVM(makeProgram(opcode.PUSHA, 0xFF, 0xFF, 0xFF, 0xFF), nil))
	t.Run("TooBig", getTestFuncForVM(makeProgram(opcode.PUSHA, 10, 0, 0, 0), nil))
	t.Run("Good", func(t *testing.T) {
		prog := makeProgram(opcode.NOP, opcode.PUSHA, 2, 0, 0, 0)
		runWithArgs(t, prog, stackitem.NewPointer(3, prog))
	})
}

func TestCALLA(t *testing.T) {
	prog := makeProgram(opcode.CALLA, opcode.PUSH2, opcode.ADD, opcode.RET, opcode.PUSH3, opcode.RET)
	t.Run("InvalidScript", getTestFuncForVM(prog, nil, stackitem.NewPointer(4, []byte{1})))
	t.Run("Good", getTestFuncForVM(prog, 5, stackitem.NewPointer(4, prog)))
}

func TestCALL(t *testing.T) {
	prog := makeProgram(
		opcode.CALL, 4, opcode.ADD, opcode.RET,
		opcode.CALL, 3, opcode.RET,
		opcode.PUSH1, opcode.PUSH2, opcode.RET)
	runWithArgs(t, prog, 3)
}

func TestNOT(t *testing.T) {
	prog := makeProgram(opcode.NOT)
	t.Run("Bool", getTestFuncForVM(prog, true, false))
	t.Run("NonZeroInt", getTestFuncForVM(prog, false, 3))
	t.Run("Array", getTestFuncForVM(prog, false, []stackitem.Item{}))
	t.Run("Struct", getTestFuncForVM(prog, false, stackitem.NewStruct([]stackitem.Item{})))
	t.Run("ByteArray0", getTestFuncForVM(prog, true, []byte{0, 0}))
	t.Run("ByteArray1", getTestFuncForVM(prog, false, []byte{0, 1}))
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("Buffer0", getTestFuncForVM(prog, false, stackitem.NewBuffer([]byte{})))
	t.Run("Buffer1", getTestFuncForVM(prog, false, stackitem.NewBuffer([]byte{1})))
}

// getBigInt returns 2^a+b.
func getBigInt(a, b int64) *big.Int {
	p := new(big.Int).Exp(big.NewInt(2), big.NewInt(a), nil)
	p.Add(p, big.NewInt(b))
	return p
}

func TestArith(t *testing.T) {
	// results for 5 and 2
	testCases := map[opcode.Opcode]int{
		opcode.ADD: 7,
		opcode.MUL: 10,
		opcode.DIV: 2,
		opcode.MOD: 1,
		opcode.SUB: 3,
	}

	for op, res := range testCases {
		t.Run(op.String(), getTestFuncForVM(makeProgram(op), res, 5, 2))
	}
}

func TestADDBigResult(t *testing.T) {
	prog := makeProgram(opcode.ADD)
	runWithArgs(t, prog, nil, getBigInt(stackitem.MaxBigIntegerSizeBits-1, -1), 1) // 0x7FFF...
}

func TestMULBigResult(t *testing.T) {
	prog := makeProgram(opcode.MUL)
	bi := getBigInt(stackitem.MaxBigIntegerSizeBits/2+1, 0)
	runWithArgs(t, prog, nil, bi, bi)
}

func TestArithNegativeArguments(t *testing.T) {
	runCase := func(op opcode.Opcode, p, q, result int64) func(t *testing.T) {
		return getTestFuncForVM(makeProgram(op), result, p, q)
	}

	t.Run("DIV", func(t *testing.T) {
		t.Run("positive/positive", runCase(opcode.DIV, 5, 2, 2))
		t.Run("positive/negative", runCase(opcode.DIV, 5, -2, -2))
		t.Run("negative/positive", runCase(opcode.DIV, -5, 2, -2))
		t.Run("negative/negative", runCase(opcode.DIV, -5, -2, 2))
	})

	t.Run("MOD", func(t *testing.T) {
		t.Run("positive/positive", runCase(opcode.MOD, 5, 2, 1))
		t.Run("positive/negative", runCase(opcode.MOD, 5, -2, 1))
		t.Run("negative/positive", runCase(opcode.MOD, -5, 2, -1))
		t.Run("negative/negative", runCase(opcode.MOD, -5, -2, -1))
	})

	t.Run("SHR", func(t *testing.T) {
		t.Run("positive/positive", runCase(opcode.SHR, 5, 2, 1))
		t.Run("negative/positive", runCase(opcode.SHR, -5, 2, -2))
	})

	t.Run("SHL", func(t *testing.T) {
		t.Run("positive/positive", runCase(opcode.SHL, 5, 2, 20))
		t.Run("negative/positive", runCase(opcode.SHL, -5, 2, -20))
	})
}

func TestSUBBigResult(t *testing.T) {
	prog := makeProgram(opcode.SUB)
	bi := getBigInt(stackitem.MaxBigIntegerSizeBits-1, -1)
	runWithArgs(t, prog, new(big.Int).Sub(big.NewInt(-1), bi), -1, bi)
	runWithArgs(t, prog, nil, -2, bi)
}

func TestPOW(t *testing.T) {
	prog := makeProgram(opcode.POW)
	t.Run("good, positive", getTestFuncForVM(prog, 9, 3, 2))
	t.Run("good, negative, even", getTestFuncForVM(prog, 4, -2, 2))
	t.Run("good, negative, odd", getTestFuncForVM(prog, -8, -2, 3))
	t.Run("zero", getTestFuncForVM(prog, 1, 3, 0))
	t.Run("negative exponent", getTestFuncForVM(prog, nil, 3, -1))
	t.Run("too big exponent", getTestFuncForVM(prog, nil, 1, maxSHLArg+1))
}

func TestSQRT(t *testing.T) {
	prog := makeProgram(opcode.SQRT)
	t.Run("good, positive", getTestFuncForVM(prog, 3, 9))
	t.Run("good, round down", getTestFuncForVM(prog, 2, 8))
	t.Run("one", getTestFuncForVM(prog, 1, 1))
	t.Run("zero", getTestFuncForVM(prog, 0, 0))
	t.Run("negative value", getTestFuncForVM(prog, nil, -1))
}

func TestMODMUL(t *testing.T) {
	prog := makeProgram(opcode.MODMUL)
	t.Run("bad, zero mod", getTestFuncForVM(prog, nil, 1, 2, 0))
	t.Run("good, positive base", getTestFuncForVM(prog, 2, 3, 4, 5))
	t.Run("good, zero base", getTestFuncForVM(prog, 0, 0, 4, 5))
	t.Run("good, negative base", getTestFuncForVM(prog, 3, -3, 4, 5))
	t.Run("good, positive base, negative mod", getTestFuncForVM(prog, 2, 3, 4, -5))
	t.Run("good, negative base, negative mod", getTestFuncForVM(prog, 3, -3, 4, -5))
}

func TestMODPOW(t *testing.T) {
	prog := makeProgram(opcode.MODPOW)
	t.Run("good, positive base", getTestFuncForVM(prog, 1, 3, 4, 5))
	t.Run("good, negative base", getTestFuncForVM(prog, 2, -3, 5, 5))
	t.Run("good, positive base, negative mod", getTestFuncForVM(prog, 1, 3, 4, -5))
	t.Run("good, negative base, negative mod", getTestFuncForVM(prog, 2, -3, 5, -5))
	t.Run("bad, big negative exponent", getTestFuncForVM(prog, nil, 3, -2, 5))
	t.Run("bad, zero modulus", getTestFuncForVM(prog, nil, 3, 4, 0))

	t.Run("inverse compatibility", func(t *testing.T) { // Tests are taken from C# node.
		t.Run("bad mod", getTestFuncForVM(prog, nil, 1, -1, 0))
		t.Run("bad mod", getTestFuncForVM(prog, nil, 1, -1, 1))
		t.Run("bad base", getTestFuncForVM(prog, nil, 0, -1, 0))
		t.Run("bad base", getTestFuncForVM(prog, nil, 0, -1, 1))
		t.Run("no inverse exists", getTestFuncForVM(prog, nil, math.MaxUint16, -1, math.MaxUint8))
		t.Run("good", getTestFuncForVM(prog, 52, 19, -1, 141))
	})
}

func TestSHR(t *testing.T) {
	prog := makeProgram(opcode.SHR)
	t.Run("Good", getTestFuncForVM(prog, 1, 4, 2))
	t.Run("Zero", getTestFuncForVM(prog, []byte{0, 1}, []byte{0, 1}, 0))
	t.Run("Negative", getTestFuncForVM(prog, nil, 5, -1))
	t.Run("very big", getTestFuncForVM(prog, nil, 5, maxu64Plus(1)))
}

func TestSHL(t *testing.T) {
	prog := makeProgram(opcode.SHL)
	t.Run("Good", getTestFuncForVM(prog, 16, 4, 2))
	t.Run("Zero", getTestFuncForVM(prog, []byte{0, 1}, []byte{0, 1}, 0))
	t.Run("BigShift", getTestFuncForVM(prog, nil, 5, maxSHLArg+1))
	t.Run("BigResult", getTestFuncForVM(prog, nil, getBigInt(stackitem.MaxBigIntegerSizeBits/2, 0), stackitem.MaxBigIntegerSizeBits/2))
	t.Run("very big shift", getTestFuncForVM(prog, nil, 5, maxu64Plus(1)))
}

func TestArithNullArg(t *testing.T) {
	for _, op := range []opcode.Opcode{opcode.LT, opcode.LE, opcode.GT, opcode.GE} {
		prog := makeProgram(op)
		t.Run(op.String(), func(t *testing.T) {
			runWithArgs(t, prog, false, stackitem.Null{}, 0)
			runWithArgs(t, prog, false, 0, stackitem.Null{})
			runWithArgs(t, prog, nil, stackitem.NewInterop(nil), 1) // also has `.Value() == nil`
		})
	}
}

func TestLT(t *testing.T) {
	prog := makeProgram(opcode.LT)
	runWithArgs(t, prog, false, 4, 3)
}

func TestLE(t *testing.T) {
	prog := makeProgram(opcode.LE)
	runWithArgs(t, prog, true, 2, 3)
}

func TestGT(t *testing.T) {
	prog := makeProgram(opcode.GT)
	runWithArgs(t, prog, true, 9, 3)
}

func TestGE(t *testing.T) {
	prog := makeProgram(opcode.GE)
	runWithArgs(t, prog, true, 3, 3)
}

func TestDepth(t *testing.T) {
	prog := makeProgram(opcode.DEPTH)
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushVal(2)
	vm.estack.PushVal(3)
	runVM(t, vm)
	assert.Equal(t, int64(3), vm.estack.Pop().BigInt().Int64())
}

func TestEQUALTrue(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.EQUAL)
	t.Run("Array", getTestFuncForVM(prog, true, []stackitem.Item{}))
	t.Run("Map", getTestFuncForVM(prog, true, stackitem.NewMap()))
	t.Run("Buffer", getTestFuncForVM(prog, true, stackitem.NewBuffer([]byte{1, 2})))
}

func TestEQUAL(t *testing.T) {
	prog := makeProgram(opcode.EQUAL)
	t.Run("NoArgs", getTestFuncForVM(prog, nil))
	t.Run("OneArgument", getTestFuncForVM(prog, nil, 1))
	t.Run("Integer", getTestFuncForVM(prog, true, 5, 5))
	t.Run("IntegerByteArray", getTestFuncForVM(prog, false, []byte{16}, 16))
	t.Run("BooleanInteger", getTestFuncForVM(prog, false, true, 1))
	t.Run("Map", getTestFuncForVM(prog, false, stackitem.NewMap(), stackitem.NewMap()))
	t.Run("Array", getTestFuncForVM(prog, false, []stackitem.Item{}, []stackitem.Item{}))
	t.Run("Buffer", getTestFuncForVM(prog, false, stackitem.NewBuffer([]byte{42}), stackitem.NewBuffer([]byte{42})))
}

func TestEQUALByteArrayWithLimit(t *testing.T) {
	prog := makeProgram(opcode.EQUAL)
	t.Run("fits limit, equal", func(t *testing.T) {
		args := make([]stackitem.Item, 2)
		for i := range args {
			args[i] = stackitem.NewStruct([]stackitem.Item{
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize/2)),
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize/2)),
			})
		}
		getTestFuncForVM(prog, true, args[0], args[1])(t)
	})
	t.Run("exceeds limit", func(t *testing.T) {
		args := make([]stackitem.Item, 2)
		for i := range args {
			args[i] = stackitem.NewStruct([]stackitem.Item{
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize/2+1)),
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize/2)),
			})
		}
		getTestFuncForVM(prog, nil, args[0], args[1])(t) // should FAULT due to comparable limit exceeding
	})
	t.Run("fits limit, second elements are not equal", func(t *testing.T) {
		args := make([]stackitem.Item, 2)
		for i := range args {
			args[i] = stackitem.NewStruct([]stackitem.Item{
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize-1)),
				stackitem.NewBuffer(make([]byte, 1)),
			})
		}
		getTestFuncForVM(prog, false, args[0], args[1])(t) // no limit is exceeded, but the second struct item is a Buffer.
	})
	t.Run("fits limit, equal", func(t *testing.T) {
		args := make([]stackitem.Item, 2)
		buf := stackitem.NewBuffer(make([]byte, 100500)) // takes only 1 comparable unit despite its length
		for i := range args {
			args[i] = stackitem.NewStruct([]stackitem.Item{
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize-1)),
				buf,
			})
		}
		getTestFuncForVM(prog, true, args[0], args[1])(t) // should HALT, because no limit exceeded
	})
	t.Run("exceeds limit, equal", func(t *testing.T) {
		args := make([]stackitem.Item, 2)
		buf := stackitem.NewBuffer(make([]byte, 100500)) // takes only 1 comparable unit despite its length
		for i := range args {
			args[i] = stackitem.NewStruct([]stackitem.Item{
				stackitem.NewByteArray(make([]byte, stackitem.MaxByteArrayComparableSize-1)), // MaxByteArrayComparableSize-1 comparable  units
				buf, // 1 comparable unit
				buf, // 1 comparable unit
			})
		}
		getTestFuncForVM(prog, nil, args[0], args[1])(t) // should FAULT, because limit is exceeded:
	})
}

func runWithArgs(t *testing.T, prog []byte, result interface{}, args ...interface{}) {
	getTestFuncForVM(prog, result, args...)(t)
}

func getCustomTestFuncForVM(prog []byte, check func(t *testing.T, v *VM), args ...interface{}) func(t *testing.T) {
	return func(t *testing.T) {
		v := load(prog)
		for i := range args {
			v.estack.PushVal(args[i])
		}
		if check == nil {
			checkVMFailed(t, v)
			return
		}
		runVM(t, v)
		check(t, v)
	}
}

func getTestFuncForVM(prog []byte, result interface{}, args ...interface{}) func(t *testing.T) {
	var f func(t *testing.T, v *VM)
	if result != nil {
		f = func(t *testing.T, v *VM) {
			require.Equal(t, 1, v.estack.Len())
			require.Equal(t, stackitem.Make(result).Value(), v.estack.Pop().Value())
		}
	}
	return getCustomTestFuncForVM(prog, f, args...)
}

func makeRETProgram(t *testing.T, argCount, localCount int) []byte {
	require.True(t, argCount+localCount <= 255)

	fProg := []opcode.Opcode{opcode.INITSLOT, opcode.Opcode(localCount), opcode.Opcode(argCount)}
	for i := 0; i < localCount; i++ {
		fProg = append(fProg, opcode.PUSH8, opcode.STLOC, opcode.Opcode(i))
	}
	fProg = append(fProg, opcode.RET)

	offset := uint32(len(fProg) + 5)
	param := make([]byte, 4)
	binary.LittleEndian.PutUint32(param, offset)

	ops := []opcode.Opcode{
		opcode.INITSSLOT, 0x01,
		opcode.PUSHA, 11, 0, 0, 0,
		opcode.STSFLD0,
		opcode.JMPL, opcode.Opcode(param[0]), opcode.Opcode(param[1]), opcode.Opcode(param[2]), opcode.Opcode(param[3]),
	}
	ops = append(ops, fProg...)

	// execute func multiple times to ensure total reference count is less than max
	callCount := MaxStackSize/(argCount+localCount) + 1
	args := make([]opcode.Opcode, argCount)
	for i := range args {
		args[i] = opcode.PUSH7
	}
	for i := 0; i < callCount; i++ {
		ops = append(ops, args...)
		ops = append(ops, opcode.LDSFLD0, opcode.CALLA)
	}
	return makeProgram(ops...)
}

func TestRETReferenceClear(t *testing.T) {
	// 42 is a canary
	t.Run("Argument", getTestFuncForVM(makeRETProgram(t, 100, 0), 42, 42))
	t.Run("Local", getTestFuncForVM(makeRETProgram(t, 0, 100), 42, 42))
}

func TestNOTEQUALByteArray(t *testing.T) {
	prog := makeProgram(opcode.NOTEQUAL)
	t.Run("True", getTestFuncForVM(prog, true, []byte{1, 2}, []byte{0, 1, 2}))
	t.Run("False", getTestFuncForVM(prog, false, []byte{1, 2}, []byte{1, 2}))
}

func TestNUMEQUAL(t *testing.T) {
	prog := makeProgram(opcode.NUMEQUAL)
	t.Run("True", getTestFuncForVM(prog, true, 2, 2))
	t.Run("False", getTestFuncForVM(prog, false, 1, 2))
}

func TestNUMNOTEQUAL(t *testing.T) {
	prog := makeProgram(opcode.NUMNOTEQUAL)
	t.Run("True", getTestFuncForVM(prog, true, 1, 2))
	t.Run("False", getTestFuncForVM(prog, false, 2, 2))
}

func TestINC(t *testing.T) {
	prog := makeProgram(opcode.INC)
	runWithArgs(t, prog, 2, 1)
}

func TestINCBigResult(t *testing.T) {
	prog := makeProgram(opcode.INC, opcode.INC)
	vm := load(prog)
	x := getBigInt(stackitem.MaxBigIntegerSizeBits-1, -2)
	vm.estack.PushVal(x)

	require.NoError(t, vm.Step())
	require.False(t, vm.HasFailed())
	require.Equal(t, 1, vm.estack.Len())
	require.Equal(t, new(big.Int).Add(x, big.NewInt(1)), vm.estack.Top().BigInt())

	checkVMFailed(t, vm)
}

func TestDECBigResult(t *testing.T) {
	prog := makeProgram(opcode.DEC, opcode.DEC)
	vm := load(prog)
	x := getBigInt(stackitem.MaxBigIntegerSizeBits-1, -1)
	x.Neg(x)
	vm.estack.PushVal(x)

	require.NoError(t, vm.Step())
	require.False(t, vm.HasFailed())
	require.Equal(t, 1, vm.estack.Len())
	require.Equal(t, new(big.Int).Sub(x, big.NewInt(1)), vm.estack.Top().BigInt())

	checkVMFailed(t, vm)
}

func TestNEWBUFFER(t *testing.T) {
	prog := makeProgram(opcode.NEWBUFFER)
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte{0, 0, 0}), 3))
	t.Run("Negative", getTestFuncForVM(prog, nil, -1))
	t.Run("TooBig", getTestFuncForVM(prog, nil, stackitem.MaxSize+1))
}

func getTRYProgram(tryBlock, catchBlock, finallyBlock []byte) []byte {
	hasCatch := catchBlock != nil
	hasFinally := finallyBlock != nil
	tryOffset := len(tryBlock) + 3 + 2 // try args + endtry args

	var (
		catchLen, finallyLen       int
		catchOffset, finallyOffset int
	)
	if hasCatch {
		catchLen = len(catchBlock) + 2 // endtry args
		catchOffset = tryOffset
	}
	if hasFinally {
		finallyLen = len(finallyBlock) + 1 // endfinally
		finallyOffset = tryOffset + catchLen
	}
	prog := []byte{byte(opcode.TRY), byte(catchOffset), byte(finallyOffset)}
	prog = append(prog, tryBlock...)
	prog = append(prog, byte(opcode.ENDTRY), byte(catchLen+finallyLen+2))
	if hasCatch {
		prog = append(prog, catchBlock...)
		prog = append(prog, byte(opcode.ENDTRY), byte(finallyLen+2))
	}
	if hasFinally {
		prog = append(prog, finallyBlock...)
		prog = append(prog, byte(opcode.ENDFINALLY))
	}
	prog = append(prog, byte(opcode.RET))
	return prog
}

func getTRYTestFunc(result interface{}, tryBlock, catchBlock, finallyBlock []byte) func(t *testing.T) {
	return func(t *testing.T) {
		prog := getTRYProgram(tryBlock, catchBlock, finallyBlock)
		runWithArgs(t, prog, result)
	}
}

func TestTRY(t *testing.T) {
	throw := []byte{byte(opcode.PUSH13), byte(opcode.THROW)}
	push1 := []byte{byte(opcode.PUSH1)}
	add5 := []byte{byte(opcode.PUSH5), byte(opcode.ADD)}
	add9 := []byte{byte(opcode.PUSH9), byte(opcode.ADD)}
	t.Run("NoCatch", func(t *testing.T) {
		t.Run("NoFinally", func(t *testing.T) {
			prog := getTRYProgram(push1, nil, nil)
			vm := load(prog)
			checkVMFailed(t, vm)
		})
		t.Run("WithFinally", getTRYTestFunc(10, push1, nil, add9))
		t.Run("Throw", getTRYTestFunc(nil, throw, nil, add9))
	})
	t.Run("WithCatch", func(t *testing.T) {
		t.Run("NoFinally", func(t *testing.T) {
			t.Run("Simple", getTRYTestFunc(1, push1, add5, nil))
			t.Run("Throw", getTRYTestFunc(18, throw, add5, nil))
			t.Run("Abort", getTRYTestFunc(nil, []byte{byte(opcode.ABORT)}, push1, nil))
			t.Run("ThrowInCatch", getTRYTestFunc(nil, throw, throw, nil))
		})
		t.Run("WithFinally", func(t *testing.T) {
			t.Run("Simple", getTRYTestFunc(10, push1, add5, add9))
			t.Run("Throw", getTRYTestFunc(27, throw, add5, add9))
		})
	})
	t.Run("Nested", func(t *testing.T) {
		t.Run("ReThrowInTry", func(t *testing.T) {
			inner := getTRYProgram(throw, []byte{byte(opcode.THROW)}, nil)
			getTRYTestFunc(27, inner, add5, add9)(t)
		})
		t.Run("ThrowInFinally", func(t *testing.T) {
			inner := getTRYProgram(throw, add5, []byte{byte(opcode.THROW)})
			getTRYTestFunc(32, inner, add5, add9)(t)
		})
		t.Run("TryMaxDepth", func(t *testing.T) {
			loopTries := []byte{byte(opcode.INITSLOT), 0x01, 0x00,
				byte(opcode.PUSH16), byte(opcode.INC), byte(opcode.STLOC0),
				byte(opcode.TRY), 1, 1, // jump target
				byte(opcode.LDLOC0), byte(opcode.DEC), byte(opcode.DUP),
				byte(opcode.STLOC0), byte(opcode.PUSH0),
				byte(opcode.JMPGT), 0xf8, byte(opcode.LDLOC0)}
			vm := load(loopTries)
			checkVMFailed(t, vm)
		})
	})
	t.Run("ThrowInCall", func(t *testing.T) {
		catchP := []byte{byte(opcode.CALL), 2, byte(opcode.PUSH1), byte(opcode.ADD), byte(opcode.THROW), byte(opcode.RET)}
		inner := getTRYProgram(throw, catchP, []byte{byte(opcode.PUSH2)})
		// add 5 to the exception, mul to the result of inner finally (2)
		getTRYTestFunc(47, inner, append(add5, byte(opcode.MUL)), add9)(t)
	})
	t.Run("nested, in throw and catch in call", func(t *testing.T) {
		catchP := []byte{byte(opcode.PUSH10), byte(opcode.ADD)}
		inner := getTRYProgram(throw, catchP, []byte{byte(opcode.PUSH2)})
		outer := getTRYProgram([]byte{byte(opcode.CALL), 0}, []byte{byte(opcode.PUSH3)}, []byte{byte(opcode.PUSH4)})
		outer = append(outer, byte(opcode.RET))
		outer[4] = byte(len(outer) - 3) // CALL argument at 3 (TRY) + 1 (CALL opcode)
		outer = append(outer, inner...)
		outer = append(outer, byte(opcode.RET))

		v := load(outer)
		runVM(t, v)
		require.Equal(t, 3, v.Estack().Len())
		require.Equal(t, big.NewInt(4), v.Estack().Pop().Value())  // outer FINALLY
		require.Equal(t, big.NewInt(2), v.Estack().Pop().Value())  // inner FINALLY
		require.Equal(t, big.NewInt(23), v.Estack().Pop().Value()) // inner THROW + CATCH
	})
}

func TestMEMCPY(t *testing.T) {
	prog := makeProgram(opcode.MEMCPY)
	t.Run("Good", func(t *testing.T) {
		buf := stackitem.NewBuffer([]byte{0, 1, 2, 3})
		runWithArgs(t, prog, stackitem.NewBuffer([]byte{0, 6, 7, 3}), buf, buf, 1, []byte{4, 5, 6, 7}, 2, 2)
	})
	t.Run("NonZeroDstIndex", func(t *testing.T) {
		buf := stackitem.NewBuffer([]byte{0, 1, 2})
		runWithArgs(t, prog, stackitem.NewBuffer([]byte{0, 6, 7}), buf, buf, 1, []byte{4, 5, 6, 7}, 2, 2)
	})
	t.Run("NegativeSize", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{0, 1}), 0, []byte{2}, 0, -1))
	t.Run("NegativeSrcIndex", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{0, 1}), 0, []byte{2}, -1, 1))
	t.Run("NegativeDstIndex", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{0, 1}), -1, []byte{2}, 0, 1))
	t.Run("BigSizeSrc", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{0, 1}), 0, []byte{2}, 0, 2))
	t.Run("BigSizeDst", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{0, 1}), 0, []byte{2, 3, 4}, 0, 3))
}

func TestNEWARRAY0(t *testing.T) {
	prog := makeProgram(opcode.NEWARRAY0)
	runWithArgs(t, prog, []stackitem.Item{})
}

func TestNEWSTRUCT0(t *testing.T) {
	prog := makeProgram(opcode.NEWSTRUCT0)
	runWithArgs(t, prog, stackitem.NewStruct([]stackitem.Item{}))
}

func TestNEWARRAYArray(t *testing.T) {
	prog := makeProgram(opcode.NEWARRAY)
	t.Run("ByteArray", getTestFuncForVM(prog, stackitem.NewArray([]stackitem.Item{}), []byte{}))
	t.Run("BadSize", getTestFuncForVM(prog, nil, MaxStackSize+1))
	t.Run("Integer", getTestFuncForVM(prog, []stackitem.Item{stackitem.Null{}}, 1))
}

func testNEWARRAYIssue437(t *testing.T, i1 opcode.Opcode, t2 stackitem.Type, appended bool) {
	prog := makeProgram(
		opcode.PUSH2, i1,
		opcode.DUP, opcode.PUSH3, opcode.APPEND,
		opcode.INITSSLOT, 1,
		opcode.STSFLD0, opcode.LDSFLD0, opcode.CONVERT, opcode.Opcode(t2),
		opcode.DUP, opcode.PUSH4, opcode.APPEND,
		opcode.LDSFLD0, opcode.PUSH5, opcode.APPEND)

	arr := makeArrayOfType(4, stackitem.AnyT)
	arr[2] = stackitem.Make(3)
	arr[3] = stackitem.Make(4)
	if appended {
		arr = append(arr, stackitem.Make(5))
	}

	if t2 == stackitem.ArrayT {
		runWithArgs(t, prog, stackitem.NewArray(arr))
	} else {
		runWithArgs(t, prog, stackitem.NewStruct(arr))
	}
}

func TestNEWARRAYIssue437(t *testing.T) {
	t.Run("Array+Array", func(t *testing.T) { testNEWARRAYIssue437(t, opcode.NEWARRAY, stackitem.ArrayT, true) })
	t.Run("Struct+Struct", func(t *testing.T) { testNEWARRAYIssue437(t, opcode.NEWSTRUCT, stackitem.StructT, true) })
	t.Run("Array+Struct", func(t *testing.T) { testNEWARRAYIssue437(t, opcode.NEWARRAY, stackitem.StructT, false) })
	t.Run("Struct+Array", func(t *testing.T) { testNEWARRAYIssue437(t, opcode.NEWSTRUCT, stackitem.ArrayT, false) })
}

func TestNEWARRAYT(t *testing.T) {
	testCases := map[stackitem.Type]stackitem.Item{
		stackitem.BooleanT:   stackitem.NewBool(false),
		stackitem.IntegerT:   stackitem.NewBigInteger(big.NewInt(0)),
		stackitem.ByteArrayT: stackitem.NewByteArray([]byte{}),
		stackitem.ArrayT:     stackitem.Null{},
		0xFF:                 nil,
	}
	for typ, item := range testCases {
		prog := makeProgram(opcode.NEWARRAYT, opcode.Opcode(typ), opcode.PUSH0, opcode.PICKITEM)
		t.Run(typ.String(), getTestFuncForVM(prog, item, 1))
	}
}

func TestNEWSTRUCT(t *testing.T) {
	prog := makeProgram(opcode.NEWSTRUCT)
	t.Run("ByteArray", getTestFuncForVM(prog, stackitem.NewStruct([]stackitem.Item{}), []byte{}))
	t.Run("BadSize", getTestFuncForVM(prog, nil, MaxStackSize+1))
	t.Run("Integer", getTestFuncForVM(prog, stackitem.NewStruct([]stackitem.Item{stackitem.Null{}}), 1))
}

func TestAPPEND(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.PUSH5, opcode.APPEND)
	arr := []stackitem.Item{stackitem.Make(5)}
	t.Run("Array", getTestFuncForVM(prog, stackitem.NewArray(arr), stackitem.NewArray(nil)))
	t.Run("Struct", getTestFuncForVM(prog, stackitem.NewStruct(arr), stackitem.NewStruct(nil)))
}

func TestAPPENDCloneStruct(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.PUSH0, opcode.NEWSTRUCT, opcode.INITSSLOT, 1, opcode.STSFLD0,
		opcode.LDSFLD0, opcode.APPEND, opcode.LDSFLD0, opcode.PUSH1, opcode.APPEND)
	arr := []stackitem.Item{stackitem.NewStruct([]stackitem.Item{})}
	runWithArgs(t, prog, stackitem.NewArray(arr), stackitem.NewArray(nil))
}

func TestAPPENDBad(t *testing.T) {
	prog := makeProgram(opcode.APPEND)
	t.Run("no arguments", getTestFuncForVM(prog, nil))
	t.Run("one argument", getTestFuncForVM(prog, nil, 1))
	t.Run("wrong type", getTestFuncForVM(prog, nil, []byte{}, 1))
}

func TestAPPENDGoodSizeLimit(t *testing.T) {
	prog := makeProgram(opcode.NEWARRAY, opcode.DUP, opcode.PUSH0, opcode.APPEND)
	vm := load(prog)
	vm.estack.PushVal(MaxStackSize - 3) // 1 for array, 1 for copy, 1 for pushed 0.
	runVM(t, vm)
	assert.Equal(t, 1, vm.estack.Len())
	assert.Equal(t, MaxStackSize-2, len(vm.estack.Pop().Array()))
}

func TestAPPENDBadSizeLimit(t *testing.T) {
	prog := makeProgram(opcode.NEWARRAY, opcode.DUP, opcode.PUSH0, opcode.APPEND)
	runWithArgs(t, prog, nil, MaxStackSize)
}

func TestAPPENDRefSizeLimit(t *testing.T) {
	prog := makeProgram(opcode.NEWARRAY0, opcode.DUP, opcode.DUP, opcode.APPEND, opcode.JMP, 0xfd)
	runWithArgs(t, prog, nil)
}

func TestPICKITEM(t *testing.T) {
	prog := makeProgram(opcode.PICKITEM)
	t.Run("bad index", getTestFuncForVM(prog, nil, []stackitem.Item{}, 0))
	t.Run("Array", getTestFuncForVM(prog, 2, []stackitem.Item{stackitem.Make(1), stackitem.Make(2)}, 1))
	t.Run("ByteArray", getTestFuncForVM(prog, 2, []byte{1, 2}, 1))
	t.Run("Buffer", getTestFuncForVM(prog, 2, stackitem.NewBuffer([]byte{1, 2}), 1))
	t.Run("Exceptions", func(t *testing.T) {
		tryProg := getTRYProgram(
			[]byte{byte(opcode.PICKITEM), byte(opcode.RET)},
			[]byte{byte(opcode.RET)}, nil)
		items := []stackitem.Item{
			stackitem.NewArray([]stackitem.Item{}),
			stackitem.NewBuffer([]byte{}),
			stackitem.NewByteArray([]byte{}),
		}
		for _, item := range items {
			t.Run(item.String()+", negative", getTestFuncForVM(tryProg,
				fmt.Sprintf("The value %d is out of range.", math.MinInt32),
				item, math.MinInt32))
			t.Run(item.String()+", very big index",
				getTestFuncForVM(tryProg, nil, item, int64(math.MaxInt32)+1))
		}

		m := stackitem.NewMap()
		t.Run("Map, missing key", getTestFuncForVM(tryProg, "Key not found in Map", m, 1))
	})
}

func TestVMPrintOps(t *testing.T) {
	w := io.NewBufBinWriter()
	emit.Bytes(w.BinWriter, make([]byte, 1000))
	emit.Opcodes(w.BinWriter, opcode.PUSH0)
	emit.Bytes(w.BinWriter, make([]byte, 8))

	buf := bytes.NewBuffer(nil)
	v := New()
	v.Load(w.Bytes())
	v.PrintOps(buf)

	ss := strings.Split(buf.String(), "\n")
	require.Equal(t, 5, len(ss)) // header + 3 opcodes + trailing newline
	require.True(t, len(ss[0]) < 1000)
	require.True(t, len(ss[1]) > 1000)
	require.True(t, len(ss[2]) < 1000)
	require.True(t, len(ss[3]) < 1000)
}

func TestPICKITEMDupArray(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.PUSH0, opcode.PICKITEM, opcode.ABS)
	vm := load(prog)
	vm.estack.PushVal([]stackitem.Item{stackitem.Make(-1)})
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	items := vm.estack.Pop().Value().([]stackitem.Item)
	assert.Equal(t, big.NewInt(-1), items[0].Value())
}

func TestPICKITEMDupMap(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.PUSHINT8, 42, opcode.PICKITEM, opcode.ABS)
	vm := load(prog)
	m := stackitem.NewMap()
	m.Add(stackitem.Make(42), stackitem.Make(-1))
	vm.estack.Push(Element{value: m})
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	items := vm.estack.Pop().Value().([]stackitem.MapElement)
	assert.Equal(t, 1, len(items))
	assert.Equal(t, big.NewInt(42), items[0].Key.Value())
	assert.Equal(t, big.NewInt(-1), items[0].Value.Value())
}

func TestPICKITEMMap(t *testing.T) {
	prog := makeProgram(opcode.PICKITEM)
	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make(3))
	runWithArgs(t, prog, 3, m, 5)
}

func TestSETITEMBuffer(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.REVERSE4, opcode.SETITEM)
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte{0, 42, 2}), 42, 1, stackitem.NewBuffer([]byte{0, 1, 2})))
	t.Run("BadValue", getTestFuncForVM(prog, nil, 256, 1, stackitem.NewBuffer([]byte{0, 1, 2})))
	t.Run("Exceptions", func(t *testing.T) {
		tryProg := getTRYProgram(
			[]byte{byte(opcode.SETITEM), byte(opcode.PUSH12), byte(opcode.RET)},
			[]byte{byte(opcode.RET)}, nil)
		t.Run("negative index", getTestFuncForVM(tryProg,
			fmt.Sprintf("The value %d is out of range.", math.MinInt32),
			stackitem.NewBuffer([]byte{0, 1, 2}), math.MinInt32, 0))
		t.Run("very big index", getTestFuncForVM(tryProg,
			nil, stackitem.NewBuffer([]byte{0, 1, 2}), int64(math.MaxInt32)+1, 0))
	})
}

func TestSETITEMArray(t *testing.T) {
	tryProg := getTRYProgram(
		[]byte{byte(opcode.SETITEM), byte(opcode.RET)},
		[]byte{byte(opcode.RET)}, nil)
	t.Run("Good", func(t *testing.T) {
		arr := stackitem.NewArray([]stackitem.Item{stackitem.Make(12), stackitem.Make(2)})
		expected := stackitem.NewArray([]stackitem.Item{stackitem.Make(12), stackitem.Make(42)})
		runWithArgs(t, tryProg, expected, arr, arr, 1, 42)
	})
	t.Run("negative index", getTestFuncForVM(tryProg,
		fmt.Sprintf("The value %d is out of range.", math.MinInt32),
		[]stackitem.Item{}, math.MinInt32, 42))
	t.Run("very big index", getTestFuncForVM(tryProg,
		nil, []stackitem.Item{}, int64(math.MaxInt32)+1, 0))
}

func TestSETITEMMap(t *testing.T) {
	prog := makeProgram(opcode.SETITEM, opcode.PICKITEM)
	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make(3))
	runWithArgs(t, prog, []byte{0, 1}, m, 5, m, 5, []byte{0, 1})

	t.Run("big key", func(t *testing.T) {
		m := stackitem.NewMap()
		key := make([]byte, stackitem.MaxKeySize)
		for i := range key {
			key[i] = 0x0F
		}
		m.Add(stackitem.NewByteArray(key), stackitem.Make(3))
		runWithArgs(t, prog, "value", m, key, m, key, "value")
	})
}

func TestSETITEMBigMapBad(t *testing.T) {
	prog := makeProgram(opcode.SETITEM)
	m := stackitem.NewMap()
	for i := 0; i < MaxStackSize; i++ {
		m.Add(stackitem.Make(i), stackitem.Make(i))
	}

	runWithArgs(t, prog, nil, m, m, MaxStackSize, 0)
}

// This test checks is SETITEM properly updates reference counter.
// 1. Create 2 arrays of size MaxStackSize/2 - 3.
// 2. SETITEM each of them to a map.
// 3. Replace each of them with a scalar value.
func TestSETITEMMapStackLimit(t *testing.T) {
	size := MaxStackSize/2 - 4
	m := stackitem.NewMap()
	m.Add(stackitem.NewBigInteger(big.NewInt(1)), stackitem.NewArray(makeArrayOfType(size, stackitem.BooleanT)))
	m.Add(stackitem.NewBigInteger(big.NewInt(2)), stackitem.NewArray(makeArrayOfType(size, stackitem.BooleanT)))

	prog := makeProgram(
		opcode.DUP, opcode.PUSH1, opcode.PUSH1, opcode.SETITEM,
		opcode.DUP, opcode.PUSH2, opcode.PUSH2, opcode.SETITEM,
		opcode.DUP, opcode.PUSH3, opcode.PUSH3, opcode.SETITEM,
		opcode.DUP, opcode.PUSH4, opcode.PUSH4, opcode.SETITEM)
	v := load(prog)
	v.estack.PushVal(m)
	runVM(t, v)
}

func TestSETITEMBigMapGood(t *testing.T) {
	prog := makeProgram(opcode.SETITEM)
	vm := load(prog)

	m := stackitem.NewMap()
	for i := 0; i < MaxStackSize-3; i++ {
		m.Add(stackitem.Make(i), stackitem.Make(i))
	}
	vm.estack.Push(Element{value: m})
	vm.estack.PushVal(0)
	vm.estack.PushVal(0)

	runVM(t, vm)
}

func TestSIZE(t *testing.T) {
	prog := makeProgram(opcode.SIZE)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("ByteArray", getTestFuncForVM(prog, 2, []byte{0, 1}))
	t.Run("Buffer", getTestFuncForVM(prog, 2, stackitem.NewBuffer([]byte{0, 1})))
	t.Run("Bool", getTestFuncForVM(prog, 1, false))
	t.Run("Array", getTestFuncForVM(prog, 2, []stackitem.Item{stackitem.Make(1), stackitem.Make([]byte{})}))
	t.Run("Map", func(t *testing.T) {
		m := stackitem.NewMap()
		m.Add(stackitem.Make(5), stackitem.Make(6))
		m.Add(stackitem.Make([]byte{0, 1}), stackitem.Make(6))
		runWithArgs(t, prog, 2, m)
	})
}

func TestKEYSMap(t *testing.T) {
	prog := makeProgram(opcode.KEYS)
	vm := load(prog)

	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make(6))
	m.Add(stackitem.Make([]byte{0, 1}), stackitem.Make(6))
	vm.estack.Push(Element{value: m})

	runVM(t, vm)
	assert.Equal(t, 1, vm.estack.Len())

	top := vm.estack.Pop().value.(*stackitem.Array)
	assert.Equal(t, 2, len(top.Value().([]stackitem.Item)))
	assert.Contains(t, top.Value().([]stackitem.Item), stackitem.Make(5))
	assert.Contains(t, top.Value().([]stackitem.Item), stackitem.Make([]byte{0, 1}))
}

func TestKEYS(t *testing.T) {
	prog := makeProgram(opcode.KEYS)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("WrongType", getTestFuncForVM(prog, nil, []stackitem.Item{}))
}

func TestTry_ENDFINALLY_before_ENDTRY(t *testing.T) {
	prog := makeProgram(opcode.TRY, 0, 3, opcode.ENDFINALLY)
	require.NoError(t, IsScriptCorrect(prog, nil))

	v := load(prog)

	var err error
	require.NotPanics(t, func() { err = v.Run() })
	require.Error(t, err)
}

func TestVALUESMap(t *testing.T) {
	prog := makeProgram(opcode.VALUES)
	vm := load(prog)

	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make([]byte{2, 3}))
	m.Add(stackitem.Make([]byte{0, 1}), stackitem.Make([]stackitem.Item{}))
	vm.estack.Push(Element{value: m})

	runVM(t, vm)
	assert.Equal(t, 1, vm.estack.Len())

	top := vm.estack.Pop().value.(*stackitem.Array)
	assert.Equal(t, 2, len(top.Value().([]stackitem.Item)))
	assert.Contains(t, top.Value().([]stackitem.Item), stackitem.Make([]byte{2, 3}))
	assert.Contains(t, top.Value().([]stackitem.Item), stackitem.Make([]stackitem.Item{}))
}

func TestVALUES(t *testing.T) {
	prog := makeProgram(opcode.VALUES)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("WrongType", getTestFuncForVM(prog, nil, 5))
	t.Run("Array", getTestFuncForVM(prog, []int{4}, []int{4}))
}

func TestHASKEY(t *testing.T) {
	prog := makeProgram(opcode.HASKEY)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("OneArgument", getTestFuncForVM(prog, nil, 1))
	t.Run("WrongKeyType", getTestFuncForVM(prog, nil, []stackitem.Item{}, []stackitem.Item{}))
	t.Run("WrongCollectionType", getTestFuncForVM(prog, nil, 1, 2))

	arr := makeArrayOfType(5, stackitem.BooleanT)
	t.Run("Array", func(t *testing.T) {
		t.Run("True", getTestFuncForVM(prog, true, stackitem.NewArray(arr), 4))
		t.Run("too big", getTestFuncForVM(prog, nil, stackitem.NewArray(arr), maxu64Plus(4)))
		t.Run("False", getTestFuncForVM(prog, false, stackitem.NewArray(arr), 5))
	})
	t.Run("Struct", func(t *testing.T) {
		t.Run("True", getTestFuncForVM(prog, true, stackitem.NewStruct(arr), 4))
		t.Run("too big", getTestFuncForVM(prog, nil, stackitem.NewStruct(arr), maxu64Plus(4)))
		t.Run("False", getTestFuncForVM(prog, false, stackitem.NewStruct(arr), 5))
	})

	t.Run("Buffer", func(t *testing.T) {
		t.Run("True", getTestFuncForVM(prog, true, stackitem.NewBuffer([]byte{5, 5, 5}), 2))
		t.Run("too big", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{5, 5, 5}), maxu64Plus(2)))
		t.Run("False", getTestFuncForVM(prog, false, stackitem.NewBuffer([]byte{5, 5, 5}), 3))
		t.Run("Negative", getTestFuncForVM(prog, nil, stackitem.NewBuffer([]byte{5, 5, 5}), -1))
	})

	t.Run("ByteArray", func(t *testing.T) {
		t.Run("True", getTestFuncForVM(prog, true, stackitem.NewByteArray([]byte{5, 5, 5}), 2))
		t.Run("too big", getTestFuncForVM(prog, nil, stackitem.NewByteArray([]byte{5, 5, 5}), maxu64Plus(2)))
		t.Run("False", getTestFuncForVM(prog, false, stackitem.NewByteArray([]byte{5, 5, 5}), 3))
		t.Run("Negative", getTestFuncForVM(prog, nil, stackitem.NewByteArray([]byte{5, 5, 5}), -1))
	})
}

func TestHASKEYMap(t *testing.T) {
	prog := makeProgram(opcode.HASKEY)
	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make(6))
	t.Run("True", getTestFuncForVM(prog, true, m, 5))
	t.Run("False", getTestFuncForVM(prog, false, m, 6))
}

func TestHASKEYBigKey(t *testing.T) {
	v := newTestVM()

	buf := io.NewBufBinWriter()
	emit.Int(buf.BinWriter, 1024*1024)
	emit.Opcodes(buf.BinWriter, opcode.NEWBUFFER, opcode.NEWMAP)
	emit.Int(buf.BinWriter, 64)
	emit.Opcodes(buf.BinWriter, opcode.NEWBUFFER)
	emit.Opcodes(buf.BinWriter, opcode.INITSLOT, opcode.Opcode(0), opcode.Opcode(3))

	emit.Opcodes(buf.BinWriter, opcode.LDARG1, opcode.LDARG0, opcode.CONVERT, opcode.Opcode(stackitem.ByteArrayT))
	emit.Opcodes(buf.BinWriter, opcode.LDARG0, opcode.SETITEM, opcode.LDARG1, opcode.LDARG2)
	emit.Opcodes(buf.BinWriter, opcode.CONVERT, opcode.Opcode(stackitem.ByteArrayT))
	emit.Opcodes(buf.BinWriter, opcode.HASKEY)

	emit.Opcodes(buf.BinWriter, opcode.JMP, opcode.Opcode(0xFB)) // -5
	v.Load(buf.Bytes())
	checkVMFailed(t, v)
}

func TestSIGN(t *testing.T) {
	prog := makeProgram(opcode.SIGN)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("WrongType", getTestFuncForVM(prog, nil, []stackitem.Item{}))
	t.Run("Bool", getTestFuncForVM(prog, 0, false))
	t.Run("PositiveInt", getTestFuncForVM(prog, 1, 2))
	t.Run("NegativeInt", getTestFuncForVM(prog, -1, -1))
	t.Run("Zero", getTestFuncForVM(prog, 0, 0))
	t.Run("ByteArray", getTestFuncForVM(prog, 1, []byte{0, 1}))
}

func TestSimpleCall(t *testing.T) {
	buf := io.NewBufBinWriter()
	w := buf.BinWriter
	emit.Opcodes(w, opcode.PUSH2)
	emit.Instruction(w, opcode.CALL, []byte{03})
	emit.Opcodes(w, opcode.RET)
	emit.Opcodes(w, opcode.PUSH10)
	emit.Opcodes(w, opcode.ADD)
	emit.Opcodes(w, opcode.RET)

	result := 12
	vm := load(buf.Bytes())
	runVM(t, vm)
	assert.Equal(t, result, int(vm.estack.Pop().BigInt().Int64()))
}

func TestNZ(t *testing.T) {
	prog := makeProgram(opcode.NZ)
	t.Run("True", getTestFuncForVM(prog, true, 1))
	t.Run("False", getTestFuncForVM(prog, false, 0))
}

func TestPICK(t *testing.T) {
	prog := makeProgram(opcode.PICK)
	t.Run("NoItem", getTestFuncForVM(prog, nil, 1))
	t.Run("Negative", getTestFuncForVM(prog, nil, -1))
	t.Run("very big", getTestFuncForVM(prog, nil, 1, 2, 3, maxu64Plus(1)))
}

func TestPICKgood(t *testing.T) {
	prog := makeProgram(opcode.PICK)
	result := 2
	vm := load(prog)
	vm.estack.PushVal(0)
	vm.estack.PushVal(1)
	vm.estack.PushVal(result)
	vm.estack.PushVal(3)
	vm.estack.PushVal(4)
	vm.estack.PushVal(5)
	vm.estack.PushVal(3)
	runVM(t, vm)
	assert.Equal(t, int64(result), vm.estack.Pop().BigInt().Int64())
}

func TestPICKDup(t *testing.T) {
	prog := makeProgram(opcode.PUSHM1, opcode.PUSH0,
		opcode.PUSH1,
		opcode.PUSH2,
		opcode.PICK,
		opcode.ABS)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, 4, vm.estack.Len())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(0), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(-1), vm.estack.Pop().BigInt().Int64())
}

func TestROTBad(t *testing.T) {
	prog := makeProgram(opcode.ROT)
	runWithArgs(t, prog, nil, 1, 2)
}

func TestROTGood(t *testing.T) {
	prog := makeProgram(opcode.ROT)
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushVal(2)
	vm.estack.PushVal(3)
	runVM(t, vm)
	assert.Equal(t, 3, vm.estack.Len())
	assert.Equal(t, stackitem.Make(1), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(3), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(2), vm.estack.Pop().value)
}

func TestROLLBad1(t *testing.T) {
	prog := makeProgram(opcode.ROLL)
	runWithArgs(t, prog, nil, 1, -1)
}

func TestROLLBad2(t *testing.T) {
	prog := makeProgram(opcode.ROLL)
	runWithArgs(t, prog, nil, 1, 2, 3, 3)
}

func maxu64Plus(x int64) *big.Int {
	bi := new(big.Int).SetUint64(math.MaxUint64)
	bi.Add(bi, big.NewInt(2))
	return bi
}

func TestROLLBad3(t *testing.T) {
	prog := makeProgram(opcode.ROLL)
	runWithArgs(t, prog, nil, 1, 2, 3, maxu64Plus(2))
}

func TestROLLGood(t *testing.T) {
	prog := makeProgram(opcode.ROLL)
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushVal(2)
	vm.estack.PushVal(3)
	vm.estack.PushVal(4)
	vm.estack.PushVal(1)
	runVM(t, vm)
	assert.Equal(t, 4, vm.estack.Len())
	assert.Equal(t, stackitem.Make(3), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(4), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(2), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(1), vm.estack.Pop().value)
}

func getCheckEStackFunc(items ...interface{}) func(t *testing.T, v *VM) {
	return func(t *testing.T, v *VM) {
		require.Equal(t, len(items), v.estack.Len())
		for i := 0; i < len(items); i++ {
			assert.Equal(t, stackitem.Make(items[i]), v.estack.Peek(i).Item())
		}
	}
}

func TestREVERSE3(t *testing.T) {
	prog := makeProgram(opcode.REVERSE3)
	t.Run("SmallStack", getTestFuncForVM(prog, nil, 1, 2))
	t.Run("Good", getCustomTestFuncForVM(prog, getCheckEStackFunc(1, 2, 3), 1, 2, 3))
}

func TestREVERSE4(t *testing.T) {
	prog := makeProgram(opcode.REVERSE4)
	t.Run("SmallStack", getTestFuncForVM(prog, nil, 1, 2, 3))
	t.Run("Good", getCustomTestFuncForVM(prog, getCheckEStackFunc(1, 2, 3, 4), 1, 2, 3, 4))
}

func TestREVERSEN(t *testing.T) {
	prog := makeProgram(opcode.REVERSEN)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("SmallStack", getTestFuncForVM(prog, nil, 1, 2, 3))
	t.Run("NegativeArgument", getTestFuncForVM(prog, nil, 1, 2, -1))
	t.Run("Zero", getCustomTestFuncForVM(prog, getCheckEStackFunc(3, 2, 1), 1, 2, 3, 0))
	t.Run("OneItem", getCustomTestFuncForVM(prog, getCheckEStackFunc(42), 42, 1))
	t.Run("Good", getCustomTestFuncForVM(prog, getCheckEStackFunc(1, 2, 3, 4, 5), 1, 2, 3, 4, 5, 5))
	t.Run("VeryBigNumber", getCustomTestFuncForVM(prog, nil, 1, 2, maxu64Plus(2)))
}

func TestTUCKbadNoitems(t *testing.T) {
	prog := makeProgram(opcode.TUCK)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("NoItem", getTestFuncForVM(prog, nil, 1))
}

func TestTUCKgood(t *testing.T) {
	prog := makeProgram(opcode.TUCK)
	vm := load(prog)
	vm.estack.PushVal(42)
	vm.estack.PushVal(34)
	runVM(t, vm)
	assert.Equal(t, int64(34), vm.estack.Peek(0).BigInt().Int64())
	assert.Equal(t, int64(42), vm.estack.Peek(1).BigInt().Int64())
	assert.Equal(t, int64(34), vm.estack.Peek(2).BigInt().Int64())
}

func TestTUCKgood2(t *testing.T) {
	prog := makeProgram(opcode.TUCK)
	vm := load(prog)
	vm.estack.PushVal(11)
	vm.estack.PushVal(42)
	vm.estack.PushVal(34)
	runVM(t, vm)
	assert.Equal(t, int64(34), vm.estack.Peek(0).BigInt().Int64())
	assert.Equal(t, int64(42), vm.estack.Peek(1).BigInt().Int64())
	assert.Equal(t, int64(34), vm.estack.Peek(2).BigInt().Int64())
	assert.Equal(t, int64(11), vm.estack.Peek(3).BigInt().Int64())
}

func TestOVER(t *testing.T) {
	prog := makeProgram(opcode.OVER)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("NoItem", getTestFuncForVM(prog, nil, 1))
}

func TestOVERgood(t *testing.T) {
	prog := makeProgram(opcode.OVER)
	vm := load(prog)
	vm.estack.PushVal(42)
	vm.estack.PushVal(34)
	runVM(t, vm)
	assert.Equal(t, int64(42), vm.estack.Peek(0).BigInt().Int64())
	assert.Equal(t, int64(34), vm.estack.Peek(1).BigInt().Int64())
	assert.Equal(t, int64(42), vm.estack.Peek(2).BigInt().Int64())
	assert.Equal(t, 3, vm.estack.Len())
}

func TestOVERDup(t *testing.T) {
	prog := makeProgram(opcode.PUSHDATA1, 2, 1, 0,
		opcode.PUSH1,
		opcode.OVER,
		opcode.PUSH1,
		opcode.LEFT,
		opcode.PUSHDATA1, 1, 2,
		opcode.CAT)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, 3, vm.estack.Len())
	assert.Equal(t, []byte{0x01, 0x02}, vm.estack.Pop().Bytes())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, []byte{0x01, 0x00}, vm.estack.Pop().Bytes())
}

func TestNIPBadNoItem(t *testing.T) {
	prog := makeProgram(opcode.NIP)
	runWithArgs(t, prog, nil, 1)
}

func TestNIPGood(t *testing.T) {
	prog := makeProgram(opcode.NIP)
	runWithArgs(t, prog, 2, 1, 2)
}

func TestDROPBadNoItem(t *testing.T) {
	prog := makeProgram(opcode.DROP)
	runWithArgs(t, prog, nil)
}

func TestDROPGood(t *testing.T) {
	prog := makeProgram(opcode.DROP)
	vm := load(prog)
	vm.estack.PushVal(1)
	runVM(t, vm)
	assert.Equal(t, 0, vm.estack.Len())
}

func TestXDROP(t *testing.T) {
	prog := makeProgram(opcode.XDROP)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("NoN", getTestFuncForVM(prog, nil, 1, 2))
	t.Run("very big argument", getTestFuncForVM(prog, nil, 1, 2, maxu64Plus(1)))
	t.Run("Negative", getTestFuncForVM(prog, nil, 1, -1))
}

func TestXDROPgood(t *testing.T) {
	prog := makeProgram(opcode.XDROP)
	vm := load(prog)
	vm.estack.PushVal(0)
	vm.estack.PushVal(1)
	vm.estack.PushVal(2)
	vm.estack.PushVal(2)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, int64(2), vm.estack.Peek(0).BigInt().Int64())
	assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
}

func TestCLEAR(t *testing.T) {
	prog := makeProgram(opcode.CLEAR)
	v := load(prog)
	v.estack.PushVal(123)
	require.Equal(t, 1, v.estack.Len())
	require.NoError(t, v.Run())
	require.Equal(t, 0, v.estack.Len())
}

func TestINVERTbadNoitem(t *testing.T) {
	prog := makeProgram(opcode.INVERT)
	runWithArgs(t, prog, nil)
}

func TestINVERTgood1(t *testing.T) {
	prog := makeProgram(opcode.INVERT)
	runWithArgs(t, prog, -1, 0)
}

func TestINVERTgood2(t *testing.T) {
	prog := makeProgram(opcode.INVERT)
	vm := load(prog)
	vm.estack.PushVal(-1)
	runVM(t, vm)
	assert.Equal(t, int64(0), vm.estack.Peek(0).BigInt().Int64())
}

func TestINVERTgood3(t *testing.T) {
	prog := makeProgram(opcode.INVERT)
	vm := load(prog)
	vm.estack.PushVal(0x69)
	runVM(t, vm)
	assert.Equal(t, int64(-0x6A), vm.estack.Peek(0).BigInt().Int64())
}

func TestINVERTWithConversion1(t *testing.T) {
	prog := makeProgram(opcode.PUSHDATA2, 0, 0, opcode.INVERT)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, int64(-1), vm.estack.Peek(0).BigInt().Int64())
}

func TestINVERTWithConversion2(t *testing.T) {
	prog := makeProgram(opcode.PUSH0, opcode.PUSH1, opcode.NUMEQUAL, opcode.INVERT)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, int64(-1), vm.estack.Peek(0).BigInt().Int64())
}

func TestCAT(t *testing.T) {
	prog := makeProgram(opcode.CAT)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("OneArgument", getTestFuncForVM(prog, nil, []byte("abc")))
	t.Run("BigItem", func(t *testing.T) {
		arg := make([]byte, stackitem.MaxSize/2+1)
		runWithArgs(t, prog, nil, arg, arg)
	})
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte("abcdef")), []byte("abc"), []byte("def")))
	t.Run("Int0ByteArray", getTestFuncForVM(prog, stackitem.NewBuffer([]byte{}), 0, []byte{}))
	t.Run("ByteArrayInt1", getTestFuncForVM(prog, stackitem.NewBuffer([]byte{1}), []byte{}, 1))
}

func TestSUBSTR(t *testing.T) {
	prog := makeProgram(opcode.SUBSTR)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("OneArgument", getTestFuncForVM(prog, nil, 1))
	t.Run("TwoArguments", getTestFuncForVM(prog, nil, 0, 2))
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte("bc")), []byte("abcdef"), 1, 2))
	t.Run("BadOffset", getTestFuncForVM(prog, nil, []byte("abcdef"), 7, 1))
	t.Run("very big offset", getTestFuncForVM(prog, nil, []byte("abcdef"), maxu64Plus(1), 1))
	t.Run("BigLen", getTestFuncForVM(prog, nil, []byte("abcdef"), 1, 6))
	t.Run("very big len", getTestFuncForVM(prog, nil, []byte("abcdef"), 1, maxu64Plus(1)))
	t.Run("NegativeOffset", getTestFuncForVM(prog, nil, []byte("abcdef"), -1, 3))
	t.Run("NegativeLen", getTestFuncForVM(prog, nil, []byte("abcdef"), 3, -1))
}

func TestSUBSTRBad387(t *testing.T) {
	prog := makeProgram(opcode.SUBSTR)
	vm := load(prog)
	b := make([]byte, 6, 20)
	copy(b, "abcdef")
	vm.estack.PushVal(b)
	vm.estack.PushVal(1)
	vm.estack.PushVal(6)
	checkVMFailed(t, vm)
}

func TestLEFT(t *testing.T) {
	prog := makeProgram(opcode.LEFT)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("NoString", getTestFuncForVM(prog, nil, 2))
	t.Run("NegativeLen", getTestFuncForVM(prog, nil, "abcdef", -1))
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte("ab")), "abcdef", 2))
	t.Run("BadBigLen", getTestFuncForVM(prog, nil, "abcdef", 8))
	t.Run("bad, very big len", getTestFuncForVM(prog, nil, "abcdef", maxu64Plus(2)))
}

func TestRIGHT(t *testing.T) {
	prog := makeProgram(opcode.RIGHT)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("NoString", getTestFuncForVM(prog, nil, 2))
	t.Run("NegativeLen", getTestFuncForVM(prog, nil, "abcdef", -1))
	t.Run("Good", getTestFuncForVM(prog, stackitem.NewBuffer([]byte("ef")), "abcdef", 2))
	t.Run("BadLen", getTestFuncForVM(prog, nil, "abcdef", 8))
	t.Run("bad, very big len", getTestFuncForVM(prog, nil, "abcdef", maxu64Plus(2)))
}

func TestPACK(t *testing.T) {
	for _, op := range []opcode.Opcode{opcode.PACK, opcode.PACKSTRUCT} {
		t.Run(op.String(), func(t *testing.T) {
			prog := makeProgram(op)
			t.Run("BadLen", getTestFuncForVM(prog, nil, 1))
			t.Run("BigLen", getTestFuncForVM(prog, nil, 100500))
			t.Run("Good0Len", getTestFuncForVM(prog, []stackitem.Item{}, 0))
		})
	}
}

func TestPACKGood(t *testing.T) {
	for _, op := range []opcode.Opcode{opcode.PACK, opcode.PACKSTRUCT} {
		t.Run(op.String(), func(t *testing.T) {
			prog := makeProgram(op)
			elements := []int{55, 34, 42}
			vm := load(prog)
			// canary
			vm.estack.PushVal(1)
			for i := len(elements) - 1; i >= 0; i-- {
				vm.estack.PushVal(elements[i])
			}
			vm.estack.PushVal(len(elements))
			runVM(t, vm)
			assert.Equal(t, 2, vm.estack.Len())
			a := vm.estack.Peek(0).Array()
			assert.Equal(t, len(elements), len(a))
			for i := 0; i < len(elements); i++ {
				e := a[i].Value().(*big.Int)
				assert.Equal(t, int64(elements[i]), e.Int64())
			}
			assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
		})
	}
}

func TestPACK_UNPACK_MaxSize(t *testing.T) {
	prog := makeProgram(opcode.PACK, opcode.UNPACK)
	elements := make([]int, MaxStackSize-2)
	vm := load(prog)
	// canary
	vm.estack.PushVal(1)
	for i := len(elements) - 1; i >= 0; i-- {
		vm.estack.PushVal(elements[i])
	}
	vm.estack.PushVal(len(elements))
	runVM(t, vm)
	// check reference counter = 1+1+1024
	assert.Equal(t, 1+1+len(elements), int(vm.refs))
	assert.Equal(t, 1+1+len(elements), vm.estack.Len()) // canary + length + elements
	assert.Equal(t, int64(len(elements)), vm.estack.Peek(0).Value().(*big.Int).Int64())
	for i := 0; i < len(elements); i++ {
		e, ok := vm.estack.Peek(i + 1).Value().(*big.Int)
		assert.True(t, ok)
		assert.Equal(t, int64(elements[i]), e.Int64())
	}
	assert.Equal(t, int64(1), vm.estack.Peek(1+len(elements)).BigInt().Int64())
}

func TestPACK_UNPACK_PACK_MaxSize(t *testing.T) {
	prog := makeProgram(opcode.PACK, opcode.UNPACK, opcode.PACK)
	elements := make([]int, MaxStackSize-2)
	vm := load(prog)
	// canary
	vm.estack.PushVal(1)
	for i := len(elements) - 1; i >= 0; i-- {
		vm.estack.PushVal(elements[i])
	}
	vm.estack.PushVal(len(elements))
	runVM(t, vm)
	// check reference counter = 1+1+1024
	assert.Equal(t, 1+1+len(elements), int(vm.refs))
	assert.Equal(t, 2, vm.estack.Len())
	a := vm.estack.Peek(0).Array()
	assert.Equal(t, len(elements), len(a))
	for i := 0; i < len(elements); i++ {
		e := a[i].Value().(*big.Int)
		assert.Equal(t, int64(elements[i]), e.Int64())
	}
	assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
}

func TestPACKMAP_UNPACK_PACKMAP_MaxSize(t *testing.T) {
	prog := makeProgram(opcode.PACKMAP, opcode.UNPACK, opcode.PACKMAP)
	elements := make([]int, (MaxStackSize-2)/2)
	vm := load(prog)
	// canary
	vm.estack.PushVal(-1)
	for i := len(elements) - 1; i >= 0; i-- {
		elements[i] = i
		vm.estack.PushVal(i * 2)
		vm.estack.PushVal(i)
	}
	vm.estack.PushVal(len(elements))
	runVM(t, vm)
	// check reference counter = 1+1+1024*2
	assert.Equal(t, 1+1+len(elements)*2, int(vm.refs))
	assert.Equal(t, 2, vm.estack.Len())
	m := vm.estack.Peek(0).value.(*stackitem.Map).Value().([]stackitem.MapElement)
	assert.Equal(t, len(elements), len(m))
	for i := 0; i < len(elements); i++ {
		k := m[i].Key.Value().(*big.Int)
		v := m[i].Value.Value().(*big.Int)
		assert.Equal(t, int64(elements[i]), k.Int64())
		assert.Equal(t, int64(elements[i])*2, v.Int64())
	}
	assert.Equal(t, int64(-1), vm.estack.Peek(1).BigInt().Int64())
}

func TestPACKMAPBadKey(t *testing.T) {
	prog := makeProgram(opcode.PACKMAP)
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushItem(stackitem.NewBuffer([]byte{1}))
	vm.estack.PushVal(1)
	checkVMFailed(t, vm)
}

func TestUNPACKBadNotArray(t *testing.T) {
	prog := makeProgram(opcode.UNPACK)
	runWithArgs(t, prog, nil, 1)
}

func TestUNPACKGood(t *testing.T) {
	prog := makeProgram(opcode.UNPACK)
	elements := []int{55, 34, 42}
	vm := load(prog)
	// canary
	vm.estack.PushVal(1)
	vm.estack.PushVal(elements)
	runVM(t, vm)
	assert.Equal(t, 5, vm.estack.Len())
	assert.Equal(t, int64(len(elements)), vm.estack.Peek(0).BigInt().Int64())
	for k, v := range elements {
		assert.Equal(t, int64(v), vm.estack.Peek(k+1).BigInt().Int64())
	}
	assert.Equal(t, int64(1), vm.estack.Peek(len(elements)+1).BigInt().Int64())
}

func TestREVERSEITEMS(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.REVERSEITEMS)
	t.Run("InvalidItem", getTestFuncForVM(prog, nil, 1))
	t.Run("Buffer", getTestFuncForVM(prog, stackitem.NewBuffer([]byte{3, 2, 1}), stackitem.NewBuffer([]byte{1, 2, 3})))
}

func testREVERSEITEMSIssue437(t *testing.T, i1 opcode.Opcode, t2 stackitem.Type, reversed bool) {
	prog := makeProgram(
		opcode.PUSH0, i1,
		opcode.DUP, opcode.PUSH1, opcode.APPEND,
		opcode.DUP, opcode.PUSH2, opcode.APPEND,
		opcode.DUP, opcode.CONVERT, opcode.Opcode(t2), opcode.REVERSEITEMS)

	arr := make([]stackitem.Item, 2)
	if reversed {
		arr[0] = stackitem.Make(2)
		arr[1] = stackitem.Make(1)
	} else {
		arr[0] = stackitem.Make(1)
		arr[1] = stackitem.Make(2)
	}

	if i1 == opcode.NEWARRAY {
		runWithArgs(t, prog, stackitem.NewArray(arr))
	} else {
		runWithArgs(t, prog, stackitem.NewStruct(arr))
	}
}

func TestREVERSEITEMSIssue437(t *testing.T) {
	t.Run("Array+Array", func(t *testing.T) { testREVERSEITEMSIssue437(t, opcode.NEWARRAY, stackitem.ArrayT, true) })
	t.Run("Struct+Struct", func(t *testing.T) { testREVERSEITEMSIssue437(t, opcode.NEWSTRUCT, stackitem.StructT, true) })
	t.Run("Array+Struct", func(t *testing.T) { testREVERSEITEMSIssue437(t, opcode.NEWARRAY, stackitem.StructT, false) })
	t.Run("Struct+Array", func(t *testing.T) { testREVERSEITEMSIssue437(t, opcode.NEWSTRUCT, stackitem.ArrayT, false) })
}

func TestREVERSEITEMSGoodOneElem(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.REVERSEITEMS)
	elements := []int{22}
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushVal(elements)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	a := vm.estack.Peek(0).Array()
	assert.Equal(t, len(elements), len(a))
	e := a[0].Value().(*big.Int)
	assert.Equal(t, int64(elements[0]), e.Int64())
}

func TestREVERSEITEMSGoodStruct(t *testing.T) {
	eodd := []int{22, 34, 42, 55, 81}
	even := []int{22, 34, 42, 55, 81, 99}
	eall := [][]int{eodd, even}

	for _, elements := range eall {
		prog := makeProgram(opcode.DUP, opcode.REVERSEITEMS)
		vm := load(prog)
		vm.estack.PushVal(1)

		arr := make([]stackitem.Item, len(elements))
		for i := range elements {
			arr[i] = stackitem.Make(elements[i])
		}
		vm.estack.Push(Element{value: stackitem.NewStruct(arr)})

		runVM(t, vm)
		assert.Equal(t, 2, vm.estack.Len())
		a := vm.estack.Peek(0).Array()
		assert.Equal(t, len(elements), len(a))
		for k, v := range elements {
			e := a[len(a)-1-k].Value().(*big.Int)
			assert.Equal(t, int64(v), e.Int64())
		}
		assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
	}
}

func TestREVERSEITEMSGood(t *testing.T) {
	eodd := []int{22, 34, 42, 55, 81}
	even := []int{22, 34, 42, 55, 81, 99}
	eall := [][]int{eodd, even}

	for _, elements := range eall {
		prog := makeProgram(opcode.DUP, opcode.REVERSEITEMS)
		vm := load(prog)
		vm.estack.PushVal(1)
		vm.estack.PushVal(elements)
		runVM(t, vm)
		assert.Equal(t, 2, vm.estack.Len())
		a := vm.estack.Peek(0).Array()
		assert.Equal(t, len(elements), len(a))
		for k, v := range elements {
			e := a[len(a)-1-k].Value().(*big.Int)
			assert.Equal(t, int64(v), e.Int64())
		}
		assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
	}
}

func TestREMOVE(t *testing.T) {
	prog := makeProgram(opcode.REMOVE)
	t.Run("NoArgument", getTestFuncForVM(prog, nil))
	t.Run("OneArgument", getTestFuncForVM(prog, nil, 1))
	t.Run("NotArray", getTestFuncForVM(prog, nil, 1, 1))
	t.Run("BadIndex", getTestFuncForVM(prog, nil, []int{22, 34, 42, 55, 81}, 10))
	t.Run("very big index", getTestFuncForVM(prog, nil, []int{22, 34, 42, 55, 81}, maxu64Plus(1)))
}

func TestREMOVEGood(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.PUSH2, opcode.REMOVE)
	elements := []int{22, 34, 42, 55, 81}
	reselements := []int{22, 34, 55, 81}
	vm := load(prog)
	vm.estack.PushVal(1)
	vm.estack.PushVal(elements)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, stackitem.Make(reselements), vm.estack.Pop().value)
	assert.Equal(t, stackitem.Make(1), vm.estack.Pop().value)
}

func TestREMOVEMap(t *testing.T) {
	prog := makeProgram(opcode.REMOVE, opcode.PUSH5, opcode.HASKEY)
	vm := load(prog)

	m := stackitem.NewMap()
	m.Add(stackitem.Make(5), stackitem.Make(3))
	m.Add(stackitem.Make([]byte{0, 1}), stackitem.Make([]byte{2, 3}))
	vm.estack.Push(Element{value: m})
	vm.estack.Push(Element{value: m})
	vm.estack.PushVal(stackitem.Make(5))

	runVM(t, vm)
	assert.Equal(t, 1, vm.estack.Len())
	assert.Equal(t, stackitem.Make(false), vm.estack.Pop().value)
}

func testCLEARITEMS(t *testing.T, item stackitem.Item) {
	prog := makeProgram(opcode.DUP, opcode.DUP, opcode.CLEARITEMS, opcode.SIZE)
	v := load(prog)
	v.estack.PushVal(item)
	runVM(t, v)
	require.Equal(t, 2, v.estack.Len())
	require.EqualValues(t, 2, int(v.refs)) // empty collection + it's size
	require.EqualValues(t, 0, v.estack.Pop().BigInt().Int64())
}

func TestCLEARITEMS(t *testing.T) {
	arr := []stackitem.Item{stackitem.NewBigInteger(big.NewInt(1)), stackitem.NewByteArray([]byte{1})}
	m := stackitem.NewMap()
	m.Add(stackitem.NewBigInteger(big.NewInt(1)), stackitem.NewByteArray([]byte{}))
	m.Add(stackitem.NewByteArray([]byte{42}), stackitem.NewBigInteger(big.NewInt(2)))

	testCases := map[string]stackitem.Item{
		"empty Array":   stackitem.NewArray([]stackitem.Item{}),
		"filled Array":  stackitem.NewArray(arr),
		"empty Struct":  stackitem.NewStruct([]stackitem.Item{}),
		"filled Struct": stackitem.NewStruct(arr),
		"empty Map":     stackitem.NewMap(),
		"filled Map":    m,
	}

	for name, item := range testCases {
		t.Run(name, func(t *testing.T) { testCLEARITEMS(t, item) })
	}

	t.Run("Integer", func(t *testing.T) {
		prog := makeProgram(opcode.CLEARITEMS)
		runWithArgs(t, prog, nil, 1)
	})
}

func TestPOPITEM(t *testing.T) {
	testPOPITEM := func(t *testing.T, item, elem, arr interface{}) {
		prog := makeProgram(opcode.DUP, opcode.POPITEM)
		v := load(prog)
		v.estack.PushVal(item)

		runVM(t, v)
		require.EqualValues(t, stackitem.Make(elem), v.estack.Pop().Item())
		require.EqualValues(t, stackitem.Make(arr), v.estack.Pop().Item())
	}

	elems := []stackitem.Item{stackitem.Make(11), stackitem.Make(31)}
	t.Run("Array", func(t *testing.T) {
		testPOPITEM(t, stackitem.NewArray(elems), 31, elems[:1])
	})
	t.Run("Struct", func(t *testing.T) {
		testPOPITEM(t, stackitem.NewStruct(elems), 31, elems[:1])
	})
	t.Run("0-length array", func(t *testing.T) {
		prog := makeProgram(opcode.NEWARRAY0, opcode.POPITEM)
		v := load(prog)
		checkVMFailed(t, v)
	})
	t.Run("primitive type", func(t *testing.T) {
		prog := makeProgram(opcode.PUSH4, opcode.POPITEM)
		v := load(prog)
		checkVMFailed(t, v)
	})
}

func TestSWAPGood(t *testing.T) {
	prog := makeProgram(opcode.SWAP)
	vm := load(prog)
	vm.estack.PushVal(2)
	vm.estack.PushVal(4)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, int64(2), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(4), vm.estack.Pop().BigInt().Int64())
}

func TestSWAP(t *testing.T) {
	prog := makeProgram(opcode.SWAP)
	t.Run("EmptyStack", getTestFuncForVM(prog, nil))
	t.Run("SmallStack", getTestFuncForVM(prog, nil, 4))
}

func TestDupInt(t *testing.T) {
	prog := makeProgram(opcode.DUP, opcode.ABS)
	vm := load(prog)
	vm.estack.PushVal(-1)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, int64(1), vm.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(-1), vm.estack.Pop().BigInt().Int64())
}

func TestNegateCopy(t *testing.T) {
	prog := makeProgram(opcode.NEGATE)
	v := load(prog)
	bi := stackitem.Make(-1)
	v.estack.PushVal(bi)
	v.estack.PushVal(bi)
	runVM(t, v)
	assert.Equal(t, 2, v.estack.Len())
	assert.Equal(t, int64(1), v.estack.Pop().BigInt().Int64())
	assert.Equal(t, int64(-1), v.estack.Pop().BigInt().Int64())
}

func TestDupByteArray(t *testing.T) {
	prog := makeProgram(opcode.PUSHDATA1, 2, 1, 0,
		opcode.DUP,
		opcode.PUSH1,
		opcode.LEFT,
		opcode.PUSHDATA1, 1, 2,
		opcode.CAT)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, []byte{0x01, 0x02}, vm.estack.Pop().Bytes())
	assert.Equal(t, []byte{0x01, 0x00}, vm.estack.Pop().Bytes())
}

func TestDupBool(t *testing.T) {
	prog := makeProgram(opcode.PUSH0, opcode.NOT,
		opcode.DUP,
		opcode.PUSH1, opcode.NOT,
		opcode.BOOLAND)
	vm := load(prog)
	runVM(t, vm)
	assert.Equal(t, 2, vm.estack.Len())
	assert.Equal(t, false, vm.estack.Pop().Bool())
	assert.Equal(t, true, vm.estack.Pop().Bool())
}

var opcodesTestCases = map[opcode.Opcode][]struct {
	name     string
	args     []interface{}
	expected interface{}
	actual   func(vm *VM) interface{}
}{
	opcode.AND: {
		{
			name:     "1_1",
			args:     []interface{}{1, 1},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "1_0",
			args:     []interface{}{1, 0},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_1",
			args:     []interface{}{0, 1},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_0",
			args:     []interface{}{0, 0},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name: "random_values",
			args: []interface{}{
				[]byte{1, 0, 1, 0, 1, 0, 1, 1},
				[]byte{1, 1, 0, 0, 0, 0, 0, 1},
			},
			expected: []byte{1, 0, 0, 0, 0, 0, 0, 1},
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bytes()
			},
		},
	},
	opcode.OR: {
		{
			name:     "1_1",
			args:     []interface{}{1, 1},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_0",
			args:     []interface{}{0, 0},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_1",
			args:     []interface{}{0, 1},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "1_0",
			args:     []interface{}{1, 0},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name: "random_values",
			args: []interface{}{
				[]byte{1, 0, 1, 0, 1, 0, 1, 1},
				[]byte{1, 1, 0, 0, 0, 0, 0, 1},
			},
			expected: []byte{1, 1, 1, 0, 1, 0, 1, 1},
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bytes()
			},
		},
	},
	opcode.XOR: {
		{
			name:     "1_1",
			args:     []interface{}{1, 1},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_0",
			args:     []interface{}{0, 0},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0_1",
			args:     []interface{}{0, 1},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "1_0",
			args:     []interface{}{1, 0},
			expected: int64(1),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name: "random_values",
			args: []interface{}{
				[]byte{1, 0, 1, 0, 1, 0, 1, 1},
				[]byte{1, 1, 0, 0, 0, 0, 0, 1},
			},
			expected: []byte{0, 1, 1, 0, 1, 0, 1},
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bytes()
			},
		},
	},
	opcode.BOOLOR: {
		{
			name:     "1_1",
			args:     []interface{}{true, true},
			expected: true,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
		{
			name:     "0_0",
			args:     []interface{}{false, false},
			expected: false,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
		{
			name:     "0_1",
			args:     []interface{}{false, true},
			expected: true,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
		{
			name:     "1_0",
			args:     []interface{}{true, false},
			expected: true,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
	},
	opcode.MIN: {
		{
			name:     "3_5",
			args:     []interface{}{3, 5},
			expected: int64(3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "5_3",
			args:     []interface{}{5, 3},
			expected: int64(3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "3_3",
			args:     []interface{}{3, 3},
			expected: int64(3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
	},
	opcode.MAX: {
		{
			name:     "3_5",
			args:     []interface{}{3, 5},
			expected: int64(5),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "5_3",
			args:     []interface{}{5, 3},
			expected: int64(5),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "3_3",
			args:     []interface{}{3, 3},
			expected: int64(3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
	},
	opcode.WITHIN: {
		{
			name:     "within",
			args:     []interface{}{4, 3, 5},
			expected: true,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
		{
			name:     "less",
			args:     []interface{}{2, 3, 5},
			expected: false,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
		{
			name:     "more",
			args:     []interface{}{6, 3, 5},
			expected: false,
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().Bool()
			},
		},
	},
	opcode.NEGATE: {
		{
			name:     "3",
			args:     []interface{}{3},
			expected: int64(-3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "-3",
			args:     []interface{}{-3},
			expected: int64(3),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
		{
			name:     "0",
			args:     []interface{}{0},
			expected: int64(0),
			actual: func(vm *VM) interface{} {
				return vm.estack.Pop().BigInt().Int64()
			},
		},
	},
}

func TestBitAndNumericOpcodes(t *testing.T) {
	for code, opcodeTestCases := range opcodesTestCases {
		t.Run(code.String(), func(t *testing.T) {
			for _, testCase := range opcodeTestCases {
				prog := makeProgram(code)
				vm := load(prog)
				t.Run(testCase.name, func(t *testing.T) {
					for _, arg := range testCase.args {
						vm.estack.PushVal(arg)
					}
					runVM(t, vm)
					assert.Equal(t, testCase.expected, testCase.actual(vm))
				})
			}
		})
	}
}

func TestSLOTOpcodes(t *testing.T) {
	t.Run("Fail", func(t *testing.T) {
		t.Run("EmptyStatic", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 0), nil))
		t.Run("EmptyLocal", getTestFuncForVM(makeProgram(opcode.INITSLOT, 0, 0), nil))
		t.Run("NotEnoughArguments", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 0, 2), nil, 1))
		t.Run("DoubleStatic", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 1, opcode.INITSSLOT, 1), nil))
		t.Run("DoubleLocal", getTestFuncForVM(makeProgram(opcode.INITSLOT, 1, 0, opcode.INITSLOT, 1, 0), nil))
		t.Run("DoubleArgument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 0, 1, opcode.INITSLOT, 0, 1), nil, 1, 2))
		t.Run("LoadBigStatic", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 2, opcode.LDSFLD2), nil))
		t.Run("LoadBigLocal", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 2, opcode.LDLOC2), nil, 1, 2))
		t.Run("LoadBigArgument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 2, opcode.LDARG2), nil, 1, 2))
		t.Run("StoreBigStatic", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 2, opcode.STSFLD2), nil, 0))
		t.Run("StoreBigLocal", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 2, opcode.STLOC2), nil, 0, 1, 2))
		t.Run("StoreBigArgument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 2, opcode.STARG2), nil, 0, 1, 2))
	})

	t.Run("Default", func(t *testing.T) {
		t.Run("DefaultStatic", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 2, opcode.LDSFLD1), stackitem.Null{}))
		t.Run("DefaultLocal", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 0, opcode.LDLOC1), stackitem.Null{}))
		t.Run("DefaultArgument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 0, 2, opcode.LDARG1), 2, 2, 1))
	})

	t.Run("Set/Get", func(t *testing.T) {
		t.Run("FailCrossLoads", func(t *testing.T) {
			t.Run("Static/Local", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 2, opcode.LDLOC1), nil))
			t.Run("Static/Argument", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 2, opcode.LDARG1), nil))
			t.Run("Local/Argument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 0, 2, opcode.LDLOC1), nil))
			t.Run("Argument/Local", getTestFuncForVM(makeProgram(opcode.INITSLOT, 2, 0, opcode.LDARG1), nil))
		})

		t.Run("Static", getTestFuncForVM(makeProgram(opcode.INITSSLOT, 8, opcode.STSFLD, 7, opcode.LDSFLD, 7), 42, 42))
		t.Run("Local", getTestFuncForVM(makeProgram(opcode.INITSLOT, 8, 0, opcode.STLOC, 7, opcode.LDLOC, 7), 42, 42))
		t.Run("Argument", getTestFuncForVM(makeProgram(opcode.INITSLOT, 0, 2, opcode.STARG, 1, opcode.LDARG, 1), 42, 42, 1, 2))
	})

	t.Run("InitStaticSlotInMethod", func(t *testing.T) {
		prog := makeProgram(
			opcode.CALL, 4, opcode.LDSFLD0, opcode.RET,
			opcode.INITSSLOT, 1, opcode.PUSH12, opcode.STSFLD0, opcode.RET,
		)
		runWithArgs(t, prog, 12)
	})
}

func TestNestedStructClone(t *testing.T) {
	progs := []string{
		// VALUES for deeply nested structs, see neo-project/neo#2534.
		"5601c501fe0360589d604a12c0db415824f7cd45",
		// APPEND of deeply nested struct to empty array.
		"5601c2c501fe0360589d604a12c0db415824f7cf45",
		// VALUES for map with deeply nested struct.
		"5601c84a11c501fe0060589d604a12c0db415824f7d0cd45",
		// VALUES for a lot of not-so-deep nested structs.
		"5601c5000a60589d604a12c0db415824f701fe03504a519d4a102afa01ff03c0cd45",
	}
	for _, h := range progs {
		prog, err := hex.DecodeString(h)
		require.NoError(t, err)
		vm := load(prog)
		checkVMFailed(t, vm)
	}
}

func TestNestedStructEquals(t *testing.T) {
	h := "560112c501fe0160589d604a12c0db415824f7509d4a102aec4597" // See neo-project/neo-vm#426.
	prog, err := hex.DecodeString(h)
	require.NoError(t, err)
	vm := load(prog)
	checkVMFailed(t, vm)
}

func TestRemoveReferrer(t *testing.T) {
	h := "560110c34a10c36058cf4540" // #2501
	prog, err := hex.DecodeString(h)
	require.NoError(t, err)
	vm := load(prog)
	require.NoError(t, vm.StepInto()) // INITSSLOT
	assert.Equal(t, 1, int(vm.refs))
	require.NoError(t, vm.StepInto()) // PUSH0
	assert.Equal(t, 2, int(vm.refs))
	require.NoError(t, vm.StepInto()) // NEWARRAY
	assert.Equal(t, 2, int(vm.refs))
	require.NoError(t, vm.StepInto()) // DUP
	assert.Equal(t, 3, int(vm.refs))
	require.NoError(t, vm.StepInto()) // PUSH0
	assert.Equal(t, 4, int(vm.refs))
	require.NoError(t, vm.StepInto()) // NEWARRAY
	assert.Equal(t, 4, int(vm.refs))
	require.NoError(t, vm.StepInto()) // STSFLD0
	assert.Equal(t, 3, int(vm.refs))
	require.NoError(t, vm.StepInto()) // LDSFLD0
	assert.Equal(t, 4, int(vm.refs))
	require.NoError(t, vm.StepInto()) // APPEND
	assert.Equal(t, 3, int(vm.refs))
	require.NoError(t, vm.StepInto()) // DROP
	assert.Equal(t, 1, int(vm.refs))
	require.NoError(t, vm.StepInto()) // RET
	assert.Equal(t, 0, int(vm.refs))
}

func makeProgram(opcodes ...opcode.Opcode) []byte {
	prog := make([]byte, len(opcodes)+1) // RET
	for i := 0; i < len(opcodes); i++ {
		prog[i] = byte(opcodes[i])
	}
	prog[len(prog)-1] = byte(opcode.RET)
	return prog
}

func load(prog []byte) *VM {
	vm := newTestVM()
	if len(prog) != 0 {
		vm.LoadScript(prog)
	}
	return vm
}

func randomBytes(n int) []byte {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	b := make([]byte, n)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return b
}

func newTestVM() *VM {
	v := New()
	v.GasLimit = -1
	return v
}