package core

import (
	"math/big"
	"testing"

	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
	"github.com/nspcc-dev/neo-go/pkg/core/dao"
	"github.com/nspcc-dev/neo-go/pkg/core/interop"
	"github.com/nspcc-dev/neo-go/pkg/core/native"
	"github.com/nspcc-dev/neo-go/pkg/core/state"
	"github.com/nspcc-dev/neo-go/pkg/core/storage"
	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/io"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/vm"
	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
	"github.com/stretchr/testify/require"
)

type testNative struct {
	meta   interop.ContractMD
	blocks chan uint32
}

func (tn *testNative) Initialize(_ *interop.Context) error {
	return nil
}

func (tn *testNative) Metadata() *interop.ContractMD {
	return &tn.meta
}

func (tn *testNative) OnPersist(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
	if ic.Trigger != trigger.System {
		panic("invalid trigger")
	}
	select {
	case tn.blocks <- ic.Block.Index:
		return stackitem.NewBool(true)
	default:
		return stackitem.NewBool(false)
	}
}

var _ interop.Contract = (*testNative)(nil)

// registerNative registers native contract in the blockchain.
func (bc *Blockchain) registerNative(c interop.Contract) {
	bc.contracts.Contracts = append(bc.contracts.Contracts, c)
}

const testSumPrice = 1000000

func newTestNative() *testNative {
	tn := &testNative{
		meta:   *interop.NewContractMD("Test.Native.Sum"),
		blocks: make(chan uint32, 1),
	}
	desc := &manifest.Method{
		Name: "sum",
		Parameters: []manifest.Parameter{
			manifest.NewParameter("addend1", smartcontract.IntegerType),
			manifest.NewParameter("addend2", smartcontract.IntegerType),
		},
		ReturnType: smartcontract.IntegerType,
	}
	md := &interop.MethodAndPrice{
		Func:          tn.sum,
		Price:         testSumPrice,
		RequiredFlags: smartcontract.NoneFlag,
	}
	tn.meta.AddMethod(md, desc, true)

	desc = &manifest.Method{Name: "onPersist", ReturnType: smartcontract.BoolType}
	md = &interop.MethodAndPrice{Func: tn.OnPersist, RequiredFlags: smartcontract.AllowModifyStates}
	tn.meta.AddMethod(md, desc, false)

	return tn
}

func (tn *testNative) sum(_ *interop.Context, args []stackitem.Item) stackitem.Item {
	s1, err := args[0].TryInteger()
	if err != nil {
		panic(err)
	}
	s2, err := args[1].TryInteger()
	if err != nil {
		panic(err)
	}
	return stackitem.NewBigInteger(s1.Add(s1, s2))
}

func TestNativeContract_Invoke(t *testing.T) {
	chain := newTestChain(t)
	defer chain.Close()

	tn := newTestNative()
	chain.registerNative(tn)

	err := chain.dao.PutContractState(&state.Contract{
		Script:   tn.meta.Script,
		Manifest: tn.meta.Manifest,
	})
	require.NoError(t, err)

	w := io.NewBufBinWriter()
	emit.AppCallWithOperationAndArgs(w.BinWriter, tn.Metadata().Hash, "sum", int64(14), int64(28))
	script := w.Bytes()
	// System.Contract.Call + "sum" itself + opcodes for pushing arguments (PACK is 7000)
	tx := transaction.New(chain.GetConfig().Magic, script, testSumPrice*2+10000)
	validUntil := chain.blockHeight + 1
	tx.ValidUntilBlock = validUntil
	require.NoError(t, addSender(tx))
	require.NoError(t, signTx(chain, tx))

	// Enough for Call and other opcodes, but not enough for "sum" call.
	tx2 := transaction.New(chain.GetConfig().Magic, script, testSumPrice*2)
	tx2.ValidUntilBlock = chain.blockHeight + 1
	require.NoError(t, addSender(tx2))
	require.NoError(t, signTx(chain, tx2))

	b := chain.newBlock(tx, tx2)
	require.NoError(t, chain.AddBlock(b))

	res, err := chain.GetAppExecResult(tx.Hash())
	require.NoError(t, err)
	require.Equal(t, vm.HaltState, res.VMState)
	require.Equal(t, 1, len(res.Stack))
	require.Equal(t, big.NewInt(42), res.Stack[0].Value())

	res, err = chain.GetAppExecResult(tx2.Hash())
	require.NoError(t, err)
	require.Equal(t, vm.FaultState, res.VMState)

	require.NoError(t, chain.persist())
	select {
	case index := <-tn.blocks:
		require.Equal(t, chain.blockHeight, index)
	default:
		require.Fail(t, "onPersist wasn't called")
	}
}

func TestNativeContract_InvokeInternal(t *testing.T) {
	chain := newTestChain(t)
	defer chain.Close()

	tn := newTestNative()
	chain.registerNative(tn)

	err := chain.dao.PutContractState(&state.Contract{
		Script:   tn.meta.Script,
		Manifest: tn.meta.Manifest,
	})
	require.NoError(t, err)

	v := vm.New()
	v.GasLimit = -1
	ic := chain.newInteropContext(trigger.Application,
		dao.NewSimple(storage.NewMemoryStore(), netmode.UnitTestNet), nil, nil)

	t.Run("fail, bad current script hash", func(t *testing.T) {
		v.LoadScriptWithHash([]byte{1}, util.Uint160{1, 2, 3}, smartcontract.All)
		v.Estack().PushVal(stackitem.NewArray([]stackitem.Item{stackitem.NewBigInteger(big.NewInt(14)), stackitem.NewBigInteger(big.NewInt(28))}))
		v.Estack().PushVal("sum")
		v.Estack().PushVal(tn.Metadata().Name)

		// it's prohibited to call natives directly
		require.Error(t, native.Call(ic, v))
	})

	t.Run("success", func(t *testing.T) {
		v.LoadScriptWithHash([]byte{1}, tn.Metadata().Hash, smartcontract.All)
		v.Estack().PushVal(stackitem.NewArray([]stackitem.Item{stackitem.NewBigInteger(big.NewInt(14)), stackitem.NewBigInteger(big.NewInt(28))}))
		v.Estack().PushVal("sum")
		v.Estack().PushVal(tn.Metadata().Name)

		require.NoError(t, native.Call(ic, v))

		value := v.Estack().Pop().BigInt()
		require.Equal(t, int64(42), value.Int64())
	})
}