package contract

import (
	"errors"
	"math/rand"
	"path"
	"testing"

	"git.frostfs.info/TrueCloudLab/contract-coverage-primer/covertest"
	"github.com/davecgh/go-spew/spew"
	"github.com/nspcc-dev/neo-go/pkg/compiler"
	"github.com/nspcc-dev/neo-go/pkg/neotest"
	"github.com/nspcc-dev/neo-go/pkg/neotest/chain"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
	"github.com/nspcc-dev/neo-go/pkg/vm"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
	"github.com/stretchr/testify/require"
)

const ctrPath = "../impulse"

// keys for tests
var (
	validKey   = []byte{1, 2, 3, 4, 5}
	invalidKey = []byte{1, 2, 3}
)

func newExecutor(t *testing.T) *neotest.Executor {
	bc, acc := chain.NewSingle(t)
	return neotest.NewExecutor(t, bc, acc, acc)
}

func TestContract(t *testing.T) {
	e := newExecutor(t)
	ctrDI := covertest.CompileFile(t, e.CommitteeHash, ctrPath, path.Join(ctrPath, "config.yml"))
	ctr := ctrDI.Contract
	e.DeployContract(t, ctr, nil)
	inv := e.CommitteeInvoker(ctr.Hash)

	// test get without put
	inv.InvokeFail(t, "Cannot get number", "getNumber", validKey)

	// test put-get with valid key
	inv.Invoke(t, stackitem.Null{}, "putNumber", validKey, 42)
	inv.Invoke(t, 42, "getNumber", validKey)

	// test invalid key
	inv.InvokeFail(t, "Invalid key size", "putNumber", invalidKey, 42)
	inv.InvokeFail(t, "Invalid key size", "getNumber", invalidKey)
}

func TestRun(t *testing.T) {
	e := newExecutor(t)
	ctrDI := covertest.CompileFile(t, e.CommitteeHash, ctrPath, path.Join(ctrPath, "config.yml"))
	e.DeployContract(t, ctrDI.Contract, nil)

	startOffsetPutNumber, err := getStartOffset(ctrDI.DebugInfo, "PutNumber")
	require.NoError(t, err)

	hasResult, err := hasResult(ctrDI.DebugInfo, "PutNumber")
	require.NoError(t, err)

	someNum := getNumToPut()

	// set up a VM for covertest.Run()
	covertestRunVM := setUpVMForPut(t, e, ctrDI.Contract, hasResult, startOffsetPutNumber, someNum, invalidKey)
	res, covErr := covertest.Run(covertestRunVM)
	t.Log("Printing collected instructions:")
	spew.Dump(res)
	t.Log("covertest.Run() returned an error: ", covErr)

	// set up a VM for vm.Run()
	origRunVM := setUpVMForPut(t, e, ctrDI.Contract, hasResult, startOffsetPutNumber, someNum, invalidKey)
	runerr := origRunVM.Run()
	t.Log("vm.Run() returned an error: ", covErr)

	// check if errors are the same
	require.Equal(t, runerr.Error(), covErr.Error())

	// check if the number of elements on the stack is the same
	require.Equal(t, origRunVM.Estack().Len(), covertestRunVM.Estack().Len())
}

func setUpVMForPut(t *testing.T, e *neotest.Executor, contract *neotest.Contract, hasResult bool, methodOff int, num int, key []byte) (v *vm.VM) {
	ic, err := e.Chain.GetTestVM(trigger.Application, nil, nil)
	require.NoError(t, err)
	ic.VM.LoadNEFMethod(contract.NEF, contract.Hash, contract.Hash, callflag.All, hasResult, methodOff, -1, nil)
	ic.VM.Context().Estack().PushVal(num)
	ic.VM.Context().Estack().PushVal(key)
	return ic.VM
}

func getStartOffset(di *compiler.DebugInfo, methodID string) (int, error) {
	for _, method := range di.Methods {
		if method.ID == methodID {
			return int(method.Range.Start), nil
		}
	}
	return 0, errors.New("Method not found")
}

func hasResult(di *compiler.DebugInfo, methodID string) (bool, error) {
	for _, method := range di.Methods {
		if method.ID == methodID {
			if method.ReturnType == "Void" {
				return false, nil
			}
			return true, nil
		}
	}
	return false, errors.New("Method not found")
}

func getNumToPut() int {
	return rand.Intn(100)
}