// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package tracers

import (
	"crypto/ecdsa"
	"crypto/rand"
	"encoding/json"
	"io/ioutil"
	"math/big"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"github.com/dexon-foundation/dexon/common"
	"github.com/dexon-foundation/dexon/common/hexutil"
	"github.com/dexon-foundation/dexon/common/math"
	"github.com/dexon-foundation/dexon/core"
	"github.com/dexon-foundation/dexon/core/types"
	"github.com/dexon-foundation/dexon/core/vm"
	"github.com/dexon-foundation/dexon/core/vm/evm"
	"github.com/dexon-foundation/dexon/core/vm/tools"
	"github.com/dexon-foundation/dexon/crypto"
	"github.com/dexon-foundation/dexon/ethdb"
	"github.com/dexon-foundation/dexon/params"
	"github.com/dexon-foundation/dexon/rlp"
	"github.com/dexon-foundation/dexon/tests"
)

// To generate a new callTracer test, copy paste the makeTest method below into
// a Geth console and call it with a transaction hash you which to export.

/*
// makeTest generates a callTracer test by running a prestate reassembled and a
// call trace run, assembling all the gathered information into a test case.
var makeTest = function(tx, rewind) {
  // Generate the genesis block from the block, transaction and prestate data
  var block   = eth.getBlock(eth.getTransaction(tx).blockHash);
  var genesis = eth.getBlock(block.parentHash);

  delete genesis.gasUsed;
  delete genesis.logsBloom;
  delete genesis.parentHash;
  delete genesis.receiptsRoot;
  delete genesis.sha3Uncles;
  delete genesis.size;
  delete genesis.transactions;
  delete genesis.transactionsRoot;
  delete genesis.uncles;

  genesis.gasLimit  = genesis.gasLimit.toString();
  genesis.number    = genesis.number.toString();
  genesis.timestamp = genesis.timestamp.toString();

  genesis.alloc = debug.traceTransaction(tx, {tracer: "prestateTracer", rewind: rewind});
  for (var key in genesis.alloc) {
    genesis.alloc[key].nonce = genesis.alloc[key].nonce.toString();
  }
  genesis.config = admin.nodeInfo.protocols.eth.config;

  // Generate the call trace and produce the test input
  var result = debug.traceTransaction(tx, {tracer: "callTracer", rewind: rewind});
  delete result.time;

  console.log(JSON.stringify({
    genesis: genesis,
    context: {
      number:     block.number.toString(),
      difficulty: block.difficulty,
      timestamp:  block.timestamp.toString(),
      gasLimit:   block.gasLimit.toString(),
      miner:      block.miner,
    },
    input:  eth.getRawTransaction(tx),
    result: result,
  }, null, 2));
}
*/
const (
	gasDiffUnit   = 204
	createGasDiff = 200
)

// callTrace is the result of a callTracer run.
type callTrace struct {
	Type    string          `json:"type"`
	From    common.Address  `json:"from"`
	To      common.Address  `json:"to"`
	Input   hexutil.Bytes   `json:"input"`
	Output  hexutil.Bytes   `json:"output"`
	Gas     *hexutil.Uint64 `json:"gas,omitempty"`
	GasUsed *hexutil.Uint64 `json:"gasUsed,omitempty"`
	Value   *hexutil.Big    `json:"value,omitempty"`
	Error   string          `json:"error,omitempty"`
	Calls   []callTrace     `json:"calls,omitempty"`
}

type callContext struct {
	Number     math.HexOrDecimal64   `json:"number"`
	Difficulty *math.HexOrDecimal256 `json:"difficulty"`
	Time       math.HexOrDecimal64   `json:"timestamp"`
	GasLimit   math.HexOrDecimal64   `json:"gasLimit"`
	Miner      common.Address        `json:"miner"`
}

// callTracerTest defines a single test to check the call tracer against.
type callTracerTest struct {
	Genesis *core.Genesis `json:"genesis"`
	Context *callContext  `json:"context"`
	Input   string        `json:"input"`
	Result  *callTrace    `json:"result"`
}

func TestPrestateTracerCreate2(t *testing.T) {
	unsigned_tx := types.NewTransaction(1, common.HexToAddress("0x00000000000000000000000000000000deadbeef"),
		new(big.Int), 5000000, big.NewInt(1), []byte{})

	privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), rand.Reader)
	if err != nil {
		t.Fatalf("err %v", err)
	}
	signer := types.NewEIP155Signer(big.NewInt(1))
	tx, err := types.SignTx(unsigned_tx, signer, privateKeyECDSA)
	if err != nil {
		t.Fatalf("err %v", err)
	}
	/**
		This comes from one of the test-vectors on the Skinny Create2 - EIP

	    address 0x00000000000000000000000000000000deadbeef
	    salt 0x00000000000000000000000000000000000000000000000000000000cafebabe
	    init_code 0xdeadbeef
	    gas (assuming no mem expansion): 32006
	    result: 0x60f3f640a8508fC6a86d45DF051962668E1e8AC7
	*/
	origin, _ := signer.Sender(tx)
	context := vm.Context{
		CanTransfer: core.CanTransfer,
		Transfer:    core.Transfer,
		Origin:      origin,
		Coinbase:    common.Address{},
		BlockNumber: new(big.Int).SetUint64(8000000),
		Time:        new(big.Int).SetUint64(5),
		Difficulty:  big.NewInt(0x30000),
		GasLimit:    uint64(6000000),
		GasPrice:    big.NewInt(1),
	}
	alloc := core.GenesisAlloc{}
	// The code pushes 'deadbeef' into memory, then the other params, and calls CREATE2, then returns
	// the address
	alloc[common.HexToAddress("0x00000000000000000000000000000000deadbeef")] = core.GenesisAccount{
		Nonce:   1,
		Code:    hexutil.MustDecode("0x63deadbeef60005263cafebabe6004601c6000F560005260206000F3"),
		Balance: big.NewInt(1),
	}
	alloc[origin] = core.GenesisAccount{
		Nonce:   1,
		Code:    []byte{},
		Balance: big.NewInt(500000000000000),
	}
	statedb := tests.MakePreState(ethdb.NewMemDatabase(), alloc)
	// Create the tracer, the EVM environment and run it
	tracer, err := New("prestateTracer")
	if err != nil {
		t.Fatalf("failed to create call tracer: %v", err)
	}
	vmConfig := [vm.NUMS]interface{}{}
	vmConfig[vm.EVM] = evm.Config{Tracer: tracer, Debug: true}
	pack := vm.NewExecPack(&context, statedb, params.MainnetChainConfig, vmConfig)

	msg, err := tx.AsMessage(signer)
	if err != nil {
		t.Fatalf("failed to prepare transaction for tracing: %v", err)
	}
	st := core.NewStateTransition(&pack, msg, new(core.GasPool).AddGas(tx.Gas()))
	core.TestingMode = true
	if _, _, _, err = st.TransitionDb(); err != nil {
		t.Fatalf("failed to execute transaction: %v", err)
	}
	// Retrieve the trace result and compare against the etalon
	res, err := tracer.GetResult()
	if err != nil {
		t.Fatalf("failed to retrieve trace result: %v", err)
	}
	ret := make(map[string]interface{})
	if err := json.Unmarshal(res, &ret); err != nil {
		t.Fatalf("failed to unmarshal trace result: %v", err)
	}
	if _, has := ret["0x60f3f640a8508fc6a86d45df051962668e1e8ac7"]; !has {
		t.Fatalf("Expected 0x60f3f640a8508fc6a86d45df051962668e1e8ac7 in result")
	}
}

func setTx(toolTx *tools.Transaction, tx *types.Transaction, patchPayload bool) (*types.Transaction, int, error) {
	rTx := new(types.Transaction)
	// Patch bytecode and load to tx
	originalLen := len(toolTx.Data.Payload)
	if patchPayload {
		toolTx.Data.Payload = tools.PatchBinary(toolTx.Data.Payload)
	}
	afterLen := len(toolTx.Data.Payload)
	payloadLenDiff := afterLen - originalLen
	toolTx.Data.GasLimit = toolTx.Data.GasLimit + uint64(payloadLenDiff*gasDiffUnit)
	encodeByte, _ := rlp.EncodeToBytes(toolTx)
	if err := rlp.DecodeBytes(encodeByte, rTx); err != nil {
		return nil, 0, err
	}
	rTx.SetFrom(tx)
	return rTx, payloadLenDiff, nil
}

// Iterates over all the input-output datasets in the tracer test harness and
// runs the JavaScript tracers against them.
func TestCallTracer(t *testing.T) {
	files, err := ioutil.ReadDir("testdata")
	if err != nil {
		t.Fatalf("failed to retrieve tracer test suite: %v", err)
	}
	for _, file := range files {
		if !strings.HasPrefix(file.Name(), "call_tracer_") {
			continue
		}
		file := file // capture range variable
		t.Run(camel(strings.TrimSuffix(strings.TrimPrefix(file.Name(), "call_tracer_"), ".json")), func(t *testing.T) {
			t.Parallel()
			// Call tracer test found, read if from disk
			blob, err := ioutil.ReadFile(filepath.Join("testdata", file.Name()))
			if err != nil {
				t.Fatalf("failed to read testcase: %v", err)
			}
			test := new(callTracerTest)
			if err := json.Unmarshal(blob, test); err != nil {
				t.Fatalf("failed to parse testcase: %v", err)
			}
			for k, v := range test.Genesis.Alloc {
				v.Code = tools.PatchBinary(v.Code)
				test.Genesis.Alloc[k] = v
			}
			// Configure a blockchain with the given prestate
			tx := new(types.Transaction)
			toolTx := new(tools.Transaction)
			if err := rlp.DecodeBytes(common.FromHex(test.Input), toolTx); err != nil {
				t.Fatalf("failed to parse testcase input: %v", err)
			}
			if err := rlp.DecodeBytes(common.FromHex(test.Input), tx); err != nil {
				t.Fatalf("failed to parse testcase input: %v", err)
			}
			signer := types.MakeSigner(test.Genesis.Config, new(big.Int).SetUint64(uint64(test.Context.Number)))

			// Get correct sender address
			origin, _ := signer.Sender(tx)
			tx.AsMessage(signer)

			tx, payloadLenDiff, err := setTx(toolTx, tx, test.Result.Type == "CREATE")
			if err != nil {
				t.Fatalf("failed to set tx: %v", err)
			}

			context := vm.Context{
				CanTransfer: core.CanTransfer,
				Transfer:    core.Transfer,
				Origin:      origin,
				Coinbase:    test.Context.Miner,
				BlockNumber: new(big.Int).SetUint64(uint64(test.Context.Number)),
				Time:        new(big.Int).SetUint64(uint64(test.Context.Time)),
				Difficulty:  (*big.Int)(test.Context.Difficulty),
				GasLimit:    uint64(test.Context.GasLimit),
				GasPrice:    tx.GasPrice(),
			}
			statedb := tests.MakePreState(ethdb.NewMemDatabase(), test.Genesis.Alloc)

			// Create the tracer, the EVM environment and run it
			tracer, err := New("callTracer")
			if err != nil {
				t.Fatalf("failed to create call tracer: %v", err)
			}
			vmConfig := [vm.NUMS]interface{}{}
			vmConfig[vm.EVM] = evm.Config{Tracer: tracer, Debug: true}
			pack := vm.NewExecPack(&context, statedb, test.Genesis.Config, vmConfig)
			msg, err := tx.AsMessage(signer)
			if err != nil {
				t.Fatalf("failed to prepare transaction for tracing: %v", err)
			}
			st := core.NewStateTransition(&pack, msg, new(core.GasPool).AddGas(tx.Gas()))
			if _, _, _, err = st.TransitionDb(); err != nil {
				t.Fatalf("failed to execute transaction: %v", err)
			}
			// Retrieve the trace result and compare against the etalon
			res, err := tracer.GetResult()
			if err != nil {
				t.Fatalf("failed to retrieve trace result: %v", err)
			}
			ret := new(callTrace)
			if err := json.Unmarshal(res, ret); err != nil {
				t.Fatalf("failed to unmarshal trace result: %v", err)
			}

			updateResultInput(test.Result, 0)
			*test.Result.Gas += hexutil.Uint64(payloadLenDiff * (gasDiffUnit - 4))
			*test.Result.GasUsed += hexutil.Uint64(payloadLenDiff * (gasDiffUnit - 4))
			if test.Result.Type == "CREATE" {
				*test.Result.GasUsed -= hexutil.Uint64(createGasDiff)
			}
			if !reflect.DeepEqual(ret, test.Result) {
				t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", ret, test.Result)
			}
		})
	}
}
func updateResultInput(result *callTrace, depth int) {
	for i := range result.Calls {
		updateResultInput(&result.Calls[i], depth+1)
	}
	if result.Type == "CREATE" {
		result.Output = tools.PatchBinary(result.Output)
	}
	result.Input = tools.PatchBinary(result.Input)
	if len(result.Input) > 0 && result.Type == "CREATE" && depth == 0 {
		result.Input = result.Input[1:]
	}
}