// 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 logger

import (
	"encoding/json"
	"io"
	"math/big"

	"github.com/holiman/uint256"
	libcommon "github.com/ledgerwatch/erigon-lib/common"

	"github.com/ledgerwatch/erigon/common"
	"github.com/ledgerwatch/erigon/common/math"
	"github.com/ledgerwatch/erigon/core/vm"
)

type JSONLogger struct {
	encoder *json.Encoder
	cfg     *LogConfig
	env     *vm.EVM
}

// NewJSONLogger creates a new EVM tracer that prints execution steps as JSON objects
// into the provided stream.
func NewJSONLogger(cfg *LogConfig, writer io.Writer) *JSONLogger {
	l := &JSONLogger{json.NewEncoder(writer), cfg, nil}
	if l.cfg == nil {
		l.cfg = &LogConfig{}
	}
	return l
}

func (l *JSONLogger) CaptureTxStart(gasLimit uint64) {}

func (l *JSONLogger) CaptureTxEnd(restGas uint64) {}

func (l *JSONLogger) CaptureStart(env *vm.EVM, from libcommon.Address, to libcommon.Address, precompile bool, create bool, input []byte, gas uint64, value *uint256.Int, code []byte) {
	l.env = env
}

func (l *JSONLogger) CaptureEnter(typ vm.OpCode, from libcommon.Address, to libcommon.Address, precompile bool, create bool, input []byte, gas uint64, value *uint256.Int, code []byte) {
}

// CaptureState outputs state information on the logger.
func (l *JSONLogger) CaptureState(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
	memory := scope.Memory
	stack := scope.Stack

	log := StructLog{
		Pc:            pc,
		Op:            op,
		Gas:           gas,
		GasCost:       cost,
		MemorySize:    memory.Len(),
		Storage:       nil,
		Depth:         depth,
		RefundCounter: l.env.IntraBlockState().GetRefund(),
		Err:           err,
	}
	if !l.cfg.DisableMemory {
		log.Memory = memory.Data()
	}
	if !l.cfg.DisableStack {
		//TODO(@holiman) improve this
		logstack := make([]*big.Int, len(stack.Data))
		for i, item := range stack.Data {
			logstack[i] = item.ToBig()
		}
		log.Stack = logstack
	}
	_ = l.encoder.Encode(log)
}

// CaptureFault outputs state information on the logger.
func (l *JSONLogger) CaptureFault(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, depth int, err error) {
}

// CaptureEnd is triggered at end of execution.
func (l *JSONLogger) CaptureEnd(output []byte, usedGas uint64, err error) {
	type endLog struct {
		Output  string              `json:"output"`
		GasUsed math.HexOrDecimal64 `json:"gasUsed"`
		Err     string              `json:"error,omitempty"`
	}
	var errMsg string
	if err != nil {
		errMsg = err.Error()
	}
	_ = l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(usedGas), errMsg})
}

func (l *JSONLogger) CaptureExit(output []byte, usedGas uint64, err error) {
}