package commands

import (
	"context"
	"fmt"

	"github.com/holiman/uint256"
	jsoniter "github.com/json-iterator/go"
	"github.com/ledgerwatch/erigon/common"
	"github.com/ledgerwatch/erigon/consensus/ethash"
	"github.com/ledgerwatch/erigon/core/rawdb"
	"github.com/ledgerwatch/erigon/core/state"
	"github.com/ledgerwatch/erigon/core/types"
	"github.com/ledgerwatch/erigon/eth/tracers"
	"github.com/ledgerwatch/erigon/internal/ethapi"
	"github.com/ledgerwatch/erigon/rpc"
	"github.com/ledgerwatch/erigon/turbo/rpchelper"
	"github.com/ledgerwatch/erigon/turbo/transactions"
)

// TraceTransaction implements debug_traceTransaction. Returns Geth style transaction traces.
func (api *PrivateDebugAPIImpl) TraceTransaction(ctx context.Context, hash common.Hash, config *tracers.TraceConfig, stream *jsoniter.Stream) error {
	tx, err := api.db.BeginRo(ctx)
	if err != nil {
		stream.WriteNil()
		return err
	}
	defer tx.Rollback()

	// Retrieve the transaction and assemble its EVM context
	txn, blockHash, _, txIndex, err := rawdb.ReadTransaction(tx, hash)
	if err != nil {
		return err
	}
	if txn == nil {
		stream.WriteNil()
		return fmt.Errorf("transaction %#x not found", hash)
	}

	chainConfig, err := api.chainConfig(tx)
	if err != nil {
		stream.WriteNil()
		return err
	}

	block, _, err := rawdb.ReadBlockByHashWithSenders(tx, blockHash)
	if err != nil {
		return err
	}
	if block == nil {
		return nil
	}
	getHeader := func(hash common.Hash, number uint64) *types.Header {
		return rawdb.ReadHeader(tx, hash, number)
	}
	msg, blockCtx, txCtx, ibs, _, err := transactions.ComputeTxEnv(ctx, block, chainConfig, getHeader, nil /* checkTEVM */, ethash.NewFaker(), tx, blockHash, txIndex)
	if err != nil {
		stream.WriteNil()
		return err
	}
	// Trace the transaction and return
	return transactions.TraceTx(ctx, msg, blockCtx, txCtx, ibs, config, chainConfig, stream)
}

func (api *PrivateDebugAPIImpl) TraceCall(ctx context.Context, args ethapi.CallArgs, blockNrOrHash rpc.BlockNumberOrHash, config *tracers.TraceConfig, stream *jsoniter.Stream) error {
	dbtx, err := api.db.BeginRo(ctx)
	if err != nil {
		stream.WriteNil()
		return err
	}
	defer dbtx.Rollback()

	chainConfig, err := api.chainConfig(dbtx)
	if err != nil {
		stream.WriteNil()
		return err
	}

	blockNumber, hash, err := rpchelper.GetBlockNumber(blockNrOrHash, dbtx, api.filters)
	if err != nil {
		stream.WriteNil()
		return err
	}
	var stateReader state.StateReader
	if num, ok := blockNrOrHash.Number(); ok && num == rpc.LatestBlockNumber {
		stateReader = state.NewPlainStateReader(dbtx)
	} else {
		stateReader = state.NewPlainKvState(dbtx, blockNumber)
	}
	header := rawdb.ReadHeader(dbtx, hash, blockNumber)
	if header == nil {
		stream.WriteNil()
		return fmt.Errorf("block %d(%x) not found", blockNumber, hash)
	}
	ibs := state.New(stateReader)

	var baseFee *uint256.Int
	if header != nil && header.BaseFee != nil {
		var overflow bool
		baseFee, overflow = uint256.FromBig(header.BaseFee)
		if overflow {
			return fmt.Errorf("header.BaseFee uint256 overflow")
		}
	}
	msg, err := args.ToMessage(api.GasCap, baseFee)
	if err != nil {
		return err
	}
	blockCtx, txCtx := transactions.GetEvmContext(msg, header, blockNrOrHash.RequireCanonical, dbtx)
	// Trace the transaction and return
	return transactions.TraceTx(ctx, msg, blockCtx, txCtx, ibs, config, chainConfig, stream)
}