package commands

import (
	"context"
	"fmt"

	"github.com/ledgerwatch/turbo-geth/common"
	"github.com/ledgerwatch/turbo-geth/common/hexutil"
	"github.com/ledgerwatch/turbo-geth/core/rawdb"
	"github.com/ledgerwatch/turbo-geth/ethdb"
	"github.com/ledgerwatch/turbo-geth/rpc"
)

// GetTransactionByHash implements eth_getTransactionByHash. Returns information about a transaction given the transaction's hash.
func (api *APIImpl) GetTransactionByHash(ctx context.Context, hash common.Hash) (*RPCTransaction, error) {
	tx, err := api.db.BeginRo(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback()

	// https://infura.io/docs/ethereum/json-rpc/eth-getTransactionByHash
	txn, blockHash, blockNumber, txIndex := rawdb.ReadTransaction(ethdb.NewRoTxDb(tx), hash)
	if txn == nil {
		return nil, nil // not error, see https://github.com/ledgerwatch/turbo-geth/issues/1645
	}
	return newRPCTransaction(txn, blockHash, blockNumber, txIndex), nil
}

// GetTransactionByBlockHashAndIndex implements eth_getTransactionByBlockHashAndIndex. Returns information about a transaction given the block's hash and a transaction index.
func (api *APIImpl) GetTransactionByBlockHashAndIndex(ctx context.Context, blockHash common.Hash, txIndex hexutil.Uint64) (*RPCTransaction, error) {
	tx, err := api.db.BeginRo(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback()

	// https://infura.io/docs/ethereum/json-rpc/eth-getTransactionByBlockHashAndIndex
	block, err := rawdb.ReadBlockByHash(ethdb.NewRoTxDb(tx), blockHash)
	if err != nil {
		return nil, err
	}
	if block == nil {
		return nil, nil // not error, see https://github.com/ledgerwatch/turbo-geth/issues/1645
	}

	txs := block.Transactions()
	if uint64(txIndex) >= uint64(len(txs)) {
		return nil, fmt.Errorf("txIndex (%d) out of range (nTxs: %d)", uint64(txIndex), uint64(len(txs)))
	}

	return newRPCTransaction(txs[txIndex], block.Hash(), block.NumberU64(), uint64(txIndex)), nil
}

// GetTransactionByBlockNumberAndIndex implements eth_getTransactionByBlockNumberAndIndex. Returns information about a transaction given a block number and transaction index.
func (api *APIImpl) GetTransactionByBlockNumberAndIndex(ctx context.Context, blockNr rpc.BlockNumber, txIndex hexutil.Uint) (*RPCTransaction, error) {
	tx, err := api.db.BeginRo(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback()

	// https://infura.io/docs/ethereum/json-rpc/eth-getTransactionByBlockNumberAndIndex
	blockNum, err := getBlockNumber(blockNr, tx)
	if err != nil {
		return nil, err
	}

	block, err := rawdb.ReadBlockByNumber(ethdb.NewRoTxDb(tx), blockNum)
	if err != nil {
		return nil, err
	}
	if block == nil {
		return nil, nil // not error, see https://github.com/ledgerwatch/turbo-geth/issues/1645
	}

	txs := block.Transactions()
	if uint64(txIndex) >= uint64(len(txs)) {
		return nil, fmt.Errorf("txIndex (%d) out of range (nTxs: %d)", uint64(txIndex), uint64(len(txs)))
	}

	return newRPCTransaction(txs[txIndex], block.Hash(), block.NumberU64(), uint64(txIndex)), nil
}