package repositories

import (
	"database/sql"

	"context"

	"errors"

	"fmt"

	"github.com/8thlight/vulcanizedb/pkg/config"
	"github.com/8thlight/vulcanizedb/pkg/core"
	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"
)

type BlockStatus int

type Postgres struct {
	Db     *sqlx.DB
	node   core.Node
	nodeId int64
}

var (
	ErrDBInsertFailed     = errors.New("postgres: insert failed")
	ErrDBDeleteFailed     = errors.New("postgres: delete failed")
	ErrDBConnectionFailed = errors.New("postgres: db connection failed")
	ErrUnableToSetNode    = errors.New("postgres: unable to set node")
)

var ErrContractDoesNotExist = func(contractHash string) error {
	return errors.New(fmt.Sprintf("Contract %v does not exist", contractHash))
}

var ErrBlockDoesNotExist = func(blockNumber int64) error {
	return errors.New(fmt.Sprintf("Block number %d does not exist", blockNumber))
}

func NewPostgres(databaseConfig config.Database, node core.Node) (Postgres, error) {
	connectString := config.DbConnectionString(databaseConfig)
	db, err := sqlx.Connect("postgres", connectString)
	if err != nil {
		return Postgres{}, ErrDBConnectionFailed
	}
	pg := Postgres{Db: db, node: node}
	err = pg.CreateNode(&node)
	if err != nil {
		return Postgres{}, ErrUnableToSetNode
	}
	return pg, nil
}

func (repository Postgres) SetBlocksStatus(chainHead int64) {
	cutoff := chainHead - blocksFromHeadBeforeFinal
	repository.Db.Exec(`
                  UPDATE blocks SET is_final = TRUE
                  WHERE is_final = FALSE AND block_number < $1`,
		cutoff)
}

func (repository Postgres) CreateLogs(logs []core.Log) error {
	tx, _ := repository.Db.BeginTx(context.Background(), nil)
	for _, tlog := range logs {
		_, err := tx.Exec(
			`INSERT INTO logs (block_number, address, tx_hash, index, topic0, topic1, topic2, topic3, data)
                VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
                ON CONFLICT (index, block_number)
                  DO UPDATE
                    SET block_number = $1,
                   	    address = $2,
                   	    tx_hash = $3,
                   	    index = $4,
                   	    topic0 = $5,
                   	    topic1 = $6,
                   	    topic2 = $7,
                   	    topic3 = $8,
                   	    data = $9
                `,
			tlog.BlockNumber, tlog.Address, tlog.TxHash, tlog.Index, tlog.Topics[0], tlog.Topics[1], tlog.Topics[2], tlog.Topics[3], tlog.Data,
		)
		if err != nil {
			tx.Rollback()
			return ErrDBInsertFailed
		}
	}
	tx.Commit()
	return nil
}

func (repository Postgres) FindLogs(address string, blockNumber int64) []core.Log {
	logRows, _ := repository.Db.Query(
		`SELECT block_number,
					  address,
					  tx_hash,
					  index,
					  topic0,
					  topic1,
					  topic2,
					  topic3,
					  data
				FROM logs
				WHERE address = $1 AND block_number = $2
				ORDER BY block_number DESC`, address, blockNumber)
	return repository.loadLogs(logRows)
}

func (repository *Postgres) CreateNode(node *core.Node) error {
	var nodeId int64
	err := repository.Db.QueryRow(
		`INSERT INTO nodes (genesis_block, network_id)
                VALUES ($1, $2)
                ON CONFLICT (genesis_block, network_id)
                  DO UPDATE
                    SET genesis_block = $1, network_id = $2
                RETURNING id`,
		node.GenesisBlock, node.NetworkId).Scan(&nodeId)
	if err != nil {
		return ErrUnableToSetNode
	}
	repository.nodeId = nodeId
	return nil
}

func (repository Postgres) CreateContract(contract core.Contract) error {
	abi := contract.Abi
	var abiToInsert *string
	if abi != "" {
		abiToInsert = &abi
	}
	_, err := repository.Db.Exec(
		`INSERT INTO watched_contracts (contract_hash, contract_abi)
				VALUES ($1, $2)
				ON CONFLICT (contract_hash)
				  DO UPDATE
					SET contract_hash = $1, contract_abi = $2
				`, contract.Hash, abiToInsert)
	if err != nil {
		return ErrDBInsertFailed
	}
	return nil
}

func (repository Postgres) ContractExists(contractHash string) bool {
	var exists bool
	repository.Db.QueryRow(
		`SELECT exists(
                   SELECT 1
                   FROM watched_contracts
                   WHERE contract_hash = $1)`, contractHash).Scan(&exists)
	return exists
}

func (repository Postgres) FindContract(contractHash string) (core.Contract, error) {
	var hash string
	var abi string
	contract := repository.Db.QueryRow(
		`SELECT contract_hash, contract_abi FROM watched_contracts WHERE contract_hash=$1`, contractHash)
	err := contract.Scan(&hash, &abi)
	if err == sql.ErrNoRows {
		return core.Contract{}, ErrContractDoesNotExist(contractHash)
	}
	savedContract := repository.addTransactions(core.Contract{Hash: hash, Abi: abi})
	return savedContract, nil
}

func (repository Postgres) MaxBlockNumber() int64 {
	var highestBlockNumber int64
	repository.Db.Get(&highestBlockNumber, `SELECT MAX(block_number) FROM blocks`)
	return highestBlockNumber
}

func (repository Postgres) MissingBlockNumbers(startingBlockNumber int64, highestBlockNumber int64) []int64 {
	numbers := []int64{}
	repository.Db.Select(&numbers,
		`SELECT all_block_numbers
			FROM (
				SELECT generate_series($1::INT, $2::INT) AS all_block_numbers) series
				LEFT JOIN blocks
					ON block_number = all_block_numbers
			WHERE block_number ISNULL`,
		startingBlockNumber,
		highestBlockNumber)
	return numbers
}

func (repository Postgres) FindBlockByNumber(blockNumber int64) (core.Block, error) {
	blockRows := repository.Db.QueryRow(
		`SELECT id,
                       block_number,
                       block_gaslimit,
                       block_gasused,
                       block_time,
                       block_difficulty,
                       block_hash,
                       block_nonce,
                       block_parenthash,
                       block_size,
                       uncle_hash,
                       is_final
               FROM blocks
               WHERE node_id = $1 AND block_number = $2`, repository.nodeId, blockNumber)
	savedBlock, err := repository.loadBlock(blockRows)
	if err != nil {
		switch err {
		case sql.ErrNoRows:
			return core.Block{}, ErrBlockDoesNotExist(blockNumber)
		default:
			return savedBlock, err
		}
	}
	return savedBlock, nil
}

func (repository Postgres) BlockCount() int {
	var count int
	repository.Db.Get(&count, `SELECT COUNT(*) FROM blocks`)
	return count
}

func (repository Postgres) getBlockHash(block core.Block) (string, bool) {
	var retrievedBlockHash string
	repository.Db.Get(&retrievedBlockHash,
		`SELECT block_hash
			   FROM blocks
			   WHERE block_number = $1 AND node_id = $2`,
		block.Number, repository.nodeId)
	return retrievedBlockHash, blockExists(retrievedBlockHash)
}

func blockExists(retrievedBlockHash string) bool {
	return retrievedBlockHash != ""
}

func (repository Postgres) CreateOrUpdateBlock(block core.Block) error {
	var err error
	retrievedBlockHash, ok := repository.getBlockHash(block)
	if !ok {
		err = repository.insertBlock(block)
		return err
	}
	if ok && retrievedBlockHash != block.Hash {
		err = repository.removeBlock(block.Number)
		if err != nil {
			return err
		}
		err = repository.insertBlock(block)
		return err
	}
	return nil
}

func (repository Postgres) insertBlock(block core.Block) error {
	var blockId int64
	tx, _ := repository.Db.BeginTx(context.Background(), nil)
	err := tx.QueryRow(
		`INSERT INTO blocks
			    (node_id, block_number, block_gaslimit, block_gasused, block_time, block_difficulty, block_hash, block_nonce, block_parenthash, block_size, uncle_hash, is_final)
			    VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)
		        RETURNING id `,
		repository.nodeId, block.Number, block.GasLimit, block.GasUsed, block.Time, block.Difficulty, block.Hash, block.Nonce, block.ParentHash, block.Size, block.UncleHash, block.IsFinal).
		Scan(&blockId)
	if err != nil {
		tx.Rollback()
		return ErrDBInsertFailed
	}
	err = repository.createTransactions(tx, blockId, block.Transactions)
	if err != nil {
		tx.Rollback()
		return ErrDBInsertFailed
	}
	tx.Commit()
	return nil
}

func (repository Postgres) removeBlock(blockNumber int64) error {
	_, err := repository.Db.Exec(
		`DELETE FROM
				blocks
				WHERE block_number=$1 AND node_id=$2`,
		blockNumber, repository.nodeId)
	if err != nil {
		return ErrDBDeleteFailed
	}
	return nil
}

func (repository Postgres) createTransactions(tx *sql.Tx, blockId int64, transactions []core.Transaction) error {
	for _, transaction := range transactions {
		_, err := tx.Exec(
			`INSERT INTO transactions
           (block_id, tx_hash, tx_nonce, tx_to, tx_from, tx_gaslimit, tx_gasprice, tx_value)
           VALUES ($1, $2, $3, $4, $5, $6, $7, $8)`,
			blockId, transaction.Hash, transaction.Nonce, transaction.To, transaction.From, transaction.GasLimit, transaction.GasPrice, transaction.Value)
		if err != nil {
			return err
		}
	}
	return nil
}

func (repository Postgres) loadBlock(blockRows *sql.Row) (core.Block, error) {
	var blockId int64
	var blockHash string
	var blockNonce string
	var blockNumber int64
	var blockParentHash string
	var blockSize int64
	var blockTime float64
	var difficulty int64
	var gasLimit float64
	var gasUsed float64
	var uncleHash string
	var isFinal bool
	err := blockRows.Scan(&blockId, &blockNumber, &gasLimit, &gasUsed, &blockTime, &difficulty, &blockHash, &blockNonce, &blockParentHash, &blockSize, &uncleHash, &isFinal)
	if err != nil {
		return core.Block{}, err
	}
	transactionRows, _ := repository.Db.Query(`
            SELECT tx_hash,
				   tx_nonce,
				   tx_to,
				   tx_from,
				   tx_gaslimit,
				   tx_gasprice,
				   tx_value
            FROM transactions
            WHERE block_id = $1
            ORDER BY tx_hash`, blockId)
	transactions := repository.loadTransactions(transactionRows)
	return core.Block{
		Difficulty:   difficulty,
		GasLimit:     int64(gasLimit),
		GasUsed:      int64(gasUsed),
		Hash:         blockHash,
		Nonce:        blockNonce,
		Number:       blockNumber,
		ParentHash:   blockParentHash,
		Size:         blockSize,
		Time:         int64(blockTime),
		Transactions: transactions,
		UncleHash:    uncleHash,
		IsFinal:      isFinal,
	}, nil
}

func (repository Postgres) loadLogs(logsRows *sql.Rows) []core.Log {
	var logs []core.Log
	for logsRows.Next() {
		var blockNumber int64
		var address string
		var txHash string
		var index int64
		var data string
		topics := make([]string, 4)
		logsRows.Scan(&blockNumber, &address, &txHash, &index, &topics[0], &topics[1], &topics[2], &topics[3], &data)
		log := core.Log{
			BlockNumber: blockNumber,
			TxHash:      txHash,
			Address:     address,
			Index:       index,
			Data:        data,
		}
		log.Topics = make(map[int]string)
		for i, topic := range topics {
			log.Topics[i] = topic
		}
		logs = append(logs, log)
	}
	return logs
}

func (repository Postgres) loadTransactions(transactionRows *sql.Rows) []core.Transaction {
	var transactions []core.Transaction
	for transactionRows.Next() {
		var hash string
		var nonce uint64
		var to string
		var from string
		var gasLimit int64
		var gasPrice int64
		var value int64
		transactionRows.Scan(&hash, &nonce, &to, &from, &gasLimit, &gasPrice, &value)
		transaction := core.Transaction{
			Hash:     hash,
			Nonce:    nonce,
			To:       to,
			From:     from,
			GasLimit: gasLimit,
			GasPrice: gasPrice,
			Value:    value,
		}
		transactions = append(transactions, transaction)
	}
	return transactions
}

func (repository Postgres) addTransactions(contract core.Contract) core.Contract {
	transactionRows, _ := repository.Db.Query(`
            SELECT tx_hash,
                   tx_nonce,
                   tx_to,
                   tx_from,
                   tx_gaslimit,
                   tx_gasprice,
                   tx_value
            FROM transactions
            WHERE tx_to = $1
            ORDER BY block_id DESC`, contract.Hash)
	transactions := repository.loadTransactions(transactionRows)
	savedContract := core.Contract{Hash: contract.Hash, Transactions: transactions, Abi: contract.Abi}
	return savedContract
}