package transfer

import (
	"database/sql"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/log"
	"github.com/status-im/status-go/services/wallet/bigint"
)

type BlockRangeDAOer interface {
	getBlockRange(chainID uint64, address common.Address) (blockRange *ethTokensBlockRanges, exists bool, err error)
	upsertRange(chainID uint64, account common.Address, newBlockRange *ethTokensBlockRanges) (err error)
	updateTokenRange(chainID uint64, account common.Address, newBlockRange *BlockRange) (err error)
	upsertEthRange(chainID uint64, account common.Address, newBlockRange *BlockRange) (err error)
}

type BlockRangeSequentialDAO struct {
	db *sql.DB
}

type BlockRange struct {
	Start      *big.Int // Block of first transfer
	FirstKnown *big.Int // Oldest scanned block
	LastKnown  *big.Int // Last scanned block
}

func NewBlockRange() *BlockRange {
	return &BlockRange{Start: nil, FirstKnown: nil, LastKnown: nil}
}

type ethTokensBlockRanges struct {
	eth              *BlockRange
	tokens           *BlockRange
	balanceCheckHash string
}

func newEthTokensBlockRanges() *ethTokensBlockRanges {
	return &ethTokensBlockRanges{eth: NewBlockRange(), tokens: NewBlockRange()}
}

func (b *BlockRangeSequentialDAO) getBlockRange(chainID uint64, address common.Address) (blockRange *ethTokensBlockRanges, exists bool, err error) {
	query := `SELECT blk_start, blk_first, blk_last, token_blk_start, token_blk_first, token_blk_last, balance_check_hash FROM blocks_ranges_sequential
	WHERE address = ?
	AND network_id = ?`

	rows, err := b.db.Query(query, address, chainID)
	if err != nil {
		return
	}
	defer rows.Close()

	blockRange = newEthTokensBlockRanges()
	if rows.Next() {
		exists = true
		efk := &bigint.NilableSQLBigInt{}
		elk := &bigint.NilableSQLBigInt{}
		es := &bigint.NilableSQLBigInt{}
		tfk := &bigint.NilableSQLBigInt{}
		tlk := &bigint.NilableSQLBigInt{}
		ts := &bigint.NilableSQLBigInt{}

		err = rows.Scan(es, efk, elk, ts, tfk, tlk, &blockRange.balanceCheckHash)

		if !es.IsNil() {
			blockRange.eth.Start = big.NewInt(es.Int64())
		}
		if !efk.IsNil() {
			blockRange.eth.FirstKnown = big.NewInt(efk.Int64())
		}
		if !elk.IsNil() {
			blockRange.eth.LastKnown = big.NewInt(elk.Int64())
		}
		if !ts.IsNil() {
			blockRange.tokens.Start = big.NewInt(ts.Int64())
		}
		if !tfk.IsNil() {
			blockRange.tokens.FirstKnown = big.NewInt(tfk.Int64())
		}
		if !tlk.IsNil() {
			blockRange.tokens.LastKnown = big.NewInt(tlk.Int64())
		}

		if err != nil {
			return nil, exists, err
		}

		return blockRange, exists, nil
	}

	return blockRange, exists, nil
}

func (b *BlockRangeSequentialDAO) deleteRange(account common.Address) error {
	log.Debug("delete blocks range", "account", account)
	delete, err := b.db.Prepare(`DELETE FROM blocks_ranges_sequential WHERE address = ?`)
	if err != nil {
		log.Error("Failed to prepare deletion of sequential block range", "error", err)
		return err
	}

	_, err = delete.Exec(account)
	return err
}

func (b *BlockRangeSequentialDAO) upsertRange(chainID uint64, account common.Address, newBlockRange *ethTokensBlockRanges) (err error) {
	ethTokensBlockRange, exists, err := b.getBlockRange(chainID, account)
	if err != nil {
		return err
	}

	ethBlockRange := prepareUpdatedBlockRange(ethTokensBlockRange.eth, newBlockRange.eth)
	tokensBlockRange := prepareUpdatedBlockRange(ethTokensBlockRange.tokens, newBlockRange.tokens)

	log.Debug("upsert eth and tokens blocks range",
		"account", account, "chainID", chainID,
		"eth.start", ethBlockRange.Start,
		"eth.first", ethBlockRange.FirstKnown,
		"eth.last", ethBlockRange.LastKnown,
		"tokens.first", tokensBlockRange.FirstKnown,
		"tokens.last", tokensBlockRange.LastKnown,
		"hash", newBlockRange.balanceCheckHash)

	var query *sql.Stmt

	if exists {
		query, err = b.db.Prepare(`UPDATE blocks_ranges_sequential SET
                                    blk_start = ?,
                                    blk_first = ?,
                                    blk_last = ?,
                                    token_blk_start = ?,
                                    token_blk_first = ?,
                                    token_blk_last = ?,
                                    balance_check_hash = ?
                                    WHERE network_id = ? AND address = ?`)

	} else {
		query, err = b.db.Prepare(`INSERT INTO blocks_ranges_sequential
					(blk_start, blk_first, blk_last, token_blk_start, token_blk_first, token_blk_last, balance_check_hash, network_id, address) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`)
	}

	if err != nil {
		return err
	}
	_, err = query.Exec((*bigint.SQLBigInt)(ethBlockRange.Start), (*bigint.SQLBigInt)(ethBlockRange.FirstKnown), (*bigint.SQLBigInt)(ethBlockRange.LastKnown),
		(*bigint.SQLBigInt)(tokensBlockRange.Start), (*bigint.SQLBigInt)(tokensBlockRange.FirstKnown), (*bigint.SQLBigInt)(tokensBlockRange.LastKnown), newBlockRange.balanceCheckHash, chainID, account)

	return err
}

func (b *BlockRangeSequentialDAO) upsertEthRange(chainID uint64, account common.Address,
	newBlockRange *BlockRange) (err error) {

	ethTokensBlockRange, exists, err := b.getBlockRange(chainID, account)
	if err != nil {
		return err
	}

	blockRange := prepareUpdatedBlockRange(ethTokensBlockRange.eth, newBlockRange)

	log.Debug("upsert eth blocks range", "account", account, "chainID", chainID,
		"start", blockRange.Start,
		"first", blockRange.FirstKnown,
		"last", blockRange.LastKnown,
		"old hash", ethTokensBlockRange.balanceCheckHash)

	var query *sql.Stmt

	if exists {
		query, err = b.db.Prepare(`UPDATE blocks_ranges_sequential SET
                                    blk_start = ?,
                                    blk_first = ?,
                                    blk_last = ?
                                    WHERE network_id = ? AND address = ?`)
	} else {
		query, err = b.db.Prepare(`INSERT INTO blocks_ranges_sequential
					(blk_start, blk_first, blk_last, network_id, address) VALUES (?, ?, ?, ?, ?)`)
	}

	if err != nil {
		return err
	}
	_, err = query.Exec((*bigint.SQLBigInt)(blockRange.Start), (*bigint.SQLBigInt)(blockRange.FirstKnown), (*bigint.SQLBigInt)(blockRange.LastKnown), chainID, account)

	return err
}

func (b *BlockRangeSequentialDAO) updateTokenRange(chainID uint64, account common.Address,
	newBlockRange *BlockRange) (err error) {

	ethTokensBlockRange, _, err := b.getBlockRange(chainID, account)
	if err != nil {
		return err
	}

	blockRange := prepareUpdatedBlockRange(ethTokensBlockRange.tokens, newBlockRange)

	log.Debug("update tokens blocks range",
		"first", blockRange.FirstKnown,
		"last", blockRange.LastKnown)

	update, err := b.db.Prepare(`UPDATE blocks_ranges_sequential SET token_blk_start = ?, token_blk_first = ?, token_blk_last = ? WHERE network_id = ? AND address = ?`)
	if err != nil {
		return err
	}

	_, err = update.Exec((*bigint.SQLBigInt)(blockRange.Start), (*bigint.SQLBigInt)(blockRange.FirstKnown),
		(*bigint.SQLBigInt)(blockRange.LastKnown), chainID, account)

	return err
}

func prepareUpdatedBlockRange(blockRange, newBlockRange *BlockRange) *BlockRange {
	if newBlockRange != nil {
		// Ovewrite start block if there was not any or if new one is older, because it can be precised only
		// to a greater value, because no history can be before some block that is considered
		// as a start of history, but due to concurrent block range checks, a newer greater block
		// can be found that matches criteria of a start block (nonce is zero, balances are equal)
		if newBlockRange.Start != nil && (blockRange.Start == nil || blockRange.Start.Cmp(newBlockRange.Start) < 0) {
			blockRange.Start = newBlockRange.Start
		}

		// Overwrite first known block if there was not any or if new one is older
		if (blockRange.FirstKnown == nil && newBlockRange.FirstKnown != nil) ||
			(blockRange.FirstKnown != nil && newBlockRange.FirstKnown != nil && blockRange.FirstKnown.Cmp(newBlockRange.FirstKnown) > 0) {
			blockRange.FirstKnown = newBlockRange.FirstKnown
		}

		// Overwrite last known block if there was not any or if new one is newer
		if (blockRange.LastKnown == nil && newBlockRange.LastKnown != nil) ||
			(blockRange.LastKnown != nil && newBlockRange.LastKnown != nil && blockRange.LastKnown.Cmp(newBlockRange.LastKnown) < 0) {
			blockRange.LastKnown = newBlockRange.LastKnown
		}
	}

	return blockRange
}