// VulcanizeDB
// Copyright © 2020 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program 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 Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package pgipfsethdb

import (
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/jmoiron/sqlx"
)

// Batch is the type that satisfies the ethdb.Batch interface for PG-IPFS Ethereum data using a direct Postgres connection
type Batch struct {
	db          *sqlx.DB
	tx          *sqlx.Tx
	valueSize   int
	replayCache map[string][]byte
}

// NewBatch returns a ethdb.Batch interface for PG-IPFS
func NewBatch(db *sqlx.DB, tx *sqlx.Tx) ethdb.Batch {
	b := &Batch{
		db:          db,
		tx:          tx,
		replayCache: make(map[string][]byte),
	}
	if tx == nil {
		b.Reset()
	}
	return b
}

// Put satisfies the ethdb.Batch interface
// Put inserts the given value into the key-value data store
// Key is expected to be the keccak256 hash of value
func (b *Batch) Put(key []byte, value []byte) (err error) {
	dsKey, prefix, err := DatastoreKeyFromGethKey(key)
	if err != nil {
		return err
	}
	if _, err = b.tx.Exec(putPgStr, dsKey, value); err != nil {
		return err
	}
	if _, err = b.tx.Exec(putPreimagePgStr, key, dsKey, prefix); err != nil {
		return err
	}
	b.valueSize += len(value)
	b.replayCache[common.Bytes2Hex(key)] = value
	return nil
}

// Delete satisfies the ethdb.Batch interface
// Delete removes the key from the key-value data store
func (b *Batch) Delete(key []byte) (err error) {
	_, err = b.tx.Exec(deletePgStr, key)
	if err != nil {
		return err
	}
	delete(b.replayCache, common.Bytes2Hex(key))
	return nil
}

// ValueSize satisfies the ethdb.Batch interface
// ValueSize retrieves the amount of data queued up for writing
// The returned value is the total byte length of all data queued to write
func (b *Batch) ValueSize() int {
	return b.valueSize
}

// Write satisfies the ethdb.Batch interface
// Write flushes any accumulated data to disk
// Reset should be called after every write
func (b *Batch) Write() error {
	if b.tx == nil {
		return nil
	}
	if err := b.tx.Commit(); err != nil {
		return err
	}
	b.replayCache = nil
	return nil
}

// Replay satisfies the ethdb.Batch interface
// Replay replays the batch contents
func (b *Batch) Replay(w ethdb.KeyValueWriter) error {
	if b.tx != nil {
		b.tx.Rollback()
		b.tx = nil
	}
	for key, value := range b.replayCache {
		if err := w.Put(common.Hex2Bytes(key), value); err != nil {
			return err
		}
	}
	b.replayCache = nil
	return nil
}

// Reset satisfies the ethdb.Batch interface
// Reset resets the batch for reuse
// This should be called after every write
func (b *Batch) Reset() {
	var err error
	b.tx, err = b.db.Beginx()
	if err != nil {
		panic(err)
	}
	b.replayCache = make(map[string][]byte)
	b.valueSize = 0
}