// VulcanizeDB
// Copyright © 2021 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 dump

import (
	"fmt"
	"io"
	"math/big"

	"github.com/cerc-io/plugeth-statediff/indexer/ipld"
	"github.com/cerc-io/plugeth-statediff/indexer/models"
	"github.com/cerc-io/plugeth-statediff/utils/log"
)

// BatchTx wraps a void with the state necessary for building the tx concurrently during trie difference iteration
type BatchTx struct {
	blockNum  string
	dump      io.Writer
	quit      chan struct{}
	iplds     chan models.IPLDModel
	ipldCache models.IPLDBatch
}

func NewBatch(number *big.Int, dest io.Writer) *BatchTx {
	batch := &BatchTx{
		blockNum:  number.String(),
		dump:      dest,
		iplds:     make(chan models.IPLDModel),
		quit:      make(chan struct{}),
		ipldCache: models.IPLDBatch{},
	}
	go batch.cache()
	return batch
}

func (self *BatchTx) Submit() error {
	close(self.quit)
	close(self.iplds)

	if err := self.flush(); err != nil {
		return err
	}
	return nil
}

func (tx *BatchTx) BlockNumber() string {
	return tx.blockNum
}

func (tx *BatchTx) RollbackOnFailure(err error) {
	if p := recover(); p != nil {
		log.Info("panic detected before tx submission, but rollback not supported", "panic", p)
		panic(p)
	} else if err != nil {
		log.Info("error detected before tx submission, but rollback not supported", "error", err)
	}
}

func (tx *BatchTx) flush() error {
	if _, err := fmt.Fprintf(tx.dump, "%+v\r\n", tx.ipldCache); err != nil {
		return err
	}
	tx.ipldCache = models.IPLDBatch{}
	return nil
}

// run in background goroutine to synchronize concurrent appends to the ipldCache
func (tx *BatchTx) cache() {
	for {
		select {
		case i := <-tx.iplds:
			tx.ipldCache.Keys = append(tx.ipldCache.Keys, i.Key)
			tx.ipldCache.Values = append(tx.ipldCache.Values, i.Data)
		case <-tx.quit:
			tx.ipldCache = models.IPLDBatch{}
			return
		}
	}
}

func (tx *BatchTx) cacheDirect(key string, value []byte) {
	tx.iplds <- models.IPLDModel{
		BlockNumber: tx.BlockNumber(),
		Key:         key,
		Data:        value,
	}
}

func (tx *BatchTx) cacheIPLD(i ipld.IPLD) {
	tx.iplds <- models.IPLDModel{
		BlockNumber: tx.BlockNumber(),
		Key:         i.Cid().String(),
		Data:        i.RawData(),
	}
}