package db

import (
	"blockbook/bchain"
	"blockbook/common"

	"github.com/golang/glog"
)

// TxCache is handle to TxCacheServer
type TxCache struct {
	db      *RocksDB
	chain   bchain.BlockChain
	metrics *common.Metrics
}

// NewTxCache creates new TxCache interface and returns its handle
func NewTxCache(db *RocksDB, chain bchain.BlockChain, metrics *common.Metrics) (*TxCache, error) {
	return &TxCache{
		db:      db,
		chain:   chain,
		metrics: metrics,
	}, nil
}

// GetTransaction returns transaction either from RocksDB or if not present from blockchain
// it the transaction is confirmed, it is stored in the RocksDB
func (c *TxCache) GetTransaction(txid string, bestheight uint32) (*bchain.Tx, uint32, error) {
	tx, h, err := c.db.GetTx(txid)
	if err != nil {
		return nil, 0, err
	}
	if tx != nil {
		// number of confirmations is not stored in cache, they change all the time
		tx.Confirmations = bestheight - h + 1
		c.metrics.TxCacheEfficiency.With(common.Labels{"status": "hit"}).Inc()
		return tx, h, nil
	}
	tx, err = c.chain.GetTransaction(txid)
	if err != nil {
		return nil, 0, err
	}
	c.metrics.TxCacheEfficiency.With(common.Labels{"status": "miss"}).Inc()
	// do not cache mempool transactions
	if tx.Confirmations > 0 {
		// the transaction in the currently best block has 1 confirmation
		h = bestheight - tx.Confirmations + 1
		err = c.db.PutTx(tx, h, tx.Blocktime)
		// do not return caching error, only log it
		if err != nil {
			glog.Error("PutTx error ", err)
		}
	} else {
		h = 0
	}
	return tx, h, nil
}