// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package rawdb

import (
	"encoding/json"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params/confp/generic"
	"github.com/ethereum/go-ethereum/params/types/ctypes"
	"github.com/ethereum/go-ethereum/rlp"
)

// ReadDatabaseVersion retrieves the version number of the database.
func ReadDatabaseVersion(db ethdb.KeyValueReader) *uint64 {
	var version uint64

	enc, _ := db.Get(databaseVerisionKey)
	if len(enc) == 0 {
		return nil
	}
	if err := rlp.DecodeBytes(enc, &version); err != nil {
		return nil
	}

	return &version
}

// WriteDatabaseVersion stores the version number of the database
func WriteDatabaseVersion(db ethdb.KeyValueWriter, version uint64) {
	enc, err := rlp.EncodeToBytes(version)
	if err != nil {
		log.Crit("Failed to encode database version", "err", err)
	}
	if err = db.Put(databaseVerisionKey, enc); err != nil {
		log.Crit("Failed to store the database version", "err", err)
	}
}

// ReadChainConfig retrieves the consensus settings based on the given genesis hash.
func ReadChainConfig(db ethdb.KeyValueReader, hash common.Hash) ctypes.ChainConfigurator {
	data, _ := db.Get(ConfigKey(hash))
	if len(data) == 0 {
		return nil
	}
	c, err := generic.UnmarshalChainConfigurator(data)
	if err != nil {
		log.Error("Invalid chain config JSON", "hash", hash, "err", err)
		return nil
	}
	return c
}

// WriteChainConfig writes the chain config settings to the database.
func WriteChainConfig(db ethdb.KeyValueWriter, hash common.Hash, cfg ctypes.ChainConfigurator) {
	if cfg == nil {
		return
	}
	data, err := json.Marshal(cfg)
	if err != nil {
		log.Crit("Failed to JSON encode chain config", "err", err)
	}
	if err := db.Put(ConfigKey(hash), data); err != nil {
		log.Crit("Failed to store chain config", "err", err)
	}
}
