// 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 (
	"fmt"

	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/ethdb/leveldb"
	"github.com/ethereum/go-ethereum/ethdb/memorydb"
)

// freezerdb is a database wrapper that enabled freezer data retrievals.
type freezerdb struct {
	ethdb.KeyValueStore
	ethdb.AncientStore
}

// Close implements io.Closer, closing both the fast key-value store as well as
// the slow ancient tables.
func (frdb *freezerdb) Close() error {
	var errs []error
	if err := frdb.KeyValueStore.Close(); err != nil {
		errs = append(errs, err)
	}
	if err := frdb.AncientStore.Close(); err != nil {
		errs = append(errs, err)
	}
	if len(errs) != 0 {
		return fmt.Errorf("%v", errs)
	}
	return nil
}

// nofreezedb is a database wrapper that disables freezer data retrievals.
type nofreezedb struct {
	ethdb.KeyValueStore
}

// HasAncient returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) HasAncient(kind string, number uint64) (bool, error) {
	return false, errNotSupported
}

// Ancient returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) Ancient(kind string, number uint64) ([]byte, error) {
	return nil, errNotSupported
}

// Ancients returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) Ancients() (uint64, error) {
	return 0, errNotSupported
}

// AppendAncient returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) AppendAncient(number uint64, hash, header, body, receipts, td []byte) error {
	return errNotSupported
}

// TruncateAncients returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) TruncateAncients(items uint64) error {
	return errNotSupported
}

// Sync returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) Sync() error {
	return errNotSupported
}

// NewDatabase creates a high level database on top of a given key-value data
// store without a freezer moving immutable chain segments into cold storage.
func NewDatabase(db ethdb.KeyValueStore) ethdb.Database {
	return &nofreezedb{
		KeyValueStore: db,
	}
}

// NewDatabaseWithFreezer creates a high level database on top of a given key-
// value data store with a freezer moving immutable chain segments into cold
// storage.
func NewDatabaseWithFreezer(db ethdb.KeyValueStore, freezer string, namespace string) (ethdb.Database, error) {
	frdb, err := newFreezer(freezer, namespace)
	if err != nil {
		return nil, err
	}
	go frdb.freeze(db)

	return &freezerdb{
		KeyValueStore: db,
		AncientStore:  frdb,
	}, nil
}

// NewMemoryDatabase creates an ephemeral in-memory key-value database without a
// freezer moving immutable chain segments into cold storage.
func NewMemoryDatabase() ethdb.Database {
	return NewDatabase(memorydb.New())
}

// NewMemoryDatabaseWithCap creates an ephemeral in-memory key-value database
// with an initial starting capacity, but without a freezer moving immutable
// chain segments into cold storage.
func NewMemoryDatabaseWithCap(size int) ethdb.Database {
	return NewDatabase(memorydb.NewWithCap(size))
}

// NewLevelDBDatabase creates a persistent key-value database without a freezer
// moving immutable chain segments into cold storage.
func NewLevelDBDatabase(file string, cache int, handles int, namespace string) (ethdb.Database, error) {
	db, err := leveldb.New(file, cache, handles, namespace)
	if err != nil {
		return nil, err
	}
	return NewDatabase(db), nil
}

// NewLevelDBDatabaseWithFreezer creates a persistent key-value database with a
// freezer moving immutable chain segments into cold storage.
func NewLevelDBDatabaseWithFreezer(file string, cache int, handles int, freezer string, namespace string) (ethdb.Database, error) {
	kvdb, err := leveldb.New(file, cache, handles, namespace)
	if err != nil {
		return nil, err
	}
	frdb, err := NewDatabaseWithFreezer(kvdb, freezer, namespace)
	if err != nil {
		kvdb.Close()
		return nil, err
	}
	return frdb, nil
}