// 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 (
	"bytes"
	"errors"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/ethdb/leveldb"
	"github.com/ethereum/go-ethereum/ethdb/memorydb"
	"github.com/ethereum/go-ethereum/log"
	"github.com/harmony-one/harmony/internal/utils"
	"github.com/olekukonko/tablewriter"
)

var errNotSupported = errors.New("not supported")

// convertLegacyFn takes a raw freezer entry in an older format and
// returns it in the new format.
type convertLegacyFn = func([]byte) ([]byte, error)

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

// AncientDatadir returns the path of root ancient directory.
func (frdb *freezerdb) AncientDatadir() (string, error) {
	return frdb.ancientRoot, nil
}

// 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.AncientStore.Close(); err != nil {
		errs = append(errs, err)
	}
	if err := frdb.KeyValueStore.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
}

// AncientRange returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) AncientRange(kind string, start, max, maxByteSize 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
}

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

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

// ModifyAncients is not supported.
func (db *nofreezedb) ModifyAncients(func(ethdb.AncientWriteOp) error) (int64, error) {
	return 0, errNotSupported
}

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

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

func (db *nofreezedb) ReadAncients(fn func(reader ethdb.AncientReaderOp) error) (err error) {
	// Unlike other ancient-related methods, this method does not return
	// errNotSupported when invoked.
	// The reason for this is that the caller might want to do several things:
	// 1. Check if something is in freezer,
	// 2. If not, check leveldb.
	//
	// This will work, since the ancient-checks inside 'fn' will return errors,
	// and the leveldb work will continue.
	//
	// If we instead were to return errNotSupported here, then the caller would
	// have to explicitly check for that, having an extra clause to do the
	// non-ancient operations.
	return fn(db)
}

// MigrateTable processes the entries in a given table in sequence
// converting them to a new format if they're of an old format.
func (db *nofreezedb) MigrateTable(kind string, convert convertLegacyFn) error {
	return errNotSupported
}

// AncientDatadir returns an error as we don't have a backing chain freezer.
func (db *nofreezedb) AncientDatadir() (string, 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}
}

// resolveChainFreezerDir is a helper function which resolves the absolute path
// of chain freezer by considering backward compatibility.
// This function is NOT used, just ported over from the Ethereum
func resolveChainFreezerDir(ancient string) string {
	// Check if the chain freezer is already present in the specified
	// sub folder, if not then two possibilities:
	// - chain freezer is not initialized
	// - chain freezer exists in legacy location (root ancient folder)
	freezer := path.Join(ancient, chainFreezerName)
	if !common.FileExist(freezer) {
		if !common.FileExist(ancient) {
			// The entire ancient store is not initialized, still use the sub
			// folder for initialization.
		} else {
			// Ancient root is already initialized, then we hold the assumption
			// that chain freezer is also initialized and located in root folder.
			// In this case fallback to legacy location.
			freezer = ancient
			log.Info("Found legacy ancient chain path", "location", ancient)
		}
	}
	return freezer
}

// 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, readonly bool) (ethdb.Database, error) {
	db, err := leveldb.New(file, cache, handles, namespace, readonly)
	if err != nil {
		return nil, err
	}
	log.Info("Using LevelDB as the backing database")
	return NewDatabase(db), nil
}

const (
	dbPebble  = "pebble"
	dbLeveldb = "leveldb"
)

// hasPreexistingDb checks the given data directory whether a database is already
// instantiated at that location, and if so, returns the type of database (or the
// empty string).
func hasPreexistingDb(path string) string {
	if _, err := os.Stat(filepath.Join(path, "CURRENT")); err != nil {
		return "" // No pre-existing db
	}
	if matches, err := filepath.Glob(filepath.Join(path, "OPTIONS*")); len(matches) > 0 || err != nil {
		if err != nil {
			panic(err) // only possible if the pattern is malformed
		}
		return dbPebble
	}
	return dbLeveldb
}

// OpenOptions contains the options to apply when opening a database.
// OBS: If AncientsDirectory is empty, it indicates that no freezer is to be used.
type OpenOptions struct {
	Type              string // "leveldb" | "pebble"
	Directory         string // the datadir
	AncientsDirectory string // the ancients-dir
	Namespace         string // the namespace for database relevant metrics
	Cache             int    // the capacity(in megabytes) of the data caching
	Handles           int    // number of files to be open simultaneously
	ReadOnly          bool
}

// openKeyValueDatabase opens a disk-based key-value database, e.g. leveldb or pebble.
//
//	                      type == null          type != null
//	                   +----------------------------------------
//	db is non-existent |  leveldb default  |  specified type
//	db is existent     |  from db          |  specified type (if compatible)
func openKeyValueDatabase(o OpenOptions) (ethdb.Database, error) {
	existingDb := hasPreexistingDb(o.Directory)
	if len(existingDb) != 0 && len(o.Type) != 0 && o.Type != existingDb {
		return nil, fmt.Errorf("db.engine choice was %v but found pre-existing %v database in specified data directory", o.Type, existingDb)
	}
	if o.Type == dbPebble || existingDb == dbPebble {
		if PebbleEnabled {
			log.Info("Using pebble as the backing database")
			return NewPebbleDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
		} else {
			return nil, errors.New("db.engine 'pebble' not supported on this platform")
		}
	}
	if len(o.Type) != 0 && o.Type != dbLeveldb {
		return nil, fmt.Errorf("unknown db.engine %v", o.Type)
	}
	log.Info("Using leveldb as the backing database")
	// Use leveldb, either as default (no explicit choice), or pre-existing, or chosen explicitly
	return NewLevelDBDatabase(o.Directory, o.Cache, o.Handles, o.Namespace, o.ReadOnly)
}

type counter uint64

func (c counter) String() string {
	return fmt.Sprintf("%d", c)
}

func (c counter) Percentage(current uint64) string {
	return fmt.Sprintf("%d", current*100/uint64(c))
}

// stat stores sizes and count for a parameter
type stat struct {
	size  common.StorageSize
	count counter
}

// Add size to the stat and increase the counter by 1
func (s *stat) Add(size common.StorageSize) {
	s.size += size
	s.count++
}

func (s *stat) Size() string {
	return s.size.String()
}

func (s *stat) Count() string {
	return s.count.String()
}

// InspectDatabase traverses the entire database and checks the size
// of all different categories of data.
// This function is NOT used, just ported over from the Ethereum
func InspectDatabase(db ethdb.Database, keyPrefix, keyStart []byte) error {
	it := db.NewIterator(keyPrefix, keyStart)
	defer it.Release()

	var (
		count  int64
		start  = time.Now()
		logged = time.Now()

		// Key-value store statistics
		headers         stat
		bodies          stat
		receipts        stat
		tds             stat
		numHashPairings stat
		hashNumPairings stat
		tries           stat
		codes           stat
		txLookups       stat
		accountSnaps    stat
		storageSnaps    stat
		preimages       stat
		bloomBits       stat
		beaconHeaders   stat
		cliqueSnaps     stat

		// Les statistic
		chtTrieNodes   stat
		bloomTrieNodes stat

		// Meta- and unaccounted data
		metadata    stat
		unaccounted stat

		// Totals
		total common.StorageSize
	)
	// Inspect key-value database first.
	for it.Next() {
		var (
			key  = it.Key()
			size = common.StorageSize(len(key) + len(it.Value()))
		)
		total += size
		switch {
		case bytes.HasPrefix(key, headerPrefix) && len(key) == (len(headerPrefix)+8+common.HashLength):
			headers.Add(size)
		case bytes.HasPrefix(key, blockBodyPrefix) && len(key) == (len(blockBodyPrefix)+8+common.HashLength):
			bodies.Add(size)
		case bytes.HasPrefix(key, blockReceiptsPrefix) && len(key) == (len(blockReceiptsPrefix)+8+common.HashLength):
			receipts.Add(size)
		case bytes.HasPrefix(key, headerPrefix) && bytes.HasSuffix(key, headerTDSuffix):
			tds.Add(size)
		case bytes.HasPrefix(key, headerPrefix) && bytes.HasSuffix(key, headerHashSuffix):
			numHashPairings.Add(size)
		case bytes.HasPrefix(key, headerNumberPrefix) && len(key) == (len(headerNumberPrefix)+common.HashLength):
			hashNumPairings.Add(size)
		case len(key) == common.HashLength:
			tries.Add(size)
		case bytes.HasPrefix(key, CodePrefix) && len(key) == len(CodePrefix)+common.HashLength:
			codes.Add(size)
		case bytes.HasPrefix(key, txLookupPrefix) && len(key) == (len(txLookupPrefix)+common.HashLength):
			txLookups.Add(size)
		case bytes.HasPrefix(key, SnapshotAccountPrefix) && len(key) == (len(SnapshotAccountPrefix)+common.HashLength):
			accountSnaps.Add(size)
		case bytes.HasPrefix(key, SnapshotStoragePrefix) && len(key) == (len(SnapshotStoragePrefix)+2*common.HashLength):
			storageSnaps.Add(size)
		case bytes.HasPrefix(key, PreimagePrefix) && len(key) == (len(PreimagePrefix)+common.HashLength):
			preimages.Add(size)
		case bytes.HasPrefix(key, configPrefix) && len(key) == (len(configPrefix)+common.HashLength):
			metadata.Add(size)
		case bytes.HasPrefix(key, genesisPrefix) && len(key) == (len(genesisPrefix)+common.HashLength):
			metadata.Add(size)
		case bytes.HasPrefix(key, bloomBitsPrefix) && len(key) == (len(bloomBitsPrefix)+10+common.HashLength):
			bloomBits.Add(size)
		case bytes.HasPrefix(key, BloomBitsIndexPrefix):
			bloomBits.Add(size)
		case bytes.HasPrefix(key, skeletonHeaderPrefix) && len(key) == (len(skeletonHeaderPrefix)+8):
			beaconHeaders.Add(size)
		case bytes.HasPrefix(key, CliqueSnapshotPrefix) && len(key) == 7+common.HashLength:
			cliqueSnaps.Add(size)
		case bytes.HasPrefix(key, ChtTablePrefix) ||
			bytes.HasPrefix(key, ChtIndexTablePrefix) ||
			bytes.HasPrefix(key, ChtPrefix): // Canonical hash trie
			chtTrieNodes.Add(size)
		case bytes.HasPrefix(key, BloomTrieTablePrefix) ||
			bytes.HasPrefix(key, BloomTrieIndexPrefix) ||
			bytes.HasPrefix(key, BloomTriePrefix): // Bloomtrie sub
			bloomTrieNodes.Add(size)
		default:
			var accounted bool
			for _, meta := range [][]byte{
				databaseVersionKey, headHeaderKey, headBlockKey, headFastBlockKey, headFinalizedBlockKey,
				lastPivotKey, fastTrieProgressKey, snapshotDisabledKey, SnapshotRootKey, snapshotJournalKey,
				snapshotGeneratorKey, snapshotRecoveryKey, txIndexTailKey, fastTxLookupLimitKey,
				uncleanShutdownKey, badBlockKey, transitionStatusKey, skeletonSyncStatusKey,
			} {
				if bytes.Equal(key, meta) {
					metadata.Add(size)
					accounted = true
					break
				}
			}
			if !accounted {
				unaccounted.Add(size)
			}
		}
		count++
		if count%1000 == 0 && time.Since(logged) > 8*time.Second {
			log.Info("Inspecting database", "count", count, "elapsed", common.PrettyDuration(time.Since(start)))
			logged = time.Now()
		}
	}
	// Display the database statistic of key-value store.
	stats := [][]string{
		{"Key-Value store", "Headers", headers.Size(), headers.Count()},
		{"Key-Value store", "Bodies", bodies.Size(), bodies.Count()},
		{"Key-Value store", "Receipt lists", receipts.Size(), receipts.Count()},
		{"Key-Value store", "Difficulties", tds.Size(), tds.Count()},
		{"Key-Value store", "Block number->hash", numHashPairings.Size(), numHashPairings.Count()},
		{"Key-Value store", "Block hash->number", hashNumPairings.Size(), hashNumPairings.Count()},
		{"Key-Value store", "Transaction index", txLookups.Size(), txLookups.Count()},
		{"Key-Value store", "Bloombit index", bloomBits.Size(), bloomBits.Count()},
		{"Key-Value store", "Contract codes", codes.Size(), codes.Count()},
		{"Key-Value store", "Trie nodes", tries.Size(), tries.Count()},
		{"Key-Value store", "Trie preimages", preimages.Size(), preimages.Count()},
		{"Key-Value store", "Account snapshot", accountSnaps.Size(), accountSnaps.Count()},
		{"Key-Value store", "Storage snapshot", storageSnaps.Size(), storageSnaps.Count()},
		{"Key-Value store", "Beacon sync headers", beaconHeaders.Size(), beaconHeaders.Count()},
		{"Key-Value store", "Clique snapshots", cliqueSnaps.Size(), cliqueSnaps.Count()},
		{"Key-Value store", "Singleton metadata", metadata.Size(), metadata.Count()},
		{"Light client", "CHT trie nodes", chtTrieNodes.Size(), chtTrieNodes.Count()},
		{"Light client", "Bloom trie nodes", bloomTrieNodes.Size(), bloomTrieNodes.Count()},
	}
	// Inspect all registered append-only file store then.
	ancients, err := inspectFreezers(db)
	if err != nil {
		return err
	}
	for _, ancient := range ancients {
		for _, table := range ancient.sizes {
			stats = append(stats, []string{
				fmt.Sprintf("Ancient store (%s)", strings.Title(ancient.name)),
				strings.Title(table.name),
				table.size.String(),
				fmt.Sprintf("%d", ancient.count()),
			})
		}
		total += ancient.size()
	}
	table := tablewriter.NewWriter(os.Stdout)
	table.SetHeader([]string{"Database", "Category", "Size", "Items"})
	table.SetFooter([]string{"", "Total", total.String(), " "})
	table.AppendBulk(stats)
	table.Render()

	if unaccounted.size > 0 {
		utils.Logger().Error().
			Interface("size", unaccounted.size).
			Interface("count", unaccounted.count).
			Msg("Database contains unaccounted data")
	}
	return nil
}