// VulcanizeDB
// Copyright © 2020 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 ipfseth

import (
	"errors"
	"fmt"
	"strings"

	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/jmoiron/sqlx"
)

var errNotSupported = errors.New("this operation is not supported")

var (
	hasPgStr    = "SELECT exists(select 1 from public.blocks WHERE key = $1)"
	getPgStr    = "SELECT data FROM public.blocks WHERE key = $1"
	putPgStr    = "INSERT INTO public.blocks (key, data) VALUES ($1, $2) ON CONFLICT (key) DO NOTHING"
	deletePgStr = "DELETE FROM public.blocks WHERE key = $1"
)

type Database struct {
	db *sqlx.DB
}

func NewKeyValueStore(db *sqlx.DB) ethdb.KeyValueStore {
	return &Database{
		db: db,
	}
}

func NewDatabase(db *sqlx.DB) ethdb.Database {
	return &Database{
		db: db,
	}
}

// Has satisfies the ethdb.KeyValueReader interface
// Has retrieves if a key is present in the key-value data store
func (d *Database) Has(key []byte) (bool, error) {
	mhKey, err := MultihashKeyFromKeccak256(key)
	if err != nil {
		return false, err
	}
	var exists bool
	return exists, d.db.Get(&exists, hasPgStr, mhKey)
}

// Get satisfies the ethdb.KeyValueReader interface
// Get retrieves the given key if it's present in the key-value data store
func (d *Database) Get(key []byte) ([]byte, error) {
	mhKey, err := MultihashKeyFromKeccak256(key)
	if err != nil {
		return nil, err
	}
	var data []byte
	return data, d.db.Get(&data, getPgStr, mhKey)
}

// Put satisfies the ethdb.KeyValueWriter interface
// Put inserts the given value into the key-value data store
func (d *Database) Put(key []byte, value []byte) error {
	mhKey, err := MultihashKeyFromKeccak256(key)
	if err != nil {
		return err
	}
	_, err = d.db.Exec(putPgStr, mhKey, value)
	return err
}

// Delete satisfies the ethdb.KeyValueWriter interface
// Delete removes the key from the key-value data store
func (d *Database) Delete(key []byte) error {
	mhKey, err := MultihashKeyFromKeccak256(key)
	if err != nil {
		return err
	}
	_, err = d.db.Exec(deletePgStr, mhKey)
	return err
}

// DatabaseProperty enum type
type DatabaseProperty int

const (
	Unknown DatabaseProperty = iota
	Size
	Idle
	InUse
	MaxIdleClosed
	MaxLifetimeClosed
	MaxOpenConnections
	OpenConnections
	WaitCount
	WaitDuration
)

// DatabasePropertyFromString helper function
func DatabasePropertyFromString(property string) (DatabaseProperty, error) {
	switch strings.ToLower(property) {
	case "size":
		return Size, nil
	case "idle":
		return Idle, nil
	case "inuse":
		return InUse, nil
	case "maxidleclosed":
		return MaxIdleClosed, nil
	case "maxlifetimeclosed":
		return MaxLifetimeClosed, nil
	case "maxopenconnections":
		return MaxOpenConnections, nil
	case "openconnections":
		return OpenConnections, nil
	case "waitcount":
		return WaitCount, nil
	case "waitduration":
		return WaitDuration, nil
	default:
		return Unknown, fmt.Errorf("unknown database property")
	}
}

// Stat satisfies the ethdb.Stater interface
// Stat returns a particular internal stat of the database
func (d *Database) Stat(property string) (string, error) {
	prop, err := DatabasePropertyFromString(property)
	if err != nil {
		return "", err
	}
	switch prop {
	case Size:
		pgStr := "SELECT pg_database_size(current_database())"
		var byteSize string
		return byteSize, d.db.Get(&byteSize, pgStr)
	case Idle:
		return string(d.db.Stats().Idle), nil
	case InUse:
		return string(d.db.Stats().InUse), nil
	case MaxIdleClosed:
		return string(d.db.Stats().MaxIdleClosed), nil
	case MaxLifetimeClosed:
		return string(d.db.Stats().MaxLifetimeClosed), nil
	case MaxOpenConnections:
		return string(d.db.Stats().MaxOpenConnections), nil
	case OpenConnections:
		return string(d.db.Stats().OpenConnections), nil
	case WaitCount:
		return string(d.db.Stats().WaitCount), nil
	case WaitDuration:
		return d.db.Stats().WaitDuration.String(), nil
	default:
		return "", fmt.Errorf("unhandled database property")
	}
}

// Compact satisfies the ethdb.Compacter interface
// Compact flattens the underlying data store for the given key range
func (d *Database) Compact(start []byte, limit []byte) error {
	return errNotSupported
}

// NewBatch satisfies the ethdb.Batcher interface
// NewBatch creates a write-only database that buffers changes to its host db
// until a final write is called
func (d *Database) NewBatch() ethdb.Batch {
	return NewBatch(d.db)
}

// NewIterator satisfies the ethdb.Iteratee interface
// it creates a binary-alphabetical iterator over a subset
// of database content with a particular key prefix, starting at a particular
// initial key (or after, if it does not exist).
//
// Note: This method assumes that the prefix is NOT part of the start, so there's
// no need for the caller to prepend the prefix to the start
func (d *Database) NewIterator(prefix []byte, start []byte) ethdb.Iterator {
	return NewIterator([]byte{}, []byte{}, d.db)
}

// Close satisfies the io.Closer interface
// Close closes the db connection
func (d *Database) Close() error {
	return d.db.DB.Close()
}

// HasAncient satisfies the ethdb.AncientReader interface
// HasAncient returns an indicator whether the specified data exists in the ancient store
func (d *Database) HasAncient(kind string, number uint64) (bool, error) {
	return false, errNotSupported
}

// Ancient satisfies the ethdb.AncientReader interface
// Ancient retrieves an ancient binary blob from the append-only immutable files
func (d *Database) Ancient(kind string, number uint64) ([]byte, error) {
	return nil, errNotSupported
}

// Ancients satisfies the ethdb.AncientReader interface
// Ancients returns the ancient item numbers in the ancient store
func (d *Database) Ancients() (uint64, error) {
	return 0, errNotSupported
}

// AncientSize satisfies the ethdb.AncientReader interface
// AncientSize returns the ancient size of the specified category
func (d *Database) AncientSize(kind string) (uint64, error) {
	return 0, errNotSupported
}

// AppendAncient satisfies the ethdb.AncientWriter interface
// AppendAncient injects all binary blobs belong to block at the end of the append-only immutable table files
func (d *Database) AppendAncient(number uint64, hash, header, body, receipt, td []byte) error {
	return errNotSupported
}

// TruncateAncients satisfies the ethdb.AncientWriter interface
// TruncateAncients discards all but the first n ancient data from the ancient store
func (d *Database) TruncateAncients(n uint64) error {
	return errNotSupported
}

// Sync satisfies the ethdb.AncientWriter interface
// Sync flushes all in-memory ancient store data to disk
func (d *Database) Sync() error {
	return errNotSupported
}