//
//  tank
//
//  Import and Playlist Daemon for autoradio project
//
//
//  Copyright (C) 2017 Christian Pointner <equinox@helsinki.at>
//
//  This file is part of tank.
//
//  tank is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  any later version.
//
//  tank 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 General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with tank. If not, see <http://www.gnu.org/licenses/>.
//

package store

import (
	"encoding/json"
	"errors"

	"github.com/coreos/bbolt"
)

func getFilesBucket(tx *bolt.Tx, group string) (files *bolt.Bucket, err error) {
	var gb *bolt.Bucket
	if gb, err = getGroupBucket(tx, group); err != nil {
		return
	}
	if gb == nil {
		if !tx.Writable() {
			return // for read-only transactions this function might return files = nil
		}
		if gb, err = createGroup(tx, group); err != nil {
			return
		}
	}
	files = gb.Bucket([]byte(filesBn))
	if files == nil {
		err = errors.New("invalid store: files bucket of group '" + group + "' not found")
	}
	return
}

func (st *Store) ListFiles(group string) (files Files, err error) {
	err = st.db.View(func(tx *bolt.Tx) error {
		fb, err := getFilesBucket(tx, group)
		if err != nil {
			return err
		}
		if fb == nil { // this is a read-only transaction getFilesBucket might return fb = nil
			return nil
		}
		files = make(Files)

		c := fb.Cursor()
		for k, v := c.First(); k != nil; k, v = c.Next() {
			var file File
			if err := json.Unmarshal(v, &file); err != nil {
				return err
			}
			files[btoi(k)] = file
		}
		return err
	})
	return
}

func (st *Store) CreateFile(group string, file File) (id uint64, err error) {
	err = st.db.Update(func(tx *bolt.Tx) error {
		fb, err := getFilesBucket(tx, group)
		if err != nil {
			return err
		}
		if id, err = getNextID(tx); err != nil {
			return err
		}
		bFile, err := json.Marshal(file)
		if err != nil {
			return err
		}
		// TODO: update affiliation with auto-playlists
		return fb.Put(itob(id), bFile)
	})
	return
}

func (st *Store) GetFile(group string, id uint64) (file File, err error) {
	err = st.db.View(func(tx *bolt.Tx) error {
		fb, err := getFilesBucket(tx, group)
		if err != nil {
			return err
		}
		if fb == nil { // this is a read-only transaction getFilesBucket might return fb = nil
			return ErrNotFound
		}
		bFile := fb.Get(itob(id))
		if bFile == nil {
			return ErrNotFound
		}
		return json.Unmarshal(bFile, &file)
	})
	return
}

func (st *Store) UpdateFile(group string, id uint64, file File) (err error) {
	err = st.db.Update(func(tx *bolt.Tx) error {
		fb, err := getFilesBucket(tx, group)
		if err != nil {
			return err
		}
		bFile := fb.Get(itob(id))
		if bFile == nil {
			return ErrNotFound
		}
		bFile, err = json.Marshal(file)
		if err != nil {
			return err
		}
		// TODO: update metdata fileheader
		// TODO: update affiliation with auto-playlists
		return fb.Put(itob(id), bFile)
	})
	return
}

func (st *Store) DeleteFile(group string, id uint64) (err error) {
	err = st.db.Update(func(tx *bolt.Tx) error {
		fb, err := getFilesBucket(tx, group)
		if err != nil {
			return err
		}
		bFile := fb.Get(itob(id))
		if bFile == nil {
			return ErrNotFound
		}
		var file File
		if err = json.Unmarshal(bFile, &file); err != nil {
			return err
		}
		if len(file.UsedBy) > 0 {
			return ErrFileInUse
		}
		// TODO: remove file from auto-playlists
		// TODO: delete file in filesystem
		return fb.Delete(itob(id))
	})
	return
}