"""Converts tracks or albums to external directory
"""
import logging
import os
import threading
import shutil
from subprocess import Popen, PIPE

import imghdr

from beets.plugins import BeetsPlugin
from beets import ui, library, util, mediafile

log = logging.getLogger('beets')
DEVNULL = open(os.devnull, 'wb')
conf = {}

def _embed(path, items):
    """Embed an image file, located at `path`, into each item.
    """
    data = open(util.syspath(path), 'rb').read()
    kindstr = imghdr.what(None, data)
    if kindstr not in ('jpeg', 'png'):
        log.error('A file of type %s is not allowed as coverart.' % kindstr)
        return
    log.debug('Embedding album art.')
    for item in items:
        try:
            f = mediafile.MediaFile(util.syspath(item.path))
        except mediafile.UnreadableFileError as exc:
            log.warn('Could not embed art in {0}: {1}'.format(
                repr(item.path), exc
            ))
            continue
        f.art = data
        f.save()

def encode(source, dest):
    log.info('Started encoding '+ source)
    temp_dest = dest + '~'

    source_ext = os.path.splitext(source)[1].lower()
    if source_ext == '.flac':
        decode = Popen([conf['flac'], '-c', '-d', '-s', source],
                       stdout=PIPE)
        encode = Popen([conf['lame']] + conf['opts'] + ['-', temp_dest],
                   stdin=decode.stdout, stderr=DEVNULL)
        decode.stdout.close()
        encode.communicate()
    elif source_ext == '.mp3':
        encode = Popen([conf['lame']] + conf['opts'] + ['--mp3input'] +
             [source, temp_dest], close_fds=True, stderr=DEVNULL)
        encode.communicate()
    else:
        log.error('Only converting from FLAC or MP3 implemented')
        return
    shutil.move(temp_dest, dest)
    log.info('Finished encoding '+ source)


def convert_item(lib, dest_dir):
    while True:
        item = yield
        if item.format != 'FLAC' and item.format != 'MP3':
            log.info('Skipping {0} : not supported format'.format(item.path))
            continue

        dest = os.path.join(dest_dir,lib.destination(item, fragment = True))
        dest = os.path.splitext(dest)[0] + '.mp3'

        if os.path.exists(dest):
            log.info('Skipping {0} : target file exists'.format(item.path))
            continue

        util.mkdirall(dest)
        if item.format == 'MP3' and item.bitrate < 1000*conf['max_bitrate']:
            log.info('Copying {0}'.format(item.path))
            shutil.copy(item.path, dest)
            dest_item = library.Item.from_path(dest)
        else:
            encode(item.path, dest)
            dest_item = library.Item.from_path(item.path)
            dest_item.path = dest
            dest_item.write()

        artpath = lib.get_album(item).artpath
        if artpath and conf['embed']:
            _embed(artpath,[dest_item])


def generator(items):
     for item in items:
        yield item


def convert_func(lib, config, opts, args):
    dest = opts.dest if opts.dest is not None else conf['dest']
    if not dest:
        log.error('No destination set')
        return
    threads = opts.threads if opts.threads is not None else conf['threads']

    fmt = '$albumartist - $album' if opts.album \
                                  else '$artist - $album - $title'
    ui.commands.list_items(lib, ui.decargs(args), opts.album, False, fmt)

    if not ui.input_yn("Convert? (Y/n)"):
        return

    if opts.album:
        items = (i for a in lib.albums(ui.decargs(args)) for i in a.items())
    else:
        items = lib.items(ui.decargs(args))
        items = generator(items)
    convert = [convert_item(lib, dest) for i in range(threads)]
    pipe = util.pipeline.Pipeline([items, convert])
    pipe.run_parallel()


class ConvertPlugin(BeetsPlugin):
    def configure(self, config):
        conf['dest'] = ui.config_val(config, 'convert', 'dest', None)
        conf['threads'] = ui.config_val(config, 'convert', 'threads', 2)
        conf['flac'] = ui.config_val(config, 'convert', 'flac', 'flac')
        conf['lame'] = ui.config_val(config, 'convert', 'lame', 'lame')
        conf['opts'] = ui.config_val(config, 'convert',
                                     'opts', '-V2').split(' ')
        conf['max_bitrate'] = int(ui.config_val(config, 'convert',
                                                'max_bitrate','500'))
        conf['embed'] = ui.config_val(config, 'convert', 'embed', True,
                                      vtype = bool)


    def commands(self):
        cmd = ui.Subcommand('convert', help='convert to external location')
        cmd.parser.add_option('-a', '--album', action='store_true',
                        help='choose albums instead of tracks')
        cmd.parser.add_option('-t', '--threads', action='store', type='int',
                        help='change the number of threads (default 2)')
        cmd.parser.add_option('-d', '--dest', action='store',
                        help='set the destination directory')
        cmd.func = convert_func
        return [cmd]