#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import datetime as dt
import mutagen
import mutagen.id3
import mutagen.mp4
import os
import re
import symuid.library.itunes
import sys


def generate_play_count_tag_label(player, library_id, reg_dt):
    return 'symuid:pcnt:{}:{}:{}'.format(player, library_id, int(reg_dt.timestamp()))


def set_play_count_tag(track_path, player, library_id, reg_dt, play_count):
    assert isinstance(reg_dt, dt.datetime), reg_dt
    tag_label = generate_play_count_tag_label(
        player=player,
        library_id=library_id,
        reg_dt=reg_dt,
    )
    track = mutagen.File(filename=track_path)
    if isinstance(track.tags, mutagen.id3.ID3):
        tag_label_id3 = 'TXXX:' + tag_label
        if not tag_label_id3 in track.tags:
            # mutagen.id3._specs.EncodedTextSpec.write encodes
            # 'desc' and 'text'
            tag = mutagen.id3.TXXX(
                encoding=mutagen.id3.Encoding.LATIN1,
                desc=tag_label,
                text=[str(play_count)],
            )
            track.tags.add(tag)
            track.save()
            print('{!r}: set ID3 tag {!r}'.format(track_path, tag))
    elif isinstance(track.tags, mutagen.mp4.MP4Tags):
        tag_label_mp4 = '----:' + tag_label
        if not tag_label_mp4 in track.tags:
            track.tags[tag_label_mp4] = tag = mutagen.mp4.MP4FreeForm(
                # "a signed big-endian integer with length one of { 1,2,3,4,8 } bytes"
                # TODO set byte length properly
                # setting signed=True just to be explicit here
                #  (irrelevant for positive integers)
                data=play_count.to_bytes(1, byteorder='big', signed=True),
                dataformat=mutagen.mp4.AtomDataType.INTEGER,
            )
            track.save()
            print('{!r}: set MP4 tag {!r}'.format(track_path, tag))
    else:
        raise Exception(track_path)


def symuid_import_itunes(xml_library_path, path_regex_sub):
    lib = symuid.library.itunes.XmlLibrary(xml_library_path)
    for track in lib.tracks:
        # TODO create tag if last_play_dt is None
        if track.last_play_dt and track.local:
            track_path = track.local_path
            for pattern, repl in path_regex_sub:
                track_path = re.sub(pattern, repl, track_path)
            if not os.path.exists(track_path):
                sys.stderr.write('{!r}: not found\n'.format(track_path))
            else:
                # TODO dt=dt.datetime.now()
                set_play_count_tag(
                    track_path=track_path,
                    player='itunes',
                    library_id=lib.id,
                    reg_dt=track.last_play_dt,
                    play_count=track.play_count,
                )


def _init_argparser():
    import argparse
    argparser = argparse.ArgumentParser(description=None)
    argparser.add_argument('xml_library_path')
    argparser.add_argument(
        '--path-regex-sub',
        nargs=2,
        action='append',
        metavar=('regex', 'replacement'),
        default=[],
        help='(default: %(default)r)',
    )
    return argparser


def main(argv):
    argparser = _init_argparser()
    args = argparser.parse_args(argv[1:])
    symuid_import_itunes(**vars(args))
    return 0

if __name__ == "__main__":
    sys.exit(main(sys.argv))