#!/usr/bin/env python

import argparse
import os
import shutil
import tempfile

from config import Config
from log import DEBUG, INFO
from model import Notes, Playdates, PlaylistTracks, Session, Tracks
from mutagen.flac import FLAC
from mutagen.mp3 import MP3
from pydub import AudioSegment, effects
from tinytag import TinyTag


def main():
    "Main loop"

    INFO("Starting")

    # Parse command line
    p = argparse.ArgumentParser()
    p.add_argument('-u', '--update',
                   action="store_true", dest="update",
                   default=False, help="Update database")
    p.add_argument('-f', '--full-update',
                   action="store_true", dest="full_update",
                   default=False, help="Update database")
    args = p.parse_args()

    # Run as required
    if args.update:
        INFO("Updating database")
        with Session() as session:
            update_db(session)
    elif args.full_update:
        INFO("Full update of database")
        with Session() as session:
            full_update_db(session)
    else:
        INFO("No action specified")

    INFO("Finished")


def create_track_from_file(session, path):
    """
    Create track in database from passed path, or update database entry
    if path already in database.

    Return track.
    """

    track = Tracks.get_or_create(session, path)
    t = get_music_info(path)
    track.title = t['title']
    track.artist = t['artist']
    track.duration = int(round(
        t['duration'], Config.MILLISECOND_SIGFIGS) * 1000)

    audio = get_audio_segment(path)
    track.start_gap = leading_silence(audio)
    track.fade_at = round(fade_point(audio) / 1000,
                          Config.MILLISECOND_SIGFIGS) * 1000
    track.silence_at = round(trailing_silence(audio) / 1000,
                             Config.MILLISECOND_SIGFIGS) * 1000
    track.mtime = os.path.getmtime(path)
    session.commit()

    if Config.NORMALISE_ON_IMPORT:
        # Check type
        ftype = os.path.splitext(path)[1][1:]
        if ftype not in ['mp3', 'flac']:
            INFO(f"File type {ftype} not implemented")
            return track

        # Get current file gid, uid and permissions
        stats = os.stat(path)
        try:
            # Copy original file
            fd, temp_path = tempfile.mkstemp()
            shutil.copyfile(path, temp_path)
        except Exception as err:
            DEBUG(f"songdb.create_track_from_file({path}): err1: {str(err)}")
            return

        # Overwrite original file with normalised output
        normalised = effects.normalize(audio)
        try:
            normalised.export(path, format=os.path.splitext(path)[1][1:])
            # Fix up permssions and ownership
            os.chown(path, stats.st_uid, stats.st_gid)
            os.chmod(path, stats.st_mode)
            # Copy tags
            if ftype == 'flac':
                tag_handler = FLAC
            elif ftype == 'mp3':
                tag_handler = MP3
            else:
                return track
            src = tag_handler(temp_path)
            dst = tag_handler(path)
            for tag in src:
                dst[tag] = src[tag]
            dst.save()
        except Exception as err:
            DEBUG(f"songdb.create_track_from_file({path}): err2: {str(err)}")
            # Restore original file
            shutil.copyfile(path, temp_path)
        finally:
            if os.path.exists(temp_path):
                os.remove(temp_path)

    return track


def full_update_db(session):
    "Rescan all entries in database"

    def log(msg):
        INFO(f"full_update_db(): {msg}")

    def check_change(track_id, title, attribute, old, new):
        if new > (old * 1.1) or new < (old * 0.9):
            log(
                "\n"
                f"track[{track_id}] ({title}) "
                f"{attribute} updated from {old} to {new}"
            )

    # Start with normal update to add new tracks and remove any missing
    # files
    log("update_db()")
    update_db(session)

    # Now update track length, silence and fade for every track in
    # database

    tracks = Tracks.get_all_tracks(session)
    total_tracks = len(tracks)
    log(f"Processing {total_tracks} tracks")
    track_count = 0
    for track in tracks:
        track_count += 1
        print(f"\rTrack {track_count} of {total_tracks}", end='')

        # Sanity check
        tag = get_music_info(track.path)
        if not tag['title']:
            log(f"track[{track.id}] {track.title=}: No tag title")
            continue

        if track.artist:
            if track.artist != tag['artist']:
                log(
                    f"track[{track.id}] artist mismatch: "
                    f"{track.artist=} {tag['artist']=}"
                )
                continue

        # Update title
        if track.title != tag['title']:
            track.title = tag['title']

        # Update numbers; log if more than 10% different
        duration = int(round(
            tag['duration'], Config.MILLISECOND_SIGFIGS) * 1000)
        check_change(track.id, track.title, "duration", track.duration,
                     duration)
        track.duration = duration

        audio = get_audio_segment(track.path)

        start_gap = leading_silence(audio)
        check_change(track.id, track.title, "start_gap", track.start_gap,
                     start_gap)
        track.start_gap = start_gap

        fade_at = fade_point(audio)
        check_change(track.id, track.title, "fade_at", track.fade_at,
                     fade_at)
        track.fade_at = fade_at

        silence_at = trailing_silence(audio)
        check_change(track.id, track.title, "silence_at", track.silence_at,
                     silence_at)
        track.silence_at = silence_at
        session.commit()


def get_audio_segment(path):
    try:
        if path.endswith('.mp3'):
            return AudioSegment.from_mp3(path)
        elif path.endswith('.flac'):
            return AudioSegment.from_file(path, "flac")
    except AttributeError:
        return None


def get_music_info(path):
    """
    Return a dictionary of title, artist, duration-in-milliseconds and path.
    """

    tag = TinyTag.get(path)

    return dict(
        title=tag.title,
        artist=tag.artist,
        duration=tag.duration,
        path=path
    )


def leading_silence(audio_segment, silence_threshold=Config.DBFS_SILENCE,
                    chunk_size=Config.AUDIO_SEGMENT_CHUNK_SIZE):
    """
    Returns the millisecond/index that the leading silence ends.
    audio_segment - the segment to find silence in
    silence_threshold - the upper bound for how quiet is silent in dFBS
    chunk_size - chunk size for interating over the segment in ms

    https://github.com/jiaaro/pydub/blob/master/pydub/silence.py
    """

    trim_ms = 0  # ms
    assert chunk_size > 0  # to avoid infinite loop
    while (
        audio_segment[trim_ms:trim_ms + chunk_size].dBFS <      # noqa W504
            silence_threshold and trim_ms < len(audio_segment)):
        trim_ms += chunk_size

    # if there is no end it should return the length of the segment
    return min(trim_ms, len(audio_segment))


def fade_point(audio_segment, fade_threshold=0,
               chunk_size=Config.AUDIO_SEGMENT_CHUNK_SIZE):
    """
    Returns the millisecond/index of the point where the volume drops below
    the maximum and doesn't get louder again.
    audio_segment - the sdlg_search_database_uiegment to find silence in
    fade_threshold - the upper bound for how quiet is silent in dFBS
    chunk_size - chunk size for interating over the segment in ms
    """

    assert chunk_size > 0  # to avoid infinite loop

    segment_length = audio_segment.duration_seconds * 1000  # ms
    trim_ms = segment_length - chunk_size
    max_vol = audio_segment.dBFS
    if fade_threshold == 0:
        fade_threshold = max_vol

    while (
        audio_segment[trim_ms:trim_ms + chunk_size].dBFS < fade_threshold
            and trim_ms > 0):       # noqa W503
        trim_ms -= chunk_size

    # if there is no trailing silence, return lenght of track (it's less
    # the chunk_size, but for chunk_size = 10ms, this may be ignored)
    return int(trim_ms)


def trailing_silence(audio_segment, silence_threshold=-50.0,
                     chunk_size=Config.AUDIO_SEGMENT_CHUNK_SIZE):
    return fade_point(audio_segment, silence_threshold, chunk_size)


def update_db(session):
    """
    Repopulate database
    """

    # Search for tracks in only one of directory and database

    db_paths = set(Tracks.get_all_paths(session))

    os_paths_list = []
    for root, dirs, files in os.walk(Config.ROOT):
        for f in files:
            path = os.path.join(root, f)
            ext = os.path.splitext(f)[1]
            if ext in [".flac", ".mp3"]:
                os_paths_list.append(path)
    os_paths = set(os_paths_list)

    # If a track is moved, only the path will have changed.
    # For any files we have found whose paths are not in the database,
    # check to see whether the filename (basename) is present in the
    # database:

    for path in list(os_paths - db_paths):
        DEBUG(f"songdb.update_db: {path=} not in database")
        # is filename in database?
        track = Tracks.get_track_from_filename(session, os.path.basename(path))
        if not track:
            INFO(f"songdb.update_db: Adding to database: {path}")
            create_track_from_file(session, path)
        else:
            # Check track info matches found track
            t = get_music_info(path)
            if t['artist'] == track.artist and t['title'] == track.title:
                track.update_path(path)
            else:
                create_track_from_file(session, path)

    # Refresh database paths
    db_paths = set(Tracks.get_all_paths(session))
    # Remote any tracks from database whose paths don't exist
    for path in list(db_paths - os_paths):
        # Manage tracks listed in database but where path is invalid
        track = Tracks.get_track_from_path(session, path)
        INFO(f"songdb.update_db(): remove from database: {path=} {track=}")

        # Remove references from Playdates
        Playdates.remove_track(session, track.id)

        # Replace playlist entries with a note
        note_txt = (
            f"File removed: {track.title=}, {track.artist=}, "
            f"{track.path=}"
        )
        for pt in PlaylistTracks.get_track_playlists(session, track.id):
            # Create note
            Notes.add_note(session, pt.playlist_id, pt.row, note_txt)
            # Remove playlist entry
            PlaylistTracks.remove_track(session, pt.playlist_id, pt.row)

        # Remove Track entry pointing to invalid path
        Tracks.remove_path(session, path)


if __name__ == '__main__' and '__file__' in globals():
    main()