import threading
import pydub
import math
import time
from transitions.extensions import HierarchicalMachine as Machine

import pyaudio as pa
import sounddevice as sd
import os.path

from .lock import Lock
file_lock = Lock("file")

pyaudio = pa.PyAudio()

class MusicFile(Machine):
    def __init__(self, filename, name = None, gain = 1):
        states = [
            'initial',
            'loading',
            'failed',
            { 'name': 'loaded', 'children': ['stopped', 'playing', 'paused', 'stopping'] }
        ]
        transitions = [
            { 'trigger': 'load', 'source':  'initial', 'dest': 'loading'},
            { 'trigger': 'fail', 'source':  'loading', 'dest': 'failed'},
            { 'trigger': 'success', 'source':  'loading', 'dest': 'loaded_stopped'},
            { 'trigger': 'start_playing', 'source':  'loaded_stopped', 'dest': 'loaded_playing'},
            { 'trigger': 'pause', 'source':  'loaded_playing', 'dest': 'loaded_paused'},
            { 'trigger': 'unpause', 'source':  'loaded_paused', 'dest': 'loaded_playing'},
            { 'trigger': 'stop_playing', 'source': ['loaded_playing','loaded_paused'], 'dest': 'loaded_stopping'},
            { 'trigger': 'stopped', 'source':  'loaded_stopping', 'dest': 'loaded_stopped'}
        ]

        Machine.__init__(self, states=states, transitions=transitions, initial='initial')

        self.filename = filename
        self.stream = None
        self.name = name or filename
        self.audio_segment = None
        self.gain = gain
        self.music_lock = Lock("music__" + filename)

        self.flag_paused = False
        threading.Thread(name = "MSMusicLoad", target = self.load).start()

    def on_enter_loading(self):
        with file_lock:
            try:
                print("Loading « {} »".format(self.name))
                volume_factor = 20 * math.log10(self.gain)
                self.audio_segment = pydub.AudioSegment.from_file(self.filename).set_frame_rate(44100).apply_gain(volume_factor)
                self.sound_duration = self.audio_segment.duration_seconds
            except Exception as e:
                print("failed to load « {} »: {}".format(self.name, e))
                self.loading_error = e
                self.fail()
            else:
                self.success()
                print("Loaded « {} »".format(self.name))

    def check_is_loaded(self):
        return self.state.startswith('loaded_')

    def is_not_stopped(self):
        return self.check_is_loaded() and not self.is_loaded_stopped()

    def is_paused(self):
        return self.is_loaded_paused()

    @property
    def sound_position(self):
        if self.is_not_stopped():
            return self.current_frame / self.current_audio_segment.frame_rate
        else:
            return 0

    def play(self, fade_in = 0, volume = 100, start_at = 0):
        self.db_gain = self.volume_to_gain(volume)
        ms = int(start_at * 1000)
        ms_fi = max(1, int(fade_in * 1000))
        with self.music_lock:
            self.current_audio_segment = (self.audio_segment + self.db_gain).fade(from_gain=-120, duration=ms_fi, start=ms)
        self.before_loaded_playing(initial_frame = int(start_at * self.audio_segment.frame_rate))
        self.start_playing()

    def before_loaded_playing(self, initial_frame = 0):
        self.current_frame = initial_frame
        with self.music_lock:
            segment = self.current_audio_segment

            self.stream = sd.RawOutputStream(samplerate=segment.frame_rate,
                            channels=segment.channels,
                            dtype='int' + str(8*segment.sample_width), # FIXME: ?
                            latency=1.,
                            callback=self.play_callback,
                            finished_callback=self.finished_callback
                            )

    def on_enter_loaded_playing(self):
        self.stream.start()

    def on_enter_loaded_paused(self):
        self.stream.stop()

    def finished_callback(self):
        if self.is_loaded_playing():
            self.stop_playing()
        if self.is_loaded_stopping():
            self.stopped()

    def play_callback(self, out_data, frame_count, time_info, status_flags):
        with self.music_lock:
            audio_segment = self.current_audio_segment.get_sample_slice_data(
                                start_sample=self.current_frame,
                                end_sample=self.current_frame + frame_count
                                )
            self.current_frame += frame_count
            if len(audio_segment) == 0:
                raise sd.CallbackStop

            out_data[:] = audio_segment.ljust(len(out_data), b'\0')

    def stop(self, fade_out = 0):
        if self.is_loaded_playing():
            ms = int(self.sound_position * 1000)
            ms_fo = max(1, int(fade_out * 1000))

            with self.music_lock:
                self.current_audio_segment = self.current_audio_segment[:ms + ms_fo].fade_out(ms_fo)
                self.stop_playing()
        else:
            self.stop_playing()
            self.stopped()

    def set_volume(self, value):
        if self.is_loaded_stopped():
            return

        db_gain = self.volume_to_gain(value)
        new_audio_segment = self.current_audio_segment + (db_gain - self.db_gain)
        self.db_gain = db_gain
        with self.music_lock:
            self.current_audio_segment = new_audio_segment

    def volume_to_gain(self, volume):
        return 20 * math.log10(max(volume, 0.0001) / 100)

    def wait_end(self):
        # FIXME: todo
        pass

# Add some more functions to AudioSegments
def get_sample_slice_data(self, start_sample=0, end_sample=float('inf')):
    max_val = int(self.frame_count())

    start_i = max(start_sample, 0) * self.frame_width
    end_i =   min(end_sample, max_val) * self.frame_width

    return self._data[start_i:end_i]

pydub.AudioSegment.get_sample_slice_data = get_sample_slice_data