#!/usr/bin/env python

"""
Example code from here: https://github.com/dnet/pySSTV/blob/master/pysstv/examples/pyaudio_sstv.py
"""


from __future__ import division
from pysstv.sstv import SSTV
from time import sleep
from itertools import islice
import struct, pyaudio


class PyAudioSSTV(object):
    def __init__(self, sstv):
        self.pa = pyaudio.PyAudio()
        self.sstv = sstv
        self.fmt = "<" + SSTV.BITS_TO_STRUCT[sstv.bits]

    def __del__(self):
        self.pa.terminate()

    def execute(self):
        self.sampler = self.sstv.gen_samples()
        stream = self.pa.open(
            format=self.pa.get_format_from_width(self.sstv.bits // 8),
            channels=1,
            rate=self.sstv.samples_per_sec,
            output=True,
            stream_callback=self.callback,
        )
        stream.start_stream()
        while stream.is_active():
            sleep(0.5)
        stream.stop_stream()
        stream.close()

    def callback(self, in_data, frame_count, time_info, status):
        frames = "".join(
            struct.pack(self.fmt, b) for b in islice(self.sampler, frame_count)
        )
        return frames, pyaudio.paContinue