from __future__ import annotations

import struct
import unittest

import discord

from zyrarbot.audio.ytdl_source import FRAME_LENGTH_SECONDS, YTDLSource


class DummyPCM(discord.AudioSource):
    def __init__(self, data: bytes):
        self._data = data
        self.cleanup_called = False

    def read(self) -> bytes:
        data = self._data
        self._data = b""
        return data

    def cleanup(self) -> None:
        self.cleanup_called = True


class TestYTDLSource(unittest.TestCase):
    def test_read_advances_elapsed_and_returns_data(self):
        # 1 sample of 16-bit stereo = 4 bytes
        pcm = struct.pack("<hh", 1000, 2000)
        source = DummyPCM(pcm)
        ytdl = YTDLSource(source, data={"title": "test"}, volume=1.0)

        self.assertEqual(ytdl.elapsed, 0.0)
        data = ytdl.read()
        self.assertEqual(data, pcm)
        self.assertAlmostEqual(ytdl.elapsed, FRAME_LENGTH_SECONDS)

        # Subsequent read returns empty and does not advance elapsed further
        empty = ytdl.read()
        self.assertEqual(empty, b"")
        self.assertAlmostEqual(ytdl.elapsed, FRAME_LENGTH_SECONDS)

    def test_read_with_high_volume_does_not_clamp_to_2(self):
        pcm = struct.pack("<hh", 5000, -5000)
        source = DummyPCM(pcm)
        ytdl = YTDLSource(source, data={"title": "distortion test"}, volume=5.0)

        data = ytdl.read()
        left, right = struct.unpack("<hh", data)
        self.assertEqual(left, 25000)
        self.assertEqual(right, -25000)

    def test_read_distortion_effect_clips_at_pcm_limits(self):
        pcm = struct.pack("<hh", 10000, -10000)
        source = DummyPCM(pcm)
        ytdl = YTDLSource(source, data={"title": "przester"}, volume=1.0)
        ytdl.set_active_effects({"distortion"})

        data = ytdl.read()
        left, right = struct.unpack("<hh", data)
        self.assertEqual(left, 32767)
        self.assertEqual(right, -32768)


if __name__ == "__main__":
    unittest.main()