"""Kokoro-backed TTS rendering."""

from __future__ import annotations

import wave
from pathlib import Path

import numpy as np

from .schema import Script

SAMPLE_RATE = 24_000
KOKORO_REPO_ID = "hexgrad/Kokoro-82M"


def render_script_wav(script: Script, output_path: Path) -> Path:
    """Render dialogue lines with Kokoro into one mono WAV.

    This is intentionally simple: no delivery FX, radio chain, ducking, or SFX yet.
    It proves that the locked voice roster can produce multi-voice audio.
    """
    from kokoro import KPipeline

    script.validate()
    output_path.parent.mkdir(parents=True, exist_ok=True)
    cast_voice = {member.id: member.voice.value for member in script.cast}
    pipelines: dict[str, KPipeline] = {}
    with wave.open(str(output_path), "wb") as wav_file:
        wav_file.setnchannels(1)
        wav_file.setsampwidth(2)
        wav_file.setframerate(SAMPLE_RATE)
        for scene in script.scenes:
            _write_silence(wav_file, 0.25)
            for line in scene.lines:
                voice = cast_voice[line.cast]
                lang = voice[0]
                pipeline = pipelines.get(lang)
                if pipeline is None:
                    pipeline = KPipeline(lang_code=lang, repo_id=KOKORO_REPO_ID)
                    pipelines[lang] = pipeline
                for result in pipeline(line.text, voice=voice, speed=1.0, split_pattern=r"\n+"):
                    if result.audio is None:
                        continue
                    audio = np.clip(result.audio.numpy(), -1.0, 1.0)
                    wav_file.writeframes((audio * 32767).astype(np.int16).tobytes())
                _write_silence(wav_file, 0.22)
    return output_path


def _write_silence(wav_file: wave.Wave_write, seconds: float) -> None:
    frames = int(SAMPLE_RATE * seconds)
    wav_file.writeframes(b"\x00\x00" * frames)