#!/usr/bin/env python3
"""OpenAI-compatible shim in front of sglang-omni s2-pro (port 8001).

Keeps the public contract: model s2pro-egy, named voices, 24 kHz output.
POST /v1/audio/speech {model, input, voice, response_format wav|pcm, stream,
                       sample_rate=24000, temperature, top_p}
GET  /health /v1/models /v1/voices
"""

import argparse
import io
import json
import struct
import time
import urllib.request
from pathlib import Path

import numpy as np
import soundfile as sf
import uvicorn
from fastapi import FastAPI, HTTPException, Response
from fastapi.responses import StreamingResponse
from loguru import logger
from pydantic import BaseModel

MODEL_ID = "s2pro-egy"
VOICES_DIR = Path("/opt/work/voices")
UPSTREAM = "http://localhost:8001/v1/audio/speech"
UPSTREAM_MODEL = "/opt/work/checkpoints/s2pro-egy-merged"
SRC_RATE = 44100

app = FastAPI()
VOICES = {}


def load_voices():
    VOICES.clear()
    for wav in sorted(VOICES_DIR.glob("*.wav")):
        txt = wav.with_suffix(".txt")
        if txt.exists():
            VOICES[wav.stem] = {
                "audio_path": str(wav),
                "text": txt.read_text(encoding="utf-8").strip(),
            }
    logger.info(f"voices: {list(VOICES)}")


def resample(audio: np.ndarray, src: int, dst: int) -> np.ndarray:
    if src == dst:
        return audio
    import torch
    import torchaudio.functional as AF
    t = torch.from_numpy(np.ascontiguousarray(audio, dtype=np.float32))
    return AF.resample(t, src, dst).numpy()


def wav_stream_header(sample_rate: int, channels: int = 1, bits: int = 16) -> bytes:
    byte_rate = sample_rate * channels * bits // 8
    block_align = channels * bits // 8
    return b"".join([
        b"RIFF", struct.pack("<I", 0xFFFFFFFF), b"WAVE",
        b"fmt ", struct.pack("<IHHIIHH", 16, 1, channels, sample_rate,
                             byte_rate, block_align, bits),
        b"data", struct.pack("<I", 0xFFFFFFFF),
    ])


class SpeechRequest(BaseModel):
    model: str = MODEL_ID
    input: str
    voice: str = "masry"
    response_format: str = "wav"
    stream: bool = False
    sample_rate: int = 24000
    temperature: float = 0.8
    top_p: float = 0.8
    speed: float | None = None


@app.get("/health")
def health():
    return {"status": "ok", "model": MODEL_ID, "engine": "sglang-omni",
            "voices": list(VOICES)}


@app.get("/v1/models")
def models():
    return {"object": "list",
            "data": [{"id": MODEL_ID, "object": "model", "owned_by": "olimi"}]}


@app.get("/v1/voices")
def voices():
    return {"voices": list(VOICES)}


@app.post("/v1/audio/speech")
def speech(req: SpeechRequest):
    if req.voice not in VOICES:
        raise HTTPException(400, f"unknown voice '{req.voice}'; have {list(VOICES)}")
    if req.response_format not in ("wav", "pcm"):
        raise HTTPException(400, "response_format must be wav or pcm")

    body = {
        "model": UPSTREAM_MODEL,
        "voice": "default",
        "input": req.input,
        "references": [VOICES[req.voice]],
        "temperature": req.temperature,
        "top_p": req.top_p,
        "stream": req.stream,
    }
    if req.stream:
        body["response_format"] = "pcm"
    t0 = time.time()
    up = urllib.request.Request(
        UPSTREAM, data=json.dumps(body).encode(),
        headers={"Content-Type": "application/json"})

    if not req.stream:
        try:
            with urllib.request.urlopen(up, timeout=300) as r:
                raw = r.read()
        except urllib.error.HTTPError as e:
            raise HTTPException(e.code, e.read().decode()[:300])
        audio, sr = sf.read(io.BytesIO(raw), dtype="float32")
        audio = resample(audio, sr, req.sample_rate)
        logger.info(f"non-stream {len(audio)/req.sample_rate:.2f}s in {time.time()-t0:.2f}s")
        if req.response_format == "pcm":
            return Response((np.clip(audio, -1, 1) * 32767).astype("<i2").tobytes(),
                            media_type="audio/pcm")
        buf = io.BytesIO()
        sf.write(buf, audio, req.sample_rate, format="WAV", subtype="PCM_16")
        return Response(buf.getvalue(), media_type="audio/wav")

    def gen():
        if req.response_format == "wav":
            yield wav_stream_header(req.sample_rate)
        first = True
        carry = b""
        try:
            with urllib.request.urlopen(up, timeout=300) as r:
                while True:
                    chunk = r.read(32768)
                    if not chunk:
                        break
                    data = carry + chunk
                    usable = len(data) - (len(data) % 2)
                    carry = data[usable:]
                    if usable == 0:
                        continue
                    audio = np.frombuffer(data[:usable], dtype="<i2").astype(np.float32) / 32768.0
                    audio = resample(audio, SRC_RATE, req.sample_rate)
                    if first:
                        logger.info(f"TTFA {time.time()-t0:.2f}s")
                        first = False
                    yield (np.clip(audio, -1, 1) * 32767).astype("<i2").tobytes()
        except urllib.error.HTTPError as e:
            logger.error(f"upstream {e.code}: {e.read()[:200]}")

    media = "audio/wav" if req.response_format == "wav" else "audio/pcm"
    return StreamingResponse(gen(), media_type=media)


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--port", type=int, default=8000)
    args = ap.parse_args()
    load_voices()
    logger.info(f"shim ready on :{args.port} -> {UPSTREAM}")
    uvicorn.run(app, host="0.0.0.0", port=args.port, log_level="warning")


if __name__ == "__main__":
    main()