import base64
import os
import tempfile
import uuid
from pathlib import Path
from threading import Lock
from typing import Dict, Optional

import requests
import torch
import torchaudio
from torchaudio.transforms import Resample
from fastapi import BackgroundTasks, Body, FastAPI, Header, HTTPException
from fastapi.responses import FileResponse, JSONResponse
from pydantic import BaseModel, Field, HttpUrl

# Environment configuration
SPACE_API_KEY = os.getenv("SPACE_API_KEY")
HF_TOKEN = (
    os.getenv("HUGGING_FACE_HUB_TOKEN")
    or os.getenv("HUGGINGFACEHUB_API_TOKEN")
    or os.getenv("HF_TOKEN")
)

# Model configuration
MODEL_REPO = "IndexTeam/IndexTTS-2"
MODEL_DIR = os.getenv("MODEL_DIR", "/data/indextts2")
MAX_TEXT_LENGTH = 1000
DEFAULT_LANGUAGE = "en"
DEVICE = "cuda" if torch.cuda.is_available() else "cpu"

# Job management
JOBS: Dict[str, Dict[str, str]] = {}
JOB_LOCK = Lock()

# Set token in environment before importing
if HF_TOKEN:
    os.environ["HUGGING_FACE_HUB_TOKEN"] = HF_TOKEN
    os.environ["HF_TOKEN"] = HF_TOKEN
    try:
        from huggingface_hub import login
        login(token=HF_TOKEN, add_to_git_credential=False)
    except ImportError:
        pass

# Download model checkpoints from Hugging Face
os.makedirs(MODEL_DIR, exist_ok=True)

try:
    from huggingface_hub import snapshot_download
    
    # Download model if not already present
    if not Path(MODEL_DIR, "config.yaml").exists():
        print(f"Downloading IndexTTS2 model from {MODEL_REPO}...")
        snapshot_download(
            repo_id=MODEL_REPO,
            local_dir=MODEL_DIR,
            token=HF_TOKEN,
        )
        print("Model download complete.")
except Exception as exc:
    print(f"Warning: Could not download model: {exc}")
    # Continue anyway - model might already be present

# Initialize IndexTTS2
try:
    from indextts.infer_v2 import IndexTTS2
    
    cfg_path = os.path.join(MODEL_DIR, "config.yaml")
    if not Path(cfg_path).exists():
        raise FileNotFoundError(
            f"Config file not found at {cfg_path}. Model may not be downloaded."
        )
    
    tts_model = IndexTTS2(
        cfg_path=cfg_path,
        model_dir=MODEL_DIR,
        use_fp16=False,  # CPU doesn't support FP16
        use_cuda_kernel=False,  # CPU mode
        use_deepspeed=False,  # CPU mode
    )
    print("IndexTTS2 model loaded successfully.")
except Exception as exc:
    raise RuntimeError(f"Failed to load IndexTTS2 model: {exc}") from exc

# Initialize FastAPI app
app = FastAPI(title="indextts2-api", version="1.0.0")


class GenerateRequest(BaseModel):
    text: str = Field(..., min_length=1, max_length=MAX_TEXT_LENGTH)
    speaker_wav: str = Field(..., description="HTTPS URL or base64-encoded audio")
    language: Optional[str] = Field(DEFAULT_LANGUAGE, description="ISO code, default en")


def _require_api_key(x_api_key: Optional[str]):
    """Validate API key if configured."""
    if not SPACE_API_KEY:
        return
    if x_api_key != SPACE_API_KEY:
        raise HTTPException(status_code=401, detail="Unauthorized")


def _write_temp_audio_from_url(url: HttpUrl) -> str:
    """Download audio from URL to temporary file."""
    response = requests.get(url, stream=True, timeout=30)
    if response.status_code >= 400:
        raise HTTPException(
            status_code=400,
            detail=f"Could not fetch speaker audio: {response.status_code}"
        )
    
    suffix = Path(url.path).suffix or ".wav"
    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as tmp:
        for chunk in response.iter_content(chunk_size=8192):
            if chunk:
                tmp.write(chunk)
    return tmp.name


def _write_temp_audio_from_base64(payload: str) -> str:
    """Decode base64 audio to temporary file."""
    try:
        raw = base64.b64decode(payload)
    except Exception as exc:
        raise HTTPException(
            status_code=400,
            detail="Invalid base64 speaker_wav"
        ) from exc
    
    with tempfile.NamedTemporaryFile(delete=False, suffix=".wav") as tmp:
        tmp.write(raw)
    return tmp.name


def _temp_speaker_file(speaker_wav: str) -> str:
    """Handle speaker audio input from URL or base64."""
    if speaker_wav.startswith("http://") or speaker_wav.startswith("https://"):
        return _write_temp_audio_from_url(HttpUrl(speaker_wav))
    return _write_temp_audio_from_base64(speaker_wav)


def _preprocess_audio_wav(
    path: str, 
    target_sr: int = 24000, 
    target_peak: float = 0.98
) -> str:
    """
    Light preprocessing to stabilize embeddings and output quality:
    - convert to mono
    - resample to target_sr
    - peak-normalize to target_peak (avoid clipping)
    """
    wav, sr = torchaudio.load(path)
    
    # Convert to mono
    if wav.shape[0] > 1:
        wav = wav.mean(dim=0, keepdim=True)
    
    # Resample if needed
    if sr != target_sr:
        resampler = Resample(orig_freq=sr, new_freq=target_sr)
        wav = resampler(wav)
        sr = target_sr
    
    # Peak normalize
    peak = wav.abs().max().item() if wav.numel() else 0.0
    if peak > 0:
        scale = min(target_peak / peak, 1.0)
        wav = wav * scale
    
    # Overwrite input file to avoid extra temp files
    torchaudio.save(path, wav, sr, bits_per_sample=16)
    return path


def _set_job(job_id: str, **kwargs):
    """Thread-safe job update."""
    with JOB_LOCK:
        JOBS[job_id] = {**JOBS.get(job_id, {}), **kwargs}


def _get_job(job_id: str) -> Optional[Dict[str, str]]:
    """Thread-safe job retrieval."""
    with JOB_LOCK:
        data = JOBS.get(job_id)
        return dict(data) if data else None


def _pop_job(job_id: str) -> Optional[Dict[str, str]]:
    """Thread-safe job removal."""
    with JOB_LOCK:
        return JOBS.pop(job_id, None)


def _cleanup_files(*files: str):
    """Background task to clean up temporary files after response is sent."""
    for file_path in files:
        if file_path and Path(file_path).exists():
            try:
                Path(file_path).unlink(missing_ok=True)
            except Exception:
                pass  # Ignore cleanup errors


def _run_generate_job(job_id: str, payload: Dict[str, str]):
    """Background job for TTS generation."""
    speaker_file = None
    output_file = None
    _set_job(job_id, status="processing")
    
    try:
        speaker_file = _temp_speaker_file(payload["speaker_wav"])
        speaker_file = _preprocess_audio_wav(speaker_file)
        
        output_file = os.path.join(
            tempfile.gettempdir(), 
            f"indextts2-{uuid.uuid4()}.wav"
        )
        
        tts_model.infer(
            spk_audio_prompt=speaker_file,
            text=payload["text"],
            output_path=output_file,
            use_random=False,
            verbose=False,
        )
        
        output_file = _preprocess_audio_wav(output_file)
        
        if not Path(output_file).exists():
            raise RuntimeError(
                f"TTS generation failed: output file was not created at {output_file}"
            )
        
        _cleanup_files(speaker_file)
        _set_job(job_id, status="completed", output_file=output_file)
    except Exception as exc:
        _cleanup_files(speaker_file, output_file)
        _set_job(job_id, status="error", error=str(exc))


@app.post("/health")
def health(x_api_key: Optional[str] = Header(default=None)):
    """Health check endpoint."""
    _require_api_key(x_api_key)
    return {"status": "ok", "model": "indextts2", "device": DEVICE}


@app.post("/generate")
def generate(
    payload: GenerateRequest = Body(...),
    background_tasks: BackgroundTasks = BackgroundTasks(),
    x_api_key: Optional[str] = Header(default=None),
):
    """
    Generate speech from text using voice cloning.
    Returns job information for async processing.
    """
    _require_api_key(x_api_key)
    
    job_id = str(uuid.uuid4())
    _set_job(job_id, status="queued")
    
    # Offload the long-running synthesis so the HTTP request stays fast (<100s)
    background_tasks.add_task(_run_generate_job, job_id, payload.dict())
    
    return JSONResponse(
        status_code=202,
        content={
            "job_id": job_id,
            "status": "queued",
            "status_url": f"/status/{job_id}",
            "result_url": f"/result/{job_id}",
        },
    )


@app.get("/status/{job_id}")
def job_status(job_id: str, x_api_key: Optional[str] = Header(default=None)):
    """Check the status of a generation job."""
    _require_api_key(x_api_key)
    
    job = _get_job(job_id)
    if not job:
        raise HTTPException(status_code=404, detail="Job not found")
    
    payload: Dict[str, str] = {
        "job_id": job_id,
        "status": job.get("status", "unknown")
    }
    
    if "error" in job:
        payload["error"] = job["error"]
    
    return payload


@app.get("/result/{job_id}")
def job_result(
    job_id: str,
    background_tasks: BackgroundTasks = BackgroundTasks(),
    x_api_key: Optional[str] = Header(default=None),
):
    """Retrieve the result of a completed generation job."""
    _require_api_key(x_api_key)
    
    job = _get_job(job_id)
    if not job:
        raise HTTPException(status_code=404, detail="Job not found")
    
    status = job.get("status")
    if status != "completed":
        raise HTTPException(
            status_code=409, 
            detail=f"Job not ready (status={status})"
        )
    
    output_file = job.get("output_file")
    if not output_file or not Path(output_file).exists():
        _pop_job(job_id)
        raise HTTPException(status_code=410, detail="Result expired or missing")
    
    # Remove job from memory and cleanup output after sending
    _pop_job(job_id)
    background_tasks.add_task(_cleanup_files, output_file)
    
    return FileResponse(
        output_file, 
        media_type="audio/wav", 
        filename="output.wav"
    )


@app.get("/")
def root():
    """API root with available endpoints."""
    return {
        "name": "indextts2-api",
        "endpoints": [
            "/health", 
            "/generate", 
            "/status/{job_id}", 
            "/result/{job_id}"
        ],
    }