import shutil
import logging
import time
from pathlib import Path
from typing import List, Dict, Any, Optional

from fastapi import FastAPI, HTTPException, UploadFile, File, BackgroundTasks, Request
from fastapi.responses import FileResponse
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.gzip import GZipMiddleware
from transformers import pipeline
import torch
import uvicorn

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Define uploads directory
UPLOAD_DIR = Path("uploads")
MAX_STORAGE_MB = 100  # Maximum storage in MB
MAX_FILE_AGE_DAYS = 1  # Maximum age of files in days

app = FastAPI(
    title="Emotion Detection API",
    description="Audio emotion detection using wav2vec2",
    version="1.0.0",
)

# Add root endpoint AFTER app is defined
@app.get("/")
async def root():
    return {"message": "Audio Emotion Detection API", "status": "running"}

# Add middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)
app.add_middleware(GZipMiddleware, minimum_size=1000)

# Preloaded classifier (global)
classifier = None

@app.on_event("startup")
async def load_model():
    global classifier
    try:
        # Use GPU if available, else CPU
        device = 0 if torch.cuda.is_available() else -1
        
        # For Hugging Face Spaces with limited resources, use quantized model if on CPU
        if device == -1:
            logger.info("Loading quantized model for CPU usage")
            classifier = pipeline(
                "audio-classification",
                model="superb/wav2vec2-base-superb-er",
                device=device,
                torch_dtype=torch.float16  # Use half precision
            )
        else:
            classifier = pipeline(
                "audio-classification",
                model="superb/wav2vec2-base-superb-er",
                device=device
            )
        
        logger.info("Loaded emotion recognition model (device=%s)", 
                    "GPU" if device == 0 else "CPU")
    except Exception as e:
        logger.error("Failed to load model: %s", e)
        # Don't raise the error - let the app start even if model fails
        # We'll handle this in the endpoints

async def cleanup_old_files():
    """Clean up old files to prevent storage issues on Hugging Face Spaces."""
    try:
        # Remove files older than MAX_FILE_AGE_DAYS
        now = time.time()
        deleted_count = 0
        for file_path in UPLOAD_DIR.iterdir():
            if file_path.is_file():
                file_age_days = (now - file_path.stat().st_mtime) / (60 * 60 * 24)
                if file_age_days > MAX_FILE_AGE_DAYS:
                    file_path.unlink()
                    deleted_count += 1
        
        if deleted_count > 0:
            logger.info(f"Cleaned up {deleted_count} old files")
    except Exception as e:
        logger.error(f"Error during file cleanup: {e}")

@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    """Add X-Process-Time header to responses."""
    start_time = time.time()
    response = await call_next(request)
    process_time = time.time() - start_time
    response.headers["X-Process-Time"] = str(process_time)
    return response

@app.get("/health")
async def health():
    """Health check endpoint."""
    return {"status": "ok", "model_loaded": classifier is not None}

@app.post("/upload")
async def upload_audio(
    file: UploadFile = File(...),
    background_tasks: BackgroundTasks = None
):
    """
    Upload an audio file and analyze emotions.
    Saves the file to the uploads directory and returns model predictions.
    """
    if not classifier:
        raise HTTPException(status_code=503, detail="Model not yet loaded")
        
    filename = Path(file.filename).name
    if not filename:
        raise HTTPException(status_code=400, detail="Invalid filename")

    # Check file extension
    valid_extensions = [".wav", ".mp3", ".ogg", ".flac"]
    if not any(filename.lower().endswith(ext) for ext in valid_extensions):
        raise HTTPException(
            status_code=400, 
            detail=f"Invalid file type. Supported types: {', '.join(valid_extensions)}"
        )

    # Read file contents
    try:
        contents = await file.read()
    except Exception as e:
        logger.error("Error reading file %s: %s", filename, e)
        raise HTTPException(status_code=500, detail=f"Failed to read file: {str(e)}")
    finally:
        await file.close()

    # Check file size (limit to 10MB for Spaces)
    if len(contents) > 10 * 1024 * 1024:
        raise HTTPException(
            status_code=413, 
            detail="File too large. Maximum size is 10MB"
        )

    # Save file to uploads directory
    file_path = UPLOAD_DIR / filename
    try:
        with open(file_path, "wb") as f:
            f.write(contents)
        logger.info("Saved uploaded file: %s", file_path)
    except Exception as e:
        logger.error("Failed to save file %s: %s", filename, e)
        raise HTTPException(status_code=500, detail=f"Failed to save file: {str(e)}")

    # Analyze the audio file using the pretrained model pipeline
    try:
        results = classifier(str(file_path))
        
        # Schedule cleanup in background
        if background_tasks:
            background_tasks.add_task(cleanup_old_files)
            
        return {"filename": filename, "predictions": results}
    except Exception as e:
        logger.error("Model inference failed for %s: %s", filename, e)
        # Try to remove the file if inference fails
        try:
            file_path.unlink(missing_ok=True)
        except Exception:
            pass
        raise HTTPException(status_code=500, detail=f"Emotion detection failed: {str(e)}")

@app.get("/recordings")
async def list_recordings():
    """
    List all uploaded recordings.
    Returns a JSON list of filenames in the uploads directory.
    """
    try:
        files = [f.name for f in UPLOAD_DIR.iterdir() if f.is_file()]
        total, used, free = shutil.disk_usage(UPLOAD_DIR)
        storage_info = {
            "total_mb": total / (1024 * 1024),
            "used_mb": used / (1024 * 1024),
            "free_mb": free / (1024 * 1024)
        }
        return {"recordings": files, "storage": storage_info}
    except Exception as e:
        logger.error("Could not list files: %s", e)
        raise HTTPException(status_code=500, detail=f"Failed to list recordings: {str(e)}")

@app.get("/recordings/{filename}")
async def get_recording(filename: str):
    """
    Stream/download an audio file from the server.
    """
    safe_name = Path(filename).name
    file_path = UPLOAD_DIR / safe_name
    if not file_path.exists() or not file_path.is_file():
        raise HTTPException(status_code=404, detail="Recording not found")
    # Guess MIME type (fallback to octet-stream)
    import mimetypes
    media_type, _ = mimetypes.guess_type(file_path)
    return FileResponse(
        file_path, 
        media_type=media_type or "application/octet-stream", 
        filename=safe_name
    )

@app.get("/analyze/{filename}")
async def analyze_recording(filename: str):
    """
    Analyze an already-uploaded recording by filename.
    Returns emotion predictions for the given file.
    """
    if not classifier:
        raise HTTPException(status_code=503, detail="Model not yet loaded")
        
    safe_name = Path(filename).name
    file_path = UPLOAD_DIR / safe_name
    if not file_path.exists() or not file_path.is_file():
        raise HTTPException(status_code=404, detail="Recording not found")
    try:
        results = classifier(str(file_path))
    except Exception as e:
        logger.error("Model inference failed for %s: %s", filename, e)
        raise HTTPException(status_code=500, detail=f"Emotion detection failed: {str(e)}")
    return {"filename": safe_name, "predictions": results}

@app.delete("/recordings/{filename}")
async def delete_recording(filename: str):
    """
    Delete a recording by filename.
    """
    safe_name = Path(filename).name
    file_path = UPLOAD_DIR / safe_name
    if not file_path.exists() or not file_path.is_file():
        raise HTTPException(status_code=404, detail="Recording not found")
    try:
        file_path.unlink()
        return {"status": "success", "message": f"Deleted {safe_name}"}
    except Exception as e:
        logger.error("Failed to delete file %s: %s", filename, e)
        raise HTTPException(status_code=500, detail=f"Failed to delete file: {str(e)}")

if __name__ == "__main__":
    # Start FastAPI with Uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860, log_level="info")