"""
FastAPI application for image colorization using ColorizeNet model
with Firebase App Check integration
"""
import os
import uuid
import logging
from pathlib import Path
from typing import Optional
from fastapi import FastAPI, File, UploadFile, HTTPException, Depends, Request
from fastapi.responses import FileResponse, JSONResponse
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
import firebase_admin
from firebase_admin import credentials, app_check, auth as firebase_auth
import numpy as np
import torch
from PIL import Image
import io

from app.colorize_model import ColorizeModel
from app.config import settings

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

# Initialize FastAPI app
app = FastAPI(
    title="Colorize API",
    description="Image colorization API using ColorizeNet model",
    version="1.0.0"
)

# CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # Configure appropriately for production
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Initialize Firebase Admin SDK
firebase_cred_path = os.getenv("FIREBASE_CREDENTIALS_PATH", "colorize-662df-firebase-adminsdk-fbsvc-e080668793.json")
if os.path.exists(firebase_cred_path):
    try:
        cred = credentials.Certificate(firebase_cred_path)
        firebase_admin.initialize_app(cred)
        logger.info("Firebase Admin SDK initialized")
    except Exception as e:
        logger.warning("Failed to initialize Firebase: %s", str(e))
        firebase_admin.initialize_app()
else:
    logger.warning("Firebase credentials file not found. App Check will be disabled.")
    try:
        firebase_admin.initialize_app()
    except:
        pass

# Create directories
UPLOAD_DIR = Path("uploads")
RESULT_DIR = Path("results")
UPLOAD_DIR.mkdir(exist_ok=True)
RESULT_DIR.mkdir(exist_ok=True)

# Mount static files for serving results
app.mount("/results", StaticFiles(directory="results"), name="results")
app.mount("/uploads", StaticFiles(directory="uploads"), name="uploads")

# Initialize ColorizeNet model
colorize_model = None

@app.get("/")
async def root():
    return {
        "app": "Colorize API",
        "version": "1.0.0",
        "health": "/health",
        "upload": "/upload",
        "colorize": "/colorize"
    }

@app.on_event("startup")
async def startup_event():
    """Initialize the colorization model on startup"""
    global colorize_model
    try:
        logger.info("Loading ColorizeNet model...")
        colorize_model = ColorizeModel(settings.MODEL_ID)
        logger.info("ColorizeNet model loaded successfully")
    except Exception as e:
        logger.error("Failed to load ColorizeNet model: %s", str(e))
        # Don't raise - allow health check to work even if model fails

@app.on_event("shutdown")
async def shutdown_event():
    """Cleanup on shutdown"""
    global colorize_model
    if colorize_model:
        del colorize_model
    logger.info("Application shutdown")

def _extract_bearer_token(authorization_header: str | None) -> str | None:
    if not authorization_header:
        return None
    parts = authorization_header.split(" ", 1)
    if len(parts) == 2 and parts[0].lower() == "bearer":
        return parts[1].strip()
    return None


async def verify_request(request: Request):
    """
    Accept either:
      - Firebase Auth id_token via Authorization: Bearer <id_token>
      - Firebase App Check token via X-Firebase-AppCheck (when ENABLE_APP_CHECK=true)
    """
    # If Firebase is not initialized or auth is explicitly disabled, allow
    if not firebase_admin._apps or os.getenv("DISABLE_AUTH", "false").lower() == "true":
        return True

    # Try Firebase Auth id_token first if present
    bearer = _extract_bearer_token(request.headers.get("Authorization"))
    if bearer:
        try:
            decoded = firebase_auth.verify_id_token(bearer)
            request.state.user = decoded  # make claims available if needed
            logger.info("Firebase Auth id_token verified for uid: %s", decoded.get("uid"))
            return True
        except Exception as e:
            logger.warning("Auth token verification failed: %s", str(e))
            # fall through to App Check if enabled

    # If App Check is enabled, require valid App Check token
    if settings.ENABLE_APP_CHECK:
        app_check_token = request.headers.get("X-Firebase-AppCheck")
        if not app_check_token:
            raise HTTPException(status_code=401, detail="Missing App Check token")
        try:
            app_check_claims = app_check.verify_token(app_check_token)
            logger.info("App Check token verified for: %s", app_check_claims.get("app_id"))
            return True
        except Exception as e:
            logger.warning("App Check token verification failed: %s", str(e))
            raise HTTPException(status_code=401, detail="Invalid App Check token")

    # Neither token required nor provided → allow (App Check disabled)
    return True

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

@app.post("/upload")
async def upload_image(
    file: UploadFile = File(...),
    verified: bool = Depends(verify_request)
):
    """
    Upload an image and return the uploaded image URL
    """
    if not file.content_type or not file.content_type.startswith("image/"):
        raise HTTPException(status_code=400, detail="File must be an image")
    
    # Generate unique filename
    file_id = str(uuid.uuid4())
    file_extension = Path(file.filename).suffix or ".jpg"
    filename = f"{file_id}{file_extension}"
    filepath = UPLOAD_DIR / filename
    
    # Save uploaded file
    try:
        contents = await file.read()
        with open(filepath, "wb") as f:
            f.write(contents)
        logger.info("Image uploaded: %s", filename)
        
        # Return the URL to access the uploaded image
        base_url = os.getenv("BASE_URL", os.getenv("SPACE_HOST", "http://localhost:7860"))
        image_url = f"{base_url}/uploads/{filename}"
        
        return {
            "success": True,
            "image_id": file_id,
            "image_url": image_url,
            "filename": filename
        }
    except Exception as e:
        logger.error("Error uploading image: %s", str(e))
        raise HTTPException(status_code=500, detail=f"Error uploading image: {str(e)}")

@app.post("/colorize")
async def colorize_image(
    file: UploadFile = File(...),
    verified: bool = Depends(verify_request)
):
    """
    Colorize an uploaded grayscale image using ColorizeNet
    Returns the colorized image URL
    """
    if colorize_model is None:
        raise HTTPException(status_code=503, detail="Colorization model not loaded")
    
    if not file.content_type or not file.content_type.startswith("image/"):
        raise HTTPException(status_code=400, detail="File must be an image")
    
    try:
        # Read image
        contents = await file.read()
        image = Image.open(io.BytesIO(contents))
        
        # Convert to RGB if needed
        if image.mode != "RGB":
            image = image.convert("RGB")
        
        # Colorize the image
        logger.info("Colorizing image...")
        colorized_image = colorize_model.colorize(image)
        
        # Save colorized image
        file_id = str(uuid.uuid4())
        result_filename = f"{file_id}.jpg"
        result_filepath = RESULT_DIR / result_filename
        
        colorized_image.save(result_filepath, "JPEG", quality=95)
        logger.info("Colorized image saved: %s", result_filename)
        
        # Return URLs
        base_url = os.getenv("BASE_URL", os.getenv("SPACE_HOST", "http://localhost:7860"))
        download_url = f"{base_url}/results/{result_filename}"
        api_download_url = f"{base_url}/download/{file_id}"
        
        return {
            "success": True,
            "result_id": file_id,
            "download_url": download_url,
            "api_download_url": api_download_url,
            "filename": result_filename
        }
    except Exception as e:
        logger.error("Error colorizing image: %s", str(e))
        raise HTTPException(status_code=500, detail=f"Error colorizing image: {str(e)}")

@app.get("/download/{file_id}")
async def download_result(
    file_id: str,
    verified: bool = Depends(verify_request)
):
    """
    Download the colorized image by file ID
    """
    result_filepath = RESULT_DIR / f"{file_id}.jpg"
    
    if not result_filepath.exists():
        raise HTTPException(status_code=404, detail="Result not found")
    
    return FileResponse(
        result_filepath,
        media_type="image/jpeg",
        filename=f"colorized_{file_id}.jpg"
    )

@app.get("/results/{filename}")
async def get_result_file(filename: str):
    """
    Serve result files directly (public endpoint for browser access)
    """
    result_filepath = RESULT_DIR / filename
    
    if not result_filepath.exists():
        raise HTTPException(status_code=404, detail="File not found")
    
    return FileResponse(
        result_filepath,
        media_type="image/jpeg"
    )

@app.get("/uploads/{filename}")
async def get_upload_file(filename: str):
    """
    Serve uploaded files directly
    """
    upload_filepath = UPLOAD_DIR / filename
    
    if not upload_filepath.exists():
        raise HTTPException(status_code=404, detail="File not found")
    
    return FileResponse(
        upload_filepath,
        media_type="image/jpeg"
    )

if __name__ == "__main__":
    import uvicorn
    port = int(os.getenv("PORT", "7860"))
    uvicorn.run(app, host="0.0.0.0", port=port)