app/api.py

import os
import base64
from fastapi import FastAPI, UploadFile, File, Form, HTTPException
from fastapi.middleware.cors import CORSMiddleware
import shutil
import uuid
import logging
from typing import Dict, Any
import torch

# Import image captioning service
from app.image_captioning_service import generate_caption, Vocabulary, ImageCaptioningModel, EncoderCNN, TransformerDecoder, PositionalEncoding

# Register these classes in the main module to help with unpickling
import __main__
setattr(__main__, 'Vocabulary', Vocabulary)
setattr(__main__, 'ImageCaptioningModel', ImageCaptioningModel)
setattr(__main__, 'EncoderCNN', EncoderCNN)
setattr(__main__, 'TransformerDecoder', TransformerDecoder)
setattr(__main__, 'PositionalEncoding', PositionalEncoding)

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

# Use /tmp directory which should be writable
UPLOAD_DIR = "/tmp/uploads"

# Create necessary directories
os.makedirs(UPLOAD_DIR, exist_ok=True)
os.makedirs("app/models", exist_ok=True)

# Initialize FastAPI app
app = FastAPI(title="Image Captioning API")

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

# Get device
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
logger.info(f"Using device: {device}")

@app.get("/")
def read_root():
    return {
        "message": "Image Captioning API is running",
        "usage": "POST /generate with an image file to generate a caption",
        "docs": "Visit /docs for API documentation"
    }

@app.post("/generate")
async def generate_image_caption(
    image: UploadFile = File(...),
    max_length: int = Form(20),
) -> Dict[str, Any]:
    try:
        # Debug information
        logger.info(f"Received file: {image.filename}, content_type: {image.content_type}")
        
        # Input validation with improved error handling
        if image is None:
            raise HTTPException(status_code=400, detail="No image file provided")
        
        if not image.content_type:
            # Set a default content type if none provided
            logger.warning("No content type provided, assuming image/jpeg")
            image.content_type = "image/jpeg"
        
        if not image.content_type.startswith("image/"):
            raise HTTPException(
                status_code=400, detail=f"Uploaded file must be an image, got {image.content_type}"
            )

        if not (0 < max_length <= 100):
            raise HTTPException(
                status_code=400, detail="Maximum caption length must be between 1 and 100"
            )

        # Generate unique ID for this job
        job_id = str(uuid.uuid4())
        short_id = job_id.split("-")[0]

        # Create directories for this job in /tmp which should be writable
        upload_job_dir = os.path.join(UPLOAD_DIR, job_id)
        
        # Create directories with explicit permission setting
        os.makedirs(upload_job_dir, exist_ok=True, mode=0o777)
        
        logger.info(f"Created upload directory: {upload_job_dir}")

        # Determine file extension
        file_ext = os.path.splitext(image.filename)[1] if image.filename else ".jpg"
        if not file_ext:
            file_ext = ".jpg"
        
        # Save the uploaded image to /tmp
        image_filename = f"{short_id}{file_ext}"
        image_path = os.path.join(upload_job_dir, image_filename)

        # Save the file with error handling
        try:
            # Explicitly open with write permissions
            with open(image_path, "wb") as buffer:
                contents = await image.read()
                buffer.write(contents)
            
            # Check if file was created and has size
            if not os.path.exists(image_path):
                raise HTTPException(status_code=400, detail=f"Failed to save uploaded file to {image_path}")
                
            if os.path.getsize(image_path) == 0:
                raise HTTPException(status_code=400, detail="Uploaded file is empty")
                
            logger.info(f"Image saved to {image_path} ({os.path.getsize(image_path)} bytes)")
        except Exception as e:
            logger.error(f"Error saving file: {str(e)}")
            raise HTTPException(status_code=500, detail=f"Error saving uploaded file: {str(e)}")

        # Define model paths
        model_path = "app/models/image_captioning_model.pth"
        vocabulary_path = "app/models/vocab.pkl"
        
        # Check if model files exist
        if not os.path.exists(model_path):
            logger.error(f"Model file not found: {model_path}")
            raise HTTPException(status_code=500, detail=f"Model file not found: {model_path}")
            
        if not os.path.exists(vocabulary_path):
            logger.error(f"Vocabulary file not found: {vocabulary_path}")
            raise HTTPException(status_code=500, detail=f"Vocabulary file not found: {vocabulary_path}")

        # Generate caption
        try:
            caption = generate_caption(
                image_path=image_path,
                model_path=model_path,
                vocab_path=vocabulary_path,
                max_length=max_length,
                device=device
            )
            
            logger.info(f"Generated caption: {caption}")
        except Exception as e:
            logger.error(f"Error generating caption: {str(e)}")
            raise HTTPException(status_code=500, detail=f"Error generating caption: {str(e)}")

        # Read the original image as base64
        try:
            with open(image_path, "rb") as img_file:
                image_base64 = base64.b64encode(img_file.read()).decode("utf-8")
                
            logger.info("Successfully encoded image as base64")
        except Exception as e:
            logger.error(f"Error reading image: {str(e)}")
            raise HTTPException(status_code=500, detail=f"Error reading image: {str(e)}")

        # Prepare response with base64 encoded image
        response = {
            "caption": caption,
            "image": image_base64
        }

        # Clean up
        try:
            shutil.rmtree(upload_job_dir)
            logger.info("Cleaned up temporary directories")
        except Exception as e:
            logger.warning(f"Error cleaning up temporary files: {str(e)}")

        return response

    except Exception as e:
        logger.error(f"Error processing image: {str(e)}", exc_info=True)
        raise HTTPException(status_code=500, detail=f"Error processing image: {str(e)}")


@app.get("/health")
def health_check():
    return {"status": "healthy"}