utils/image_processor.py

"""
Image Processor Utilities.

This module handles image processing for structure diagrams and scanned documents.

Design Note:
Image processing here is limited to:
- Basic image validation
- Path management
- Potential OCR preparation (TODO)

Actual chemical structure recognition would require external services
(e.g., OSRA, ChemDraw API) and is out of scope for this implementation.
"""

from typing import Optional, Tuple
from pathlib import Path
import base64


class ImageProcessor:
    """
    Image processor for structure diagrams and scanned documents.
    
    Primary responsibilities:
    - Validate image files
    - Prepare images for LLM vision APIs (if supported)
    - Encode images for embedding
    """
    
    SUPPORTED_FORMATS = {'.png', '.jpg', '.jpeg', '.gif', '.webp', '.bmp'}
    
    def __init__(self):
        """Initialize the image processor."""
        self._pil_available = self._check_pil()
    
    def _check_pil(self) -> bool:
        """Check if PIL/Pillow is available."""
        try:
            from PIL import Image
            return True
        except ImportError:
            return False
    
    def validate_image(self, file_path: str) -> bool:
        """
        Validate that a file is a readable image.
        
        Args:
            file_path: Path to the image file
            
        Returns:
            True if valid image, False otherwise
        """
        path = Path(file_path)
        
        # Check extension
        if path.suffix.lower() not in self.SUPPORTED_FORMATS:
            return False
        
        # Check file exists
        if not path.exists():
            return False
        
        # Try to open with PIL if available
        if self._pil_available:
            try:
                from PIL import Image
                with Image.open(file_path) as img:
                    img.verify()
                return True
            except Exception:
                return False
        
        return True
    
    def get_image_info(self, file_path: str) -> Optional[dict]:
        """
        Get basic information about an image.
        
        Args:
            file_path: Path to the image file
            
        Returns:
            Dictionary with image info, or None if failed
        """
        if not self._pil_available:
            return {"path": file_path, "status": "PIL not available"}
        
        try:
            from PIL import Image
            
            with Image.open(file_path) as img:
                return {
                    "path": file_path,
                    "format": img.format,
                    "mode": img.mode,
                    "size": img.size,  # (width, height)
                    "width": img.size[0],
                    "height": img.size[1],
                }
        except Exception as e:
            return {"path": file_path, "error": str(e)}
    
    def encode_base64(self, file_path: str) -> Optional[str]:
        """
        Encode an image as base64 string.
        
        Useful for embedding in HTML or sending to vision APIs.
        
        Args:
            file_path: Path to the image file
            
        Returns:
            Base64 encoded string, or None if failed
        """
        try:
            with open(file_path, "rb") as f:
                image_data = f.read()
            return base64.b64encode(image_data).decode('utf-8')
        except Exception as e:
            print(f"Error encoding image: {e}")
            return None
    
    def get_data_uri(self, file_path: str) -> Optional[str]:
        """
        Get a data URI for embedding an image directly in HTML.
        
        Args:
            file_path: Path to the image file
            
        Returns:
            Data URI string, or None if failed
        """
        path = Path(file_path)
        suffix = path.suffix.lower()
        
        # Map extension to MIME type
        mime_types = {
            '.png': 'image/png',
            '.jpg': 'image/jpeg',
            '.jpeg': 'image/jpeg',
            '.gif': 'image/gif',
            '.webp': 'image/webp',
            '.bmp': 'image/bmp',
        }
        
        mime_type = mime_types.get(suffix, 'image/png')
        base64_data = self.encode_base64(file_path)
        
        if base64_data:
            return f"data:{mime_type};base64,{base64_data}"
        return None
    
    def resize_for_report(
        self, 
        file_path: str, 
        max_width: int = 400,
        max_height: int = 300
    ) -> Optional[str]:
        """
        Resize an image for report embedding.
        
        Creates a temporary resized copy suitable for report generation.
        
        Args:
            file_path: Path to the original image
            max_width: Maximum width in pixels
            max_height: Maximum height in pixels
            
        Returns:
            Path to resized image, or original path if resizing fails
        """
        if not self._pil_available:
            return file_path
        
        try:
            from PIL import Image
            import tempfile
            
            with Image.open(file_path) as img:
                # Calculate new size maintaining aspect ratio
                img.thumbnail((max_width, max_height), Image.Resampling.LANCZOS)
                
                # Save to temp file
                suffix = Path(file_path).suffix
                with tempfile.NamedTemporaryFile(
                    suffix=suffix, 
                    delete=False
                ) as tmp:
                    img.save(tmp.name)
                    return tmp.name
                    
        except Exception as e:
            print(f"Error resizing image: {e}")
            return file_path
    
    def prepare_for_llm(self, file_path: str) -> Optional[dict]:
        """
        Prepare an image for LLM vision API submission.
        
        Returns a dictionary suitable for vision model APIs.
        
        Args:
            file_path: Path to the image file
            
        Returns:
            Dictionary with image data for API submission
        """
        if not self.validate_image(file_path):
            return None
        
        base64_data = self.encode_base64(file_path)
        if not base64_data:
            return None
        
        path = Path(file_path)
        mime_types = {
            '.png': 'image/png',
            '.jpg': 'image/jpeg',
            '.jpeg': 'image/jpeg',
            '.gif': 'image/gif',
            '.webp': 'image/webp',
        }
        mime_type = mime_types.get(path.suffix.lower(), 'image/png')
        
        return {
            "type": "image",
            "source": {
                "type": "base64",
                "media_type": mime_type,
                "data": base64_data,
            }
        }