#!/usr/bin/env python3
"""
Edit existing images using Gemini API.

Usage:
    python edit_image.py input.png "edit instruction" output.png [options]

Examples:
    python edit_image.py photo.png "Add a rainbow in the sky" edited.png
    python edit_image.py room.jpg "Change the sofa to red leather" room_edited.jpg
    python edit_image.py portrait.png "Make it look like a Van Gogh painting" artistic.png --model gemini-3-pro-image-preview

Environment:
    GEMINI_API_KEY - Required API key
"""

import argparse
import os
import sys

from PIL import Image
from google import genai
from google.genai import types


def edit_image(
    input_path: str,
    instruction: str,
    output_path: str,
    model: str = "gemini-2.5-flash-image",
    aspect_ratio: str | None = None,
    image_size: str | None = None,
) -> str | None:
    """Edit an existing image based on text instructions.
    
    Args:
        input_path: Path to the input image
        instruction: Text description of edits to make
        output_path: Path to save the edited image
        model: Gemini model to use
        aspect_ratio: Output aspect ratio
        image_size: Output resolution
    
    Returns:
        Any text response from the model, or None
    """
    api_key = os.environ.get("GEMINI_API_KEY")
    if not api_key:
        raise EnvironmentError("GEMINI_API_KEY environment variable not set")
    
    if not os.path.exists(input_path):
        raise FileNotFoundError(f"Input image not found: {input_path}")
    
    client = genai.Client(api_key=api_key)
    
    # Load input image
    input_image = Image.open(input_path)
    
    # Build config
    config_kwargs = {"response_modalities": ["TEXT", "IMAGE"]}
    
    image_config_kwargs = {}
    if aspect_ratio:
        image_config_kwargs["aspect_ratio"] = aspect_ratio
    if image_size:
        image_config_kwargs["image_size"] = image_size
    
    if image_config_kwargs:
        config_kwargs["image_config"] = types.ImageConfig(**image_config_kwargs)
    
    config = types.GenerateContentConfig(**config_kwargs)
    
    response = client.models.generate_content(
        model=model,
        contents=[instruction, input_image],
        config=config,
    )
    
    text_response = None
    image_saved = False
    
    for part in response.parts:
        if part.text is not None:
            text_response = part.text
        elif part.inline_data is not None:
            image = part.as_image()
            image.save(output_path)
            image_saved = True
    
    if not image_saved:
        raise RuntimeError("No image was generated. Check your instruction and try again.")
    
    return text_response


def main():
    parser = argparse.ArgumentParser(
        description="Edit images using Gemini API",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=__doc__
    )
    parser.add_argument("input", help="Input image path")
    parser.add_argument("instruction", help="Edit instruction")
    parser.add_argument("output", help="Output file path")
    parser.add_argument(
        "--model", "-m",
        default="gemini-2.5-flash-image",
        choices=["gemini-2.5-flash-image", "gemini-3-pro-image-preview"],
        help="Model to use (default: gemini-2.5-flash-image)"
    )
    parser.add_argument(
        "--aspect", "-a",
        choices=["1:1", "2:3", "3:2", "3:4", "4:3", "4:5", "5:4", "9:16", "16:9", "21:9"],
        help="Output aspect ratio"
    )
    parser.add_argument(
        "--size", "-s",
        choices=["1K", "2K", "4K"],
        help="Output resolution"
    )
    
    args = parser.parse_args()
    
    try:
        text = edit_image(
            input_path=args.input,
            instruction=args.instruction,
            output_path=args.output,
            model=args.model,
            aspect_ratio=args.aspect,
            image_size=args.size,
        )
        
        print(f"Edited image saved to: {args.output}")
        if text:
            print(f"Model response: {text}")
            
    except Exception as e:
        print(f"Error: {e}", file=sys.stderr)
        sys.exit(1)


if __name__ == "__main__":
    main()