#!/usr/bin/env python3
"""PNG to Animated GIF encoder using Pillow."""

import argparse
import json
import sys
from pathlib import Path
from PIL import Image


def create_gif(input_files, output_path, delays=None, quality=256, loop=True):
    """Create an animated GIF from a list of PNG files.

    Args:
        input_files: List of PNG file paths
        output_path: Output GIF file path
        delays: List of delays per frame in ms, or single int for uniform delay
        quality: Color quantization quality (2-256 colors)
        loop: True for infinite loop, False for play once
    """
    if not input_files:
        return {"success": False, "error": "No input files provided"}

    frames = []
    for f in input_files:
        img = Image.open(f)
        if img.mode == "RGBA":
            bg = Image.new("RGB", img.size, (255, 255, 255))
            bg.paste(img, mask=img.split()[3])
            img = bg
        elif img.mode != "RGB":
            img = img.convert("RGB")
        frames.append(img)

    if not frames:
        return {"success": False, "error": "No valid frames loaded"}

    # Resolve delays: per-frame list or single value
    if isinstance(delays, list):
        # Pad or trim to match frame count
        while len(delays) < len(frames):
            delays.append(delays[-1] if delays else 500)
        delays = delays[:len(frames)]
    elif isinstance(delays, int):
        delays = [delays] * len(frames)
    else:
        delays = [500] * len(frames)

    colors = max(2, min(256, quality))
    quantized = [frame.quantize(colors=colors, method=Image.Quantize.MEDIANCUT) for frame in frames]

    output = Path(output_path)
    output.parent.mkdir(parents=True, exist_ok=True)

    # loop=0 means infinite, loop=1 means play once (no repeat)
    loop_count = 0 if loop else 1

    quantized[0].save(
        str(output),
        save_all=True,
        append_images=quantized[1:],
        duration=delays,
        loop=loop_count,
        optimize=True,
    )

    return {"success": True, "output": str(output), "frames": len(frames)}


def main():
    parser = argparse.ArgumentParser(description="PNG to Animated GIF encoder")
    parser.add_argument("--input", nargs="+", required=True, help="Input PNG files")
    parser.add_argument("--output", required=True, help="Output GIF path")
    parser.add_argument("--delays", help="Comma-separated delays per frame in ms (e.g. 500,200,800)")
    parser.add_argument("--delay", type=int, default=500, help="Uniform delay for all frames (ms)")
    parser.add_argument("--quality", type=int, default=256, help="Color count (2-256)")
    parser.add_argument("--no-loop", action="store_true", help="Play once instead of looping")

    args = parser.parse_args()

    if args.delays:
        delays = [int(d.strip()) for d in args.delays.split(",")]
    else:
        delays = args.delay

    result = create_gif(args.input, args.output, delays, args.quality, loop=not args.no_loop)
    print(json.dumps(result))
    sys.exit(0 if result["success"] else 1)


if __name__ == "__main__":
    main()