#!/usr/bin/env python3
"""Convert PNG images to standard TGA RLE image files."""

import argparse
from pathlib import Path


def iter_inputs(input_path, recursive):
    if input_path.is_file():
        if input_path.suffix.lower() != ".png":
            raise SystemExit(f"input file is not a PNG: {input_path}")
        yield input_path
        return

    pattern = "**/*.png" if recursive else "*.png"
    yield from sorted(input_path.glob(pattern))


def output_path_for(input_file, input_root, output):
    if output is None:
        return input_file.with_suffix(".rle")

    if input_root.is_file():
        return output

    relative = input_file.relative_to(input_root)
    return (output / relative).with_suffix(".rle")


def convert_file(input_file, input_root, output):
    try:
        from PIL import Image
    except ImportError as exc:
        raise SystemExit(
            "Pillow is required. Install it with: python -m pip install Pillow"
        ) from exc

    out_path = output_path_for(input_file, input_root, output)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    with Image.open(input_file) as image:
        converted = image.convert("RGBA")
        width, height = converted.size
        converted.save(out_path, format="TGA", compression="tga_rle")
    print(f"{input_file} -> {out_path} ({width}x{height})")


def main():
    parser = argparse.ArgumentParser(
        description="Convert PNG files to standard TGA RLE files using Pillow.",
    )
    parser.add_argument("input", type=Path, help="PNG file or directory containing PNG files.")
    parser.add_argument(
        "-o",
        "--output",
        type=Path,
        help="Output .rle file for one input file, or output directory for an input directory.",
    )
    parser.add_argument(
        "-r",
        "--recursive",
        action="store_true",
        help="Recursively convert PNG files when input is a directory.",
    )
    args = parser.parse_args()

    input_path = args.input.resolve()
    if not input_path.exists():
        raise SystemExit(f"input path does not exist: {input_path}")

    output = args.output.resolve() if args.output is not None else None
    inputs = list(iter_inputs(input_path, args.recursive))
    if not inputs:
        raise SystemExit(f"no PNG files found in: {input_path}")

    if input_path.is_file() and output is not None and output.suffix.lower() != ".rle":
        raise SystemExit("single-file output must use a .rle suffix")

    for input_file in inputs:
        convert_file(input_file, input_path, output)


if __name__ == "__main__":
    main()