#!/usr/bin/env python3
"""Convert the repository's runtime image assets to WebP.

This is intentionally a one-time migration helper. It keeps the source files
untouched and writes converted files into a caller-provided temporary folder.
"""

from __future__ import annotations

import argparse
import hashlib
import json
import os
from pathlib import Path

from PIL import Image, ImageOps


IMAGE_EXTENSIONS = {".jpg", ".jpeg", ".png"}
LOSSLESS_PATH_PARTS = {"routes", "train-intro", "volumes", "products", "source"}


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser()
    parser.add_argument("--root", type=Path, required=True)
    parser.add_argument("--output", type=Path, required=True)
    parser.add_argument("--manifest", type=Path, required=True)
    return parser.parse_args()


def source_files(root: Path) -> list[tuple[Path, str]]:
    public_root = root / "public" / "assets"
    files: list[tuple[Path, str]] = []
    for path in sorted(public_root.rglob("*")):
        if path.is_file() and path.suffix.lower() in IMAGE_EXTENSIONS:
            relative = path.relative_to(public_root).as_posix()
            files.append((path, relative))

    logo = root / "apps" / "miniprogram" / "src" / "assets" / "wanderq-logo.png"
    if logo.is_file():
        files.append((logo, "brand/wanderq-logo.png"))
    return files


def should_use_lossless(source: Path, relative: str) -> bool:
    if source.suffix.lower() == ".png":
        return True
    parts = set(Path(relative).parts)
    return bool(parts & LOSSLESS_PATH_PARTS) or relative.endswith("train/price-overview.jpg")


def convert(source: Path, target: Path, lossless: bool) -> None:
    target.parent.mkdir(parents=True, exist_ok=True)
    with Image.open(source) as opened:
        image = ImageOps.exif_transpose(opened)
        save_options = {
            "format": "WEBP",
            "method": 6,
            "lossless": lossless,
        }
        if not lossless:
            save_options["quality"] = 84
        icc_profile = image.info.get("icc_profile")
        if icc_profile:
            save_options["icc_profile"] = icc_profile
        image.save(target, **save_options)


def main() -> None:
    args = parse_args()
    root = args.root.resolve()
    output = args.output.resolve()
    output.mkdir(parents=True, exist_ok=True)

    manifest: list[dict[str, object]] = []
    files = source_files(root)
    if not files:
        raise SystemExit("未找到本地静态图片源；为避免生成空清单，请确认源素材仍在 public/assets 或小程序 logo 路径中")

    for source, relative in files:
        output_relative = f"{Path(relative).with_suffix('')}.webp"
        target = output / output_relative
        lossless = should_use_lossless(source, relative)
        convert(source, target, lossless)
        source_bytes = source.stat().st_size
        output_bytes = target.stat().st_size
        digest = hashlib.sha256(target.read_bytes()).hexdigest()
        if relative == "brand/wanderq-logo.png":
            reference = None
            object_key = "wanqu/miniapp/static/brand/wanderq-logo.webp"
            source_path = "apps/miniprogram/src/assets/wanderq-logo.png"
        else:
            reference = f"/assets/{relative}"
            object_key = f"wanqu/miniapp/static/{output_relative}"
            source_path = f"public/assets/{relative}"
        manifest.append(
            {
                "sourcePath": source_path,
                "reference": reference,
                "outputPath": output_relative,
                "objectKey": object_key,
                "lossless": lossless,
                "sourceBytes": source_bytes,
                "outputBytes": output_bytes,
                "sha256": digest,
            }
        )

    args.manifest.parent.mkdir(parents=True, exist_ok=True)
    args.manifest.write_text(json.dumps({"assets": manifest}, ensure_ascii=False, indent=2) + os.linesep)
    source_total = sum(int(item["sourceBytes"]) for item in manifest)
    output_total = sum(int(item["outputBytes"]) for item in manifest)
    print(
        json.dumps(
            {
                "assets": len(manifest),
                "sourceBytes": source_total,
                "outputBytes": output_total,
                "savedBytes": source_total - output_total,
                "lossless": sum(1 for item in manifest if item["lossless"]),
                "lossy": sum(1 for item in manifest if not item["lossless"]),
            },
            ensure_ascii=False,
        )
    )


if __name__ == "__main__":
    main()