"""生成 PWA 图标。

设计：天蓝色底 + 三根白色半透明圆角竖条（看板的三列），
每根竖条内从上往下堆叠若干不透明白色卡片，数量各不相同。

注意：Pillow 的 ImageDraw 不做 alpha 混合（半透明填充会直接覆盖像素），
因此所有半透明元素必须画在独立图层上，再用 alpha_composite 合成。

Maskable 版本把内容缩到安全区（中心 80%）内，避免被系统裁成圆形时切掉。
"""

from __future__ import annotations

import os

from PIL import Image, ImageDraw

OUT_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "public")

BACKGROUND = (2, 132, 199, 255)  # sky-600
TRACK = (255, 255, 255, 70)  # 半透明的列轨道
CARD = (255, 255, 255, 255)

# 每列的卡片高度（相对内容区高度的比例），从上往下堆叠
COLUMNS = [
    [0.22, 0.15],
    [0.16, 0.22, 0.13],
    [0.14],
]

SUPERSAMPLE = 4


def draw_icon(size: int, content_ratio: float) -> Image.Image:
    """content_ratio: 内容占据画布的比例（1.0 表示铺满）"""
    canvas = size * SUPERSAMPLE
    background = Image.new("RGBA", (canvas, canvas), BACKGROUND)
    layer = Image.new("RGBA", (canvas, canvas), (0, 0, 0, 0))
    draw = ImageDraw.Draw(layer)

    content = canvas * content_ratio
    offset = (canvas - content) / 2

    gap = content * 0.07
    column_width = (content - gap * (len(COLUMNS) - 1)) / len(COLUMNS)
    track_radius = max(2, int(column_width * 0.24))

    for index, cards in enumerate(COLUMNS):
        left = offset + index * (column_width + gap)
        top = offset
        bottom = offset + content

        draw.rounded_rectangle(
            [left, top, left + column_width, bottom],
            radius=track_radius,
            fill=TRACK,
        )

        pad = column_width * 0.17
        card_width = column_width - pad * 2
        card_gap = content * 0.035
        cursor = top + pad

        for ratio in cards:
            card_height = content * ratio
            draw.rounded_rectangle(
                [left + pad, cursor, left + pad + card_width, cursor + card_height],
                radius=max(2, int(track_radius * 0.5)),
                fill=CARD,
            )
            cursor += card_height + card_gap

    image = Image.alpha_composite(background, layer)
    return image.resize((size, size), Image.LANCZOS)


def main() -> None:
    os.makedirs(OUT_DIR, exist_ok=True)

    targets = [
        ("pwa-192x192.png", 192, 0.88),
        ("pwa-512x512.png", 512, 0.88),
        ("maskable-512x512.png", 512, 0.60),  # 留出安全区
        ("apple-touch-icon.png", 180, 0.88),
    ]

    for name, size, ratio in targets:
        path = os.path.join(OUT_DIR, name)
        draw_icon(size, ratio).convert("RGB").save(path, "PNG", optimize=True)
        print(f"generated {name} ({size}x{size})")


if __name__ == "__main__":
    main()