#!/usr/bin/env python3
"""
生成 DMG 美化背景圖（640×400），對齊 Wails 控制台深色 splash 風格。

用法：
    python3 installer/macos/make-dmg-background.py

輸出：
    installer/macos/background.png        (1x, 640×400)
    installer/macos/background@2x.png     (2x, 1280×800 Retina)

create-dmg 會自動挑 @2x 版本用於 Retina 螢幕。
"""
from pathlib import Path

from PIL import Image, ImageDraw, ImageFont

OUT_DIR = Path(__file__).resolve().parent
W, H = 640, 400

BG_TOP = (17, 24, 39)
BG_BOTTOM = (11, 15, 25)
TEXT = (229, 231, 235)
MUTED = (148, 163, 184)
ACCENT = (56, 189, 248)


def make(scale: int, out_path: Path) -> None:
    w, h = W * scale, H * scale
    img = Image.new("RGB", (w, h), BG_TOP)
    px = img.load()
    for y in range(h):
        t = y / (h - 1)
        r = int(BG_TOP[0] + (BG_BOTTOM[0] - BG_TOP[0]) * t)
        g = int(BG_TOP[1] + (BG_BOTTOM[1] - BG_TOP[1]) * t)
        b = int(BG_TOP[2] + (BG_BOTTOM[2] - BG_TOP[2]) * t)
        for x in range(w):
            px[x, y] = (r, g, b)

    draw = ImageDraw.Draw(img)

    try:
        font_title = ImageFont.truetype("/System/Library/Fonts/Helvetica.ttc", 22 * scale)
        font_hint = ImageFont.truetype("/System/Library/Fonts/Helvetica.ttc", 14 * scale)
    except OSError:
        font_title = ImageFont.load_default()
        font_hint = ImageFont.load_default()

    title = "Drag visionA-local to Applications"
    tw = draw.textlength(title, font=font_title)
    draw.text(((w - tw) / 2, 28 * scale), title, fill=TEXT, font=font_title)

    hint = "拖曳圖示到右邊的 Applications 即可安裝"
    hw = draw.textlength(hint, font=font_hint)
    draw.text(((w - hw) / 2, 60 * scale), hint, fill=MUTED, font=font_hint)

    # 箭頭位置：左右兩個 icon 約在 y=230，中心。icon 本身 128×128，由 create-dmg 擺。
    # create-dmg 預設 app icon x=180, Applications x=460（y=200）。箭頭畫在中間 240-400 區段。
    arrow_y = 200 * scale
    arrow_x1 = 260 * scale
    arrow_x2 = 380 * scale
    line_w = 3 * scale
    draw.line([(arrow_x1, arrow_y), (arrow_x2, arrow_y)], fill=ACCENT, width=line_w)
    # 箭頭頭
    head = 12 * scale
    draw.polygon(
        [
            (arrow_x2, arrow_y),
            (arrow_x2 - head, arrow_y - head // 2 - 2 * scale),
            (arrow_x2 - head, arrow_y + head // 2 + 2 * scale),
        ],
        fill=ACCENT,
    )

    img.save(out_path, "PNG", optimize=True)
    print(f"wrote {out_path} ({out_path.stat().st_size // 1024} KB)")


def main() -> None:
    make(1, OUT_DIR / "background.png")
    make(2, OUT_DIR / "background@2x.png")


if __name__ == "__main__":
    main()