#!/usr/bin/env bun

// Generates the PWA icon set from public/logo.svg.
//
//   bun run scripts/gen-icons.ts
//
// The output is committed rather than gitignored: Caddy serves /public/* straight
// from /opt/lichen/public on the host (see deploy/Caddyfile.snippet), so icons
// built only inside the container image would never be reachable in production.

import { mkdir } from "node:fs/promises";
import { join } from "node:path";
import sharp from "sharp";

const PUBLIC_DIR = join(import.meta.dir, "..", "public");
const OUT_DIR = join(PUBLIC_DIR, "icons");

// Matches THEME.light.bg — the mark is teal, so it needs a light ground to read.
const BACKGROUND = "#fafaf9";

// Android crops maskable icons to a circle 80% of the canvas width. A square mark
// only fits inside that circle at ~56%, so maskable variants shrink the mark
// instead of letting the crop clip it.
const STANDARD_MARK_RATIO = 0.72;
const MASKABLE_MARK_RATIO = 0.55;

// librsvg rasterizes at this DPI before the downscale; the viewBox is ~135 units
// wide, so 384 renders ~720px and keeps the 512px icons crisp.
const RENDER_DENSITY = 384;

interface IconSpec {
	file: string;
	size: number;
	markRatio: number;
}

const ICONS: IconSpec[] = [
	{ file: "icon-192.png", size: 192, markRatio: STANDARD_MARK_RATIO },
	{ file: "icon-512.png", size: 512, markRatio: STANDARD_MARK_RATIO },
	{ file: "icon-192-maskable.png", size: 192, markRatio: MASKABLE_MARK_RATIO },
	{ file: "icon-512-maskable.png", size: 512, markRatio: MASKABLE_MARK_RATIO },
	// iOS ignores transparency and applies its own rounding, so this is the
	// standard ratio on the same opaque ground.
	{ file: "apple-touch-icon.png", size: 180, markRatio: STANDARD_MARK_RATIO },
];

async function renderIcon(logo: Buffer, spec: IconSpec): Promise<void> {
	const markSize = Math.round(spec.size * spec.markRatio);
	const mark = await sharp(logo, { density: RENDER_DENSITY })
		.resize(markSize, markSize, {
			fit: "contain",
			background: { r: 0, g: 0, b: 0, alpha: 0 },
		})
		.png()
		.toBuffer();

	await sharp({
		create: {
			width: spec.size,
			height: spec.size,
			channels: 4,
			background: BACKGROUND,
		},
	})
		.composite([{ input: mark, gravity: "centre" }])
		.png()
		.toFile(join(OUT_DIR, spec.file));
}

const logo = Buffer.from(
	await Bun.file(join(PUBLIC_DIR, "logo.svg")).arrayBuffer(),
);
await mkdir(OUT_DIR, { recursive: true });
await Promise.all(ICONS.map((spec) => renderIcon(logo, spec)));

console.log(`Wrote ${ICONS.length} icons to public/icons/`);