1 files changed, 108 insertions, 0 deletions
diff --git a/packages/frontend-embed/src/theme.ts b/packages/frontend-embed/src/theme.ts
new file mode 100644
index 0000000000..23e70cd0d3
--- /dev/null
+++ b/packages/frontend-embed/src/theme.ts
@@ -0,0 +1,108 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import tinycolor from 'tinycolor2';
+import lightTheme from '@@/themes/_light.json5';
+import darkTheme from '@@/themes/_dark.json5';
+import type { BundledTheme } from 'shiki/themes';
+
+export type Theme = {
+	id: string;
+	name: string;
+	author: string;
+	desc?: string;
+	base?: 'dark' | 'light';
+	props: Record<string, string>;
+	codeHighlighter?: {
+		base: BundledTheme;
+		overrides?: Record<string, any>;
+	} | {
+		base: '_none_';
+		overrides: Record<string, any>;
+	};
+};
+
+let timeout: number | null = null;
+
+export function assertIsTheme(theme: Record<string, unknown>): theme is Theme {
+	return typeof theme === 'object' && theme !== null && 'id' in theme && 'name' in theme && 'author' in theme && 'props' in theme;
+}
+
+export function applyTheme(theme: Theme, persist = true) {
+	if (timeout) window.clearTimeout(timeout);
+
+	document.documentElement.classList.add('_themeChanging_');
+
+	timeout = window.setTimeout(() => {
+		document.documentElement.classList.remove('_themeChanging_');
+	}, 1000);
+
+	const colorScheme = theme.base === 'dark' ? 'dark' : 'light';
+
+	document.documentElement.dataset.colorScheme = colorScheme;
+
+	// Deep copy
+	const _theme = JSON.parse(JSON.stringify(theme));
+
+	if (_theme.base) {
+		const base = [lightTheme, darkTheme].find(x => x.id === _theme.base);
+		if (base) _theme.props = Object.assign({}, base.props, _theme.props);
+	}
+
+	const props = compile(_theme);
+
+	for (const tag of document.head.children) {
+		if (tag.tagName === 'META' && tag.getAttribute('name') === 'theme-color') {
+			tag.setAttribute('content', props['htmlThemeColor']);
+			break;
+		}
+	}
+
+	for (const [k, v] of Object.entries(props)) {
+		document.documentElement.style.setProperty(`--${k}`, v.toString());
+	}
+
+	// iframeを正常に透過させるために、cssのcolor-schemeは `light dark;` 固定にしてある。style.scss参照
+}
+
+function compile(theme: Theme): Record<string, string> {
+	function getColor(val: string): tinycolor.Instance {
+		if (val[0] === '@') { // ref (prop)
+			return getColor(theme.props[val.substring(1)]);
+		} else if (val[0] === '$') { // ref (const)
+			return getColor(theme.props[val]);
+		} else if (val[0] === ':') { // func
+			const parts = val.split('<');
+			const func = parts.shift().substring(1);
+			const arg = parseFloat(parts.shift());
+			const color = getColor(parts.join('<'));
+
+			switch (func) {
+				case 'darken': return color.darken(arg);
+				case 'lighten': return color.lighten(arg);
+				case 'alpha': return color.setAlpha(arg);
+				case 'hue': return color.spin(arg);
+				case 'saturate': return color.saturate(arg);
+			}
+		}
+
+		// other case
+		return tinycolor(val);
+	}
+
+	const props = {};
+
+	for (const [k, v] of Object.entries(theme.props)) {
+		if (k.startsWith('$')) continue; // ignore const
+
+		props[k] = v.startsWith('"') ? v.replace(/^"\s*/, '') : genValue(getColor(v));
+	}
+
+	return props;
+}
+
+function genValue(c: tinycolor.Instance): string {
+	return c.toRgbString();
+}