misskey/packages/frontend-shared/js/theme.ts

/*
 * SPDX-FileCopyrightText: syuilo and misskey-project
 * SPDX-License-Identifier: AGPL-3.0-only
 */

import tinycolor from 'tinycolor2';
import JSON5 from 'json5';
import lightTheme from '@@/themes/_light.json5';
import type { BundledTheme } from 'shiki/themes';

export type Theme = {
	id: string;
	name: string;
	author: string;
	desc?: string;
	base?: 'dark' | 'light';
	kind?: 'dark' | 'light'; // legacy
	props: Record<string, string>;
	codeHighlighter?: {
		base: BundledTheme;
		// eslint-disable-next-line @typescript-eslint/no-explicit-any
		overrides?: Record<string, any>;
	} | {
		base: '_none_';
		// eslint-disable-next-line @typescript-eslint/no-explicit-any
		overrides: Record<string, any>;
	};
};

export type CompiledTheme = Record<string, string>;

const MAX_THEME_REFERENCE_DEPTH = 8;

export const themeProps = Object.keys(lightTheme.props).filter(key => !key.startsWith('X'));

export const getBuiltinThemes = () => Promise.all(
	[
		'l-light',
		'l-coffee',
		'l-apricot',
		'l-rainy',
		'l-botanical',
		'l-vivid',
		'l-cherry',
		'l-sushi',
		'l-u0',

		'd-dark',
		'd-persimmon',
		'd-astro',
		'd-future',
		'd-botanical',
		'd-green-lime',
		'd-green-orange',
		'd-cherry',
		'd-ice',
		'd-u0',
	].map(name => import(`@@/themes/${name}.json5`).then(({ default: _default }): Theme => _default)),
);

function getThemeReferenceColor(theme: Theme, key: string, stack: string[], depth: number): tinycolor.Instance {
	if (depth >= MAX_THEME_REFERENCE_DEPTH) {
		throw new Error('Theme reference limit exceeded');
	}

	if (stack.includes(key)) {
		throw new Error('Theme contains circular references');
	}

	const nextValue = theme.props[key];
	if (typeof nextValue !== 'string') {
		throw new Error(`Theme references missing property: ${key}`);
	}

	return getColor(theme, nextValue, [...stack, key], depth + 1);
}

function getColor(theme: Theme, val: string, stack: string[] = [], depth = 0): tinycolor.Instance {
	if (val[0] === '@') { // ref (prop)
		return getThemeReferenceColor(theme, val.substring(1), stack, depth);
	} else if (val[0] === '$') { // ref (const)
		return getThemeReferenceColor(theme, val, stack, depth);
	} else if (val[0] === ':') { // func
		if (depth >= MAX_THEME_REFERENCE_DEPTH) {
			throw new Error('Theme reference limit exceeded');
		}

		const parts = val.split('<');
		const funcTxt = parts.shift();
		const argTxt = parts.shift();

		if (funcTxt && argTxt) {
			const func = funcTxt.substring(1);
			const arg = parseFloat(argTxt);
			const color = getColor(theme, parts.join('<'), stack, depth + 1);

			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);
}

export function compile(theme: Theme): CompiledTheme {
	const props = {} as CompiledTheme;

	for (const [k, v] of Object.entries(theme.props)) {
		if (k.startsWith('$')) continue; // ignore const

		props[k] = v.startsWith('"') ? v.replace(/^"\s*/, '') : genValue(getColor(theme, v));
	}

	return Object.fromEntries(
		Object.entries(props).filter(([key]) => themeProps.includes(key)),
	) as CompiledTheme;
}

function genValue(c: tinycolor.Instance): string {
	return c.toRgbString();
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export function validateTheme(theme: Record<string, any>): boolean {
	if (theme.id == null || typeof theme.id !== 'string') return false;
	if (theme.name == null || typeof theme.name !== 'string') return false;
	if (theme.base == null || !['light', 'dark'].includes(theme.base)) return false;
	if (theme.props == null || typeof theme.props !== 'object') return false;
	return true;
}

export function parseThemeCode(code: string): Theme {
	let theme;

	try {
		theme = JSON5.parse(code);
	} catch (_) {
		throw new Error('Failed to parse theme json');
	}
	if (!validateTheme(theme)) {
		throw new Error('This theme is invaild');
	}

	return theme;
}