import { Platform, SYSTEM_FONTS } from './constants'

const GeckoFonts: Record<string, string> = {
    '-apple-system': Platform.MAC,
    'Segoe UI': Platform.WINDOWS,
    'Tahoma': Platform.WINDOWS,
    'Yu Gothic UI': Platform.WINDOWS,
    'Microsoft JhengHei UI': Platform.WINDOWS,
    'Microsoft YaHei UI': Platform.WINDOWS,
    'Meiryo UI': Platform.WINDOWS,
    'Cantarell': Platform.LINUX,
    'Ubuntu': Platform.LINUX,
    'Sans': Platform.LINUX,
    'sans-serif': Platform.LINUX,
    'Fira Sans': Platform.LINUX,
    'Roboto': Platform.ANDROID,
}

export function getSystemFonts(): string {
    const { body } = document
    const el = document.createElement('div')
    body.appendChild(el)
    try {
        const systemFonts = String(
            [
                ...SYSTEM_FONTS.reduce((acc, font) => {
                    el.setAttribute('style', `font: ${font} !important`)
                    return acc.add(getComputedStyle(el).fontFamily)
                }, new Set()),
            ],
        )
        const geckoPlatform = GeckoFonts[systemFonts]
        return GeckoFonts[systemFonts] ? `${systemFonts}:${geckoPlatform}` : systemFonts
    } catch (err) {
        return ''
    } finally {
        body.removeChild(el)
    }
}