'use strict';

var caniuse = require('caniuse-lite');
var browserslist = require('browserslist');

function _interopDefaultLegacy (e) { return e && typeof e === 'object' && 'default' in e ? e : { 'default': e }; }

var browserslist__default = /*#__PURE__*/_interopDefaultLegacy(browserslist);

const NO = "No";
const APPLE_SYSTEM = "AppleSystem";
const BLINK_MAC_SYSTEM_FONT = "BlinkMacSystemFont";

function computePolyfillFlagFromStatus(statusString) {
  const flags = [];
  const statusArr = Array.from(statusString.split(" "));

  for (const status of statusArr) {
    if (status === "y") {
      return [];
    } else if (status.includes("n")) {
      flags.push(NO);
    } else if (status.includes("#1")) {
      // #1: Supported as the -apple-system value (only on Mac)
      flags.push(APPLE_SYSTEM);
    } else if (status.includes("#2")) {
      // #2: Supported as the 'BlinkMacSystemFont' value (only on Mac)
      flags.push(BLINK_MAC_SYSTEM_FONT);
    }
  }

  return flags;
}

function generatePolyfillFlags(stats, supportedBrowsers) {
  const polyfillFlags = {
    [APPLE_SYSTEM]: false,
    [BLINK_MAC_SYSTEM_FONT]: false,
    [NO]: false
  };
  const visitedStatus = {};

  for (const browserAndVersion of supportedBrowsers) {
    const [browser, version] = browserAndVersion.split(" ");
    const status = stats[browser][version];

    if (status === undefined || visitedStatus[status]) {
      continue;
    }

    visitedStatus[status] = true;
    const shouldPolyfillFlags = computePolyfillFlagFromStatus(status);
    shouldPolyfillFlags.forEach(flag => {
      polyfillFlags[flag] = true;
    });
  }

  return polyfillFlags;
}

function getSystemUiFamily(supportedBrowsers, preserve) {
  const {
    stats
  } = caniuse.feature(caniuse.features["font-family-system-ui"]);
  const polyfillFlags = generatePolyfillFlags(stats, supportedBrowsers);
  const polyfill = [[APPLE_SYSTEM, ["-apple-system" // macOS, Safari >= 9.2 < 11, Firefox >= 43
  ]], [BLINK_MAC_SYSTEM_FONT, ["BlinkMacSystemFont" // macOS, Chrome < 56
  ]], [NO, ["Segoe UI", // Windows >= Vista
  "Roboto", // Android >= 4
  "Noto Sans", // Plasma >= 5.5
  "Ubuntu", // Ubuntu >= 10.10
  "Cantarell", // GNOME >= 3
  "Helvetica Neue"]]];
  const result = [].concat.apply([], polyfill.filter(([flag]) => polyfillFlags[flag]).map(v => v[1]));

  if (!result.length || preserve) {
    result.unshift("system-ui");
  }

  return result;
}

// tooling

const creator = opts => {
  const {
    family,
    preserve = true,
    browsers
  } = Object(opts);
  let systemUiFamily = family;

  if (typeof family === "string") {
    systemUiFamily = family.trim().split(/\s*,\s*/);
  } else if (!family) {
    // browsers supported by the configuration
    const supportedBrowsers = browserslist__default['default'](browsers, {
      ignoreUnknownVersions: true
    });
    systemUiFamily = getSystemUiFamily(supportedBrowsers, preserve);
  } // system-ui and fallbacks match


  const whitespace = "[\\f\\n\\r\\x09\\x20]";
  const systemUiMatch = new RegExp(`(^|,|${whitespace}+)(?:system-ui${whitespace}*)(?:,${whitespace}*(?:${systemUiFamily.join("|")})${whitespace}*)?(,|$)`, "i"); // system-ui fallback replacement

  const systemUiReplace = `$1${systemUiFamily.join(", ")}$2`;
  const visited = new WeakSet();
  return {
    postcssPlugin: "postcss-font-family-system-ui",

    // update font declarations to polyfill system-ui usage
    Declaration(decl) {
      if (decl.prop.match(fontPropertyMatch) && !visited.has(decl)) {
        decl.value = decl.value.replace(systemUiMatch, systemUiReplace);
        visited.add(decl);
      }
    }

  };
}; // Required by PostCSS 8


creator.postcss = true;
/* match the following properties:
 * - font
 * - font-family
 * - custom properties (see https://www.w3.org/TR/css-variables-1/#custom-property)
 */

const fontPropertyMatch = /(?:^(?:-|\\002d){2})|(?:^font(?:-family)?$)/i;

module.exports = creator;