"use strict";

const {

  utils: Cu,

  classes: Cc,

  interfaces: Ci

} = Components;

ChromeUtils.import("resource://gre/modules/PromiseMessage.jsm");

var ManifestIcons = {

  async browserFetchIcon(aBrowser, manifest, iconSize) {

    const msgKey = "DOM:WebManifest:fetchIcon";

    const mm = aBrowser.messageManager;

    const {data: {success, result}} =

      await PromiseMessage.send(mm, msgKey, {manifest, iconSize});

    if (!success) {

      throw result;

    }

    return result;

  },

  async contentFetchIcon(aWindow, manifest, iconSize) {

    return await getIcon(aWindow, toIconArray(manifest.icons), iconSize);

  }

};

function parseIconSize(size) {

  if (size === "any" || size === "") {

    // We want icons without size specified to sorted

    // as the largest available icons

    return Number.MAX_SAFE_INTEGER;

  }

  // 100x100 will parse as 100

  return parseInt(size, 10);

}

// Create an array of icons sorted by their size

function toIconArray(icons) {

  const iconBySize = [];

  icons.forEach(icon => {

    const sizes = ("sizes" in icon) ? icon.sizes : "";

    sizes.split(" ").forEach(size => {

      iconBySize.push({src: icon.src, size: parseIconSize(size)});

    });

  });

  return iconBySize.sort((a, b) => a.size - b.size);

}

async function getIcon(aWindow, icons, expectedSize) {

  if (!icons.length) {

    throw new Error("Could not find valid icon");

  }

  // We start trying the smallest icon that is larger than the requested

  // size and go up to the largest icon if they fail, if all those fail

  // go back down to the smallest

  let index = icons.findIndex(icon => icon.size >= expectedSize);

  if (index === -1) {

    index = icons.length - 1;

  }

  return fetchIcon(aWindow, icons[index].src).catch(err => {

    // Remove all icons with the failed source, the same source

    // may have been used for multiple sizes

    icons = icons.filter(x => x.src !== icons[index].src);

    return getIcon(aWindow, icons, expectedSize);

  });

}

async function fetchIcon(aWindow, src) {

  const iconURL = new aWindow.URL(src, aWindow.location);

  const request = new aWindow.Request(iconURL, {mode: "cors"});

  request.overrideContentPolicyType(Ci.nsIContentPolicy.TYPE_IMAGE);

  return aWindow.fetch(request)

    .then(response => response.blob())

    .then(blob => new Promise((resolve, reject) => {

      var reader = new FileReader();

      reader.onloadend = () => resolve(reader.result);

      reader.onerror = reject;

      reader.readAsDataURL(blob);

    }));

}

var EXPORTED_SYMBOLS = ["ManifestIcons"]; // jshint ignore:line