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/* vim: set ts=2 sts=2 sw=2 et tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
"use strict";
(function() {
function makeUrlAbsolute(base, relative) {
return new URL(relative, base).href;
}
function parseUrl(url) {
return new URL(url).host;
}
function getProvider(host) {
return host
.replace(/www[a-zA-Z0-9]*\./, '')
.replace('.co.', '.')
.split('.')
.slice(0, -1)
.join(' ');
}
function buildRuleSet(ruleSet) {
return (doc, context) => {
let maxScore = 0;
let maxValue;
for (let currRule = 0; currRule < ruleSet.rules.length; currRule++) {
const [query, handler] = ruleSet.rules[currRule];
const elements = Array.from(doc.querySelectorAll(query));
if(elements.length) {
for (const element of elements) {
let score = ruleSet.rules.length - currRule;
if (ruleSet.scorers) {
for (const scorer of ruleSet.scorers) {
const newScore = scorer(element, score);
if (newScore) {
score = newScore;
}
}
}
if (score > maxScore) {
maxScore = score;
maxValue = handler(element);
}
}
}
}
if (!maxValue && ruleSet.defaultValue) {
maxValue = ruleSet.defaultValue(context);
}
if (maxValue) {
if (ruleSet.processors) {
for (const processor of ruleSet.processors) {
maxValue = processor(maxValue, context);
}
}
if (maxValue.trim) {
maxValue = maxValue.trim();
}
return maxValue;
}
};
}
const metadataRuleSets = {
description: {
rules: [
['meta[property="og:description"]', element => element.getAttribute('content')],
['meta[name="description" i]', element => element.getAttribute('content')],
],
},
icon: {
rules: [
['link[rel="apple-touch-icon"]', element => element.getAttribute('href')],
['link[rel="apple-touch-icon-precomposed"]', element => element.getAttribute('href')],
['link[rel="icon" i]', element => element.getAttribute('href')],
['link[rel="fluid-icon"]', element => element.getAttribute('href')],
['link[rel="shortcut icon"]', element => element.getAttribute('href')],
['link[rel="Shortcut Icon"]', element => element.getAttribute('href')],
['link[rel="mask-icon"]', element => element.getAttribute('href')],
],
scorers: [
// Handles the case where multiple icons are listed with specific sizes ie
// <link rel="icon" href="small.png" sizes="16x16">
// <link rel="icon" href="large.png" sizes="32x32">
(element, score) => {
const sizes = element.getAttribute('sizes');
if (sizes) {
const sizeMatches = sizes.match(/\d+/g);
if (sizeMatches) {
return sizeMatches[0];
}
}
}
],
defaultValue: (context) => 'favicon.ico',
processors: [
(icon_url, context) => makeUrlAbsolute(context.url, icon_url)
]
},
image: {
rules: [
['meta[property="og:image:secure_url"]', element => element.getAttribute('content')],
['meta[property="og:image:url"]', element => element.getAttribute('content')],
['meta[property="og:image"]', element => element.getAttribute('content')],
['meta[name="twitter:image"]', element => element.getAttribute('content')],
['meta[property="twitter:image"]', element => element.getAttribute('content')],
['meta[name="thumbnail"]', element => element.getAttribute('content')],
],
processors: [
(image_url, context) => makeUrlAbsolute(context.url, image_url)
],
},
keywords: {
rules: [
['meta[name="keywords" i]', element => element.getAttribute('content')],
],
processors: [
(keywords, context) => keywords.split(',').map((keyword) => keyword.trim())
]
},
title: {
rules: [
['meta[property="og:title"]', element => element.getAttribute('content')],
['meta[name="twitter:title"]', element => element.getAttribute('content')],
['meta[property="twitter:title"]', element => element.getAttribute('content')],
['meta[name="hdl"]', element => element.getAttribute('content')],
['title', element => element.text],
],
},
language: {
rules: [
['html[lang]', element => element.getAttribute('lang')],
['meta[name="language" i]', element => element.getAttribute('content')],
],
processors: [
(language, context) => language.split('-')[0]
]
},
type: {
rules: [
['meta[property="og:type"]', element => element.getAttribute('content')],
],
},
url: {
rules: [
['a.amp-canurl', element => element.getAttribute('href')],
['link[rel="canonical"]', element => element.getAttribute('href')],
['meta[property="og:url"]', element => element.getAttribute('content')],
],
defaultValue: (context) => context.url,
processors: [
(url, context) => makeUrlAbsolute(context.url, url)
]
},
provider: {
rules: [
['meta[property="og:site_name"]', element => element.getAttribute('content')]
],
defaultValue: (context) => getProvider(parseUrl(context.url))
},
};
function getMetadata(doc, url, customRuleSets) {
const metadata = {};
const context = {
url,
};
const ruleSets = customRuleSets || metadataRuleSets;
Object.keys(ruleSets).map(ruleSetKey => {
const ruleSet = ruleSets[ruleSetKey];
const builtRuleSet = buildRuleSet(ruleSet);
metadata[ruleSetKey] = builtRuleSet(doc, context);
});
return metadata;
}
function MetadataWrapper() {
this.getMetadata = function() {
let metadata = getMetadata(document, document.URL);
// Default to using `document.URL` as the "official" URL.
metadata.url = document.URL;
// However, if this is an AMP page and a `link[rel="canonical"]`
// URL is available, use that instead. This is more reliable and
// produces better results than the URL extracted by the page
// metadata parser.
if (location.pathname.startsWith("/amp/")) {
let canonicalLink = document.querySelector("link[rel=\"canonical\"]");
let canonicalHref = canonicalLink && canonicalLink.href;
if (canonicalHref) {
metadata.url = canonicalHref;
}
}
return metadata;
};
}
Object.defineProperty(window.__firefox__, "metadata", {
enumerable: false,
configurable: false,
writable: false,
value: Object.freeze(new MetadataWrapper())
});
})();