faster install from known sites

background/background.js

@@ -1,8 +1,8 @@
 /* global download prefs openURL FIREFOX CHROME
-  URLS ignoreChromeError usercssHelper chromeLocal semverCompare
+  URLS ignoreChromeError chromeLocal semverCompare
   styleManager msg navigatorUtil workerUtil contentScripts sync
   findExistingTab activateTab isTabReplaceable getActiveTab
-  tabManager */
+*/
 
 'use strict';
 
@@ -111,14 +111,6 @@ navigatorUtil.onUrlChange(({tabId, frameId}, type) => {
   }
 });
 
-tabManager.onUpdate(({tabId, url, oldUrl = ''}) => {
-  if (usercssHelper.testUrl(url) && !oldUrl.startsWith(URLS.installUsercss)) {
-    usercssHelper.testContents(tabId, url).then(data => {
-      if (data.code) usercssHelper.openInstallerPage(tabId, url, data);
-    });
-  }
-});
-
 if (FIREFOX) {
   // FF misses some about:blank iframes so we inject our content script explicitly
   navigatorUtil.onDOMContentLoaded(webNavIframeHelperFF, {

background/usercss-helper.js

@@ -1,15 +1,8 @@
-/* global API_METHODS usercss styleManager deepCopy openURL download URLS */
+/* global API_METHODS usercss styleManager deepCopy */
 /* exported usercssHelper */
 'use strict';
 
 const usercssHelper = (() => {
-  const installCodeCache = {};
-  const clearInstallCode = url => delete installCodeCache[url];
-  const isResponseText = r => /^text\/(css|plain)(;.*?)?$/i.test(r.headers.get('content-type'));
-  // in Firefox we have to use a content script to read file://
-  const fileLoader = !chrome.app && // not relying on navigator.ua which can be spoofed
-    (tabId => browser.tabs.executeScript(tabId, {file: '/content/install-hook-usercss.js'}).then(r => r[0]));
-
   API_METHODS.installUsercss = installUsercss;
   API_METHODS.editSaveUsercss = editSaveUsercss;
   API_METHODS.configUsercssVars = configUsercssVars;
@@ -17,50 +10,6 @@ const usercssHelper = (() => {
   API_METHODS.buildUsercss = build;
   API_METHODS.findUsercss = find;
 
-  API_METHODS.getUsercssInstallCode = url => {
-    // when the installer tab is reloaded after the cache is expired, this will throw intentionally
-    const {code, timer} = installCodeCache[url];
-    clearInstallCode(url);
-    clearTimeout(timer);
-    return code;
-  };
-
-  return {
-
-    testUrl(url) {
-      return url.includes('.user.') &&
-        /^(https?|file|ftps?):/.test(url) &&
-        /\.user\.(css|styl)$/.test(url.split(/[#?]/, 1)[0]);
-    },
-
-    /** @return {Promise<{ code:string, inTab:boolean } | false>} */
-    testContents(tabId, url) {
-      const isFile = url.startsWith('file:');
-      const inTab = isFile && Boolean(fileLoader);
-      return Promise.resolve(isFile || fetch(url, {method: 'HEAD'}).then(isResponseText))
-        .then(ok => ok && (inTab ? fileLoader(tabId) : download(url)))
-        .then(code => /==userstyle==/i.test(code) && {code, inTab});
-    },
-
-    openInstallerPage(tabId, url, {code, inTab} = {}) {
-      const newUrl = `${URLS.installUsercss}?updateUrl=${encodeURIComponent(url)}`;
-      if (inTab) {
-        browser.tabs.get(tabId).then(tab =>
-          openURL({
-            url: `${newUrl}&tabId=${tabId}`,
-            active: tab.active,
-            index: tab.index + 1,
-            openerTabId: tabId,
-            currentWindow: null,
-          }));
-      } else {
-        const timer = setTimeout(clearInstallCode, 10e3, url);
-        installCodeCache[url] = {code, timer};
-        chrome.tabs.update(tabId, {url: newUrl});
-      }
-    },
-  };
-
   function buildMeta(style) {
     if (style.usercssData) {
       return Promise.resolve(style);

background/usercss-install-helper.js

@@ -0,0 +1,82 @@
+/* global API_METHODS openURL download URLS tabManager */
+'use strict';
+
+(() => {
+  const installCodeCache = {};
+  const clearInstallCode = url => delete installCodeCache[url];
+  const isContentTypeText = type => /^text\/(css|plain)(;.*?)?$/i.test(type);
+
+  // in Firefox we have to use a content script to read file://
+  const fileLoader = !chrome.app && (
+    async tabId =>
+      (await browser.tabs.executeScript(tabId, {file: '/content/install-hook-usercss.js'}))[0]);
+
+  const urlLoader =
+    async (tabId, url) => (
+      url.startsWith('file:') ||
+      tabManager.get(tabId, isContentTypeText.name) ||
+      isContentTypeText((await fetch(url, {method: 'HEAD'})).headers.get('content-type'))
+    ) && download(url);
+
+  API_METHODS.getUsercssInstallCode = url => {
+    // when the installer tab is reloaded after the cache is expired, this will throw intentionally
+    const {code, timer} = installCodeCache[url];
+    clearInstallCode(url);
+    clearTimeout(timer);
+    return code;
+  };
+
+  // Faster installation on known distribution sites to avoid flicker of css text
+  chrome.webRequest.onBeforeSendHeaders.addListener(({tabId, url}) => {
+    openInstallerPage(tabId, url, {});
+    // Silently suppressing navigation like it never happened
+    return {redirectUrl: 'javascript:void 0'}; // eslint-disable-line no-script-url
+  }, {
+    urls: [
+      URLS.usoArchiveRaw + 'usercss/*.user.css',
+      '*://greasyfork.org/scripts/*/code/*.user.css',
+      '*://sleazyfork.org/scripts/*/code/*.user.css',
+    ],
+    types: ['main_frame'],
+  }, ['blocking']);
+
+  // Remember Content-Type to avoid re-fetching of the headers in urlLoader as it can be very slow
+  chrome.webRequest.onHeadersReceived.addListener(({tabId, responseHeaders}) => {
+    const h = responseHeaders.find(h => h.name.toLowerCase() === 'content-type');
+    tabManager.set(tabId, isContentTypeText.name, h && isContentTypeText(h.value) || undefined);
+  }, {
+    urls: '%css,%css?*,%styl,%styl?*'.replace(/%/g, '*://*/*.user.').split(','),
+    types: ['main_frame'],
+  }, ['responseHeaders']);
+
+  tabManager.onUpdate(async ({tabId, url, oldUrl = ''}) => {
+    if (url.includes('.user.') &&
+        /^(https?|file|ftps?):/.test(url) &&
+        /\.user\.(css|styl)$/.test(url.split(/[#?]/, 1)[0]) &&
+        !oldUrl.startsWith(URLS.installUsercss)) {
+      const inTab = url.startsWith('file:') && Boolean(fileLoader);
+      const code = await (inTab ? fileLoader : urlLoader)(tabId, url);
+      if (/==userstyle==/i.test(code)) {
+        openInstallerPage(tabId, url, {code, inTab});
+      }
+    }
+  });
+
+  function openInstallerPage(tabId, url, {code, inTab} = {}) {
+    const newUrl = `${URLS.installUsercss}?updateUrl=${encodeURIComponent(url)}`;
+    if (inTab) {
+      browser.tabs.get(tabId).then(tab =>
+        openURL({
+          url: `${newUrl}&tabId=${tabId}`,
+          active: tab.active,
+          index: tab.index + 1,
+          openerTabId: tabId,
+          currentWindow: null,
+        }));
+    } else {
+      const timer = setTimeout(clearInstallCode, 10e3, url);
+      installCodeCache[url] = {code, timer};
+      chrome.tabs.update(tabId, {url: newUrl});
+    }
+  }
+})();

install-usercss/install-usercss.js

@@ -318,7 +318,9 @@
     let sequence = null;
     if (tabId < 0) {
       getData = DirectDownloader();
-      sequence = API.getUsercssInstallCode(initialUrl).catch(getData);
+      sequence = API.getUsercssInstallCode(initialUrl)
+        .then(code => code || getData())
+        .catch(getData);
     } else {
       getData = PortDownloader();
       sequence = getData({timer: false});

js/messaging.js

@@ -72,6 +72,10 @@ const URLS = {
     url.startsWith(URLS.usoArchiveRaw) &&
     parseInt(url.match(/\/(\d+)\.user\.css|$/)[1]),
 
+  extractGreasyForkId: url =>
+    /^https:\/\/(?:greasy|sleazy)fork\.org\/scripts\/(\d+)[^/]*\/code\/[^/]*\.user\.css$/.test(url) &&
+    RegExp.$1,
+
   supported: url => (
     url.startsWith('http') && (FIREFOX || !url.startsWith(URLS.browserWebStore)) ||
     url.startsWith('ftp') ||

manifest.json

@@ -51,6 +51,7 @@
       "background/icon-manager.js",
       "background/background.js",
       "background/usercss-helper.js",
+      "background/usercss-install-helper.js",
       "background/style-via-api.js",
       "background/search-db.js",
       "background/update.js",