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extensions/chromium/extension-router.js

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+/*
+Copyright 2013 Mozilla Foundation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+"use strict";
+
+(function ExtensionRouterClosure() {
+  var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
+  var CRX_BASE_URL = chrome.runtime.getURL("/");
+
+  var schemes = [
+    "http",
+    "https",
+    "file",
+    "chrome-extension",
+    "blob",
+    "data",
+    // Chromium OS
+    "filesystem",
+    // Chromium OS, shorthand for filesystem:<origin>/external/
+    "drive",
+  ];
+
+  /**
+   * @param {string} url The URL prefixed with chrome-extension://.../
+   * @returns {string|undefined} The percent-encoded URL of the (PDF) file.
+   */
+  function parseExtensionURL(url) {
+    url = url.substring(CRX_BASE_URL.length);
+    // Find the (url-encoded) colon and verify that the scheme is allowed.
+    var schemeIndex = url.search(/:|%3A/i);
+    if (schemeIndex === -1) {
+      return undefined;
+    }
+    var scheme = url.slice(0, schemeIndex).toLowerCase();
+    if (schemes.includes(scheme)) {
+      // NOTE: We cannot use the `updateUrlHash` function in this context.
+      url = url.split("#", 1)[0];
+      if (url.charAt(schemeIndex) === ":") {
+        url = encodeURIComponent(url);
+      }
+      return url;
+    }
+    return undefined;
+  }
+
+  function resolveViewerURL(originalUrl) {
+    if (originalUrl.startsWith(CRX_BASE_URL)) {
+      // This listener converts chrome-extension://.../http://...pdf to
+      // chrome-extension://.../content/web/viewer.html?file=http%3A%2F%2F...pdf
+      var url = parseExtensionURL(originalUrl);
+      if (url) {
+        url = VIEWER_URL + "?file=" + url;
+        var i = originalUrl.indexOf("#");
+        if (i > 0) {
+          url += originalUrl.slice(i);
+        }
+        return url;
+      }
+    }
+    return undefined;
+  }
+
+  self.addEventListener("fetch", event => {
+    const req = event.request;
+    if (req.destination === "document") {
+      var url = resolveViewerURL(req.url);
+      if (url) {
+        console.log("Redirecting " + req.url + " to " + url);
+        event.respondWith(Response.redirect(url));
+      }
+    }
+  });
+
+  // Ctrl + F5 bypasses service worker. the pretty extension URLs will fail to
+  // resolve in that case. Catch this and redirect to destination.
+  chrome.webNavigation.onErrorOccurred.addListener(
+    details => {
+      if (details.frameId !== 0) {
+        // Not a top-level frame. Cannot easily navigate a specific child frame.
+        return;
+      }
+      const url = resolveViewerURL(details.url);
+      if (url) {
+        console.log(`Redirecting ${details.url} to ${url} (fallback)`);
+        chrome.tabs.update(details.tabId, { url });
+      }
+    },
+    { url: [{ urlPrefix: CRX_BASE_URL }] }
+  );
+
+  console.log("Set up extension URL router.");
+})();