/* 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 file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

/* global ExtensionCommon, ExtensionAPI, Glean, Services, XPCOMUtils, ExtensionUtils */

const { AddonManager } = ChromeUtils.importESModule(
  "resource://gre/modules/AddonManager.sys.mjs"
);
const { WebRequest } = ChromeUtils.importESModule(
  "resource://gre/modules/WebRequest.sys.mjs"
);
const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  AddonSearchEngine: "resource://gre/modules/AddonSearchEngine.sys.mjs",
  AppProvidedSearchEngine:
    "resource://gre/modules/AppProvidedSearchEngine.sys.mjs",
});

// eslint-disable-next-line mozilla/reject-importGlobalProperties
XPCOMUtils.defineLazyGlobalGetters(this, ["ChannelWrapper"]);

const SEARCH_TOPIC_ENGINE_MODIFIED = "browser-search-engine-modified";

this.addonsSearchDetection = class extends ExtensionAPI {
  getAPI(context) {
    Services.telemetry.setEventRecordingEnabled("addonsSearchDetection", true);
    const { extension } = context;

    // We want to temporarily store the first monitored URLs that have been
    // redirected, indexed by request IDs, so that the background script can
    // find the add-on IDs to report.
    this.firstMatchedUrls = {};

    return {
      addonsSearchDetection: {
        // `getMatchPatterns()` returns a map where each key is an URL pattern
        // to monitor and its corresponding value is a list of add-on IDs
        // (search engines).
        //
        // Note: We don't return a simple list of URL patterns because the
        // background script might want to lookup add-on IDs for a given URL in
        // the case of server-side redirects.
        async getMatchPatterns() {
          const patterns = {};

          try {
            await Services.search.promiseInitialized;
            const engines = await Services.search.getEngines();

            for (let engine of engines) {
              if (
                !(engine instanceof lazy.AddonSearchEngine) &&
                !(engine instanceof lazy.AppProvidedSearchEngine)
              ) {
                continue;
              }

              // The search term isn't used, but avoids a warning of an empty
              // term.
              let submission = engine.getSubmission("searchTerm");
              if (submission) {
                // If this is changed, double check the code in the background
                // script because `getAddonIdsForUrl` truncates the last
                // character.
                const pattern =
                  submission.uri.prePath + submission.uri.filePath + "*";

                // Multiple search engines could register URL templates that
                // would become the same URL pattern as defined above so we
                // store a list of extension IDs per URL pattern.
                if (!patterns[pattern]) {
                  patterns[pattern] = [];
                }

                // We don't store ids for application provided search engines
                // because we don't need to report them. However, we do ensure
                // the pattern is recorded (above), so that we check for
                // redirects against those.
                const _extensionID = engine.wrappedJSObject._extensionID;
                if (_extensionID && !patterns[pattern].includes(_extensionID)) {
                  patterns[pattern].push(_extensionID);
                }
              }
            }
          } catch (err) {
            console.error(err);
          }

          return patterns;
        },

        // `getAddonVersion()` returns the add-on version if it exists.
        async getAddonVersion(addonId) {
          const addon = await AddonManager.getAddonByID(addonId);

          return addon && addon.version;
        },

        // `getPublicSuffix()` returns the public suffix/Effective TLD Service
        // of the given URL.
        // See: https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIEffectiveTLDService
        async getPublicSuffix(url) {
          try {
            return Services.eTLD.getBaseDomain(Services.io.newURI(url));
          } catch (err) {
            console.error(err);
            return null;
          }
        },

        // Report a redirect via Glean and Telemetry.
        report(maybeServerSideRedirect, extra) {
          if (maybeServerSideRedirect) {
            Glean.addonsSearchDetection.etldChangeOther.record(extra);
          } else {
            Glean.addonsSearchDetection.etldChangeWebrequest.record(extra);
          }
        },

        // `onSearchEngineModified` is an event that occurs when the list of
        // search engines has changed, e.g., a new engine has been added or an
        // engine has been removed.
        //
        // See: https://searchfox.org/mozilla-central/rev/cb44fc4f7bb84f2a18fedba64c8563770df13e34/toolkit/components/search/SearchUtils.sys.mjs#185-193
        onSearchEngineModified: new ExtensionCommon.EventManager({
          context,
          name: "addonsSearchDetection.onSearchEngineModified",
          register: fire => {
            const onSearchEngineModifiedObserver = (
              aSubject,
              aTopic,
              aData
            ) => {
              if (
                aTopic !== SEARCH_TOPIC_ENGINE_MODIFIED ||
                // We are only interested in these modified types.
                !["engine-added", "engine-removed", "engine-changed"].includes(
                  aData
                )
              ) {
                return;
              }

              fire.async();
            };

            Services.obs.addObserver(
              onSearchEngineModifiedObserver,
              SEARCH_TOPIC_ENGINE_MODIFIED
            );

            return () => {
              Services.obs.removeObserver(
                onSearchEngineModifiedObserver,
                SEARCH_TOPIC_ENGINE_MODIFIED
              );
            };
          },
        }).api(),

        // `onRedirected` is an event fired after a request has stopped and
        // this request has been redirected once or more. The registered
        // listeners will received the following properties:
        //
        //   - `addonId`: the add-on ID that redirected the request, if any.
        //   - `firstUrl`: the first monitored URL of the request that has
        //      been redirected.
        //   - `lastUrl`: the last URL loaded for the request, after one or
        //      more redirects.
        onRedirected: new ExtensionCommon.EventManager({
          context,
          name: "addonsSearchDetection.onRedirected",
          register: (fire, filter) => {
            const stopListener = event => {
              if (event.type != "stop") {
                return;
              }

              const wrapper = event.currentTarget;
              const { channel, id: requestId } = wrapper;

              // When we detected a redirect, we read the request property,
              // hoping to find an add-on ID corresponding to the add-on that
              // initiated the redirect. It might not return anything when the
              // redirect is a search server-side redirect but it can also be
              // caused by an error.
              let addonId;
              try {
                addonId = channel
                  ?.QueryInterface(Ci.nsIPropertyBag)
                  ?.getProperty("redirectedByExtension");
              } catch (err) {
                console.error(err);
              }

              const firstUrl = this.firstMatchedUrls[requestId];
              // We don't need this entry anymore.
              delete this.firstMatchedUrls[requestId];

              const lastUrl = wrapper.finalURL;

              if (!firstUrl || !lastUrl) {
                // Something went wrong but there is nothing we can do at this
                // point.
                return;
              }

              fire.sync({ addonId, firstUrl, lastUrl });
            };

            const remoteTab = context.xulBrowser.frameLoader.remoteTab;

            const listener = ({ requestId, url, originUrl }) => {
              // We exclude requests not originating from the location bar,
              // bookmarks and other "system-ish" requests.
              if (originUrl !== undefined) {
                return;
              }

              // Keep the first monitored URL that was redirected for the
              // request until the request has stopped.
              if (!this.firstMatchedUrls[requestId]) {
                this.firstMatchedUrls[requestId] = url;

                const wrapper = ChannelWrapper.getRegisteredChannel(
                  requestId,
                  context.extension.policy,
                  remoteTab
                );

                wrapper.addEventListener("stop", stopListener);
              }
            };

            const ensureRegisterChannel = data => {
              // onRedirected depends on ChannelWrapper.getRegisteredChannel,
              // which in turn depends on registerTraceableChannel to have been
              // called. When a blocking webRequest listener is present, the
              // parent/ext-webRequest.js implementation already calls that.
              //
              // A downside to a blocking webRequest listener is that it delays
              // the network request until a roundtrip to the listener in the
              // extension process has happened. Since we don't need to handle
              // the onBeforeRequest event, avoid the overhead by handling the
              // event and registration here, in the parent process.
              data.registerTraceableChannel(extension.policy, remoteTab);
            };

            const parsedFilter = {
              types: ["main_frame"],
              urls: ExtensionUtils.parseMatchPatterns(filter.urls),
            };

            WebRequest.onBeforeRequest.addListener(
              ensureRegisterChannel,
              parsedFilter,
              // blocking is needed to unlock data.registerTraceableChannel.
              ["blocking"],
              {
                addonId: extension.id,
                policy: extension.policy,
                blockingAllowed: true,
              }
            );

            WebRequest.onBeforeRedirect.addListener(
              listener,
              parsedFilter,
              // info
              [],
              // listener details
              {
                addonId: extension.id,
                policy: extension.policy,
                blockingAllowed: false,
              }
            );

            return () => {
              WebRequest.onBeforeRequest.removeListener(ensureRegisterChannel);
              WebRequest.onBeforeRedirect.removeListener(listener);
            };
          },
        }).api(),
      },
    };
  }
};
