From 5208a333943894edc5caaabddb9356d4ac4edea3 Mon Sep 17 00:00:00 2001
From: Dale Harvey <dale@arandomurl.com>
Date: Thu, 11 Jun 2020 08:10:50 +0000
Subject: [PATCH] Bug 1627550 - Trigger download of region maps when pref
 enabled r=leplatrem

Differential Revision: https://phabricator.services.mozilla.com/D78884
---
 toolkit/modules/Region.jsm | 106 ++++++++++++++++++++++++++++++++++---
 1 file changed, 98 insertions(+), 8 deletions(-)

diff --git a/toolkit/modules/Region.jsm b/toolkit/modules/Region.jsm
index 8b18986b9edd..55c73f6c4a3f 100644
--- a/toolkit/modules/Region.jsm
+++ b/toolkit/modules/Region.jsm
@@ -10,6 +10,10 @@ const { XPCOMUtils } = ChromeUtils.import(
   "resource://gre/modules/XPCOMUtils.jsm"
 );
 
+const { RemoteSettings } = ChromeUtils.import(
+  "resource://services-settings/remote-settings.js"
+);
+
 XPCOMUtils.defineLazyModuleGetters(this, {
   AppConstants: "resource://gre/modules/AppConstants.jsm",
   LocationHelper: "resource://gre/modules/LocationHelper.jsm",
@@ -40,12 +44,20 @@ XPCOMUtils.defineLazyPreferenceGetter(
   false
 );
 
+XPCOMUtils.defineLazyPreferenceGetter(
+  this,
+  "localGeocodingEnabled",
+  "browser.region.local-geocoding",
+  false
+);
+
 const log = console.createInstance({
   prefix: "Region.jsm",
   maxLogLevel: loggingEnabled ? "All" : "Warn",
 });
 
 const REGION_PREF = "browser.search.region";
+const COLLECTION_ID = "regions";
 
 /**
  * This module keeps track of the users current region (country).
@@ -53,6 +65,8 @@ const REGION_PREF = "browser.search.region";
  * specific customisations.
  */
 class RegionDetector {
+  // The RemoteSettings client used to sync region files.
+  _rsClient = null;
   // Keep track of the wifi data across listener events.
   wifiDataPromise = null;
   // Topic for Observer events fired by Region.jsm.
@@ -76,6 +90,11 @@ class RegionDetector {
     if (!region) {
       Services.tm.idleDispatchToMainThread(this._fetchRegion.bind(this));
     }
+    if (localGeocodingEnabled) {
+      Services.tm.idleDispatchToMainThread(
+        this._setupRemoteSettings.bind(this)
+      );
+    }
     this._home = region;
   }
 
@@ -246,6 +265,85 @@ class RegionDetector {
     }
   }
 
+  /**
+   * Setup the RemoteSetting client + sync listener and ensure
+   * the map files are downloaded.
+   */
+  async _setupRemoteSettings() {
+    log.info("_setupRemoteSettings");
+    this._rsClient = RemoteSettings(COLLECTION_ID);
+    this._rsClient.on("sync", this._onRegionFilesSync.bind(this));
+    await this._ensureRegionFilesDownloaded();
+  }
+
+  /**
+   * Called when RemoteSettings syncs new data, clean up any
+   * stale attachments and download any new ones.
+   *
+   * @param {Object} syncData
+   *   Object describing the data that has just been synced.
+   */
+  async _onRegionFilesSync({ data: { deleted } }) {
+    log.info("_onRegionFilesSync");
+    const toDelete = deleted.filter(d => d.attachment);
+    // Remove local files of deleted records
+    await Promise.all(
+      toDelete.map(entry => this._rsClient.attachments.delete(entry))
+    );
+    await this._ensureRegionFilesDownloaded();
+  }
+
+  /**
+   * Download the RemoteSetting record attachments, when they are
+   * successfully downloaded set a flag so we can start using them
+   * for geocoding.
+   */
+  async _ensureRegionFilesDownloaded() {
+    log.info("_ensureRegionFilesDownloaded");
+    let records = (await this._rsClient.get()).filter(d => d.attachment);
+    log.info("_ensureRegionFilesDownloaded", records);
+    if (!records.length) {
+      log.info("_ensureRegionFilesDownloaded: Nothing to download");
+      return;
+    }
+    let opts = { useCache: true };
+    await Promise.all(
+      records.map(r => this._rsClient.attachments.download(r, opts))
+    );
+    log.info("_ensureRegionFilesDownloaded complete");
+    this._regionFilesReady = true;
+  }
+
+  /**
+   * Fetch an attachment from RemoteSettings.
+   *
+   * @param {String} id
+   *   The id of the record to fetch the attachment from.
+   */
+  async _fetchAttachment(id) {
+    let record = (await this._rsClient.get({ filters: { id } })).pop();
+    let { buffer } = await this._rsClient.attachments.download(record, {
+      useCache: true,
+    });
+    let text = new TextDecoder("utf-8").decode(buffer);
+    return JSON.parse(text);
+  }
+
+  /**
+   * Get a map of the world with region definitions.
+   */
+  async _getPlainMap() {
+    return this._fetchAttachment("world");
+  }
+
+  /**
+   * Get a map with the regions expanded by a few km to help
+   * fallback lookups when a location is not within a region.
+   */
+  async _getBufferedMap() {
+    return this._fetchAttachment("world-buffered");
+  }
+
   /**
    * Gets the users current location using the same reverse IP
    * request that is used for GeoLocation requests.
@@ -276,14 +374,6 @@ class RegionDetector {
     return this._geoCode(location);
   }
 
-  // TODO: Stubs for testing
-  async _getPlainMap() {
-    return null;
-  }
-  async _getBufferedMap() {
-    return null;
-  }
-
   /**
    * Take a location and return the region code for that location
    * by looking up the coordinates in geojson map files.