[gnome-maps/wip/mlundblad/override-transit-plugin: 2/3] transitRouter: Allow overriding plugin

[Marcus Lundblad <mlundblad src gnome org>]

commit 6ad60155432685578d1db019db47fa36b85b7fcf
Author: Marcus Lundblad <ml update uu se>
Date:   Fri Jan 8 23:22:06 2021 +0100

    transitRouter: Allow overriding plugin
    
    Allow setting the environment variable TRANSIT_PLUGIN
    to override the plugin to use.

 src/transitRouter.js | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)
---
diff --git a/src/transitRouter.js b/src/transitRouter.js
index 61d8650a..e2a3e5ec 100644
--- a/src/transitRouter.js
+++ b/src/transitRouter.js
@@ -19,6 +19,7 @@
  * Author: Marcus Lundblad <ml update uu se>
  */
 
+const GLib = imports.gi.GLib;
 const Champlain = imports.gi.Champlain;
 
 const Service = imports.service;
@@ -54,15 +55,36 @@ var TransitRouter = class TransitRoute {
      * of results-
      */
     fetchFirstResults() {
-        let bestProvider = this._getBestProviderForQuery();
+        let pluginOverride = GLib.getenv('TRANSIT_PLUGIN');
+
+        if (pluginOverride) {
+            // override plugin was specified, try instanciating if not done yet
+            if (!this._currPluginInstance) {
+                let module = this._availablePlugins[pluginOverride];
+
+                if (module) {
+                    this._currPluginInstance =
+                        new imports.transitplugins[module][pluginOverride]();
+                } else {
+                    throw new Error('Specified override plugin not found');
+                }
+            }
+        } else {
+            let bestProvider = this._getBestProviderForQuery();
+
+            this._currPluginInstance = null;
 
-        if (bestProvider) {
-            let provider = bestProvider[0];
+            if (bestProvider) {
+                let provider = bestProvider[0];
+
+                this._currPluginInstance = bestProvider[1];
+                this._plan.attribution = this._getAttributionForProvider(provider);
+                if (provider.attributionUrl)
+                    this._plan.attributionUrl = provider.attributionUrl;
+            }
+        }
 
-            this._currPluginInstance = bestProvider[1];
-            this._plan.attribution = this._getAttributionForProvider(provider);
-            if (provider.attributionUrl)
-                this._plan.attributionUrl = provider.attributionUrl;
+        if (this._currPluginInstance) {
             this._currPluginInstance.fetchFirstResults();
         } else {
             this._plan.reset();