environment: Fallback to Soup 2.4

We cannot assume yet that Soup3 is available everywhere. Until that
is the case, allow falling back to Soup 2.4 by imitating the bits
of the Soup3 API we use with monkey-patching.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1940>

js/ui/environment.js

@@ -11,6 +11,14 @@ imports.gi.versions.Soup = '3.0';
 imports.gi.versions.TelepathyGLib = '0.12';
 imports.gi.versions.TelepathyLogger = '0.2';
 
+try {
+    const Soup_ = imports.gi.Soup;
+} catch (e) {
+    imports.gi.versions.Soup = '2.4';
+    const { Soup } = imports.gi;
+    _injectSoup3Compat(Soup);
+}
+
 const { Clutter, Gio, GLib, GObject, Meta, Polkit, Shell, St } = imports.gi;
 const Gettext = imports.gettext;
 const System = imports.system;
@@ -69,6 +77,44 @@ function _patchLayoutClass(layoutClass, styleProps) {
     }
 }
 
+/**
+ * Mimick the Soup 3 APIs we use when falling back to Soup 2.4
+ *
+ * @param {object} Soup 2.4 namespace
+ * @returns {void}
+ */
+function _injectSoup3Compat(Soup) {
+    const ByteArray = imports.byteArray;
+
+    Soup.StatusCode = Soup.KnownStatusCode;
+
+    Soup.Message.new_from_encoded_form =
+        function (method, uri, form) {
+            const soupUri = new Soup.URI(uri);
+            soupUri.set_query(form);
+            return Soup.Message.new_from_uri(method, soupUri);
+        };
+    Soup.Message.prototype.set_request_body_from_bytes =
+        function (contentType, bytes) {
+            this.set_request(
+                contentType,
+                Soup.MemoryUse.COPY,
+                ByteArray.toString(bytes.get_data()));
+        };
+
+    Soup.Session.prototype.send_and_read_async =
+        function (message, prio, cancellable, callback) {
+            this.queue_message(message, () => callback(this, message));
+        };
+    Soup.Session.prototype.send_and_read_finish =
+        function (message) {
+            if (message.status_code !== Soup.KnownStatusCode.OK)
+                return null;
+
+            return message.response_body.flatten().get_as_bytes();
+        };
+}
+
 function _makeEaseCallback(params, cleanup) {
     let onComplete = params.onComplete;
     delete params.onComplete;