[geary/mjog/email-templates: 11/17] Plugin.FolderPluginContext: Support registering special use folders

[Michael Gratton <mjog src gnome org>]

commit bbbafadbce6360c4cc3d2f8f72171edafd6836ec
Author: Michael Gratton <mike vee net>
Date:   Mon Apr 6 14:09:55 2020 +1000

    Plugin.FolderPluginContext: Support registering special use folders
    
    Add `register_folder_used_as` and `unregister_folder_used_as`, implement
    both `Application.FolderContextPlugin`.

 .../application-folder-plugin-context.vala         | 31 ++++++++++++++++++++++
 src/client/plugin/plugin-folder-extension.vala     | 19 +++++++++++++
 2 files changed, 50 insertions(+)
---
diff --git a/src/client/application/application-folder-plugin-context.vala 
b/src/client/application/application-folder-plugin-context.vala
index 1031e958..c4994693 100644
--- a/src/client/application/application-folder-plugin-context.vala
+++ b/src/client/application/application-folder-plugin-context.vala
@@ -64,6 +64,37 @@ internal class Application.FolderPluginContext :
         }
     }
 
+    public void register_folder_used_as(Plugin.Folder target,
+                                        string name,
+                                        string icon_name) throws Plugin.Error {
+        var context = this.folders_factory.get_folder_context(target);
+        if (context != null) {
+            try {
+                context.folder.set_used_as_custom(true);
+            } catch (Geary.EngineError err) {
+                throw new Plugin.Error.NOT_SUPPORTED(
+                    "Failed to register folder use: %s", err.message
+                );
+            }
+            context.display_name = name;
+            context.icon_name = icon_name;
+        }
+    }
+
+    public void unregister_folder_used_as(Plugin.Folder target)
+        throws Plugin.Error {
+        var context = this.folders_factory.get_folder_context(target);
+        if (context != null) {
+            try {
+                context.folder.set_used_as_custom(false);
+            } catch (Geary.EngineError err) {
+                throw new Plugin.Error.NOT_SUPPORTED(
+                    "Failed to unregister folder use: %s", err.message
+                );
+            }
+        }
+    }
+
     internal void destroy() {
         this.folders_factory.destroy_folder_store(this.folders);
     }
diff --git a/src/client/plugin/plugin-folder-extension.vala b/src/client/plugin/plugin-folder-extension.vala
index c90f0283..66b66df5 100644
--- a/src/client/plugin/plugin-folder-extension.vala
+++ b/src/client/plugin/plugin-folder-extension.vala
@@ -75,4 +75,23 @@ public interface Plugin.FolderContext : Geary.BaseObject {
     public abstract void remove_folder_info_bar(Folder selected,
                                                 InfoBar infobar);
 
+    /**
+     * Registers a folder for a well-known use.
+     *
+     * This promotes a folder from a label to a special-use folder,
+     * causing it to appear with other special-use folders with the
+     * given name and icon.
+     */
+    public abstract void register_folder_used_as(Folder target,
+                                                 string name,
+                                                 string icon_name) throws Error;
+
+    /**
+     * Unregisters a folder for a well-known use.
+     *
+     * This demotes the folder from a special-use to an ordinary
+     * label.
+     */
+    public abstract void unregister_folder_used_as(Folder target) throws Error;
+
 }