Plugin: Add EmailExtension plugin extension type

Add EmailExtension plugin extenion with context object and
Application.EmailContext implementing it. Check for plugins with
this type in PluginManager and init/deinit their contexts as needed.

po/POTFILES.in

@@ -23,6 +23,7 @@ src/client/application/application-configuration.vala
 src/client/application/application-contact-store.vala
 src/client/application/application-contact.vala
 src/client/application/application-controller.vala
+src/client/application/application-email-context.vala
 src/client/application/application-email-store-factory.vala
 src/client/application/application-folder-context.vala
 src/client/application/application-folder-store-factory.vala
@@ -92,6 +93,7 @@ src/client/plugin/plugin-account.vala
 src/client/plugin/plugin-application.vala
 src/client/plugin/plugin-button.vala
 src/client/plugin/plugin-contact-store.vala
+src/client/plugin/plugin-email-extension.vala
 src/client/plugin/plugin-email-store.vala
 src/client/plugin/plugin-email.vala
 src/client/plugin/plugin-error.vala

src/client/application/application-email-context.vala

@@ -0,0 +1,36 @@
+/*
+ * Copyright © 2020 Michael Gratton <mike@vee.net>
+ *
+ * This software is licensed under the GNU Lesser General Public License
+ * (version 2.1 or later). See the COPYING file in this distribution.
+ */
+
+/**
+ * Implementation of the email plugin extension context.
+ */
+internal class Application.EmailContext :
+    Geary.BaseObject, Plugin.EmailContext {
+
+
+    private unowned Client application;
+    private EmailStoreFactory email_factory;
+    private Plugin.EmailStore email;
+
+
+    internal EmailContext(Client application,
+                          EmailStoreFactory email_factory) {
+        this.application = application;
+        this.email_factory = email_factory;
+        this.email = email_factory.new_email_store();
+    }
+
+    public async Plugin.EmailStore get_email()
+        throws Plugin.Error.PERMISSION_DENIED {
+        return this.email;
+    }
+
+    internal void destroy() {
+        this.email_factory.destroy_email_store(this.email);
+    }
+
+}

src/client/application/application-plugin-manager.vala

@@ -313,6 +313,14 @@ public class Application.PluginManager : GLib.Object {
                 notification.notifications = context;
             }
 
+            var email = plugin as Plugin.EmailExtension;
+            if (email != null) {
+                email.email = new EmailContext(
+                    this.application,
+                    this.email_factory
+                );
+            }
+
             var folder = plugin as Plugin.FolderExtension;
             if (folder != null) {
                 folder.folders = new FolderContext(
@@ -389,9 +397,17 @@ public class Application.PluginManager : GLib.Object {
 
         var folder = context.plugin as Plugin.FolderExtension;
         if (folder != null) {
-            var folders = folder.folders as FolderContext;
-            if (folders != null) {
-                folders.destroy();
+            var folder_context = folder.folders as FolderContext;
+            if (folder_context != null) {
+                folder_context.destroy();
+            }
+        }
+
+        var email = context.plugin as Plugin.EmailExtension;
+        if (email != null) {
+            var email_context = email.email as Application.EmailContext;
+            if (email_context != null) {
+                email_context.destroy();
             }
         }
 

src/client/meson.build

@@ -20,6 +20,7 @@ geary_client_vala_sources = files(
   'application/application-contact-store.vala',
   'application/application-contact.vala',
   'application/application-controller.vala',
+  'application/application-email-context.vala',
   'application/application-email-store-factory.vala',
   'application/application-folder-context.vala',
   'application/application-folder-store-factory.vala',
@@ -111,6 +112,7 @@ geary_client_vala_sources = files(
   'plugin/plugin-application.vala',
   'plugin/plugin-button.vala',
   'plugin/plugin-contact-store.vala',
+  'plugin/plugin-email-extension.vala',
   'plugin/plugin-email-store.vala',
   'plugin/plugin-email.vala',
   'plugin/plugin-error.vala',

src/client/plugin/plugin-email-extension.vala

@@ -0,0 +1,53 @@
+/*
+ * Copyright © 2020 Michael Gratton <mike@vee.net>
+ *
+ * This software is licensed under the GNU Lesser General Public License
+ * (version 2.1 or later). See the COPYING file in this distribution.
+ */
+
+/**
+ * A plugin extension point for working with email messages.
+ */
+public interface Plugin.EmailExtension : PluginBase {
+
+    /**
+     * Context object for accessing email.
+     *
+     * This will be set during (or just after) plugin construction,
+     * before {@link PluginBase.activate} is called.
+     */
+    public abstract EmailContext email {
+        get; set construct;
+    }
+
+}
+
+
+// XXX this should be an inner interface of EmailExtension, but
+// GNOME/vala#918 prevents that.
+
+/**
+ * Provides a context for email plugins.
+ *
+ * The context provides an interface for email plugins to interface
+ * with the Geary client application. Plugins that implement the
+ * {@link EmailExtension} interface will be given an instance of this
+ * class.
+ *
+ * @see Plugin.EmailExtension.email
+ */
+public interface Plugin.EmailContext : Geary.BaseObject {
+
+
+    /**
+     * Returns a store to lookup email.
+     *
+     * This method may prompt for permission before returning.
+     *
+     * @throws Error.PERMISSIONS if permission to access
+     * this resource was not given
+     */
+    public abstract async EmailStore get_email()
+        throws Error.PERMISSION_DENIED;
+
+}