[geary/mjog/email-templates: 5/7] Plugin.Composer: Support disabling sending a composer

[Michael Gratton <mjog src gnome org>]

commit 10510727b6eddd071cb99b58e5f07c1af15a7dd9
Author: Michael Gratton <mike vee net>
Date:   Tue Apr 21 16:21:23 2020 +1000

    Plugin.Composer: Support disabling sending a composer
    
    Allow disabling send in the composer for editing templates.

 .../application/application-plugin-manager.vala       |  4 +++-
 src/client/composer/composer-headerbar.vala           |  7 +++++++
 src/client/composer/composer-widget.vala              | 19 +++++++++++++++++--
 src/client/plugin/plugin-composer.vala                |  5 +++++
 4 files changed, 32 insertions(+), 3 deletions(-)
---
diff --git a/src/client/application/application-plugin-manager.vala 
b/src/client/application/application-plugin-manager.vala
index 4db5fa5b..7809861e 100644
--- a/src/client/application/application-plugin-manager.vala
+++ b/src/client/application/application-plugin-manager.vala
@@ -178,6 +178,8 @@ public class Application.PluginManager : GLib.Object {
     private class ComposerImpl : Geary.BaseObject, Plugin.Composer {
 
 
+        public override bool can_send { get; set; default = true; }
+
         private Client application;
         private AccountContext account;
         private FolderStoreFactory folders;
@@ -241,7 +243,7 @@ public class Application.PluginManager : GLib.Object {
                     this.save_location
                 );
             }
-            //composer.can_send = this.can_send;
+            composer.can_send = this.can_send;
         }
 
     }
diff --git a/src/client/composer/composer-headerbar.vala b/src/client/composer/composer-headerbar.vala
index 33cb3652..6fb21386 100644
--- a/src/client/composer/composer-headerbar.vala
+++ b/src/client/composer/composer-headerbar.vala
@@ -13,6 +13,11 @@ public class Composer.Headerbar : Gtk.HeaderBar {
         set { this.save_and_close_button.visible = value; }
     }
 
+    public bool show_send {
+        get { return this.send_button.visible; }
+        set { this.send_button.visible = value; }
+    }
+
     private Application.Configuration config;
 
     private bool is_attached = true;
@@ -28,6 +33,8 @@ public class Composer.Headerbar : Gtk.HeaderBar {
     [GtkChild]
     private Gtk.Button save_and_close_button;
 
+    [GtkChild]
+    private Gtk.Button send_button;
 
     /** Fired when the user wants to expand a compact composer. */
     public signal void expand_composer();
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index c340218b..a2186d7c 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -283,7 +283,19 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
         }
     }
 
-    public WebView editor { get; private set; }
+    /** Determines if the composer can send the message. */
+    public bool can_send {
+        get {
+            return this._can_send;
+        }
+        set {
+            this._can_send = value;
+            validate_send_button();
+        }
+    }
+    private bool _can_send = true;
+
+    internal WebView editor { get; private set; }
 
     internal Headerbar header { get; private set; }
 
@@ -1636,7 +1648,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
 
         Geary.Folder? target = this.save_to;
         if (target == null) {
-            this.sender_context.account.get_required_special_folder_async(
+            target = yield this.sender_context.account.get_required_special_folder_async(
                 DRAFTS, internal_cancellable
             );
         }
@@ -2037,11 +2049,14 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
         // To must be valid (and hence non-empty), the other email
         // fields must be either empty or valid.
         get_action(ACTION_SEND).set_enabled(
+            this.can_send &&
             this.to_entry.is_valid &&
             (this.cc_entry.is_empty || this.cc_entry.is_valid) &&
             (this.bcc_entry.is_empty || this.bcc_entry.is_valid) &&
             (this.reply_to_entry.is_empty || this.reply_to_entry.is_valid)
         );
+
+        this.header.show_send = this.can_send;
     }
 
     private void set_compact_header_recipients() {
diff --git a/src/client/plugin/plugin-composer.vala b/src/client/plugin/plugin-composer.vala
index 9635f39b..146721dd 100644
--- a/src/client/plugin/plugin-composer.vala
+++ b/src/client/plugin/plugin-composer.vala
@@ -11,6 +11,11 @@
 public interface Plugin.Composer : Geary.BaseObject {
 
 
+    /**
+     * Determines if the email in the composer can be sent.
+     */
+    public abstract bool can_send { get; set; }
+
     /**
      * Causes the composer to be made visible.
      *