[geary/mjog/draft-errors: 4/6] Composer.Widget: Rework draft manager management

[Michael Gratton <mjog src gnome org>]

commit 6d5b0bc5b6ee45b6f31ba53d98c6a6c77e5ce2cd
Author: Michael Gratton <mike vee net>
Date:   Sun Oct 25 18:57:47 2020 +1100

    Composer.Widget: Rework draft manager management
    
    Since the draft manager will now block until a remote for the draft
    folder has been obtained, it now must be ensured that all calls to
    opening the manager are backgrounded so that the UI isn't blocked
    when offline.

 src/client/composer/composer-widget.vala | 76 +++++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 26 deletions(-)
---
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index fe29011d0..61e3a84cc 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -971,7 +971,21 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
         this.header.set_sensitive(enabled);
 
         if (enabled) {
-            this.open_draft_manager.begin(this.saved_id, null);
+            var current_account = this.sender_context.account;
+            this.open_draft_manager.begin(
+                this.saved_id,
+                (obj, res) => {
+                    try {
+                        this.open_draft_manager.end(res);
+                    } catch (GLib.Error error) {
+                        this.application.report_problem(
+                            new Geary.AccountProblemReport(
+                                current_account.information, error
+                            )
+                        );
+                    }
+                }
+            );
         } else {
             if (this.container != null) {
                 this.container.close();
@@ -984,7 +998,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
     public async void set_save_to_override(Geary.Folder? save_to)
         throws GLib.Error {
         this.save_to = save_to;
-        yield reopen_draft_manager();
+        this.reopen_draft_manager.begin();
     }
 
     /**
@@ -1423,11 +1437,21 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
             is_body_complete
         );
 
-        try {
-            yield open_draft_manager(this.saved_id);
-        } catch (Error e) {
-            debug("Could not open draft manager: %s", e.message);
-        }
+        var current_account = this.sender_context.account;
+        this.open_draft_manager.begin(
+            this.saved_id,
+            (obj, res) => {
+                try {
+                    this.open_draft_manager.end(res);
+                } catch (GLib.Error error) {
+                    this.application.report_problem(
+                        new Geary.AccountProblemReport(
+                            current_account.information, error
+                        )
+                    );
+                }
+            }
+        );
     }
 
     private async bool should_send() {
@@ -1501,6 +1525,11 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
 
     /**
      * Creates and opens the composer's draft manager.
+     *
+     * Note that since the draft manager may block until a remote
+     * connection is open, this method may likewise do so. Hence this
+     * method typically needs to be called from the main loop as a
+     * background async task using the `begin` async call form.
      */
     private async void open_draft_manager(Geary.EmailIdentifier? editing_draft_id)
         throws GLib.Error {
@@ -1572,13 +1601,21 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
     /**
      * Closes current draft manager, if any, then opens a new one.
      */
-    private async void reopen_draft_manager()
-        throws GLib.Error {
+    private async void reopen_draft_manager() {
         // Discard the draft, if any, since it may be on a different
         // account
-        yield close_draft_manager(DISCARD);
-        yield open_draft_manager(null);
-        yield save_draft();
+        var current_account = this.sender_context.account;
+        try {
+            yield close_draft_manager(DISCARD);
+            yield open_draft_manager(null);
+            yield save_draft();
+        } catch (GLib.Error error) {
+            this.application.report_problem(
+                new Geary.AccountProblemReport(
+                    current_account.information, error
+                )
+            );
+        }
     }
 
     private async void close_draft_manager(DraftPolicy draft_policy)
@@ -2254,20 +2291,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
                 this.update_signature.begin(null);
                 load_entry_completions();
 
-                var current_account = this.sender_context.account;
-                this.reopen_draft_manager.begin(
-                    (obj, res) => {
-                        try {
-                            this.reopen_draft_manager.end(res);
-                        } catch (GLib.Error error) {
-                            this.application.report_problem(
-                                new Geary.AccountProblemReport(
-                                    current_account.information, error
-                                )
-                            );
-                        }
-                    }
-                );
+                this.reopen_draft_manager.begin();
             }
         }
     }