[geary/wip/conversation-polish: 5/22] Replace pair of ConversationEmail body load state bools with single enum

[Michael Gratton <mjog src gnome org>]

commit 43080b891180f68ffbb1a679f5de88fe286a1ad0
Author: Michael Gratton <mike vee net>
Date:   Wed Jan 23 16:27:36 2019 +1100

    Replace pair of ConversationEmail body load state bools with single enum
    
    Reduces complexity a bit, provides a single property to track load state
    changes.

 .../conversation-viewer/conversation-email.vala    | 26 +++++++++++++++-------
 .../conversation-viewer/conversation-list-box.vala |  8 +++----
 2 files changed, 22 insertions(+), 12 deletions(-)
---
diff --git a/src/client/conversation-viewer/conversation-email.vala 
b/src/client/conversation-viewer/conversation-email.vala
index 1593c19c..297c382f 100644
--- a/src/client/conversation-viewer/conversation-email.vala
+++ b/src/client/conversation-viewer/conversation-email.vala
@@ -41,6 +41,19 @@ public class ConversationEmail : Gtk.Box, Geary.BaseInterface {
     private const int BODY_LOAD_TIMEOUT_MSEC = 250;
 
 
+    /** Specifies the loading state for a message part. */
+    public enum LoadState {
+
+        /** Loading has not started. */
+        NOT_STARTED,
+
+        /** Loading has started, but not completed. */
+        STARTED,
+
+        /** Loading has started and completed. */
+        COMPLETED;
+     }
+
     /**
      * Iterator that returns all message views in an email view.
      */
@@ -282,11 +295,8 @@ public class ConversationEmail : Gtk.Box, Geary.BaseInterface {
     private Gee.List<ConversationMessage> _attached_messages =
         new Gee.LinkedList<ConversationMessage>();
 
-    /** Determines if message bodies have started loading. */
-    public bool message_body_load_started { get; private set; default = false; }
-
-    /** Determines if all message have had loaded their bodies. */
-    public bool message_bodies_loaded { get; private set; default = false; }
+    /** Determines the message body loading state. */
+    public LoadState message_body_state { get; private set; default = NOT_STARTED; }
 
     // Store from which to load message content, if needed
     private Geary.App.EmailStore email_store;
@@ -568,7 +578,7 @@ public class ConversationEmail : Gtk.Box, Geary.BaseInterface {
      */
     public async void load_body()
         throws GLib.Error {
-        this.message_body_load_started = true;
+        this.message_body_state = STARTED;
 
         // Ensure we have required data to load the message
 
@@ -993,8 +1003,8 @@ public class ConversationEmail : Gtk.Box, Geary.BaseInterface {
                 break;
             }
         }
-        if (all_loaded && !this.message_bodies_loaded) {
-            this.message_bodies_loaded = true;
+        if (all_loaded && this.message_body_state != COMPLETED) {
+            this.message_body_state = COMPLETED;
             this.message_bodies_loaded_lock.blind_notify();
 
             // Update attachments once the web views have finished
diff --git a/src/client/conversation-viewer/conversation-list-box.vala 
b/src/client/conversation-viewer/conversation-list-box.vala
index 47f81ae0..e1f29e56 100644
--- a/src/client/conversation-viewer/conversation-list-box.vala
+++ b/src/client/conversation-viewer/conversation-list-box.vala
@@ -147,7 +147,7 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
             throws GLib.Error {
             this.is_expanded = true;
             update_row_expansion();
-            if (!this.view.message_body_load_started) {
+            if (this.view.message_body_state == NOT_STARTED) {
                 yield this.view.load_body();
             }
             foreach (ConversationMessage message in this.view) {
@@ -840,7 +840,7 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
             // size of the body will be off, affecting the visibility
             // of emails further down the conversation.
             if (email_view.email.is_unread().is_certain() &&
-                email_view.message_bodies_loaded &&
+                email_view.message_body_state == COMPLETED &&
                 !email_view.is_manually_read) {
                  int body_top = 0;
                  int body_left = 0;
@@ -881,10 +881,10 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
     }
 
     private void apply_search_terms(EmailRow row) {
-        if (row.view.message_bodies_loaded) {
+        if (row.view.message_body_state == COMPLETED) {
             this.apply_search_terms_impl.begin(row);
         } else {
-            row.view.notify["message-bodies-loaded"].connect(() => {
+            row.view.notify["message-body-state"].connect(() => {
                     this.apply_search_terms_impl.begin(row);
                 });
         }