[geary/wip/conversation-polish: 15/22] Modernise FetchOperation somewhat

[Michael Gratton <mjog src gnome org>]

commit 2401a0738a0b0c3162571f3365e7058bb13fe263
Author: Michael Gratton <mike vee net>
Date:   Thu Jan 24 18:52:52 2019 +1100

    Modernise FetchOperation somewhat
    
    Tidy up the op's implementation, don't bother throwing new errors in
    MinimalFolder, they should be covered by the op.

 .../imap-engine/imap-engine-minimal-folder.vala    | 21 +++++++++------------
 .../replay-ops/imap-engine-fetch-email.vala        | 22 +++++++++++-----------
 2 files changed, 20 insertions(+), 23 deletions(-)
---
diff --git a/src/engine/imap-engine/imap-engine-minimal-folder.vala 
b/src/engine/imap-engine/imap-engine-minimal-folder.vala
index e9204bba..bef43a4a 100644
--- a/src/engine/imap-engine/imap-engine-minimal-folder.vala
+++ b/src/engine/imap-engine/imap-engine-minimal-folder.vala
@@ -1185,20 +1185,17 @@ private class Geary.ImapEngine.MinimalFolder : Geary.Folder, Geary.FolderSupport
         check_open("fetch_email_async");
         check_flags("fetch_email_async", flags);
         check_id("fetch_email_async", id);
-        
-        FetchEmail op = new FetchEmail(this, (ImapDB.EmailIdentifier) id, required_fields, flags,
-            cancellable);
+
+        FetchEmail op = new FetchEmail(
+            this,
+            (ImapDB.EmailIdentifier) id,
+            required_fields,
+            flags,
+            cancellable
+        );
         replay_queue.schedule(op);
-        
+
         yield op.wait_for_ready_async(cancellable);
-        
-        if (op.email == null) {
-            throw new EngineError.NOT_FOUND("Email %s not found in %s", id.to_string(), to_string());
-        } else if (!op.email.fields.fulfills(required_fields)) {
-            throw new EngineError.INCOMPLETE_MESSAGE("Email %s in %s does not fulfill required fields %Xh 
(has %Xh)",
-                id.to_string(), to_string(), required_fields, op.email.fields);
-        }
-        
         return op.email;
     }
 
diff --git a/src/engine/imap-engine/replay-ops/imap-engine-fetch-email.vala 
b/src/engine/imap-engine/replay-ops/imap-engine-fetch-email.vala
index 6c0d21bb..d5e3ed95 100644
--- a/src/engine/imap-engine/replay-ops/imap-engine-fetch-email.vala
+++ b/src/engine/imap-engine/replay-ops/imap-engine-fetch-email.vala
@@ -49,6 +49,7 @@ private class Geary.ImapEngine.FetchEmail : Geary.ImapEngine.SendReplayOperation
             return CONTINUE;
         }
 
+        Geary.Email? email = null;
         try {
             email = yield engine.local_folder.fetch_email_async(id, required_fields,
                 ImapDB.Folder.ListFlags.PARTIAL_OK, cancellable);
@@ -57,15 +58,17 @@ private class Geary.ImapEngine.FetchEmail : Geary.ImapEngine.SendReplayOperation
             if (!(err is Geary.EngineError.NOT_FOUND) && !(err is Geary.EngineError.INCOMPLETE_MESSAGE))
                 throw err;
         }
-        
+
         // If returned in full, done
-        if (email != null && email.fields.fulfills(required_fields))
+        if (email.fields.fulfills(required_fields)) {
+            this.email = email;
             return ReplayOperation.Status.COMPLETED;
+        }
 
         // If local only, ensure the email has all required fields
         if (flags.is_all_set(Folder.ListFlags.LOCAL_ONLY)) {
             throw new EngineError.INCOMPLETE_MESSAGE(
-                "Email %s with fields %Xh not found in %s",
+                "Email %s with fields %Xh locally incomplete %s",
                 id.to_string(),
                 required_fields,
                 to_string()
@@ -104,16 +107,13 @@ private class Geary.ImapEngine.FetchEmail : Geary.ImapEngine.SendReplayOperation
             new Imap.MessageSet.uid(uid), remaining_fields, cancellable);
         if (list == null || list.size != 1)
             throw new EngineError.NOT_FOUND("Unable to fetch %s in %s", id.to_string(), engine.to_string());
-        
-        // save to local store
-        email = list[0];
-        assert(email != null);
-        
+
         Gee.Map<Geary.Email, bool> created_or_merged =
             yield engine.local_folder.create_or_merge_email_async(
-                Geary.iterate<Geary.Email>(email).to_array_list(), cancellable);
-        
-        // true means created
+                list, cancellable
+            );
+
+        Geary.Email email = list[0];
         if (created_or_merged.get(email)) {
             Gee.Collection<Geary.EmailIdentifier> ids
                 = Geary.iterate<Geary.EmailIdentifier>(email.id).to_array_list();