mod_storage_*: Include timestamp of latest message in :summary API

Clients may want to show a list of conversations ordered by how
timestamp of most recent message.

The counts allow a badge with unread message counter.

plugins/mod_storage_internal.lua

@@ -218,11 +218,14 @@ function archive:summary(username, query)
 	local iter, err = self:find(username, query)
 	if not iter then return iter, err; end
 	local counts = {};
-	for _, _, _, with in iter do
+	local latest = {};
+	for _, _, when, with in iter do
 		counts[with] = (counts[with] or 0) + 1;
+		latest[with] = when;
 	end
 	return {
 		counts = counts;
+		latest = latest;
 	};
 end
 

plugins/mod_storage_memory.lua

@@ -171,11 +171,14 @@ function archive_store:summary(username, query)
 	local iter, err = self:find(username, query)
 	if not iter then return iter, err; end
 	local counts = {};
-	for _, _, _, with in iter do
+	local latest = {};
+	for _, _, when, with in iter do
 		counts[with] = (counts[with] or 0) + 1;
+		latest[with] = when;
 	end
 	return {
 		counts = counts;
+		latest = latest;
 	};
 end
 

plugins/mod_storage_sql.lua

@@ -424,7 +424,7 @@ function archive_store:summary(username, query)
 	local user,store = username,self.store;
 	local ok, result = engine:transaction(function()
 		local sql_query = [[
-		SELECT DISTINCT "with", COUNT(*)
+		SELECT DISTINCT "with", COUNT(*), MAX("when")
 		FROM "prosodyarchive"
 		WHERE %s
 		GROUP BY "with"
@@ -447,12 +447,15 @@ function archive_store:summary(username, query)
 	end);
 	if not ok then return ok, result end
 	local counts = {};
+	local latest = {};
 	for row in result do
 		local with, count = row[1], row[2];
 		counts[with] = count;
+		latest[with] = row[3];
 	end
 	return {
 		counts = counts;
+		latest = latest;
 	};
 end