REST: Extend get issue to return 1 or many

- Use consistent response payload when returning 1 or many.  This changed the
payload when getting a single issue.
- Support pagination when returning multiple issues.
- Support returning multiple issues based on a `project_id`.
- Support returning multiple issues based on a filter id + `project_id`.

api/rest/restcore/issues_rest.php

@@ -40,11 +40,43 @@
  * @return \Slim\Http\Response The augmented response.
  */
 function rest_issue_get( \Slim\Http\Request $p_request, \Slim\Http\Response $p_response, array $p_args ) {
-	# Username and password below are ignored, since middleware already done the auth.
-	$t_result = mc_issue_get( /* username */ '', /* password */ '', $p_request->getParam( 'id' ) );
+	$t_issue_id = $p_request->getParam( 'id' );
 
-	if( ApiObjectFactory::isFault( $t_result ) ) {
-		return $p_response->withStatus( $t_result->status_code, $t_result->fault_string );
+	if( !is_blank( $t_issue_id ) ) {
+		# Get Issue By Id
+
+		# Username and password below are ignored, since middleware already done the auth.
+		$t_issue = mc_issue_get( /* username */ '', /* password */ '', $t_issue_id );
+
+		if( ApiObjectFactory::isFault( $t_issue ) ) {
+			return $p_response->withStatus( $t_result->status_code, $t_result->fault_string );
+		}
+
+		$t_result = array( 'issues' => array( $t_issue ) );
+	} else {
+		$t_page_number = $p_request->getParam( 'page', 1 );
+		$t_page_size = $p_request->getParam( 'page_size', 50 );
+
+		# Get a set of issues
+		$t_project_id = (int)$p_request->getParam( 'project_id', ALL_PROJECTS );
+		if( $t_project_id != ALL_PROJECTS && !project_exists( $t_project_id ) ) {
+			# TODO: What's best was to escape $t_project?
+			$t_message = "Project '$t_project_id' doesn't exist";
+			return $p_response->withStatus( HTTP_STATUS_NOT_FOUND, $t_message );
+		}
+
+		$t_filter_id = (int)$p_request->getParam( 'filter_id', 0 );
+		if( $t_filter_id !== 0 ) {
+			# TODO: we should have a better way to do this.
+			global $g_project_override;
+			$g_project_override = $t_project_id;
+
+			$t_issues = mc_filter_get_issues( '', '', $t_project_id, $t_filter_id, $t_page_number, $t_page_size );
+		} else {
+			$t_issues = mc_project_get_issues( '', '', $t_project_id, $t_page_number, $t_page_size );
+		}
+
+		$t_result = array( 'issues' => $t_issues );
 	}
 
 	return $p_response->withStatus( HTTP_STATUS_SUCCESS )->withJson( $t_result );