Custom sort order for section dropdown.

See #113.

classes/Server/Question/Query.php

@@ -245,6 +245,54 @@ public function get_filter_options( $filter ) {
 			break;
 		}
 
+		// Custom sort for sections.
+		if ( 'section' === $filter ) {
+			$semesters = array();
+			foreach ( $options as $option ) {
+				$parts = explode( '-', $option['name'] );
+				if ( 3 > count( $parts ) ) {
+					$semester = 'S10';
+				} else {
+					$semester = $parts[1];
+				}
+
+				$semesters[ $semester ][] = $option;
+			}
+
+			uksort( $semesters, function( $a, $b ) {
+				$term_a = substr( $a, 0, 1 );
+				$term_b = substr( $b, 0, 1 );
+
+				$year_a = substr( $a, 1 );
+				$year_b = substr( $b, 1 );
+
+				if ( $year_a === $year_b ) {
+					if ( 'F' === $a ) {
+						return 1;
+					} else {
+						return -1;
+					}
+				} else {
+					return $year_a < $year_b ? 1 : -1;
+				}
+
+				return 0;
+			} );
+
+			$options = array();
+			foreach ( $semesters as &$sections ) {
+				usort( $sections, function( $a, $b ) {
+					if ( $a['name'] === $b['name'] ) {
+						return 0;
+					}
+
+					return $a['name'] > $b['name'] ? 1 : -1;
+				} );
+
+				$options = array_merge( $options, $sections );
+			}
+		}
+
 		return $options;
 	}
 }