Gradation: add route to add missing users

users.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -169,6 +170,33 @@ func getUsers() (users []User, err error) {
 	}
 }
 
+func getFilteredUsers(promo uint, group string) (users []User, err error) {
+	// Avoid SQL injection: check group name doesn't contains harmful content
+	var validGroup = regexp.MustCompile(`^[a-z0-9-]*$`)
+	if !validGroup.MatchString(group) {
+		return nil, fmt.Errorf("%q is not a valid group name", group)
+	}
+
+	if rows, errr := DBQuery("SELECT id_user, login, email, firstname, lastname, time, promo, groups, is_admin FROM users WHERE promo = ? AND groups LIKE '%,"+group+",%' ORDER BY promo DESC, id_user DESC", promo); errr != nil {
+		return nil, errr
+	} else {
+		defer rows.Close()
+
+		for rows.Next() {
+			var u User
+			if err = rows.Scan(&u.Id, &u.Login, &u.Email, &u.Firstname, &u.Lastname, &u.Time, &u.Promo, &u.Groups, &u.IsAdmin); err != nil {
+				return
+			}
+			users = append(users, u)
+		}
+		if err = rows.Err(); err != nil {
+			return
+		}
+
+		return
+	}
+}
+
 func getPromos() (promos []uint, err error) {
 	if rows, errr := DBQuery("SELECT DISTINCT promo FROM users ORDER BY promo DESC"); errr != nil {
 		return nil, errr