Update src/main/java/services/SchoolSystem.java

src/main/java/services/SchoolSystem.java

@@ -16,7 +16,28 @@ public class SchoolSystem {
     }
 
     // ========== Student Management ==========
-   //TODO
+    public boolean registerStudent(String username, String password) {
+        if (findStudent(username) != null) {
+            return false;
+        }
+        students.add(new Student(username, password));
+        return true;
+    }
+
+    public Student loginStudent(String username, String password) {
+        Student student = findStudent(username);
+        if (student != null && student.checkPassword(password)) {
+            return student;
+        }
+        return null;
+    }
+
+    private Student findStudent(String username) {
+        for (Student s : students) {
+            if (s.getUsername().equals(username)) return s;
+        }
+        return null;
+    }
 
     // ========== Teacher Management ==========
     public boolean registerTeacher(String username, String password) {
@@ -44,12 +65,19 @@ public class SchoolSystem {
 
     // ========== Course Management ==========
     public boolean addCourseToSystem(String courseName) {
-        //TODO
+        for (Course c : allCourses) {
+            if (c.getName().equals(courseName)) {
+                return false;
+            }
+        }
+        allCourses.add(new Course(courseName));
         return true;
     }
 
     public Course findCourseById(int id) {
-       //TODO
+        for (Course c : allCourses) {
+            if (c.getId() == id) return c;
+        }
         return null;
     }