feat: add course approval history endpoint for instructors to view rejection reasons and approval timeline

Backend/src/controllers/CoursesInstructorController.ts

@@ -20,6 +20,7 @@ import {
     GetQuizScoresResponse,
     GetQuizAttemptDetailResponse,
     GetEnrolledStudentDetailResponse,
+    GetCourseApprovalHistoryResponse,
 } from '../types/CoursesInstructor.types';
 import { CreateCourseValidator } from "../validators/CoursesInstructor.validator";
 
@@ -398,4 +399,24 @@ export class CoursesInstructorController {
             student_id: studentId,
         });
     }
+
+    /**
+     * ดึงประวัติการขออนุมัติคอร์ส
+     * Get course approval history for instructor to see rejection reasons
+     * @param courseId - รหัสคอร์ส / Course ID
+     */
+    @Get('{courseId}/approval-history')
+    @Security('jwt', ['instructor'])
+    @SuccessResponse('200', 'Approval history retrieved successfully')
+    @Response('401', 'Invalid or expired token')
+    @Response('403', 'Not an instructor of this course')
+    @Response('404', 'Course not found')
+    public async getCourseApprovalHistory(
+        @Request() request: any,
+        @Path() courseId: number
+    ): Promise<GetCourseApprovalHistoryResponse> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) throw new ValidationError('No token provided');
+        return await CoursesInstructorService.getCourseApprovalHistory(token, courseId);
+    }
 }