feat: integrate audit logging across authentication, course management, and user operations

Add comprehensive audit trail tracking by integrating auditService throughout the application. Track user authentication (LOGIN, REGISTER), course lifecycle (CREATE, APPROVE_COURSE, REJECT_COURSE, ENROLL), content management (CREATE/DELETE Chapter/Lesson), file operations (UPLOAD_FILE, DELETE_FILE for videos and attachments), password management (CHANGE_PASSWORD, RESET_PASSWORD), user role updates (UPDATE

Backend/src/controllers/AuditController.ts

@@ -0,0 +1,182 @@
+import { Get, Path, Query, Request, Response, Route, Security, SuccessResponse, Tags, Delete } from 'tsoa';
+import { ValidationError } from '../middleware/errorHandler';
+import { auditService } from '../services/audit.service';
+import { AuditAction } from '@prisma/client';
+import {
+    ListAuditLogsResponse,
+    AuditLogResponse,
+    AuditLogStats,
+} from '../types/audit.types';
+
+@Route('api/admin/audit-logs')
+@Tags('Admin/AuditLogs')
+export class AuditController {
+
+    /**
+     * ดึงรายการ audit logs ทั้งหมด
+     * Get all audit logs with filters and pagination
+     * @param userId - กรองตาม user ID
+     * @param action - กรองตาม action type
+     * @param entityType - กรองตาม entity type (Course, User, Lesson, etc.)
+     * @param entityId - กรองตาม entity ID
+     * @param startDate - วันที่เริ่มต้น (ISO format)
+     * @param endDate - วันที่สิ้นสุด (ISO format)
+     * @param page - หน้าที่ต้องการ
+     * @param limit - จำนวนรายการต่อหน้า
+     */
+    @Get('')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'Audit logs retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    public async getAuditLogs(
+        @Request() request: any,
+        @Query() userId?: number,
+        @Query() action?: AuditAction,
+        @Query() entityType?: string,
+        @Query() entityId?: number,
+        @Query() startDate?: string,
+        @Query() endDate?: string,
+        @Query() page?: number,
+        @Query() limit?: number
+    ): Promise<ListAuditLogsResponse> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        return await auditService.getLogs({
+            userId,
+            action,
+            entityType,
+            entityId,
+            startDate: startDate ? new Date(startDate) : undefined,
+            endDate: endDate ? new Date(endDate) : undefined,
+            page: page || 1,
+            limit: limit || 50,
+        });
+    }
+
+    /**
+     * ดึง audit log by ID
+     * Get audit log detail by ID
+     * @param logId - รหัส audit log
+     */
+    @Get('{logId}')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'Audit log retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    @Response('404', 'Audit log not found')
+    public async getAuditLogById(
+        @Request() request: any,
+        @Path() logId: number
+    ): Promise<AuditLogResponse> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        const log = await auditService.getLogById(logId);
+        if (!log) {
+            throw new ValidationError('Audit log not found');
+        }
+        return log;
+    }
+
+    /**
+     * ดึงสถิติ audit logs สำหรับ dashboard
+     * Get audit log statistics for admin dashboard
+     */
+    @Get('stats/summary')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'Audit stats retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    public async getAuditStats(@Request() request: any): Promise<AuditLogStats> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        return await auditService.getStats();
+    }
+
+    /**
+     * ดึง history ของ entity เฉพาะ
+     * Get audit history for a specific entity
+     * @param entityType - ประเภท entity (Course, User, Lesson, etc.)
+     * @param entityId - รหัส entity
+     */
+    @Get('entity/{entityType}/{entityId}')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'Entity history retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    public async getEntityHistory(
+        @Request() request: any,
+        @Path() entityType: string,
+        @Path() entityId: number
+    ): Promise<AuditLogResponse[]> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        return await auditService.getEntityHistory(entityType, entityId);
+    }
+
+    /**
+     * ดึง activity ของ user เฉพาะ
+     * Get activity logs for a specific user
+     * @param userId - รหัส user
+     * @param limit - จำนวนรายการ
+     */
+    @Get('user/{userId}/activity')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'User activity retrieved successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    public async getUserActivity(
+        @Request() request: any,
+        @Path() userId: number,
+        @Query() limit?: number
+    ): Promise<AuditLogResponse[]> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        return await auditService.getUserActivity(userId, limit || 50);
+    }
+
+    /**
+     * ลบ audit logs เก่า (maintenance)
+     * Delete old audit logs for maintenance
+     * @param days - ลบ logs ที่เก่ากว่ากี่วัน
+     */
+    @Delete('cleanup')
+    @Security('jwt', ['admin'])
+    @SuccessResponse('200', 'Old logs deleted successfully')
+    @Response('401', 'Unauthorized')
+    @Response('403', 'Forbidden - Admin only')
+    public async deleteOldLogs(
+        @Request() request: any,
+        @Query() days: number = 90
+    ): Promise<{ deleted: number; message: string }> {
+        const token = request.headers.authorization?.replace('Bearer ', '');
+        if (!token) {
+            throw new ValidationError('No token provided');
+        }
+
+        if (days < 30) {
+            throw new ValidationError('Cannot delete logs newer than 30 days');
+        }
+
+        const deleted = await auditService.deleteOldLogs(days);
+        return {
+            deleted,
+            message: `Deleted ${deleted} audit logs older than ${days} days`,
+        };
+    }
+}

Backend/src/services/AdminCourseApproval.service.ts

@@ -9,6 +9,8 @@ import {
     ApproveCourseResponse,
     RejectCourseResponse,
 } from '../types/AdminCourseApproval.types';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 export class AdminCourseApprovalService {
 
@@ -235,6 +237,17 @@ export class AdminCourseApprovalService {
                 })
             ]);
 
+            // Audit log - APPROVE_COURSE
+            await auditService.logSync({
+                userId: decoded.id,
+                action: AuditAction.APPROVE_COURSE,
+                entityType: 'Course',
+                entityId: courseId,
+                oldValue: { status: 'PENDING' },
+                newValue: { status: 'APPROVED' },
+                metadata: { comment: comment || null }
+            });
+
             return {
                 code: 200,
                 message: 'Course approved successfully'
@@ -290,6 +303,17 @@ export class AdminCourseApprovalService {
                 })
             ]);
 
+            // Audit log - REJECT_COURSE
+            await auditService.logSync({
+                userId: decoded.id,
+                action: AuditAction.REJECT_COURSE,
+                entityType: 'Course',
+                entityId: courseId,
+                oldValue: { status: 'PENDING' },
+                newValue: { status: 'DRAFT' },
+                metadata: { comment: comment }
+            });
+
             return {
                 code: 200,
                 message: 'Course rejected successfully'

Backend/src/services/ChaptersLesson.service.ts

@@ -52,6 +52,8 @@ import {
     QuizData,
 } from "../types/ChaptersLesson.typs";
 import { CoursesInstructorService } from './CoursesInstructor.service';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 /**
  * ตรวจสอบสิทธิ์เข้าถึง Course (สำหรับทั้ง Instructor และ Student)
@@ -127,6 +129,16 @@ export class ChaptersLessonService {
                 throw new ForbiddenError('You are not permitted to create chapter');
             }
             const chapter = await prisma.chapter.create({ data: { course_id, title, description, sort_order } });
+
+            // Audit log - CREATE Chapter
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.CREATE,
+                entityType: 'Chapter',
+                entityId: chapter.id,
+                newValue: { course_id, title, sort_order }
+            });
+
             return { code: 200, message: 'Chapter created successfully', data: chapter as ChapterData };
         } catch (error) {
             logger.error(`Error creating chapter: ${error}`);
@@ -170,6 +182,15 @@ export class ChaptersLessonService {
             }
             await prisma.chapter.delete({ where: { id: chapter_id } });
 
+            // Audit log - DELETE Chapter
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.DELETE,
+                entityType: 'Chapter',
+                entityId: chapter_id,
+                oldValue: { course_id, chapter_id }
+            });
+
             // Normalize sort_order for remaining chapters (fill gaps)
             await this.normalizeChapterSortOrder(course_id);
 
@@ -308,9 +329,28 @@ export class ChaptersLessonService {
                     where: { id: lesson.id },
                     include: { quiz: true }
                 });
+
+                // Audit log - CREATE Lesson (QUIZ)
+                auditService.log({
+                    userId: decodedToken.id,
+                    action: AuditAction.CREATE,
+                    entityType: 'Lesson',
+                    entityId: lesson.id,
+                    newValue: { chapter_id, title, type: 'QUIZ', sort_order }
+                });
+
                 return { code: 200, message: 'Lesson created successfully', data: completeLesson as LessonData };
             }
 
+            // Audit log - CREATE Lesson
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.CREATE,
+                entityType: 'Lesson',
+                entityId: lesson.id,
+                newValue: { chapter_id, title, type, sort_order }
+            });
+
             return { code: 200, message: 'Lesson created successfully', data: lesson as LessonData };
         } catch (error) {
             logger.error(`Error creating lesson: ${error}`);
@@ -621,6 +661,15 @@ export class ChaptersLessonService {
             // Based on Prisma schema: onDelete: Cascade
             await prisma.lesson.delete({ where: { id: lesson_id } });
 
+            // Audit log - DELETE Lesson
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.DELETE,
+                entityType: 'Lesson',
+                entityId: lesson_id,
+                oldValue: { chapter_id: chapterId, title: lesson.title, type: lesson.type }
+            });
+
             // Normalize sort_order for remaining lessons (fill gaps)
             await this.normalizeLessonSortOrder(chapterId);
 
@@ -683,6 +732,15 @@ export class ChaptersLessonService {
             // Get presigned URL
             const video_url = await getPresignedUrl(videoPath, 3600);
 
+            // Audit log - UPLOAD_FILE (Video)
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.UPLOAD_FILE,
+                entityType: 'Lesson',
+                entityId: lesson_id,
+                newValue: { file_name: video.originalname, file_size: video.size, mime_type: video.mimetype }
+            });
+
             return {
                 code: 200,
                 message: 'Video uploaded successfully',
@@ -909,6 +967,15 @@ export class ChaptersLessonService {
             // Get presigned URL
             const presigned_url = await getPresignedUrl(attachmentPath, 3600);
 
+            // Audit log - UPLOAD_FILE (Attachment)
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.UPLOAD_FILE,
+                entityType: 'LessonAttachment',
+                entityId: newAttachment.id,
+                newValue: { lesson_id, file_name: attachment.originalname, file_size: attachment.size }
+            });
+
             return {
                 code: 200,
                 message: 'Attachment uploaded successfully',
@@ -972,6 +1039,15 @@ export class ChaptersLessonService {
             // Delete attachment record from database
             await prisma.lessonAttachment.delete({ where: { id: attachment_id } });
 
+            // Audit log - DELETE_FILE (Attachment)
+            auditService.log({
+                userId: decodedToken.id,
+                action: AuditAction.DELETE_FILE,
+                entityType: 'LessonAttachment',
+                entityId: attachment_id,
+                oldValue: { lesson_id, file_name: attachment.file_name, file_path: attachment.file_path }
+            });
+
             return { code: 200, message: 'Attachment deleted successfully' };
         } catch (error) {
             logger.error(`Error deleting attachment: ${error}`);

Backend/src/services/CoursesInstructor.service.ts

@@ -33,6 +33,8 @@ import {
     GetEnrolledStudentDetailInput,
     GetEnrolledStudentDetailResponse,
 } from "../types/CoursesInstructor.types";
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 export class CoursesInstructorService {
     static async createCourse(courseData: CreateCourseInput, userId: number, thumbnailFile?: Express.Multer.File): Promise<createCourseResponse> {
@@ -81,6 +83,15 @@ export class CoursesInstructorService {
                 return courseCreated;
             });
 
+            // Audit log - CREATE Course
+            auditService.log({
+                userId: userId,
+                action: AuditAction.CREATE,
+                entityType: 'Course',
+                entityId: result.id,
+                newValue: { title: courseData.title, slug: courseData.slug, status: 'DRAFT' }
+            });
+
             return {
                 code: 201,
                 message: 'Course created successfully',

Backend/src/services/CoursesStudent.service.ts

@@ -27,6 +27,8 @@ import {
     GetQuizAttemptsResponse,
 } from "../types/CoursesStudent.types";
 import { getPresignedUrl, listObjects, getVideoFolder, getAttachmentsFolder } from '../config/minio';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 
 export class CoursesStudentService {
@@ -162,6 +164,16 @@ export class CoursesStudentService {
                     enrolled_at: new Date(),
                 },
             });
+
+            // Audit log - ENROLL
+            auditService.log({
+                userId: decoded.id,
+                action: AuditAction.ENROLL,
+                entityType: 'Enrollment',
+                entityId: enrollment.id,
+                newValue: { course_id, user_id: decoded.id, status: 'ENROLLED' }
+            });
+
             return {
                 code: 200,
                 message: 'Enrollment successful',

Backend/src/services/audit.service.ts

@@ -0,0 +1,245 @@
+import { prisma } from '../config/database';
+import { AuditAction } from '@prisma/client';
+import { logger } from '../config/logger';
+import {
+    CreateAuditLogParams,
+    AuditLogFilters,
+    ListAuditLogsResponse,
+    AuditLogResponse,
+    AuditLogStats,
+} from '../types/audit.types';
+
+export class AuditService {
+    /**
+     * สร้าง audit log entry
+     */
+    async log(params: CreateAuditLogParams): Promise<void> {
+        try {
+            await prisma.auditLog.create({
+                data: {
+                    user_id: params.userId,
+                    action: params.action,
+                    entity_type: params.entityType,
+                    entity_id: params.entityId,
+                    old_value: params.oldValue,
+                    new_value: params.newValue,
+                    ip_address: params.ipAddress,
+                    user_agent: params.userAgent,
+                    metadata: params.metadata,
+                },
+            });
+        } catch (error) {
+            logger.error('Failed to create audit log', { error, params });
+        }
+    }
+
+    /**
+     * Log พร้อม await (สำหรับ critical actions)
+     */
+    async logSync(params: CreateAuditLogParams): Promise<void> {
+        await prisma.auditLog.create({
+            data: {
+                user_id: params.userId,
+                action: params.action,
+                entity_type: params.entityType,
+                entity_id: params.entityId,
+                old_value: params.oldValue,
+                new_value: params.newValue,
+                ip_address: params.ipAddress,
+                user_agent: params.userAgent,
+                metadata: params.metadata,
+            },
+        });
+    }
+
+    /**
+     * ดึง audit logs พร้อม filters และ pagination
+     */
+    async getLogs(filters: AuditLogFilters): Promise<ListAuditLogsResponse> {
+        const { page = 1, limit = 50 } = filters;
+        const skip = (page - 1) * limit;
+
+        const where: any = {};
+
+        if (filters.userId) {
+            where.user_id = filters.userId;
+        }
+        if (filters.action) {
+            where.action = filters.action;
+        }
+        if (filters.entityType) {
+            where.entity_type = filters.entityType;
+        }
+        if (filters.entityId) {
+            where.entity_id = filters.entityId;
+        }
+        if (filters.startDate || filters.endDate) {
+            where.created_at = {};
+            if (filters.startDate) {
+                where.created_at.gte = filters.startDate;
+            }
+            if (filters.endDate) {
+                where.created_at.lte = filters.endDate;
+            }
+        }
+
+        const [logs, total] = await Promise.all([
+            prisma.auditLog.findMany({
+                where,
+                include: {
+                    user: {
+                        select: {
+                            id: true,
+                            username: true,
+                            email: true,
+                        },
+                    },
+                },
+                orderBy: { created_at: 'desc' },
+                skip,
+                take: limit,
+            }),
+            prisma.auditLog.count({ where }),
+        ]);
+
+        return {
+            data: logs as AuditLogResponse[],
+            pagination: {
+                page,
+                limit,
+                total,
+                totalPages: Math.ceil(total / limit),
+            },
+        };
+    }
+
+    /**
+     * ดึง audit log by ID
+     */
+    async getLogById(id: number): Promise<AuditLogResponse | null> {
+        const log = await prisma.auditLog.findUnique({
+            where: { id },
+            include: {
+                user: {
+                    select: {
+                        id: true,
+                        username: true,
+                        email: true,
+                    },
+                },
+            },
+        });
+
+        return log as AuditLogResponse | null;
+    }
+
+    /**
+     * ดึง logs ของ entity เฉพาะ (เช่น ดู history ของ course)
+     */
+    async getEntityHistory(entityType: string, entityId: number): Promise<AuditLogResponse[]> {
+        const logs = await prisma.auditLog.findMany({
+            where: {
+                entity_type: entityType,
+                entity_id: entityId,
+            },
+            include: {
+                user: {
+                    select: {
+                        id: true,
+                        username: true,
+                        email: true,
+                    },
+                },
+            },
+            orderBy: { created_at: 'desc' },
+        });
+
+        return logs as AuditLogResponse[];
+    }
+
+    /**
+     * ดึง logs ของ user เฉพาะ
+     */
+    async getUserActivity(userId: number, limit: number = 50): Promise<AuditLogResponse[]> {
+        const logs = await prisma.auditLog.findMany({
+            where: { user_id: userId },
+            include: {
+                user: {
+                    select: {
+                        id: true,
+                        username: true,
+                        email: true,
+                    },
+                },
+            },
+            orderBy: { created_at: 'desc' },
+            take: limit,
+        });
+
+        return logs as AuditLogResponse[];
+    }
+
+    /**
+     * ดึงสถิติ audit logs สำหรับ dashboard
+     */
+    async getStats(): Promise<AuditLogStats> {
+        const today = new Date();
+        today.setHours(0, 0, 0, 0);
+
+        const [totalLogs, todayLogs, actionCounts, recentActivity] = await Promise.all([
+            prisma.auditLog.count(),
+            prisma.auditLog.count({
+                where: {
+                    created_at: { gte: today },
+                },
+            }),
+            prisma.auditLog.groupBy({
+                by: ['action'],
+                _count: { action: true },
+                orderBy: { _count: { action: 'desc' } },
+            }),
+            prisma.auditLog.findMany({
+                include: {
+                    user: {
+                        select: {
+                            id: true,
+                            username: true,
+                            email: true,
+                        },
+                    },
+                },
+                orderBy: { created_at: 'desc' },
+                take: 10,
+            }),
+        ]);
+
+        return {
+            totalLogs,
+            todayLogs,
+            actionSummary: actionCounts.map((item) => ({
+                action: item.action,
+                count: item._count.action,
+            })),
+            recentActivity: recentActivity as AuditLogResponse[],
+        };
+    }
+
+    /**
+     * ลบ logs เก่า (สำหรับ maintenance)
+     */
+    async deleteOldLogs(olderThanDays: number): Promise<number> {
+        const cutoffDate = new Date();
+        cutoffDate.setDate(cutoffDate.getDate() - olderThanDays);
+
+        const result = await prisma.auditLog.deleteMany({
+            where: {
+                created_at: { lt: cutoffDate },
+            },
+        });
+
+        logger.info(`Deleted ${result.count} old audit logs older than ${olderThanDays} days`);
+        return result.count;
+    }
+}
+
+export const auditService = new AuditService();

Backend/src/services/auth.service.ts

@@ -17,6 +17,8 @@ import { UserResponse } from '../types/user.types';
 import { UnauthorizedError, ValidationError, ForbiddenError } from '../middleware/errorHandler';
 import nodemailer from 'nodemailer';
 import { getPresignedUrl } from '../config/minio';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 export class AuthService {
     /**
@@ -57,6 +59,15 @@ export class AuthService {
 
         logger.info('User logged in successfully', { userId: user.id, email: user.email });
 
+        // Audit log - LOGIN
+        auditService.log({
+            userId: user.id,
+            action: AuditAction.LOGIN,
+            entityType: 'User',
+            entityId: user.id,
+            metadata: { email: user.email, role: user.role.code }
+        });
+
         return {
             code: 200,
             message: 'Login successful',
@@ -138,6 +149,15 @@ export class AuthService {
 
         logger.info('New user registered', { userId: user.id, username: user.username });
 
+        // Audit log - REGISTER (Student)
+        auditService.log({
+            userId: user.id,
+            action: AuditAction.CREATE,
+            entityType: 'User',
+            entityId: user.id,
+            newValue: { username: user.username, email: user.email, role: 'STUDENT' }
+        });
+
         return {
             user: this.formatUserResponseSync(user),
             message: 'Registration successful'
@@ -211,6 +231,15 @@ export class AuthService {
 
         logger.info('New user registered', { userId: user.id, username: user.username });
 
+        // Audit log - REGISTER (Instructor)
+        auditService.log({
+            userId: user.id,
+            action: AuditAction.CREATE,
+            entityType: 'User',
+            entityId: user.id,
+            newValue: { username: user.username, email: user.email, role: 'INSTRUCTOR' }
+        });
+
         return {
             user: this.formatUserResponseSync(user),
             message: 'Registration successful'
@@ -341,6 +370,16 @@ export class AuthService {
             });
 
             logger.info('Password reset successfully', { userId: user.id });
+
+            // Audit log - RESET_PASSWORD
+            auditService.log({
+                userId: user.id,
+                action: AuditAction.RESET_PASSWORD,
+                entityType: 'User',
+                entityId: user.id,
+                metadata: { email: user.email }
+            });
+
             return {
                 code: 200,
                 message: 'Password reset successfully'

Backend/src/services/user.service.ts

@@ -19,6 +19,8 @@ import {
 import nodemailer from 'nodemailer';
 import { UnauthorizedError, ValidationError, ForbiddenError } from '../middleware/errorHandler';
 import { uploadFile, deleteFile, getPresignedUrl } from '../config/minio';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 export class UserService {
     async getUserProfile(token: string): Promise<UserResponse> {
@@ -109,6 +111,16 @@ export class UserService {
             });
 
             logger.info('Password changed successfully', { userId: user.id });
+
+            // Audit log - CHANGE_PASSWORD
+            auditService.log({
+                userId: user.id,
+                action: AuditAction.CHANGE_PASSWORD,
+                entityType: 'User',
+                entityId: user.id,
+                metadata: { email: user.email }
+            });
+
             return {
                 code: 200,
                 message: 'Password changed successfully'

Backend/src/services/usermanagement.service.ts

@@ -14,6 +14,8 @@ import {
 import { UserResponse } from '../types/user.types';
 import { UnauthorizedError, ValidationError, ForbiddenError } from '../middleware/errorHandler';
 import { getPresignedUrl } from '../config/minio';
+import { auditService } from './audit.service';
+import { AuditAction } from '@prisma/client';
 
 export class UserManagementService {
     async listUsers(): Promise<ListUsersResponse> {
@@ -71,11 +73,22 @@ export class UserManagementService {
             const role = await prisma.role.findUnique({ where: { id: role_id } });
             if (!role) throw new UnauthorizedError('Role not found');
 
+            const oldRoleId = user.role_id;
             await prisma.user.update({
                 where: { id },
                 data: { role_id }
             });
 
+            // Audit log - UPDATE (role change)
+            auditService.log({
+                userId: id,
+                action: AuditAction.UPDATE,
+                entityType: 'User',
+                entityId: id,
+                oldValue: { role_id: oldRoleId },
+                newValue: { role_id: role_id }
+            });
+
             return {
                 code: 200,
                 message: 'User role updated successfully'
@@ -122,6 +135,17 @@ export class UserManagementService {
             });
 
             logger.info('Account deactivated successfully', { userId: user.id });
+
+            // Audit log - DEACTIVATE_USER
+            auditService.log({
+                userId: user.id,
+                action: AuditAction.DEACTIVATE_USER,
+                entityType: 'User',
+                entityId: user.id,
+                oldValue: { is_deactivated: false },
+                newValue: { is_deactivated: true }
+            });
+
             return {
                 code: 200,
                 message: 'Account deactivated successfully'
@@ -158,6 +182,17 @@ export class UserManagementService {
             });
 
             logger.info('Account activated successfully', { userId: user.id });
+
+            // Audit log - ACTIVATE_USER
+            auditService.log({
+                userId: user.id,
+                action: AuditAction.ACTIVATE_USER,
+                entityType: 'User',
+                entityId: user.id,
+                oldValue: { is_deactivated: true },
+                newValue: { is_deactivated: false }
+            });
+
             return {
                 code: 200,
                 message: 'Account activated successfully'

Backend/src/types/audit.types.ts

@@ -0,0 +1,65 @@
+import { AuditAction } from '@prisma/client';
+
+export interface CreateAuditLogParams {
+    userId?: number;
+    action: AuditAction;
+    entityType: string;
+    entityId?: number;
+    oldValue?: any;
+    newValue?: any;
+    ipAddress?: string;
+    userAgent?: string;
+    metadata?: any;
+}
+
+export interface AuditLogFilters {
+    userId?: number;
+    action?: AuditAction;
+    entityType?: string;
+    entityId?: number;
+    startDate?: Date;
+    endDate?: Date;
+    page?: number;
+    limit?: number;
+}
+
+export interface AuditLogResponse {
+    id: number;
+    user_id: number | null;
+    action: AuditAction;
+    entity_type: string;
+    entity_id: number | null;
+    old_value: any;
+    new_value: any;
+    ip_address: string | null;
+    user_agent: string | null;
+    metadata: any;
+    created_at: Date;
+    user?: {
+        id: number;
+        username: string;
+        email: string;
+    } | null;
+}
+
+export interface ListAuditLogsResponse {
+    data: AuditLogResponse[];
+    pagination: {
+        page: number;
+        limit: number;
+        total: number;
+        totalPages: number;
+    };
+}
+
+export interface AuditLogSummary {
+    action: AuditAction;
+    count: number;
+}
+
+export interface AuditLogStats {
+    totalLogs: number;
+    todayLogs: number;
+    actionSummary: AuditLogSummary[];
+    recentActivity: AuditLogResponse[];
+}