elearning/Backend/src/controllers/LessonsController.ts

import { Request, Response, NextFunction } from 'express';
import { ChaptersLessonService } from '../services/ChaptersLesson.service';
import { ValidationError } from '../middleware/errorHandler';
import {
    lessonUpload,
    LessonUploadRequest,
    validateTotalAttachmentSize,
    validateVideoSize
} from '../middleware/upload';
import { UploadedFileInfo, CreateLessonInput } from '../types/ChaptersLesson.typs';

const chaptersLessonService = new ChaptersLessonService();

/**
 * Controller for handling lesson CRUD operations with file uploads
 */
export class LessonsController {
    /**
     * สร้างบทเรียนใหม่พร้อมไฟล์แนบ
     * Create a new lesson with optional video and attachments
     * 
     * @route POST /api/instructors/courses/:courseId/chapters/:chapterId/lessons
     * @contentType multipart/form-data
     * 
     * @param {number} courseId - รหัสคอร์ส / Course ID
     * @param {number} chapterId - รหัสบท / Chapter ID
     * @param {string} title - ชื่อบทเรียน (JSON: { th: "", en: "" })
     * @param {string} [content] - เนื้อหาบทเรียน (JSON: { th: "", en: "" })
     * @param {string} type - ประเภทบทเรียน (VIDEO | QUIZ)
     * @param {number} [sort_order] - ลำดับการแสดงผล
     * @param {File} [video] - ไฟล์วิดีโอ (สำหรับ type=VIDEO เท่านั้น)
     * @param {File[]} [attachments] - ไฟล์แนบ (PDFs, เอกสาร, รูปภาพ)
     */
    async createLesson(req: LessonUploadRequest, res: Response, next: NextFunction): Promise<void> {
        try {
            const token = req.headers.authorization?.replace('Bearer ', '');
            if (!token) {
                throw new ValidationError('No token provided');
            }

            const courseId = parseInt(req.params.courseId as string, 10);
            const chapterId = parseInt(req.params.chapterId as string, 10);

            if (isNaN(courseId) || isNaN(chapterId)) {
                throw new ValidationError('Invalid course ID or chapter ID');
            }

            // Parse JSON fields from multipart form
            const title = JSON.parse(req.body.title || '{}');
            const content = req.body.content ? JSON.parse(req.body.content) : undefined;
            const type = req.body.type as 'VIDEO' | 'QUIZ';
            const sortOrder = req.body.sort_order ? parseInt(req.body.sort_order, 10) : undefined;

            if (!type || !['VIDEO', 'QUIZ'].includes(type)) {
                throw new ValidationError('Invalid lesson type. Must be VIDEO or QUIZ');
            }

            if (!title.th || !title.en) {
                throw new ValidationError('Title must have both Thai (th) and English (en) values');
            }

            // Process uploaded files
            const files = req.files as { video?: Express.Multer.File[]; attachments?: Express.Multer.File[] } | undefined;

            let video: UploadedFileInfo | undefined;
            let attachments: UploadedFileInfo[] | undefined;

            if (files?.video && files.video.length > 0) {
                const videoFile = files.video[0];
                validateVideoSize(videoFile);
                video = {
                    originalname: videoFile.originalname,
                    mimetype: videoFile.mimetype,
                    size: videoFile.size,
                    buffer: videoFile.buffer,
                };
            }

            if (files?.attachments && files.attachments.length > 0) {
                validateTotalAttachmentSize(files.attachments);
                attachments = files.attachments.map(file => ({
                    originalname: file.originalname,
                    mimetype: file.mimetype,
                    size: file.size,
                    buffer: file.buffer,
                }));
            }

            // Validate VIDEO type must have video file (optional - can be uploaded later)
            // if (type === 'VIDEO' && !video) {
            //     throw new ValidationError('Video file is required for VIDEO type lessons');
            // }

            const input: CreateLessonInput = {
                token,
                course_id: courseId,
                chapter_id: chapterId,
                title,
                content,
                type,
                sort_order: sortOrder,
                video,
                attachments,
            };

            const result = await chaptersLessonService.createLesson(input);
            res.status(201).json(result);
        } catch (error) {
            next(error);
        }
    }
}

/**
 * Express router middleware wrapper for file upload
 * Use this in routes like:
 * 
 * router.post(
 *     '/api/instructors/courses/:courseId/chapters/:chapterId/lessons',
 *     authenticateMiddleware,
 *     handleLessonUpload,
 *     lessonsController.createLesson.bind(lessonsController)
 * );
 */
export const handleLessonUpload = (req: Request, res: Response, next: NextFunction) => {
    lessonUpload(req, res, (err) => {
        if (err) {
            return res.status(400).json({
                error: {
                    code: 'FILE_UPLOAD_ERROR',
                    message: err.message,
                }
            });
        }
        next();
    });
};

export const lessonsController = new LessonsController();