const { Class } = require('../models');
const { StudentDetail, UserProfile, UsersAuth, School } = require('../models');
const { cacheUtils } = require('../config/redis');

/**
 * Class Controller - Quản lý thông tin lớp học
 */
class ClassController {
  /**
   * Get all classes with pagination and caching
   */
  async getAllClasses(req, res, next) {
    try {
      const { page = 1, limit = 20, school_id, grade_level, academic_year_id } = req.query;
      const offset = (page - 1) * limit;
      
      // Generate cache key
      const cacheKey = `classes:list:${page}:${limit}:${school_id || 'all'}:${grade_level || 'all'}:${academic_year_id || 'all'}`;
      
      // Try to get from cache first
      const cached = await cacheUtils.get(cacheKey);
      if (cached) {
        return res.json({
          success: true,
          data: cached,
          cached: true,
        });
      }
      
      // Build query conditions
      const where = {};
      if (school_id) where.school_id = school_id;
      if (grade_level) where.grade_level = parseInt(grade_level);
      if (academic_year_id) where.academic_year_id = academic_year_id;
      
      // Query from database (through ProxySQL)
      const { count, rows } = await Class.findAndCountAll({
        where,
        limit: parseInt(limit),
        offset: parseInt(offset),
        order: [['class_name', 'ASC']],
      });
      
      const result = {
        classes: rows,
        pagination: {
          total: count,
          page: parseInt(page),
          limit: parseInt(limit),
          totalPages: Math.ceil(count / limit),
        },
      };
      
      // Cache the result
      await cacheUtils.set(cacheKey, result, 1800); // Cache for 30 minutes
      
      res.json({
        success: true,
        data: result,
        cached: false,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Get class by ID with caching
   */
  async getClassById(req, res, next) {
    try {
      const { id } = req.params;
      const cacheKey = `class:${id}`;
      
      // Try cache first
      const cached = await cacheUtils.get(cacheKey);
      if (cached) {
        return res.json({
          success: true,
          data: cached,
          cached: true,
        });
      }
      
      // Query from database
      const classData = await Class.findByPk(id);
      
      if (!classData) {
        return res.status(404).json({
          success: false,
          message: 'Class not found',
        });
      }
      
      // Cache the result
      await cacheUtils.set(cacheKey, classData, 3600); // Cache for 1 hour
      
      res.json({
        success: true,
        data: classData,
        cached: false,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Create new class
   */
  async createClass(req, res, next) {
    try {
      const classData = req.body;
      
      // Create class directly
      const newClass = await Class.create(classData);
      
      // Invalidate related caches
      await cacheUtils.deletePattern('classes:list:*');
      
      res.status(201).json({
        success: true,
        message: 'Class created successfully',
        data: newClass,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Update class
   */
  async updateClass(req, res, next) {
    try {
      const { id } = req.params;
      const updates = req.body;
      
      const classData = await Class.findByPk(id);
      
      if (!classData) {
        return res.status(404).json({
          success: false,
          message: 'Class not found',
        });
      }
      
      // Update class directly
      await classData.update(updates);
      
      // Invalidate related caches
      await cacheUtils.delete(`class:${id}`);
      await cacheUtils.deletePattern('classes:list:*');
      
      res.json({
        success: true,
        message: 'Class updated successfully',
        data: classData,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Delete class
   */
  async deleteClass(req, res, next) {
    try {
      const { id } = req.params;
      
      const classData = await Class.findByPk(id);
      
      if (!classData) {
        return res.status(404).json({
          success: false,
          message: 'Class not found',
        });
      }
      
      // Delete class directly
      await classData.destroy();
      
      // Invalidate related caches
      await cacheUtils.delete(`class:${id}`);
      await cacheUtils.deletePattern('classes:list:*');
      
      res.json({
        success: true,
        message: 'Class deleted successfully',
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Get class statistics
   */
  async getClassStatistics(req, res, next) {
    try {
      const { school_id } = req.query;
      const cacheKey = `class:stats:${school_id || 'all'}`;
      
      // Try cache first
      const cached = await cacheUtils.get(cacheKey);
      if (cached) {
        return res.json({
          success: true,
          data: cached,
          cached: true,
        });
      }
      
      const where = {};
      if (school_id) where.school_id = school_id;
      
      const stats = {
        totalClasses: await Class.count({ where }),
        byGradeLevel: await Class.findAll({
          where,
          attributes: [
            'grade_level',
            [require('sequelize').fn('COUNT', require('sequelize').col('id')), 'count'],
          ],
          group: ['grade_level'],
          raw: true,
        }),
      };
      
      // Cache for 1 hour
      await cacheUtils.set(cacheKey, stats, 3600);
      
      res.json({
        success: true,
        data: stats,
        cached: false,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Get class datatypes
   */
  async getClassDatatypes(req, res, next) {
    try {
      const datatypes = Class.rawAttributes;
      res.json({
        success: true,
        data: datatypes,
      });
    } catch (error) {
      next(error);
    }
  }

  /**
   * Get students in a class
   */
  async getStudentsByClass(req, res, next) {
    try {
      const { id } = req.params;
      const { page = 1, limit = 20, status = 'active' } = req.query;
      const offset = (page - 1) * limit;

      // Generate cache key
      const cacheKey = `class:${id}:students:${page}:${limit}:${status}`;

      // Try cache first
      const cached = await cacheUtils.get(cacheKey);
      if (cached) {
        return res.json({
          success: true,
          data: cached,
          cached: true,
        });
      }

      // Check if class exists and get school info
      const classData = await Class.findByPk(id, {
        include: [
          {
            model: School,
            as: 'school',
            attributes: ['school_name', 'school_code', 'address', 'city', 'district'],
          },
        ],
      });
      if (!classData) {
        return res.status(404).json({
          success: false,
          message: 'Class not found',
        });
      }

      // Query students
      const { count, rows: students } = await StudentDetail.findAndCountAll({
        where: {
          current_class_id: id,
          status: status,
        },
        include: [
          {
            model: UserProfile,
            as: 'profile',
            attributes: [
              'full_name',
              'first_name',
              'last_name',
              'date_of_birth',
              'phone',
              'address',
              'city',
              'district',
            ],
            include: [
              {
                model: UsersAuth,
                as: 'auth',
                attributes: ['username', 'email', 'is_active'],
              },
              {
                model: School,
                as: 'school',
                attributes: ['school_name', 'school_code'],
              },
            ],
          },
        ],
        limit: parseInt(limit),
        offset: parseInt(offset),
        order: [[{ model: UserProfile, as: 'profile' }, 'full_name', 'ASC']],
      });

      const result = {
        class: {
          id: classData.id,
          class_name: classData.class_name,
          class_code: classData.class_code,
          grade_level: classData.grade_level,
          max_students: classData.max_students,
          current_students: classData.current_students,
          school: classData.school ? {
            school_name: classData.school.school_name,
            school_code: classData.school.school_code,
            address: classData.school.address,
            city: classData.school.city,
            district: classData.school.district,
          } : null,
        },
        students: students,
        pagination: {
          total: count,
          page: parseInt(page),
          limit: parseInt(limit),
          totalPages: Math.ceil(count / limit),
        },
      };

      // Cache for 10 minutes
      await cacheUtils.set(cacheKey, result, 600);

      res.json({
        success: true,
        data: result,
        cached: false,
      });
    } catch (error) {
      next(error);
    }
  }
}

module.exports = new ClassController();