const crypto = require('crypto');
const { runQuery, getQuery, allQuery } = require('../database/database');

class ActivationCode {
  // 生成批量激活码
  static async generateCodes(count, days = 30) {
    try {
      const codes = [];
      const insertPromises = [];

      for (let i = 0; i < count; i++) {
        const code = this.generateUniqueCode();
        codes.push(code);
        
        const insertPromise = runQuery(
          `INSERT INTO activation_codes (code, days) VALUES (?, ?)`,
          [code, days]
        );
        insertPromises.push(insertPromise);
      }

      await Promise.all(insertPromises);
      return codes;
    } catch (error) {
      throw error;
    }
  }

  // 生成唯一激活码
  static generateUniqueCode() {
    // 生成16位激活码，格式：XXXX-XXXX-XXXX-XXXX
    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    let code = '';
    
    for (let i = 0; i < 16; i++) {
      if (i > 0 && i % 4 === 0) {
        code += '-';
      }
      code += chars.charAt(Math.floor(Math.random() * chars.length));
    }
    
    return code;
  }

  // 验证激活码
  static async validateCode(code) {
    try {
      const activationCode = await getQuery(
        `SELECT * FROM activation_codes WHERE code = ? AND is_used = 0`,
        [code]
      );

      if (!activationCode) {
        throw new Error('激活码无效或已被使用');
      }

      return activationCode;
    } catch (error) {
      throw error;
    }
  }

  // 使用激活码
  static async useCode(code, userId) {
    try {
      // 验证激活码
      const activationCode = await this.validateCode(code);

      // 标记激活码为已使用
      await runQuery(
        `UPDATE activation_codes SET is_used = 1, used_by = ?, used_at = strftime('%s', 'now') WHERE code = ?`,
        [userId, code]
      );

      return activationCode;
    } catch (error) {
      throw error;
    }
  }

  // 获取所有激活码
  static async getAllCodes(page = 1, pageSize = 50) {
    try {
      const offset = (page - 1) * pageSize;
      
      const codes = await allQuery(
        `SELECT ac.*, u.email as used_by_email 
         FROM activation_codes ac
         LEFT JOIN users u ON ac.used_by = u.id
         ORDER BY ac.created_at DESC
         LIMIT ? OFFSET ?`,
        [pageSize, offset]
      );

      const totalResult = await getQuery(
        `SELECT COUNT(*) as total FROM activation_codes`
      );

      return {
        codes,
        total: totalResult.total,
        page,
        pageSize,
        totalPages: Math.ceil(totalResult.total / pageSize)
      };
    } catch (error) {
      throw error;
    }
  }

  // 获取激活码统计
  static async getStatistics() {
    try {
      const totalResult = await getQuery(
        `SELECT COUNT(*) as total FROM activation_codes`
      );

      const usedResult = await getQuery(
        `SELECT COUNT(*) as used FROM activation_codes WHERE is_used = 1`
      );

      const unusedResult = await getQuery(
        `SELECT COUNT(*) as unused FROM activation_codes WHERE is_used = 0`
      );

      const todayResult = await getQuery(
        `SELECT COUNT(*) as today FROM activation_codes 
         WHERE created_at > strftime('%s', 'now', '-1 day')`
      );

      return {
        total: totalResult.total,
        used: usedResult.used,
        unused: unusedResult.unused,
        todayGenerated: todayResult.today
      };
    } catch (error) {
      throw error;
    }
  }

  // 删除激活码
  static async deleteCode(codeId) {
    try {
      const result = await runQuery(
        `DELETE FROM activation_codes WHERE id = ? AND is_used = 0`,
        [codeId]
      );
      
      return result.changes > 0;
    } catch (error) {
      throw error;
    }
  }
}

module.exports = ActivationCode;