/**
 * 邮件服务类 - 负责邮件通知功能
 * 遵循单一职责原则：只负责邮件发送相关的业务逻辑
 */
public class EmailService {
    
    /**
     * 发送员工入职通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param department 部门
     * @param hireDate 入职日期字符串
     */
    public void sendWelcomeEmail(String employeeId, String employeeName, String employeeEmail, 
                                String department, String hireDate) {
        String subject = "欢迎加入我们的团队！";
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "恭喜您成功加入我们的团队！\n" +
            "员工ID：%s\n" +
            "部门：%s\n" +
            "入职日期：%s\n\n" +
            "我们期待您的贡献！如有任何问题，请随时联系人力资源部门。\n\n" +
            "此致\n" +
            "人力资源部",
            employeeName, employeeId, department, hireDate
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 发送员工离职通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param lastWorkingDay 最后工作日字符串
     */
    public void sendFarewellEmail(String employeeId, String employeeName, String employeeEmail, 
                                 String lastWorkingDay) {
        String subject = "离职通知确认";
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "感谢您在公司工作期间的贡献。\n" +
            "员工ID：%s\n" +
            "最后工作日：%s\n\n" +
            "祝您未来一切顺利！\n\n" +
            "此致\n" +
            "人力资源部",
            employeeName, employeeId, lastWorkingDay
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 发送薪资调整通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param oldSalary 调整前薪资
     * @param newSalary 调整后薪资
     * @param effectiveDate 生效日期字符串
     */
    public void sendSalaryAdjustmentEmail(String employeeId, String employeeName, String employeeEmail, 
                                         double oldSalary, double newSalary, String effectiveDate) {
        String subject = "薪资调整通知";
        double changeAmount = newSalary - oldSalary;
        double changePercentage = (changeAmount / oldSalary) * 100;
        
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "很高兴通知您，您的薪资已进行调整。\n" +
            "员工ID：%s\n" +
            "调整前薪资：%.2f\n" +
            "调整后薪资：%.2f\n" +
            "调整金额：%.2f (%.2f%%)\n" +
            "生效日期：%s\n\n" +
            "感谢您的努力工作！\n\n" +
            "此致\n" +
            "人力资源部",
            employeeName, employeeId, oldSalary, newSalary, 
            changeAmount, changePercentage, effectiveDate
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 发送职位变动通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param oldPosition 原职位
     * @param newPosition 新职位
     * @param effectiveDate 生效日期字符串
     */
    public void sendPositionChangeEmail(String employeeId, String employeeName, String employeeEmail, 
                                       String oldPosition, String newPosition, String effectiveDate) {
        String subject = "职位变动通知";
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "很高兴通知您，您的职位已进行调整。\n" +
            "员工ID：%s\n" +
            "原职位：%s\n" +
            "新职位：%s\n" +
            "生效日期：%s\n\n" +
            "祝贺您！\n\n" +
            "此致\n" +
            "人力资源部",
            employeeName, employeeId, oldPosition, newPosition, effectiveDate
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 发送培训通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param courseName 课程名称
     * @param trainingDate 培训日期字符串
     * @param trainer 培训师
     */
    public void sendTrainingNotificationEmail(String employeeId, String employeeName, String employeeEmail, 
                                             String courseName, String trainingDate, String trainer) {
        String subject = "培训课程通知";
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "您已被安排参加以下培训课程：\n" +
            "员工ID：%s\n" +
            "课程名称：%s\n" +
            "培训日期：%s\n" +
            "培训师：%s\n\n" +
            "请提前做好准备。\n\n" +
            "此致\n" +
            "培训部门",
            employeeName, employeeId, courseName, trainingDate, trainer
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 发送证书发放通知邮件
     * @param employeeId 员工ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @param certificateName 证书名称
     * @param issueDate 发放日期字符串
     */
    public void sendCertificateEmail(String employeeId, String employeeName, String employeeEmail, 
                                    String certificateName, String issueDate) {
        String subject = "证书发放通知";
        String content = String.format(
            "尊敬的 %s 先生/女士：\n\n" +
            "恭喜您获得以下证书：\n" +
            "员工ID：%s\n" +
            "证书名称：%s\n" +
            "发放日期：%s\n\n" +
            "您的证书已生成，可在系统中查看和下载。\n\n" +
            "此致\n" +
            "培训部门",
            employeeName, employeeId, certificateName, issueDate
        );
        sendEmail(employeeEmail, subject, content);
    }
    
    /**
     * 实际的邮件发送方法（模拟实现）
     * 在实际应用中，这里应该集成真实的邮件发送API
     */
    private void sendEmail(String toEmail, String subject, String content) {
        // 模拟邮件发送过程
        System.out.println("========================================");
        System.out.println("【邮件已发送】");
        System.out.println("收件人: " + toEmail);
        System.out.println("主题: " + subject);
        System.out.println("内容:\n" + content);
        System.out.println("========================================");
    }
}