import java.time.LocalDate;

/**
 * 证书类 - 负责证书信息管理
 * 遵循单一职责原则：只负责证书数据的存储和状态管理
 */
public class Certificate {
    private String certificateId;      // 证书ID
    private String employeeId;         // 员工ID
    private String courseId;           // 课程ID
    private String courseName;         // 课程名称
    private LocalDate issueDate;       // 颁发日期
    private LocalDate expiryDate;      // 过期日期
    private String issuer;             // 颁发机构
    private String trainer;            // 培训师
    private double score;              // 成绩
    private boolean active;            // 是否有效
    private String certificateNumber;  // 证书编号
    private String description;        // 证书描述
    
    /**
     * 构造函数 - 创建证书
     */
    public Certificate(String certificateId, String employeeId, String courseId, 
                      String courseName, String issuer, String trainer, double score) {
        this.certificateId = certificateId;
        this.employeeId = employeeId;
        this.courseId = courseId;
        this.courseName = courseName;
        this.issuer = issuer;
        this.trainer = trainer;
        this.score = score;
        this.issueDate = LocalDate.now();
        this.active = true;
        this.certificateNumber = generateCertificateNumber(certificateId, employeeId);
        this.description = "";
    }
    
    /**
     * 生成证书编号
     */
    private String generateCertificateNumber(String certificateId, String employeeId) {
        LocalDate now = LocalDate.now();
        return String.format("CERT-%s-%s-%d", 
                employeeId, certificateId, now.getYear() * 10000 + now.getMonthValue() * 100 + now.getDayOfMonth());
    }
    
    /**
     * 设置证书有效期
     * @param years 有效期年数
     */
    public void setValidYears(int years) {
        if (years <= 0) {
            throw new IllegalArgumentException("有效期必须大于0");
        }
        this.expiryDate = issueDate.plusYears(years);
    }
    
    /**
     * 检查证书是否过期
     * @return true如果证书已过期
     */
    public boolean isExpired() {
        if (expiryDate == null) {
            return false; // 没有设置过期日期的证书永不过期
        }
        return LocalDate.now().isAfter(expiryDate);
    }
    
    /**
     * 吊销证书
     * @param reason 吊销原因
     */
    public void revokeCertificate(String reason) {
        this.active = false;
        this.description = reason;
    }
    
    /**
     * 恢复证书
     */
    public void reinstateCertificate() {
        if (!isExpired()) {
            this.active = true;
        } else {
            throw new IllegalStateException("已过期的证书无法恢复");
        }
    }
    
    /**
     * 获取证书状态描述
     * @return 证书状态描述
     */
    public String getStatusDescription() {
        if (!active) {
            return "已吊销";
        } else if (isExpired()) {
            return "已过期";
        } else {
            return "有效";
        }
    }
    
    /**
     * 获取剩余有效天数
     * @return 剩余有效天数，如果不过期则返回null
     */
    public Long getRemainingValidDays() {
        if (expiryDate == null || isExpired()) {
            return null;
        }
        return (long) LocalDate.now().until(expiryDate).getDays();
    }
    
    /**
     * 获取成绩等级
     * @return 成绩等级
     */
    public String getScoreGrade() {
        if (score >= 90) return "优秀";
        else if (score >= 80) return "良好";
        else if (score >= 70) return "中等";
        else if (score >= 60) return "及格";
        else return "不及格";
    }
    
    // Getter和Setter方法
    
    public String getCertificateId() { return certificateId; }
    
    public String getEmployeeId() { return employeeId; }
    
    public String getCourseId() { return courseId; }
    
    public String getCourseName() { return courseName; }
    
    public void setCourseName(String courseName) { this.courseName = courseName; }
    
    public LocalDate getIssueDate() { return issueDate; }
    
    public LocalDate getExpiryDate() { return expiryDate; }
    
    public String getIssuer() { return issuer; }
    
    public void setIssuer(String issuer) { this.issuer = issuer; }
    
    public String getTrainer() { return trainer; }
    
    public void setTrainer(String trainer) { this.trainer = trainer; }
    
    public double getScore() { return score; }
    
    public boolean isActive() { return active; }
    
    public String getCertificateNumber() { return certificateNumber; }
    
    public String getDescription() { return description; }
    
    public void setDescription(String description) { this.description = description; }
    
    @Override
    public String toString() {
        return "Certificate{" +
               "certificateId='" + certificateId + "'" +
               ", certificateNumber='" + certificateNumber + "'" +
               ", courseName='" + courseName + "'" +
               ", employeeId='" + employeeId + "'" +
               ", score=" + score + "(" + getScoreGrade() + ")" +
               ", issueDate=" + issueDate + "'" +
               ", expiryDate=" + (expiryDate != null ? expiryDate : "永不过期") + "'" +
               ", status=" + getStatusDescription() + "'" +
               "}";
    }
}