import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.*;
import java.util.stream.Collectors;

/**
 * 培训管理系统类 - 负责培训相关业务逻辑协调
 * 遵循单一职责原则：只负责培训业务流程的协调和管理
 */
public class TrainingManagementSystem {
    // 数据存储
    private final Map<String, TrainingCourse> courses;
    private final Map<String, TrainingRecord> trainingRecords;
    private final Map<String, Certificate> certificates;
    private final EmailService emailService;
    private final Map<String, List<TrainingRecord>> employeeRecords; // 员工培训记录映射
    
    /**
     * 构造函数
     */
    public TrainingManagementSystem() {
        this.courses = new HashMap<>();
        this.trainingRecords = new HashMap<>();
        this.certificates = new HashMap<>();
        this.emailService = new EmailService();
        this.employeeRecords = new HashMap<>();
    }
    
    // ====================== 课程管理功能 ======================
    
    /**
     * 添加课程
     * @param course 课程对象
     * @return true如果添加成功
     */
    public boolean addCourse(TrainingCourse course) {
        if (courses.containsKey(course.getCourseId())) {
            System.out.println("课程ID已存在: " + course.getCourseId());
            return false;
        }
        courses.put(course.getCourseId(), course);
        System.out.println("课程添加成功: " + course.getCourseName());
        return true;
    }
    
    /**
     * 获取课程
     * @param courseId 课程ID
     * @return 课程对象，如果不存在则返回null
     */
    public TrainingCourse getCourse(String courseId) {
        return courses.get(courseId);
    }
    
    /**
     * 更新课程信息
     * @param course 课程对象
     * @return true如果更新成功
     */
    public boolean updateCourse(TrainingCourse course) {
        if (!courses.containsKey(course.getCourseId())) {
            System.out.println("课程不存在: " + course.getCourseId());
            return false;
        }
        courses.put(course.getCourseId(), course);
        System.out.println("课程更新成功: " + course.getCourseName());
        return true;
    }
    
    /**
     * 删除课程
     * @param courseId 课程ID
     * @return true如果删除成功
     */
    public boolean deleteCourse(String courseId) {
        if (!courses.containsKey(courseId)) {
            System.out.println("课程不存在: " + courseId);
            return false;
        }
        // 检查是否有相关的培训记录
        boolean hasRecords = trainingRecords.values().stream()
                .anyMatch(record -> record.getCourseId().equals(courseId));
        if (hasRecords) {
            System.out.println("无法删除课程：存在相关的培训记录");
            return false;
        }
        courses.remove(courseId);
        System.out.println("课程删除成功: " + courseId);
        return true;
    }
    
    /**
     * 获取所有启用的课程
     * @return 启用的课程列表
     */
    public List<TrainingCourse> getActiveCourses() {
        return courses.values().stream()
                .filter(TrainingCourse::isActive)
                .collect(Collectors.toList());
    }
    
    /**
     * 按部门获取课程
     * @param department 部门
     * @return 部门的课程列表
     */
    public List<TrainingCourse> getCoursesByDepartment(String department) {
        return courses.values().stream()
                .filter(course -> course.getDepartment().equals(department))
                .collect(Collectors.toList());
    }
    
    // ====================== 培训记录管理功能 ======================
    
    /**
     * 员工报名课程
     * @param employeeId 员工ID
     * @param courseId 课程ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @return 培训记录ID
     */
    public String enrollEmployee(String employeeId, String courseId, 
                                String employeeName, String employeeEmail) {
        // 检查课程是否存在且可报名
        TrainingCourse course = courses.get(courseId);
        if (course == null || !course.isEnrollable()) {
            System.out.println("课程不存在或不可报名: " + courseId);
            return null;
        }
        
        // 生成记录ID
        String recordId = generateRecordId(employeeId, courseId);
        
        // 创建培训记录
        TrainingRecord record = new TrainingRecord(recordId, employeeId, courseId);
        trainingRecords.put(recordId, record);
        
        // 添加到员工培训记录映射
        employeeRecords.computeIfAbsent(employeeId, k -> new ArrayList<>()).add(record);
        
        // 发送报名通知邮件
        emailService.sendTrainingNotificationEmail(employeeId, employeeName, employeeEmail,
                course.getCourseName(), LocalDate.now().toString(), course.getTrainer());
        
        System.out.println("员工报名成功: " + employeeId + " -> " + course.getCourseName());
        return recordId;
    }
    
    /**
     * 开始培训
     * @param recordId 培训记录ID
     * @param startDate 开始日期
     * @return true如果开始成功
     */
    public boolean startTraining(String recordId, LocalDate startDate) {
        TrainingRecord record = trainingRecords.get(recordId);
        if (record == null) {
            System.out.println("培训记录不存在: " + recordId);
            return false;
        }
        
        try {
            TrainingCourse course = courses.get(record.getCourseId());
            record.startTraining(startDate, course.getTrainer());
            System.out.println("培训开始成功: " + recordId);
            return true;
        } catch (Exception e) {
            System.out.println("培训开始失败: " + e.getMessage());
            return false;
        }
    }
    
    /**
     * 完成培训
     * @param recordId 培训记录ID
     * @param completionDate 完成日期
     * @param score 成绩
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @return true如果完成成功
     */
    public boolean completeTraining(String recordId, LocalDate completionDate, double score,
                                   String employeeName, String employeeEmail) {
        TrainingRecord record = trainingRecords.get(recordId);
        if (record == null) {
            System.out.println("培训记录不存在: " + recordId);
            return false;
        }
        
        try {
            record.completeTraining(completionDate, score);
            
            // 如果成绩合格，自动颁发证书
            if (record.isPassed()) {
                issueCertificate(recordId, employeeName, employeeEmail);
            }
            
            System.out.println("培训完成成功: " + recordId);
            return true;
        } catch (Exception e) {
            System.out.println("培训完成失败: " + e.getMessage());
            return false;
        }
    }
    
    /**
     * 取消培训
     * @param recordId 培训记录ID
     * @param reason 取消原因
     * @return true如果取消成功
     */
    public boolean cancelTraining(String recordId, String reason) {
        TrainingRecord record = trainingRecords.get(recordId);
        if (record == null) {
            System.out.println("培训记录不存在: " + recordId);
            return false;
        }
        
        try {
            record.cancelTraining(reason);
            System.out.println("培训取消成功: " + recordId);
            return true;
        } catch (Exception e) {
            System.out.println("培训取消失败: " + e.getMessage());
            return false;
        }
    }
    
    // ====================== 证书管理功能 ======================
    
    /**
     * 颁发证书
     * @param recordId 培训记录ID
     * @param employeeName 员工姓名
     * @param employeeEmail 员工邮箱
     * @return 证书ID
     */
    public String issueCertificate(String recordId, String employeeName, String employeeEmail) {
        TrainingRecord record = trainingRecords.get(recordId);
        if (record == null) {
            System.out.println("培训记录不存在: " + recordId);
            return null;
        }
        
        TrainingCourse course = courses.get(record.getCourseId());
        
        try {
            // 生成证书ID
            String certificateId = generateCertificateId(record.getEmployeeId(), course.getCourseId());
            
            // 创建证书
            Certificate certificate = new Certificate(certificateId, 
                    record.getEmployeeId(), 
                    course.getCourseId(),
                    course.getCourseName(),
                    "公司培训部门",
                    course.getTrainer(),
                    record.getScore());
            
            // 设置证书有效期（默认3年）
            certificate.setValidYears(3);
            
            // 颁发证书
            record.issueCertificate(certificateId);
            certificates.put(certificateId, certificate);
            
            // 发送证书通知邮件
            emailService.sendCertificateEmail(record.getEmployeeId(), employeeName, employeeEmail,
                    course.getCourseName(), LocalDate.now().toString());
            
            System.out.println("证书颁发成功: " + certificateId);
            return certificateId;
        } catch (Exception e) {
            System.out.println("证书颁发失败: " + e.getMessage());
            return null;
        }
    }
    
    /**
     * 获取证书
     * @param certificateId 证书ID
     * @return 证书对象
     */
    public Certificate getCertificate(String certificateId) {
        return certificates.get(certificateId);
    }
    
    /**
     * 吊销证书
     * @param certificateId 证书ID
     * @param reason 吊销原因
     * @return true如果吊销成功
     */
    public boolean revokeCertificate(String certificateId, String reason) {
        Certificate certificate = certificates.get(certificateId);
        if (certificate == null) {
            System.out.println("证书不存在: " + certificateId);
            return false;
        }
        
        certificate.revokeCertificate(reason);
        System.out.println("证书吊销成功: " + certificateId);
        return true;
    }
    
    // ====================== 查询功能 ======================
    
    /**
     * 获取员工的所有培训记录
     * @param employeeId 员工ID
     * @return 培训记录列表
     */
    public List<TrainingRecord> getEmployeeTrainingRecords(String employeeId) {
        return employeeRecords.getOrDefault(employeeId, new ArrayList<>());
    }
    
    /**
     * 获取员工的有效证书
     * @param employeeId 员工ID
     * @return 有效证书列表
     */
    public List<Certificate> getEmployeeActiveCertificates(String employeeId) {
        return certificates.values().stream()
                .filter(cert -> cert.getEmployeeId().equals(employeeId) && 
                               cert.isActive() && !cert.isExpired())
                .collect(Collectors.toList());
    }
    
    /**
     * 获取课程的所有培训记录
     * @param courseId 课程ID
     * @return 培训记录列表
     */
    public List<TrainingRecord> getCourseTrainingRecords(String courseId) {
        return trainingRecords.values().stream()
                .filter(record -> record.getCourseId().equals(courseId))
                .collect(Collectors.toList());
    }
    
    /**
     * 生成培训统计报告
     * @return 培训统计信息
     */
    public Map<String, Object> generateTrainingReport() {
        Map<String, Object> report = new HashMap<>();
        
        // 总课程数
        report.put("totalCourses", courses.size());
        
        // 启用课程数
        report.put("activeCourses", getActiveCourses().size());
        
        // 总培训记录数
        report.put("totalRecords", trainingRecords.size());
        
        // 各状态记录数
        Map<TrainingRecord.RecordStatus, Long> statusCount = trainingRecords.values().stream()
                .collect(Collectors.groupingBy(TrainingRecord::getStatus, Collectors.counting()));
        report.put("statusCount", statusCount);
        
        // 总证书数
        report.put("totalCertificates", certificates.size());
        
        // 有效证书数
        long activeCertificates = certificates.values().stream()
                .filter(cert -> cert.isActive() && !cert.isExpired())
                .count();
        report.put("activeCertificates", activeCertificates);
        
        // 平均成绩
        Double averageScore = trainingRecords.values().stream()
                .filter(record -> record.getScore() != null)
                .mapToDouble(TrainingRecord::getScore)
                .average()
                .orElse(0);
        report.put("averageScore", averageScore);
        
        return report;
    }
    
    // ====================== 辅助方法 ======================
    
    /**
     * 生成培训记录ID
     */
    private String generateRecordId(String employeeId, String courseId) {
        return String.format("REC-%s-%s-%d", 
                employeeId, courseId, System.currentTimeMillis());
    }
    
    /**
     * 生成证书ID
     */
    private String generateCertificateId(String employeeId, String courseId) {
        return String.format("CERT-%s-%s-%d", 
                employeeId, courseId, System.currentTimeMillis());
    }
    
    /**
     * 获取系统中的员工数量
     * @return 员工数量
     */
    public int getEmployeeCount() {
        return employeeRecords.size();
    }
    
    /**
     * 获取即将到期的证书
     * @param days 天数
     * @return 即将到期的证书列表
     */
    public List<Certificate> getExpiringCertificates(int days) {
        LocalDate futureDate = LocalDate.now().plusDays(days);
        return certificates.values().stream()
                .filter(cert -> cert.isActive() && 
                               cert.getExpiryDate() != null &&
                               !cert.isExpired() &&
                               cert.getExpiryDate().isBefore(futureDate))
                .collect(Collectors.toList());
    }
}