/**
 * 员工历史记录类
 * 负责记录员工的历史变更信息，如职位变更、薪资调整等
 * 遵循单一职责原则，只负责历史记录的管理
 */
package com.employeetraining.history;

import com.employeetraining.model.Employee;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

public class EmployeeHistory {
    private String employeeId;
    private List<HistoryRecord> historyRecords;
    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    
    public EmployeeHistory(String employeeId) {
        this.employeeId = employeeId;
        this.historyRecords = new ArrayList<>();
    }
    
    /**
     * 记录职位变更
     */
    public void recordPositionChange(String oldPosition, String newPosition) {
        String description = String.format("职位变更: 从 '%s' 变更为 '%s'", oldPosition, newPosition);
        addRecord(HistoryType.POSITION_CHANGE, description);
    }
    
    /**
     * 记录薪资调整
     */
    public void recordSalaryChange(double oldSalary, double newSalary) {
        String description = String.format("薪资调整: 从 %.2f 调整为 %.2f", oldSalary, newSalary);
        addRecord(HistoryType.SALARY_CHANGE, description);
    }
    
    /**
     * 记录部门变更
     */
    public void recordDepartmentChange(String oldDepartment, String newDepartment) {
        String description = String.format("部门变更: 从 '%s' 变更为 '%s'", oldDepartment, newDepartment);
        addRecord(HistoryType.DEPARTMENT_CHANGE, description);
    }
    
    /**
     * 添加自定义记录
     */
    public void addCustomRecord(String description) {
        addRecord(HistoryType.CUSTOM, description);
    }
    
    /**
     * 内部方法：添加记录
     */
    private void addRecord(HistoryType type, String description) {
        HistoryRecord record = new HistoryRecord(LocalDateTime.now(), type, description);
        historyRecords.add(record);
    }
    
    /**
     * 获取所有历史记录
     */
    public List<HistoryRecord> getAllRecords() {
        return new ArrayList<>(historyRecords); // 返回副本，防止外部修改
    }
    
    /**
     * 根据类型获取历史记录
     */
    public List<HistoryRecord> getRecordsByType(HistoryType type) {
        return historyRecords.stream()
                .filter(record -> record.getType() == type)
                .toList();
    }
    
    /**
     * 获取最新的历史记录
     */
    public Optional<HistoryRecord> getLatestRecord() {
        if (historyRecords.isEmpty()) {
            return Optional.empty();
        }
        return Optional.of(historyRecords.get(historyRecords.size() - 1));
    }
    
    /**
     * 获取记录总数
     */
    public int getRecordCount() {
        return historyRecords.size();
    }
    
    /**
     * 历史记录类型枚举
     */
    public enum HistoryType {
        POSITION_CHANGE,
        SALARY_CHANGE,
        DEPARTMENT_CHANGE,
        CUSTOM
    }
    
    /**
     * 历史记录内部类
     */
    public class HistoryRecord {
        private final LocalDateTime timestamp;
        private final HistoryType type;
        private final String description;
        
        public HistoryRecord(LocalDateTime timestamp, HistoryType type, String description) {
            this.timestamp = timestamp;
            this.type = type;
            this.description = description;
        }
        
        public LocalDateTime getTimestamp() {
            return timestamp;
        }
        
        public String getFormattedTimestamp() {
            return timestamp.format(formatter);
        }
        
        public HistoryType getType() {
            return type;
        }
        
        public String getDescription() {
            return description;
        }
        
        @Override
        public String toString() {
            return "[" + getFormattedTimestamp() + "] " + type + ": " + description;
        }
    }
}