package com.ruoyi.inspectiontask.service.impl;

import java.time.DayOfWeek;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.YearMonth;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.HashSet;
import java.util.Set;

final class TimingTaskScheduleUtils {

    private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("HH:mm");

    private TimingTaskScheduleUtils() {
    }

    static LocalDateTime calculateFirstExecutionTime(String frequencyType, String frequencyDetail) {
        return calculateNextExecutionTime(frequencyType, frequencyDetail, LocalDateTime.now().minusSeconds(1));
    }

    static LocalDateTime calculateNextExecutionTime(String frequencyType, String frequencyDetail, LocalDateTime currentTime) {
        if (frequencyType == null || frequencyDetail == null) {
            throw new IllegalArgumentException("任务参数不能为空");
        }
        switch (frequencyType.toUpperCase()) {
            case "DAILY":
                return calculateDailyNextTime(frequencyDetail, currentTime);
            case "WEEKLY":
                return calculateWeeklyNextTime(frequencyDetail, currentTime);
            case "MONTHLY":
                return calculateMonthlyNextTime(frequencyDetail, currentTime);
            case "QUARTERLY":
                return calculateQuarterlyNextTime(frequencyDetail, currentTime);
            default:
                throw new IllegalArgumentException("不支持的频率类型: " + frequencyType);
        }
    }

    private static LocalDateTime calculateDailyNextTime(String timeStr, LocalDateTime current) {
        LocalTime executionTime = parseTime(timeStr);
        LocalDateTime nextTime = LocalDateTime.of(current.toLocalDate(), executionTime);
        return current.isBefore(nextTime) ? nextTime : nextTime.plusDays(1);
    }

    private static LocalDateTime calculateWeeklyNextTime(String detail, LocalDateTime current) {
        String[] parts = validateAndSplit(detail, ",", 2);
        Set<DayOfWeek> targetDays = parseDayOfWeeks(parts[0]);
        LocalTime time = parseTime(parts[1]);

        LocalDateTime nextTime = current;
        for (int i = 0; i < 366; i++) {
            nextTime = nextTime.plusDays(1);
            if (targetDays.contains(nextTime.getDayOfWeek())) {
                return LocalDateTime.of(nextTime.toLocalDate(), time);
            }
        }
        throw new IllegalArgumentException("无法找到下一次执行时间");
    }

    private static LocalDateTime calculateMonthlyNextTime(String detail, LocalDateTime current) {
        String[] parts = validateAndSplit(detail, ",", 2);
        int dayOfMonth = validateDayOfMonth(parts[0]);
        LocalTime time = parseTime(parts[1]);

        for (int i = 0; i < 24; i++) {
            YearMonth targetYearMonth = YearMonth.from(current).plusMonths(i);
            int adjustedDay = Math.min(dayOfMonth, targetYearMonth.lengthOfMonth());
            LocalDateTime target = LocalDateTime.of(
                    targetYearMonth.getYear(),
                    targetYearMonth.getMonthValue(),
                    adjustedDay,
                    time.getHour(),
                    time.getMinute()
            );
            if (target.isAfter(current)) {
                return target;
            }
        }
        throw new IllegalArgumentException("无法找到下一次执行时间");
    }

    private static LocalDateTime calculateQuarterlyNextTime(String detail, LocalDateTime current) {
        String[] parts = validateAndSplit(detail, ",", 3);
        int startMonth = validateMonth(parts[0]);
        int dayOfMonth = validateDayOfMonth(parts[1]);
        LocalTime time = parseTime(parts[2]);

        YearMonth anchor = YearMonth.of(current.getYear(), startMonth);
        for (int i = 0; i < 12; i++) {
            YearMonth targetYearMonth = anchor.plusMonths(3L * i);
            int adjustedDay = Math.min(dayOfMonth, targetYearMonth.lengthOfMonth());
            LocalDateTime target = LocalDateTime.of(
                    targetYearMonth.getYear(),
                    targetYearMonth.getMonthValue(),
                    adjustedDay,
                    time.getHour(),
                    time.getMinute()
            );
            if (target.isAfter(current)) {
                return target;
            }
        }
        throw new IllegalArgumentException("无法找到下一次执行时间");
    }

    private static LocalTime parseTime(String timeStr) {
        try {
            return LocalTime.parse(timeStr, TIME_FORMATTER);
        } catch (DateTimeParseException e) {
            throw new IllegalArgumentException("时间格式必须为HH:mm", e);
        }
    }

    private static String[] validateAndSplit(String input, String delimiter, int expectedParts) {
        String[] parts = input.split(delimiter);
        if (parts.length != expectedParts) {
            throw new IllegalArgumentException("参数格式错误");
        }
        return parts;
    }

    private static int validateDayOfMonth(String dayStr) {
        int day = Integer.parseInt(dayStr.trim());
        if (day < 1 || day > 31) {
            throw new IllegalArgumentException("日期必须在1-31之间");
        }
        return day;
    }

    private static int validateMonth(String monthStr) {
        int month = Integer.parseInt(monthStr.trim());
        if (month < 1 || month > 12) {
            throw new IllegalArgumentException("月份必须在1-12之间");
        }
        return month;
    }

    private static Set<DayOfWeek> parseDayOfWeeks(String dayOfWeekStr) {
        Set<DayOfWeek> days = new HashSet<>();
        for (String dayStr : dayOfWeekStr.split("\\|")) {
            switch (dayStr.trim().toUpperCase()) {
                case "MON":
                    days.add(DayOfWeek.MONDAY);
                    break;
                case "TUE":
                    days.add(DayOfWeek.TUESDAY);
                    break;
                case "WED":
                    days.add(DayOfWeek.WEDNESDAY);
                    break;
                case "THU":
                    days.add(DayOfWeek.THURSDAY);
                    break;
                case "FRI":
                    days.add(DayOfWeek.FRIDAY);
                    break;
                case "SAT":
                    days.add(DayOfWeek.SATURDAY);
                    break;
                case "SUN":
                    days.add(DayOfWeek.SUNDAY);
                    break;
                default:
                    throw new IllegalArgumentException("无效的星期几: " + dayStr);
            }
        }
        return days;
    }
}