import dayjs from "dayjs";
import { FinanceAutoRepeatType } from "@/types/finance";

/** repeat_date 以 ! 开头表示"排除模式"：指定的日期/星期几不执行 */
function isExcludeMode(repeatDate: string): boolean {
  return repeatDate.startsWith("!");
}

/** 去掉排除前缀，返回干净的日期字符串 */
function cleanRepeatDate(repeatDate: string): string {
  return isExcludeMode(repeatDate) ? repeatDate.slice(1) : repeatDate;
}

/**
 * 粗粒度判断：从上次执行至今，是否"可能"有遗漏的触发日期
 * 只做时间周期级别的判断，不做具体日期匹配（日期匹配交给 shouldRunOnDate / getMissedDates）
 */
export function shouldRun(repeatType: number, repeatDate: string, lastRun: string | null | undefined): boolean {
  const today = dayjs();
  if (!lastRun) return true; // 从未执行过，需要尝试

  const last = dayjs(lastRun);

  // 排除模式下每天都是潜在触发日，简单判断 lastRun 不是今天即可
  if (isExcludeMode(repeatDate)) {
    return !last.isSame(today, "day");
  }

  switch (repeatType) {
    case FinanceAutoRepeatType.Daily:
      return !last.isSame(today, "day");

    case FinanceAutoRepeatType.Weekly: {
      const days = (repeatDate || "").split(",").map(Number).filter((d) => !isNaN(d));
      if (days.length === 0) return false;
      let check = today;
      for (let i = 0; i < 7; i++) {
        if (days.includes(check.day())) {
          return check.isAfter(last, "day");
        }
        check = check.subtract(1, "day");
      }
      return false;
    }

    case FinanceAutoRepeatType.Monthly:
      return !last.isSame(today, "month");

    case FinanceAutoRepeatType.Quarterly:
      return last.quarter() !== today.quarter() || last.year() !== today.year();

    case FinanceAutoRepeatType.Yearly:
      // 支持同一年内多个触发日（如 3/15 和 6/1），不再仅按年份判断
      return last.isBefore(today, "day");

    default:
      return false;
  }
}

/**
 * 获取应该补记账的日期列表（从上次执行到今天）
 * 逐日遍历，通过 shouldRunOnDate 精确匹配触发日
 */
export function getMissedDates(
  repeatType: number,
  repeatDate: string,
  lastRun: string | null | undefined,
): string[] {
  const today = dayjs();

  // 首次执行：只在今天恰好是触发日时才创建账单
  if (!lastRun) {
    if (shouldRunOnDate(repeatType, repeatDate, today)) {
      return [today.format("YYYY-MM-DD")];
    }
    return [];
  }

  const last = dayjs(lastRun);
  const dates: string[] = [];
  let cursor = last.add(1, "day");

  while (cursor.isBefore(today, "day") || cursor.isSame(today, "day")) {
    const d = cursor.format("YYYY-MM-DD");
    if (shouldRunOnDate(repeatType, repeatDate, cursor)) {
      dates.push(d);
    }
    cursor = cursor.add(1, "day");
  }

  return dates;
}

function shouldRunOnDate(repeatType: number, repeatDate: string, date: dayjs.Dayjs): boolean {
  const exclude = isExcludeMode(repeatDate);
  const raw = cleanRepeatDate(repeatDate);

  switch (repeatType) {
    case FinanceAutoRepeatType.Daily: {
      if (!exclude || !raw) return true;
      // 每天 排除星期几（如 "!0" → 排除周日）
      const excludedDays = raw.split(",").map(Number).filter((d) => !isNaN(d));
      return !excludedDays.includes(date.day());
    }

    case FinanceAutoRepeatType.Weekly: {
      const days = raw.split(",").map(Number).filter((d) => !isNaN(d));
      if (days.length === 0) return false;
      const match = days.includes(date.day());
      return exclude ? !match : match;
    }

    case FinanceAutoRepeatType.Monthly:
    case FinanceAutoRepeatType.Quarterly: {
      const dates = raw.split(",").map(Number).filter((d) => !isNaN(d));
      if (dates.length === 0) return false;
      const match = dates.includes(date.date());
      return exclude ? !match : match;
    }

    case FinanceAutoRepeatType.Yearly: {
      // 月,日 成对存储，如 "3,15,6,1" → 3月15日 + 6月1日
      const parts = raw.split(",").map(Number).filter((n) => !isNaN(n));
      for (let i = 0; i < parts.length - 1; i += 2) {
        if (parts[i] === date.month() + 1 && parts[i + 1] === date.date()) {
          return exclude ? false : true;
        }
      }
      return exclude; // 排除模式未命中 → 执行；正常模式未命中 → 不执行
    }

    default:
      return false;
  }
}

export const REPEAT_LABELS: Record<number, string> = {
  [FinanceAutoRepeatType.Daily]: "每天",
  [FinanceAutoRepeatType.Weekly]: "每周",
  [FinanceAutoRepeatType.Monthly]: "每月",
};

export const WEEK_DAYS = [
  { value: 1, label: "一" },
  { value: 2, label: "二" },
  { value: 3, label: "三" },
  { value: 4, label: "四" },
  { value: 5, label: "五" },
  { value: 6, label: "六" },
  { value: 0, label: "日" },
];