import { isDate, isISO8601 } from "class-validator";
import { DateOptions } from "../Column";
import { format, parse, parseISO } from "date-fns";
import { utcToZonedTime, zonedTimeToUtc } from "date-fns-tz";
import { zhCN } from "date-fns/locale";
export enum TimeFormat {
  TwelveHour = "12hour",
  TwentyFourHour = "24hour",
}
export enum AwareDate {
  LLL = "LLL", // 12小时
  lll = "lll", // 24小时
  LL = "LL", // 日期
  L = "L", // 年月
}

// 目前没有时区功能，默认设置为中国时区
export enum DateFormat {
  Local = "Local",
  Friendly = "Friendly",
  US = "US",
  European = "European",
  ISO = "ISO",
}
export type LocaleFormat = Record<AwareDate, string>;
type CustomLocale = {
  format: LocaleFormat;
};

const zhCNLocale: CustomLocale = {
  format: {
    [AwareDate.L]: "yyyy年MM月",
    [AwareDate.LL]: "yyyy年MM月dd日",
    [AwareDate.LLL]: "yyyy年MM月dd日 hh:mm a",
    [AwareDate.lll]: "yyyy年MM月dd日 HH:mm",
  },
};

const euLocale: CustomLocale = {
  format: {
    [AwareDate.L]: "MM/yyyy",
    [AwareDate.LL]: "dd/MM/yyyy",
    [AwareDate.LLL]: "dd/MM/yyyy hh:mm a",
    [AwareDate.lll]: "dd/MM/yyyy HH:mm",
  },
};

const enUSLocale: CustomLocale = {
  format: {
    [AwareDate.L]: "MM/yyyy",
    [AwareDate.LL]: "MM/dd/yyyy",
    [AwareDate.LLL]: "MM/dd/yyyy hh:mm a",
    [AwareDate.lll]: "MM/dd/yyyy HH:mm",
  },
};

const ISOLocale: CustomLocale = {
  format: {
    [AwareDate.L]: "yyyy-MM",
    [AwareDate.LL]: "yyyy-MM-dd",
    [AwareDate.LLL]: "yyyy-MM-dd hh:mm a",
    [AwareDate.lll]: "yyyy-MM-dd HH:mm",
  },
};

const locals = {
  [DateFormat.Friendly]: zhCNLocale,
  [DateFormat.Local]: ISOLocale,
  [DateFormat.ISO]: ISOLocale,
  [DateFormat.European]: euLocale,
  [DateFormat.US]: enUSLocale,
};

export function dateToString(
  dateOptions: DateOptions,
  dateStr: string | null
): string {
  if (!dateStr) {
    return "";
  }

  const date = new Date(dateStr);

  if (!isDate(date)) {
    return "";
  } else {
    const zonedDate = utcToZonedTime(date, "Asia/Shanghai");

    let awareDate: AwareDate;

    if (!dateOptions.isDate) {
      awareDate = AwareDate.L;
    } else {
      awareDate = AwareDate.LL;

      if (dateOptions.isDateTime) {
        if (dateOptions.timeFormat === TimeFormat.TwelveHour) {
          awareDate = AwareDate.LLL;
        } else {
          awareDate = AwareDate.lll;
        }
      }
    }

    const locale = locals[dateOptions.dateFormat];

    return format(zonedDate, locale.format[awareDate], { locale: zhCN });
  }
}

function parseLocaleDateText(dateStr: string, locale: CustomLocale) {
  const parseDate = (format: AwareDate) => {
    const date = parse(dateStr, locale.format[format], new Date(), {
      locale: zhCN,
    });

    if (isDate(date)) {
      return date;
    }
    return null;
  };

  let date = parseDate(AwareDate.LLL); // 12小时
  if (!date) {
    date = parseDate(AwareDate.lll); // 24小时
  }
  if (!date) {
    date = parseDate(AwareDate.LL); // 日期
  }
  if (!date) {
    date = parseDate(AwareDate.L); // 年月
  }

  return date;
}

export function parseDateByString(dateStr: string) {
  if (!dateStr) {
    return null;
  }

  let date = parseLocaleDateText(dateStr, zhCNLocale); // yyyy年M月dd日
  if (!date) {
    date = parseLocaleDateText(dateStr, ISOLocale); // yyyy-MM-dd
  }

  if (!date) {
    date = parseLocaleDateText(dateStr, enUSLocale); // MM-dd-yyyy
  }
  if (!date) {
    date = parseLocaleDateText(dateStr, euLocale); // dd-MM-yyyy
  }

  if (date) {
    return zonedTimeToUtc(date, "Asia/Shanghai"); // 非ISO字符串转换日期需要当作北京时间(+8)转为UTC(0)
  }

  if (isISO8601(dateStr, { strict: true })) {
    const isoDate = parseISO(dateStr);
    if (isDate(isoDate)) {
      return isoDate;
    }
  }

  return date;
}