frontend/src/common/datetime/format_date.ts

import type { HassConfig } from "home-assistant-js-websocket";
import memoizeOne from "memoize-one";
import type { FrontendLocaleData } from "../../data/translation";
import { DateFormat } from "../../data/translation";
import { resolveTimeZone } from "./resolve-time-zone";

// Tuesday, August 10
export const formatDateWeekdayDay = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateWeekdayDayMem(locale, config.time_zone).format(dateObj);

const formatDateWeekdayDayMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      weekday: "long",
      month: "long",
      day: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// August 10, 2021
export const formatDate = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateMem(locale, config.time_zone).format(dateObj);

const formatDateMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      year: "numeric",
      month: "long",
      day: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Aug 10, 2021
export const formatDateShort = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateShortMem(locale, config.time_zone).format(dateObj);

const formatDateShortMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      year: "numeric",
      month: "short",
      day: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// 10/08/2021
export const formatDateNumeric = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => {
  const formatter = formatDateNumericMem(locale, config.time_zone);

  if (
    locale.date_format === DateFormat.language ||
    locale.date_format === DateFormat.system
  ) {
    return formatter.format(dateObj);
  }

  const parts = formatter.formatToParts(dateObj);

  const literal = parts.find((value) => value.type === "literal")?.value;
  const day = parts.find((value) => value.type === "day")?.value;
  const month = parts.find((value) => value.type === "month")?.value;
  const year = parts.find((value) => value.type === "year")?.value;

  const lastPart = parts[parts.length - 1];
  let lastLiteral = lastPart?.type === "literal" ? lastPart?.value : "";

  if (locale.language === "bg" && locale.date_format === DateFormat.YMD) {
    lastLiteral = "";
  }

  const formats = {
    [DateFormat.DMY]: `${day}${literal}${month}${literal}${year}${lastLiteral}`,
    [DateFormat.MDY]: `${month}${literal}${day}${literal}${year}${lastLiteral}`,
    [DateFormat.YMD]: `${year}${literal}${month}${literal}${day}${lastLiteral}`,
  };

  return formats[locale.date_format];
};

const formatDateNumericMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) => {
    const localeString =
      locale.date_format === DateFormat.system ? undefined : locale.language;

    if (
      locale.date_format === DateFormat.language ||
      locale.date_format === DateFormat.system
    ) {
      return new Intl.DateTimeFormat(localeString, {
        year: "numeric",
        month: "numeric",
        day: "numeric",
        timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
      });
    }

    return new Intl.DateTimeFormat(localeString, {
      year: "numeric",
      month: "numeric",
      day: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    });
  }
);

// Aug 10
export const formatDateVeryShort = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateVeryShortMem(locale, config.time_zone).format(dateObj);

const formatDateVeryShortMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      day: "numeric",
      month: "short",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// August 2021
export const formatDateMonthYear = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateMonthYearMem(locale, config.time_zone).format(dateObj);

const formatDateMonthYearMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      month: "long",
      year: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// August
export const formatDateMonth = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateMonthMem(locale, config.time_zone).format(dateObj);

const formatDateMonthMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      month: "long",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Aug
export const formatDateMonthShort = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateMonthShortMem(locale, config.time_zone).format(dateObj);

const formatDateMonthShortMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      month: "short",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// 2021
export const formatDateYear = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateYearMem(locale, config.time_zone).format(dateObj);

const formatDateYearMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      year: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Monday
export const formatDateWeekday = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateWeekdayMem(locale, config.time_zone).format(dateObj);

const formatDateWeekdayMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      weekday: "long",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Mon
export const formatDateWeekdayShort = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateWeekdayShortMem(locale, config.time_zone).format(dateObj);

const formatDateWeekdayShortMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      weekday: "short",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Mon, Aug 10
export const formatDateWeekdayVeryShortDate = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) =>
  formatDateWeekdayVeryShortDateMem(locale, config.time_zone).format(dateObj);

const formatDateWeekdayVeryShortDateMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      weekday: "short",
      month: "short",
      day: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

// Mon, Aug 10, 2021
export const formatDateWeekdayShortDate = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => formatDateWeekdayShortDateMem(locale, config.time_zone).format(dateObj);

const formatDateWeekdayShortDateMem = memoizeOne(
  (locale: FrontendLocaleData, serverTimeZone: string) =>
    new Intl.DateTimeFormat(locale.language, {
      weekday: "short",
      month: "short",
      day: "numeric",
      year: "numeric",
      timeZone: resolveTimeZone(locale.time_zone, serverTimeZone),
    })
);

/**
 * Format a date as YYYY-MM-DD. Uses "en-CA" because it's the only
 * Intl locale that natively outputs ISO 8601 date format.
 * Locale/config are only used to resolve the time zone.
 */
export const formatISODateOnly = (
  dateObj: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => {
  const timeZone = resolveTimeZone(locale.time_zone, config.time_zone);
  const formatter = new Intl.DateTimeFormat("en-CA", {
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    timeZone,
  });
  return formatter.format(dateObj);
};

// 2026-08-10/2026-08-15
export const formatCallyDateRange = (
  start: Date,
  end: Date,
  locale: FrontendLocaleData,
  config: HassConfig
) => {
  const startDate = formatISODateOnly(start, locale, config);
  const endDate = formatISODateOnly(end, locale, config);

  return `${startDate}/${endDate}`;
};