/**
 * Date and Time Formatting Utilities
 * Uses global Yatra settings for consistent date/time formatting across all pages
 */

// Supported PHP date formats:
// 'Y-m-d'   -> 2025-12-15
// 'm/d/Y'   -> 12/15/2025
// 'd/m/Y'   -> 15/12/2025
// 'd-m-Y'   -> 15-12-2025
// 'M d, Y'  -> Dec 15, 2025
// 'F d, Y'  -> December 15, 2025
// 'd M Y'   -> 15 Dec 2025
// 'd F Y'   -> 15 December 2025

// Supported PHP time formats:
// 'H:i'     -> 14:30 (24-hour)
// 'h:i A'   -> 02:30 PM (12-hour)
// 'h:i a'   -> 02:30 pm (12-hour lowercase)
// 'H:i:s'   -> 14:30:00 (24-hour with seconds)
// 'h:i:s A' -> 02:30:00 PM (12-hour with seconds)

/**
 * Get date format from Yatra settings
 */
export function getDateFormat(): string {
  const w = window as any;
  return (
    w?.yatraAdmin?.date_format ||
    w?.yatraAdmin?.dateFormat ||
    // Customer account pages localize their settings under yatraAccountPage.
    w?.yatraAccountPage?.date_format ||
    "Y-m-d"
  );
}

/**
 * Get time format from Yatra settings
 */
export function getTimeFormat(): string {
  const w = window as any;
  return (
    w?.yatraAdmin?.time_format ||
    w?.yatraAdmin?.timeFormat ||
    w?.yatraAccountPage?.time_format ||
    "H:i"
  );
}

/**
 * Get timezone from Yatra settings
 */
export function getTimezone(): string {
  const w = window as any;
  return w?.yatraAdmin?.timezone || w?.yatraAccountPage?.timezone || "UTC";
}

/**
 * Parse a value into a Date, treating a date-only string ("YYYY-MM-DD") as a
 * LOCAL calendar date.
 *
 * `new Date("2026-08-01")` parses as UTC midnight, but the formatters read it
 * back with local getters (getDate/getMonth/…), so in any behind-UTC timezone
 * the day rolls back (Aug 1 → Jul 31) — e.g. a booking's travel_date showing
 * one day early. Building the Date from its parts pins it to the intended
 * calendar day regardless of timezone. Datetime strings (with a time part) and
 * Date objects are parsed/returned as before.
 */
export function toDateValue(value: string | Date | null | undefined): Date {
  // Never hand back a non-Date. This previously returned `value` unchanged for
  // anything that wasn't a string, so a missing date came back as `undefined`
  // and the caller's `.toLocaleDateString()` threw — taking the whole admin
  // dashboard down with it via the error boundary. An Invalid Date keeps every
  // caller's date maths working (comparisons are simply false) and lets the
  // display helpers fall back to "-".
  if (value === null || value === undefined) return new Date(NaN);
  if (value instanceof Date) return value;
  if (typeof value !== "string") return new Date(NaN);
  const dateOnly = /^(\d{4})-(\d{2})-(\d{2})$/.exec(value.trim());
  if (dateOnly) {
    return new Date(
      Number(dateOnly[1]),
      Number(dateOnly[2]) - 1,
      Number(dateOnly[3]),
    );
  }
  return new Date(value);
}

/**
 * Format a date string according to Yatra settings
 * @param dateString - Date string in any parseable format (ISO, YYYY-MM-DD, etc.)
 * @param includeTime - Whether to include time in the output
 * @returns Formatted date string
 */
export function formatDate(
  dateString: string | Date | null | undefined,
  includeTime: boolean = false,
): string {
  if (!dateString) return "-";

  try {
    const date = toDateValue(dateString);

    if (isNaN(date.getTime())) {
      return String(dateString);
    }

    const phpDateFormat = getDateFormat();
    const phpTimeFormat = getTimeFormat();

    // Format date part
    const formattedDate = formatDatePart(date, phpDateFormat);

    // Format time part if requested
    if (includeTime) {
      const formattedTime = formatTimePart(date, phpTimeFormat);
      return `${formattedDate} ${formattedTime}`;
    }

    return formattedDate;
  } catch (e) {
    return String(dateString);
  }
}

/**
 * Format only the date part
 */
function formatDatePart(date: Date, phpFormat: string): string {
  const year = date.getFullYear();
  const month = date.getMonth();
  const day = date.getDate();

  const monthNames = [
    "January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December",
  ];
  const monthShort = [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec",
  ];

  const pad = (n: number) => n.toString().padStart(2, "0");

  const dayNames = [
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday",
  ];
  const dayShort = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
  const dayOfWeek = date.getDay();

  switch (phpFormat) {
    // Numeric formats
    case "Y-m-d":
      return `${year}-${pad(month + 1)}-${pad(day)}`;
    case "Y/m/d":
      return `${year}/${pad(month + 1)}/${pad(day)}`;
    case "m/d/Y":
      return `${pad(month + 1)}/${pad(day)}/${year}`;
    case "d/m/Y":
      return `${pad(day)}/${pad(month + 1)}/${year}`;
    case "d-m-Y":
      return `${pad(day)}-${pad(month + 1)}-${year}`;
    case "d.m.Y":
      return `${pad(day)}.${pad(month + 1)}.${year}`;
    // Month name formats with padded day
    case "M d, Y":
      return `${monthShort[month]} ${pad(day)}, ${year}`;
    case "F d, Y":
      return `${monthNames[month]} ${pad(day)}, ${year}`;
    case "d M Y":
      return `${pad(day)} ${monthShort[month]} ${year}`;
    case "d F Y":
      return `${pad(day)} ${monthNames[month]} ${year}`;
    // Month name formats with day without leading zero
    case "M j, Y":
      return `${monthShort[month]} ${day}, ${year}`;
    case "F j, Y":
      return `${monthNames[month]} ${day}, ${year}`;
    case "j M Y":
      return `${day} ${monthShort[month]} ${year}`;
    case "j F Y":
      return `${day} ${monthNames[month]} ${year}`;
    // Year first with month name
    case "Y M j":
      return `${year} ${monthShort[month]} ${day}`;
    case "Y F j":
      return `${year} ${monthNames[month]} ${day}`;
    // With weekday
    case "l, F j, Y":
      return `${dayNames[dayOfWeek]}, ${monthNames[month]} ${day}, ${year}`;
    case "D, M j, Y":
      return `${dayShort[dayOfWeek]}, ${monthShort[month]} ${day}, ${year}`;
    default:
      // Default to ISO format
      return `${year}-${pad(month + 1)}-${pad(day)}`;
  }
}

/**
 * Format only the time part
 */
function formatTimePart(date: Date, phpFormat: string): string {
  const hours = date.getHours();
  const minutes = date.getMinutes();
  const seconds = date.getSeconds();

  const pad = (n: number) => n.toString().padStart(2, "0");

  const hours12 = hours % 12 || 12;
  const ampm = hours >= 12 ? "PM" : "AM";

  switch (phpFormat) {
    case "H:i":
      return `${pad(hours)}:${pad(minutes)}`;
    case "h:i A":
      return `${pad(hours12)}:${pad(minutes)} ${ampm}`;
    case "h:i a":
      return `${pad(hours12)}:${pad(minutes)} ${ampm.toLowerCase()}`;
    case "H:i:s":
      return `${pad(hours)}:${pad(minutes)}:${pad(seconds)}`;
    case "h:i:s A":
      return `${pad(hours12)}:${pad(minutes)}:${pad(seconds)} ${ampm}`;
    default:
      return `${pad(hours)}:${pad(minutes)}`;
  }
}

/**
 * Format a date for display with time
 * @param dateString - Date string
 * @returns Formatted date and time string
 */
export function formatDateTime(
  dateString: string | Date | null | undefined,
): string {
  return formatDate(dateString, true);
}

/**
 * Format time only
 * @param dateString - Date string or time string
 * @returns Formatted time string
 */
export function formatTime(
  dateString: string | Date | null | undefined,
): string {
  if (!dateString) return "-";

  try {
    const date = toDateValue(dateString);

    if (isNaN(date.getTime())) {
      // Try to parse as time only (HH:mm or HH:mm:ss)
      if (
        typeof dateString === "string" &&
        /^\d{1,2}:\d{2}(:\d{2})?$/.test(dateString)
      ) {
        const [hours, minutes] = dateString.split(":").map(Number);
        const tempDate = new Date();
        tempDate.setHours(hours, minutes, 0, 0);
        return formatTimePart(tempDate, getTimeFormat());
      }
      return String(dateString);
    }

    return formatTimePart(date, getTimeFormat());
  } catch (e) {
    return String(dateString);
  }
}

/**
 * Get relative time (e.g., "2 hours ago", "3 days ago")
 * @param dateString - Date string
 * @returns Relative time string
 */
export function formatRelativeTime(
  dateString: string | Date | null | undefined,
): string {
  if (!dateString) return "-";

  try {
    const date = toDateValue(dateString);

    if (isNaN(date.getTime())) {
      return String(dateString);
    }

    const now = new Date();
    const diffMs = now.getTime() - date.getTime();
    const diffSecs = Math.floor(diffMs / 1000);
    const diffMins = Math.floor(diffSecs / 60);
    const diffHours = Math.floor(diffMins / 60);
    const diffDays = Math.floor(diffHours / 24);
    const diffWeeks = Math.floor(diffDays / 7);
    const diffMonths = Math.floor(diffDays / 30);
    const diffYears = Math.floor(diffDays / 365);

    if (diffSecs < 60) return "Just now";
    if (diffMins < 60)
      return `${diffMins} minute${diffMins > 1 ? "s" : ""} ago`;
    if (diffHours < 24)
      return `${diffHours} hour${diffHours > 1 ? "s" : ""} ago`;
    if (diffDays < 7) return `${diffDays} day${diffDays > 1 ? "s" : ""} ago`;
    if (diffWeeks < 4)
      return `${diffWeeks} week${diffWeeks > 1 ? "s" : ""} ago`;
    if (diffMonths < 12)
      return `${diffMonths} month${diffMonths > 1 ? "s" : ""} ago`;
    return `${diffYears} year${diffYears > 1 ? "s" : ""} ago`;
  } catch (e) {
    return String(dateString);
  }
}

/**
 * Parse a date string to Date object
 * @param dateString - Date string in various formats
 * @returns Date object or null if invalid
 */
export function parseDate(dateString: string | null | undefined): Date | null {
  if (!dateString) return null;

  try {
    const date = toDateValue(dateString);
    return isNaN(date.getTime()) ? null : date;
  } catch (e) {
    return null;
  }
}

/**
 * Format date for input fields (always YYYY-MM-DD for HTML date inputs)
 * @param dateString - Date string
 * @returns Date in YYYY-MM-DD format for input fields
 */
/**
 * Today's date as a LOCAL "YYYY-MM-DD" string.
 *
 * Use this instead of `new Date().toISOString().split("T")[0]` for default/
 * "today" date values: toISOString() yields the UTC date, which is the wrong
 * calendar day for a user whose local date differs from UTC at that moment
 * (e.g. late evening in a behind-UTC zone, or early morning ahead of UTC) —
 * saving a payment/booking/rule date a day off. This reads the browser's local
 * calendar day.
 */
export function todayYmd(): string {
  return formatDateForInput(new Date());
}

export function formatDateForInput(
  dateString: string | Date | null | undefined,
): string {
  if (!dateString) return "";

  try {
    const date = toDateValue(dateString);

    if (isNaN(date.getTime())) {
      return "";
    }

    const year = date.getFullYear();
    const month = (date.getMonth() + 1).toString().padStart(2, "0");
    const day = date.getDate().toString().padStart(2, "0");

    return `${year}-${month}-${day}`;
  } catch (e) {
    return "";
  }
}