import type { DateFormat, TimeFormat } from "../api/client";

export interface DateTimeSettings {
  dateFormat: DateFormat;
  timeFormat: TimeFormat;
}

let current: DateTimeSettings = { dateFormat: "ymd", timeFormat: "24h" };

/** Called once at app startup (and whenever the setting is changed) so every formatDateTime() call site picks it up without prop-drilling. */
export function setDateTimeSettings(settings: DateTimeSettings): void {
  current = settings;
}

/** Current 12h/24h preference, for formatters outside this file (e.g. cronstrue's use24HourTimeFormat option). */
export function is24HourFormat(): boolean {
  return current.timeFormat === "24h";
}

function pad(n: number): string {
  return String(n).padStart(2, "0");
}

/** Formats a date using the app-wide date/time display settings (defaults to "YYYY-MM-DD HH:mm:ss" on a 24-hour clock). */
export function formatDateTime(date: Date): string {
  const year = date.getFullYear();
  const month = pad(date.getMonth() + 1);
  const day = pad(date.getDate());

  let datePart: string;
  switch (current.dateFormat) {
    case "dmy":
      datePart = `${day}/${month}/${year}`;
      break;
    case "mdy":
      datePart = `${month}/${day}/${year}`;
      break;
    case "ymd":
    default:
      datePart = `${year}-${month}-${day}`;
      break;
  }

  const minutes = pad(date.getMinutes());
  const seconds = pad(date.getSeconds());
  let timePart: string;
  if (current.timeFormat === "12h") {
    const hour24 = date.getHours();
    const period = hour24 >= 12 ? "PM" : "AM";
    const hour12 = hour24 % 12 || 12;
    timePart = `${hour12}:${minutes}:${seconds} ${period}`;
  } else {
    timePart = `${pad(date.getHours())}:${minutes}:${seconds}`;
  }

  return `${datePart} ${timePart}`;
}