export const createPlaceholders = ( arr: any[] ) => {
    return arr.map(() => '?').join(', ');
}

export type AddDollarPrefix<T> = {
  [K in keyof T as `$${string & K}`]: T[K];
};

export function prefixKeysWithDollar<T extends Record<string, any>>(obj: T): AddDollarPrefix<T> {
  const result = {} as AddDollarPrefix<T>;

  for (const key in obj) {
    const newKey = `$${key}` as keyof AddDollarPrefix<T>;
    result[newKey] = obj[key] as any;
  }

  return result;
}

export function transformArray<T extends Record<string, any>>(arr: T[]): AddDollarPrefix<T>[] {
  return arr.map(prefixKeysWithDollar);
}

export function pad_l2 ( _thing: string | number ): string {
  if ( typeof _thing == "number" ) {
    _thing = JSON.stringify(_thing);
  };
  return _thing.padStart(2, "0");
}

export function getTsNow() {
  const now = new Date();
  const rtn = {
    year: now.getFullYear(),
    month: now.getMonth() + 1,
    day: now.getDate(),
    minute: now.getMinutes(),
    seconds: now.getSeconds()
  }
  return rtn;
}

export function unixToDate( unix_timestamp: number ) { return new Date(unix_timestamp * 1000) }
export function dateToUnix( date: Date ) { return Math.round( date.getTime()/1000 ) }

export function formatTimeDiff(dateA: Date, dateB: Date) {
  // Difference in milliseconds
  const diffMs = dateB.getTime() - dateA.getTime();

  // Get sign (+ or -)
  const sign = diffMs < 0 ? "-" : "";

  // Convert to absolute minutes
  const diffMinutes = Math.floor(Math.abs(diffMs) / 60000);

  // Split into hours and minutes
  const hours = Math.floor(diffMinutes / 60);
  const minutes = diffMinutes % 60;

  // Return formatted string
  return `${sign}${String(hours).padStart(2, "0")}:${String(minutes).padStart(2, "0")}`;
}

export function subtractHours(date: Date, hours: number) {
  // Create a new Date so we don't mutate the original
  return new Date(date.getTime() - hours * 60 * 60 * 1000);
}

// Helper: get last Sunday of a given month
function lastSundayOfMonth(year: number, month: number ) {
  const lastDay = new Date(Date.UTC(year, month + 1, 0)); // last day of month
  const day = lastDay.getUTCDay(); // 0 = Sunday
  const diff = day === 0 ? 0 : day; // how far back to go to reach Sunday
  lastDay.setUTCDate(lastDay.getUTCDate() - diff);
  return lastDay;
}

export function isEuropeanDST( date: Date ) {
  const year = date.getFullYear();

  // DST starts: last Sunday in March, 01:00 UTC
  const start = lastSundayOfMonth(year, 2); // March (month = 2)
  start.setUTCHours(1, 0, 0, 0);

  // DST ends: last Sunday in October, 01:00 UTC
  const end = lastSundayOfMonth(year, 9); // October (month = 9)
  end.setUTCHours(1, 0, 0, 0);

  // Return true if within DST period
  return date >= start && date < end;
}

export function createQS (params: Record<string, string | number | boolean>): string {
  const queryString = Object.entries(params)
  .map(([key, value]) => `${encodeURIComponent(key)}=${encodeURIComponent(value)}`)
  .join("&");
  return queryString;
}