export type DailyCountRow = { day: Date | string; count: number };

export type DailyActivityPoint = {
  date: string;
  count: number;
};

export type DailyActivityResponse = {
  days: number;
  total: number;
  items: DailyActivityPoint[];
};

/** Local calendar day at 00:00:00, `offsetDays` before today (0 = today). */
export function startOfLocalDay(offsetDays = 0): Date {
  const date = new Date();
  date.setHours(0, 0, 0, 0);
  date.setDate(date.getDate() - offsetDays);
  return date;
}

/** Start of the current local week. `weekStartsOn`: 0 Sun … 6 Sat. Default Saturday (Iran). */
export function startOfLocalWeek(weekStartsOn = 6): Date {
  const today = startOfLocalDay(0);
  const diff = (today.getDay() - weekStartsOn + 7) % 7;
  return startOfLocalDay(diff);
}

/** First day of the current local month at 00:00:00. */
export function startOfLocalMonth(): Date {
  const date = new Date();
  date.setDate(1);
  date.setHours(0, 0, 0, 0);
  return date;
}

function pad2(n: number) {
  return String(n).padStart(2, '0');
}

/** Calendar date key from a PG `date` (UTC midnight) or ISO string. */
function toDateKey(value: Date | string): string {
  if (typeof value === 'string') {
    return value.slice(0, 10);
  }
  return `${value.getUTCFullYear()}-${pad2(value.getUTCMonth() + 1)}-${pad2(value.getUTCDate())}`;
}

function toLocalDateKey(date: Date): string {
  return `${date.getFullYear()}-${pad2(date.getMonth() + 1)}-${pad2(date.getDate())}`;
}

/** Fill a continuous series of the last `days` local calendar days. */
export function buildDailyActivitySeries(
  days: number,
  rows: DailyCountRow[],
): DailyActivityResponse {
  const byDay = new Map<string, number>();
  for (const row of rows) {
    byDay.set(toDateKey(row.day), Number(row.count) || 0);
  }

  const items: DailyActivityPoint[] = [];
  let total = 0;
  const end = startOfLocalDay(0);

  for (let i = days - 1; i >= 0; i -= 1) {
    const date = new Date(end);
    date.setDate(end.getDate() - i);
    const key = toLocalDateKey(date);
    const count = byDay.get(key) ?? 0;
    total += count;
    items.push({ date: key, count });
  }

  return { days, total, items };
}

export type DualDailyActivityResponse = {
  days: number;
  primary: DailyActivityResponse;
  secondary: DailyActivityResponse;
};

export function buildDualDailyActivitySeries(
  days: number,
  primaryRows: DailyCountRow[],
  secondaryRows: DailyCountRow[],
): DualDailyActivityResponse {
  return {
    days,
    primary: buildDailyActivitySeries(days, primaryRows),
    secondary: buildDailyActivitySeries(days, secondaryRows),
  };
}