export type SupportedTimeRange = '24hr' | '1week' | '1month';

const SUPPORTED_RANGES: SupportedTimeRange[] = ['24hr', '1week', '1month'];

export function isSupportedTimeRange(value: unknown): value is SupportedTimeRange {
  return typeof value === 'string' && SUPPORTED_RANGES.includes(value as SupportedTimeRange);
}

export function toIsoDateTime(input: string): string {
  const parsedDate = new Date(input);
  if (Number.isNaN(parsedDate.getTime())) {
    throw new Error(`Invalid datetime format: ${input}. Expected ISO datetime string.`);
  }

  return parsedDate.toISOString();
}

export function normalizeGraphDateTime(dateTime: string, timeZone = 'UTC') {
  return {
    dateTime: toIsoDateTime(dateTime),
    timeZone,
  };
}

export function resolveTimeRangeStart(range: SupportedTimeRange, now = new Date()): Date {
  const start = new Date(now);
  if (range === '24hr') {
    start.setHours(start.getHours() - 24);
    return start;
  }

  if (range === '1week') {
    start.setDate(start.getDate() - 7);
    return start;
  }

  start.setMonth(start.getMonth() - 1);
  return start;
}

export function buildReceivedDateFilter(params: { timeRange?: unknown; startDateTime?: unknown; endDateTime?: unknown }): string {
  const { timeRange, startDateTime, endDateTime } = params;
  const filters: string[] = [];

  if (typeof startDateTime === 'string' && startDateTime.length > 0) {
    filters.push(`receivedDateTime ge ${toIsoDateTime(startDateTime)}`);
  }

  if (typeof endDateTime === 'string' && endDateTime.length > 0) {
    filters.push(`receivedDateTime le ${toIsoDateTime(endDateTime)}`);
  }

  if (filters.length > 0) {
    return `?$filter=${filters.join(' and ')}`;
  }

  if (timeRange === undefined) {
    return '';
  }

  if (!isSupportedTimeRange(timeRange)) {
    throw new Error('Invalid timeRange. Supported values: 24hr, 1week, 1month');
  }

  const fromDate = resolveTimeRangeStart(timeRange).toISOString();
  return `?$filter=receivedDateTime ge ${fromDate}`;
}