/**
 * Time range + period helpers. Mirrors the Shopify embed implementation so
 * Hourly/Daily/Monthly behave identically across surfaces.
 *
 * (c) 2026 TWWIM UG. All rights reserved. (www.twwim.com)
 */

import type { IntelligenceGranularity } from '@/infrastructure/http/api/intelligence';

export type TimeRange = 'hourly' | 'daily' | 'monthly';
export const TIME_RANGES: ReadonlyArray<TimeRange> = ['hourly', 'daily', 'monthly'];

export interface ResolvedRange {
  range: TimeRange;
  startDate: Date;
  endDate: Date;
  granularity: IntelligenceGranularity;
}

export function resolveRange(input: string | null | undefined): ResolvedRange {
  const range: TimeRange = (TIME_RANGES as readonly string[]).includes(input ?? '') ? (input as TimeRange) : 'daily';
  const endDate = new Date();
  const startDate = new Date(endDate);
  switch (range) {
    case 'hourly':
      startDate.setUTCHours(startDate.getUTCHours() - 24);
      return { range, startDate, endDate, granularity: 'hour' };
    case 'daily':
      startDate.setUTCDate(startDate.getUTCDate() - 30);
      return { range, startDate, endDate, granularity: 'day' };
    case 'monthly':
      startDate.setUTCMonth(startDate.getUTCMonth() - 12);
      return { range, startDate, endDate, granularity: 'month' };
  }
}

export interface PeriodOption {
  key: string;
  start: Date;
  end: Date;
  label: string;
  longLabel: string;
}

export function generatePeriods(range: TimeRange, now: Date = new Date()): PeriodOption[] {
  const out: PeriodOption[] = [];
  if (range === 'hourly') {
    for (let i = 0; i < 24; i++) {
      const start = new Date(now);
      start.setUTCMinutes(0, 0, 0);
      start.setUTCHours(start.getUTCHours() - i);
      const end = new Date(start);
      end.setUTCHours(end.getUTCHours() + 1);
      out.push({
        key: start.toISOString(),
        start, end,
        label: start.toLocaleTimeString(undefined, { hour: '2-digit', minute: '2-digit', hour12: false }),
        longLabel: start.toLocaleString(undefined, { year: 'numeric', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', hour12: false }),
      });
    }
  } else if (range === 'daily') {
    for (let i = 0; i < 30; i++) {
      const start = new Date(now);
      start.setUTCHours(0, 0, 0, 0);
      start.setUTCDate(start.getUTCDate() - i);
      const end = new Date(start);
      end.setUTCDate(end.getUTCDate() + 1);
      out.push({
        key: start.toISOString().substring(0, 10),
        start, end,
        label: String(start.getUTCDate()),
        longLabel: start.toLocaleDateString(undefined, { dateStyle: 'long' }),
      });
    }
  } else if (range === 'monthly') {
    const year = now.getUTCFullYear();
    for (let m = 11; m >= 0; m--) {
      const start = new Date(Date.UTC(year, m, 1));
      const end = new Date(Date.UTC(year, m + 1, 1));
      out.push({
        key: `${year}-${String(m + 1).padStart(2, '0')}`,
        start, end,
        label: start.toLocaleDateString(undefined, { month: 'short' }),
        longLabel: start.toLocaleDateString(undefined, { month: 'long', year: 'numeric' }),
      });
    }
  }
  return out;
}

export function resolvePeriod(range: TimeRange, periodKey: string | null | undefined): PeriodOption {
  const periods = generatePeriods(range);
  const match = periodKey ? periods.find((p) => p.key === periodKey) : null;
  return match ?? periods[0];
}

export type KpiWindowScope = 'today' | 'week' | 'month';
export interface KpiWindow { scope: KpiWindowScope; startDate: Date; endDate: Date }

export function kpiWindow(range: TimeRange, now: Date = new Date()): KpiWindow {
  const endDate = new Date();
  const startDate = new Date(now);
  if (range === 'hourly') {
    startDate.setUTCHours(0, 0, 0, 0);
    return { scope: 'today', startDate, endDate };
  }
  if (range === 'daily') {
    const dow = startDate.getUTCDay();
    const daysFromMonday = (dow + 6) % 7;
    startDate.setUTCDate(startDate.getUTCDate() - daysFromMonday);
    startDate.setUTCHours(0, 0, 0, 0);
    return { scope: 'week', startDate, endDate };
  }
  startDate.setUTCDate(1);
  startDate.setUTCHours(0, 0, 0, 0);
  return { scope: 'month', startDate, endDate };
}

export const RANGE_LABELS: Record<TimeRange, { en: string; de: string }> = {
  hourly:  { en: 'Hourly (24h)',        de: 'Stundlich (24 Std.)' },
  daily:   { en: 'Daily (30 days)',     de: 'Taglich (30 Tage)' },
  monthly: { en: 'Monthly (this year)', de: 'Monatlich (dieses Jahr)' },
};