/**
 * @file dateRange — the Analytics date range: the preset ids kept in `?range=`
 * (today / this week from Monday / this month from the 1st / 7d / 30d / 90d /
 * all / custom), and `rangeDates`, which turns a preset (or
 * a custom from/to) into the local `YYYY-MM-DD` bounds sent as `from`/`to`.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

export const RANGE_PRESETS = [
  "today",
  "week",
  "month",
  "7d",
  "30d",
  "90d",
  "all",
  "custom",
] as const;
export type RangePreset = (typeof RANGE_PRESETS)[number];

/** Local, inclusive bounds; an absent end is open. */
export interface DateRange {
  from?: string;
  to?: string;
}

/** A `?range=` value, or `all` for anything else. */
export function parsePreset(v: string | null): RangePreset {
  return (RANGE_PRESETS as readonly string[]).includes(v ?? "") ? (v as RangePreset) : "all";
}

/** `d` as a local `YYYY-MM-DD`. */
export function localDate(d: Date): string {
  const p = (n: number) => String(n).padStart(2, "0");
  return `${d.getFullYear()}-${p(d.getMonth() + 1)}-${p(d.getDate())}`;
}

/** The bounds of a preset: `7d` = today and the 6 days before it; `week`
 *  starts on Monday, `month` on the 1st, both ending today. */
export function rangeDates(
  preset: RangePreset,
  custom: DateRange = {},
  today: Date = new Date()
): DateRange {
  if (preset === "all") return {};
  if (preset === "custom") {
    return { from: custom.from || undefined, to: custom.to || undefined };
  }
  const start = new Date(today);
  if (preset === "week") start.setDate(today.getDate() - ((today.getDay() + 6) % 7));
  else if (preset === "month") start.setDate(1);
  else if (preset !== "today") start.setDate(today.getDate() - (parseInt(preset, 10) - 1));
  return { from: localDate(start), to: localDate(today) };
}

/** Set `from`/`to` (and `tz_offset`, which reads them) on a query string. */
export function applyRange(qs: URLSearchParams, range?: DateRange): URLSearchParams {
  if (range?.from) qs.set("from", range.from);
  if (range?.to) qs.set("to", range.to);
  if ((range?.from || range?.to) && !qs.has("tz_offset")) {
    qs.set("tz_offset", String(new Date().getTimezoneOffset()));
  }
  return qs;
}