import { tz } from "@date-fns/tz";

import { addDays, parse, startOfDay, subDays } from "date-fns";

export function rollingPeriod(days = 7) {

  const periodEnd = new Date();

  const periodStart = new Date();

  periodStart.setDate(periodEnd.getDate() - days);

  return {

    periodStart: periodStart.toISOString(),

    periodEnd: periodEnd.toISOString(),

  };

}

const APP_TIMEZONE = tz("America/Sao_Paulo");

// pt-BR label for the app-timezone day window, kept beside the window helpers

// so the wording and the window it names live in one place

export const DAY_WINDOW_LABEL = "hoje";

// Start of the day containing `date`, in the app's timezone

export function startOfAppDay(date: Date = new Date()): Date {

  return startOfDay(date, { in: APP_TIMEZONE });

}

// Start of the app-timezone day immediately before the one containing `date`

export function previousAppDay(date: Date = new Date()): Date {

  return startOfDay(subDays(date, 1, { in: APP_TIMEZONE }), {

    in: APP_TIMEZONE,

  });

}

// Start of the app-timezone day named by a YYYY-MM-DD string

export function parseAppDay(day: string): Date {

  return parse(day, "yyyy-MM-dd", new Date(), { in: APP_TIMEZONE });

}

// The app-timezone day containing `date`, as a half-open [start, end) window

export function appDayWindow(date: Date = new Date()): {

  start: Date;

  end: Date;

} {

  const start = startOfDay(date, { in: APP_TIMEZONE });

  const end = startOfDay(addDays(start, 1, { in: APP_TIMEZONE }), {

    in: APP_TIMEZONE,

  });

  return { start, end };

}

export function appDayPeriod(date: Date = new Date()): {

  periodStart: string;

  periodEnd: string;

} {

  const { start, end } = appDayWindow(date);

  return { periodStart: start.toISOString(), periodEnd: end.toISOString() };

}