import {describe, it, beforeEach, expect} from 'vitest';
import {DateTimeFormatTimeZone, Instant} from '@/';
import type {TimeZone} from '@clarify/zone-data';
import importer from '@clarify/zone-data/importer';
import {getPossibleMilliseconds} from '@/utilities.js';

describe('TimeZone', () => {
  describe('Precalculated', () => {
    let timeZone!: TimeZone;

    beforeEach(async () => {
      timeZone = await importer['Europe/Paris']();
    });

    describe('#getPossibleMilliseconds', () => {
      it('finds the next transition (at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000, 1729990800000]);
      });

      it('finds the next transition (not at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000 + 3456).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987203456, 1729990803456]);
      });

      it('finds the next transition (outside of range)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000 - 1).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000 - 1]);
      });

      it('finds the previous transition (at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729990800000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000, 1729990800000]);
      });

      it('finds the previous transition (outside of edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729994400000 + 1).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729994400000 + 1]);
      });

      it('finds the previous transition (not at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729990800000 - 3456).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729990800000 - 3456, 1729994400000 - 3456]);
      });
    });
  });

  describe('DateFormatter', () => {
    let timeZone!: DateTimeFormatTimeZone;

    beforeEach(async () => {
      timeZone = new DateTimeFormatTimeZone('Europe/Berlin');
    });

    describe('#getPossibleMilliseconds', () => {
      it('finds the next transition (at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000, 1729990800000]);
      });

      it('finds the next transition (not at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000 + 3456).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987203456, 1729990803456]);
      });

      it('finds the next transition (outside of range)', async () => {
        let now = Instant.fromEpochMilliseconds(1729987200000 - 1).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000 - 1]);
      });

      it('finds the previous transition (at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729990800000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729987200000, 1729990800000]);
      });

      it('finds the previous transition (outside of edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729994400000 + 1).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729994400000 + 1]);
      });

      it('finds the previous transition (not at edge)', async () => {
        let now = Instant.fromEpochMilliseconds(1729990800000 - 3456).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1729990800000 - 3456, 1729994400000 - 3456]);
      });

      it('finds the next transition (jump forward)', async () => {
        let now = Instant.fromEpochMilliseconds(1743292800000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1743292800000]);
      });

      it('finds the previous transition (jump forward)', async () => {
        let now = Instant.fromEpochMilliseconds(1743296400000).toZonedDateTimeISO(timeZone);
        let timestamps = getPossibleMilliseconds(now.epochMilliseconds, timeZone);
        expect(timestamps).toEqual([1743296400000]);
      });
    });
  });
});