dhis2/d2

import { generateWeeklyPeriodsForYear } from '../weekly'

describe('Weekly period', () => {
    describe('generateWeeklyPeriodsForYear()', () => {
        it('should generate 52 periods for the year 2017', () => {
            expect(generateWeeklyPeriodsForYear(2017)).toHaveLength(52)
        })

        it('should generate 53 periods for common years starting on Thursday', () => {
            // https://en.wikipedia.org/wiki/Common_year_starting_on_Thursday
            expect(generateWeeklyPeriodsForYear(1705)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2009)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2015)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2026)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2099)).toHaveLength(53)
        })

        it('should generate 53 periods for leap years starting on Thursday', () => {
            // https://en.wikipedia.org/wiki/Leap_year_starting_on_Thursday
            expect(generateWeeklyPeriodsForYear(1948)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(1976)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2004)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2032)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2060)).toHaveLength(53)
        })

        it('should generate 53 periods for leap years starting on Wednesday', () => {
            // https://en.wikipedia.org/wiki/Leap_year_starting_on_Wednesday
            expect(generateWeeklyPeriodsForYear(1936)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(1964)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(1992)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2020)).toHaveLength(53)
            expect(generateWeeklyPeriodsForYear(2048)).toHaveLength(53)
        })

        it('should generate 52 periods for the year 2016', () => {
            expect(generateWeeklyPeriodsForYear(2016)).toHaveLength(52)
        })

        it('should generate the correct result for each period', () => {
            const periods = generateWeeklyPeriodsForYear(2017)

            expect(periods[0]).toEqual({
                startDate: '2017-01-02',
                endDate: '2017-01-08',
                name: 'W1 - 2017-01-02 - 2017-01-08',
                id: '2017W1',
            })
        })

        it('should start the first week of 2015 in the previous year', () => {
            const weeksFor2015 = generateWeeklyPeriodsForYear(2015)

            expect(weeksFor2015[0]).toEqual({
                startDate: '2014-12-29',
                endDate: '2015-01-04',
                name: 'W1 - 2014-12-29 - 2015-01-04',
                id: '2015W1',
            })
        })

        it('should return the correct first week for 2014', () => {
            const weeksFor2014 = generateWeeklyPeriodsForYear(2014)

            expect(weeksFor2014[0]).toEqual({
                startDate: '2013-12-30',
                endDate: '2014-01-05',
                name: 'W1 - 2013-12-30 - 2014-01-05',
                id: '2014W1',
            })
        })

        it('should return the correct first week for 2004', () => {
            const weeksFor2004 = generateWeeklyPeriodsForYear(2004)

            expect(weeksFor2004[0]).toEqual({
                startDate: '2003-12-29',
                endDate: '2004-01-04',
                name: 'W1 - 2003-12-29 - 2004-01-04',
                id: '2004W1',
            })
        })

        it('should return the correct last week for 2015', () => {
            const weeksFor2015 = generateWeeklyPeriodsForYear(2015)

            expect(weeksFor2015[weeksFor2015.length - 1]).toEqual({
                startDate: '2015-12-28',
                endDate: '2016-01-03',
                name: 'W53 - 2015-12-28 - 2016-01-03',
                id: '2015W53',
            })
        })

        it('should return the correct last week for 2017', () => {
            const weeksFor2015 = generateWeeklyPeriodsForYear(2017)

            expect(weeksFor2015[weeksFor2015.length - 1]).toEqual({
                startDate: '2017-12-25',
                endDate: '2017-12-31',
                name: 'W52 - 2017-12-25 - 2017-12-31',
                id: '2017W52',
            })
        })

        it('should not allow years before the year zero', () => {
            expect(() => generateWeeklyPeriodsForYear(-10)).toThrowError()
        })

        it('should throw an error when passing a Date object', () => {
            expect(() =>
                generateWeeklyPeriodsForYear(new Date())
            ).toThrowError()
        })

        it('should generate the same periods when called without as when called with the current year', () => {
            expect(generateWeeklyPeriodsForYear()).toEqual(
                generateWeeklyPeriodsForYear(new Date().getFullYear())
            )
        })

        it('should have 71 years in 400-year cycle with iso week 53', () => {
            let count = 0

            for (let i = 0; i < 400; i++) {
                count +=
                    generateWeeklyPeriodsForYear(2000 + i).length === 53 ? 1 : 0
            }

            expect(count).toBe(71)
        })
    })
})