import {describe, expect, it} from 'vitest'
import {formatIsoToDisplay, isDateInRange, isValidIso, parseDisplayToIso} from './dateFormat'

describe('dateFormat', () => {
  describe('isValidIso', () => {
    it('accepts a real ISO date', () => {
      expect(isValidIso('2026-05-19')).toBe(true)
    })
    it('rejects a malformed string', () => {
      expect(isValidIso('19/05/2026')).toBe(false)
      expect(isValidIso('2026-5-9')).toBe(false)
      expect(isValidIso('')).toBe(false)
    })
    it('rejects an impossible date', () => {
      expect(isValidIso('2026-02-30')).toBe(false)
      expect(isValidIso('2026-13-01')).toBe(false)
    })
    it('accepts Feb 29 on a leap year and rejects it otherwise', () => {
      expect(isValidIso('2024-02-29')).toBe(true)
      expect(isValidIso('2026-02-29')).toBe(false)
    })
  })

  describe('formatIsoToDisplay', () => {
    it('formats ISO to DD/MM/YYYY', () => {
      expect(formatIsoToDisplay('2026-05-19')).toBe('19/05/2026')
    })
    it('returns empty string for null or invalid input', () => {
      expect(formatIsoToDisplay(null)).toBe('')
      expect(formatIsoToDisplay('nope')).toBe('')
    })
  })

  describe('parseDisplayToIso', () => {
    it('parses DD/MM/YYYY to ISO', () => {
      expect(parseDisplayToIso('19/05/2026')).toBe('2026-05-19')
    })
    it('returns null for malformed or impossible input', () => {
      expect(parseDisplayToIso('2026-05-19')).toBeNull()
      expect(parseDisplayToIso('31/02/2026')).toBeNull()
      expect(parseDisplayToIso('')).toBeNull()
    })
  })

  describe('isDateInRange', () => {
    it('returns true when no bounds are given', () => {
      expect(isDateInRange('2026-05-19')).toBe(true)
    })
    it('respects the min bound (inclusive)', () => {
      expect(isDateInRange('2026-05-19', '2026-05-19')).toBe(true)
      expect(isDateInRange('2026-05-18', '2026-05-19')).toBe(false)
    })
    it('respects the max bound (inclusive)', () => {
      expect(isDateInRange('2026-05-19', undefined, '2026-05-19')).toBe(true)
      expect(isDateInRange('2026-05-20', undefined, '2026-05-19')).toBe(false)
    })
    it('respects both bounds', () => {
      expect(isDateInRange('2026-05-15', '2026-05-10', '2026-05-20')).toBe(true)
      expect(isDateInRange('2026-05-25', '2026-05-10', '2026-05-20')).toBe(false)
    })
  })
})