import { describe, expect, it } from 'vitest'
import { isExpired, pickFefoBatch, sortFefo, type BatchStock } from '@sims/domain'

/**
 * S5 FEFO — the single batch-pick rule shared by the POS picker and the expiry
 * dashboard. Dates are ISO strings so ordering is lexicographic; "today" here is
 * 2026-07-10 (the demo business date).
 */
const TODAY = '2026-07-10'

const b = (id: string, batchNo: string, expiryDate: string | undefined, onHand = 10): BatchStock => ({
  id, itemId: 'i-107', batchNo, ...(expiryDate !== undefined ? { expiryDate } : {}), onHand,
})

describe('S5 FEFO — sortFefo', () => {
  it('orders earliest expiry first, undated lots last', () => {
    const sorted = sortFefo([
      b('c', 'B-C', '2026-12-31'),
      b('u', 'B-U', undefined),
      b('a', 'B-A', '2026-07-15'),
      b('x', 'B-X', '2026-07-05'), // already expired — still earliest
    ])
    expect(sorted.map((x) => x.id)).toEqual(['x', 'a', 'c', 'u'])
  })

  it('breaks an exact expiry tie by batch_no and does not mutate the input', () => {
    const input = [b('2', 'B-Z', '2026-07-20'), b('1', 'B-A', '2026-07-20')]
    const sorted = sortFefo(input)
    expect(sorted.map((x) => x.batchNo)).toEqual(['B-A', 'B-Z'])
    expect(input.map((x) => x.id)).toEqual(['2', '1']) // original order intact
  })
})

describe('S5 FEFO — isExpired', () => {
  it('is true only for a dated lot strictly before today', () => {
    expect(isExpired({ expiryDate: '2026-07-09' }, TODAY)).toBe(true)
    expect(isExpired({ expiryDate: TODAY }, TODAY)).toBe(false) // expires today = still sellable
    expect(isExpired({ expiryDate: '2026-07-11' }, TODAY)).toBe(false)
    expect(isExpired({ expiryDate: undefined }, TODAY)).toBe(false) // undated never expires
  })
})

describe('S5 FEFO — pickFefoBatch', () => {
  it('preselects the earliest NON-expired lot, skipping expired ones', () => {
    const pick = pickFefoBatch([
      b('x', 'B-X', '2026-07-05'), // expired — skipped
      b('a', 'B-A', '2026-07-15'), // earliest sellable
      b('c', 'B-C', '2026-12-31'),
    ], TODAY)
    expect(pick?.id).toBe('a')
  })

  it('falls back to the earliest-expiring lot when every lot is expired', () => {
    const pick = pickFefoBatch([
      b('y', 'B-Y', '2026-07-08'),
      b('x', 'B-X', '2026-07-01'), // earliest of the expired
    ], TODAY)
    expect(pick?.id).toBe('x')
  })

  it('returns undefined for an empty list', () => {
    expect(pickFefoBatch([], TODAY)).toBeUndefined()
  })
})