import { describe, expect, it } from 'vitest'
import { paginationRange } from '../../frontend/shared/utils/pagination'

describe('paginationRange', () => {
  it('returns an empty array for zero or negative totals', () => {
    expect(paginationRange(1, 0)).toEqual([])
  })

  it('returns every page when the total fits within the visible window', () => {
    expect(paginationRange(1, 5)).toEqual([1, 2, 3, 4, 5])
    expect(paginationRange(3, 7)).toEqual([1, 2, 3, 4, 5, 6, 7])
  })

  it('collapses the right side when near the start', () => {
    expect(paginationRange(1, 20)).toEqual([1, 2, 3, 4, 5, 'ellipsis', 20])
    expect(paginationRange(2, 20)).toEqual([1, 2, 3, 4, 5, 'ellipsis', 20])
  })

  it('collapses the left side when near the end', () => {
    expect(paginationRange(20, 20)).toEqual([1, 'ellipsis', 16, 17, 18, 19, 20])
    expect(paginationRange(19, 20)).toEqual([1, 'ellipsis', 16, 17, 18, 19, 20])
  })

  it('collapses both sides when in the middle', () => {
    expect(paginationRange(10, 20)).toEqual([1, 'ellipsis', 9, 10, 11, 'ellipsis', 20])
  })

  it('always includes the current page', () => {
    for (let current = 1; current <= 27; current++) {
      expect(paginationRange(current, 27)).toContain(current)
    }
  })
})