import { describe, expect, it } from 'vitest'
import { accumulatePage, firstPage, type CursorPage } from './cursorList'

const pageOf = <T>(items: T[], nextCursor: string | null): CursorPage<T> => ({
  items,
  nextCursor,
  hasMore: nextCursor !== null
})

describe('cursorList 游标累积', () => {
  it('首页整页替换并保留游标', () => {
    const state = firstPage(pageOf([1, 2], 'c1'))
    expect(state.items).toEqual([1, 2])
    expect(state.nextCursor).toBe('c1')
    expect(state.hasMore).toBe(true)
  })

  it('加载更多按序追加，nextCursor 为 null 即到底', () => {
    let state = firstPage(pageOf([1, 2], 'c1'))
    state = accumulatePage(state, pageOf([3], 'c2'))
    expect(state.items).toEqual([1, 2, 3])
    expect(state.hasMore).toBe(true)
    state = accumulatePage(state, pageOf([4], null))
    expect(state.items).toEqual([1, 2, 3, 4])
    expect(state.hasMore).toBe(false)
  })

  it('keyOf 去重：跨页重复行不重复 append', () => {
    let state = firstPage(pageOf([{ id: 'a' }, { id: 'b' }], 'c1'))
    state = accumulatePage(state, pageOf([{ id: 'b' }, { id: 'c' }], null), (x) => x.id)
    expect(state.items.map((x) => x.id)).toEqual(['a', 'b', 'c'])
  })
})