import { describe, expect, it } from 'vitest'

import { resolveDrop, shouldAllowMove } from './drag'

function makeList(columnId?: string): HTMLElement {
  const element = document.createElement('div')
  if (columnId !== undefined) element.dataset.columnId = columnId
  return element
}

function makeItem(taskId?: string): HTMLElement {
  const element = document.createElement('article')
  if (taskId !== undefined) element.dataset.taskId = taskId
  return element
}

describe('resolveDrop', () => {
  it('解析出任务 id、目标列与下标', () => {
    const drop = resolveDrop({
      item: makeItem('task-1'),
      to: makeList('doing'),
      newIndex: 2,
    })
    expect(drop).toEqual({ taskId: 'task-1', toColumn: 'doing', toIndex: 2 })
  })

  it('下标为 0 是合法值', () => {
    expect(resolveDrop({ item: makeItem('t'), to: makeList('todo'), newIndex: 0 })).toEqual({
      taskId: 't',
      toColumn: 'todo',
      toIndex: 0,
    })
  })

  it('缺少 taskId 时返回 null', () => {
    expect(resolveDrop({ item: makeItem(), to: makeList('todo'), newIndex: 0 })).toBeNull()
  })

  it('目标列 id 非法时返回 null', () => {
    expect(
      resolveDrop({ item: makeItem('t'), to: makeList('archived'), newIndex: 0 }),
    ).toBeNull()
    expect(resolveDrop({ item: makeItem('t'), to: makeList(), newIndex: 0 })).toBeNull()
  })

  it('下标缺失或非法时返回 null', () => {
    const item = makeItem('t')
    const to = makeList('todo')
    expect(resolveDrop({ item, to })).toBeNull()
    expect(resolveDrop({ item, to, newIndex: -1 })).toBeNull()
    expect(resolveDrop({ item, to, newIndex: 1.5 })).toBeNull()
  })
})

describe('shouldAllowMove', () => {
  it('列内为全量渲染时一律允许', () => {
    const a = makeList('todo')
    const b = makeList('doing')
    expect(shouldAllowMove(a, a, false)).toBe(true)
    expect(shouldAllowMove(a, b, false)).toBe(true)
  })

  it('列内为子集时禁止列内排序', () => {
    const column = makeList('todo')
    expect(shouldAllowMove(column, column, true)).toBe(false)
  })

  it('列内为子集时仍允许跨列移动', () => {
    expect(shouldAllowMove(makeList('todo'), makeList('doing'), true)).toBe(true)
  })

  it('子集状态下元素信息缺失时保守拒绝', () => {
    expect(shouldAllowMove(null, makeList('todo'), true)).toBe(false)
    expect(shouldAllowMove(makeList('todo'), undefined, true)).toBe(false)
  })
})