import { flushPromises, mount } from '@vue/test-utils'
import type { VueWrapper } from '@vue/test-utils'
import { createPinia, setActivePinia } from 'pinia'
import { beforeEach, describe, expect, it, vi } from 'vitest'

import { createMemoryTaskRepository } from '@/data/taskRepository'
import { useTaskStore } from '@/stores/tasks'

import BackupPanel from './BackupPanel.vue'

vi.mock('@/utils/exportFile', async (importOriginal) => {
  const actual = await importOriginal<typeof import('@/utils/exportFile')>()
  return { ...actual, downloadText: vi.fn() }
})

const { downloadText } = await import('@/utils/exportFile')

function makePayload(titles: string[]): string {
  return JSON.stringify({
    schemaVersion: 1,
    tasks: titles.map((title, index) => ({
      id: `imported-${index}`,
      title,
      status: 'todo',
      priority: 2,
      sortOrder: (index + 1) * 1024,
    })),
  })
}

async function setup(open = true) {
  const pinia = createPinia()
  setActivePinia(pinia)
  const store = useTaskStore()
  const repository = createMemoryTaskRepository()
  store.init({ repository, crossTab: false })
  store.createTask({ title: '原有任务' })

  const wrapper = mount(BackupPanel, {
    props: { open },
    global: { plugins: [pinia], stubs: { teleport: true } },
    attachTo: document.body,
  })
  return { store, wrapper }
}

async function chooseFile(wrapper: VueWrapper, content: string, fileName = 'backup.json') {
  const input = wrapper.find('input[type="file"]')
  const file = new File([content], fileName, { type: 'application/json' })
  // jsdom 的 input.files 是只读的，需要直接定义
  Object.defineProperty(input.element, 'files', { value: [file], configurable: true })
  await input.trigger('change')
  await flushPromises()
}

function buttonByText(wrapper: VueWrapper, text: string) {
  return wrapper.findAll('button').find((node) => node.text().includes(text))
}

describe('BackupPanel 显示', () => {
  beforeEach(() => {
    setActivePinia(createPinia())
    vi.mocked(downloadText).mockClear()
  })

  it('open 为 false 时不渲染内容', () => {
    const wrapper = mount(BackupPanel, {
      props: { open: false },
      global: { stubs: { teleport: true } },
    })
    expect(wrapper.text()).not.toContain('导出为 JSON')
  })

  it('展示数据风险提示', async () => {
    const { wrapper } = await setup()
    expect(wrapper.text()).toContain('清理浏览器数据会导致任务丢失')
  })
})

describe('BackupPanel 导出', () => {
  beforeEach(() => {
    setActivePinia(createPinia())
    vi.mocked(downloadText).mockClear()
  })

  it('点击导出会生成带日期的文件名并写入内容', async () => {
    const { store, wrapper } = await setup()
    await buttonByText(wrapper, '导出为 JSON')?.trigger('click')

    expect(downloadText).toHaveBeenCalledTimes(1)
    const [content, fileName] = vi.mocked(downloadText).mock.calls[0] ?? []
    expect(fileName).toMatch(/^kanban-\d{4}-\d{2}-\d{2}\.json$/)
    expect(content).toContain('原有任务')
    expect(wrapper.text()).toContain(`已导出 ${store.tasks.length} 个任务`)
  })
})

describe('BackupPanel 导入', () => {
  beforeEach(() => {
    setActivePinia(createPinia())
    vi.mocked(downloadText).mockClear()
  })

  it('选择合法文件后先请求确认，不立即改动数据', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, makePayload(['新任务一', '新任务二']))

    expect(wrapper.text()).toContain('导入 2 个任务')
    expect(wrapper.text()).toContain('覆盖当前全部 1 个任务')
    expect(store.tasks.map((task) => task.title)).toEqual(['原有任务'])
  })

  it('确认后覆盖导入', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, makePayload(['新任务一', '新任务二']))

    await buttonByText(wrapper, '确认覆盖导入')?.trigger('click')

    expect(store.tasks.map((task) => task.title).sort()).toEqual(['新任务一', '新任务二'])
    expect(wrapper.text()).toContain('已从 backup.json 导入 2 个任务')
    expect(wrapper.text()).toContain('导入前的数据已自动备份')
  })

  it('取消确认后数据保持不变', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, makePayload(['新任务']))

    await buttonByText(wrapper, '取消')?.trigger('click')

    expect(wrapper.text()).not.toContain('确认覆盖导入')
    expect(store.tasks.map((task) => task.title)).toEqual(['原有任务'])
  })

  it('非法 JSON 给出明确错误且不破坏现有数据', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, '{broken json')

    expect(wrapper.text()).toContain('不是合法的 JSON')
    expect(store.tasks.map((task) => task.title)).toEqual(['原有任务'])
  })

  it('结构不合法时给出错误且不进入确认流程', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, JSON.stringify({ tasks: [{ id: 'broken' }] }))

    expect(wrapper.text()).toContain('第 1 条任务格式不合法')
    expect(wrapper.text()).not.toContain('确认覆盖导入')
    expect(store.tasks.map((task) => task.title)).toEqual(['原有任务'])
  })

  it('版本过高时拒绝导入', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, JSON.stringify({ schemaVersion: 99, tasks: [] }))

    expect(wrapper.text()).toContain('高于当前支持')
    expect(store.tasks.map((task) => task.title)).toEqual(['原有任务'])
  })
})

describe('BackupPanel 合并导入', () => {
  beforeEach(() => {
    setActivePinia(createPinia())
    vi.mocked(downloadText).mockClear()
  })

  it('预览显示新增 / 更新 / 保持数量', async () => {
    const { store, wrapper } = await setup()
    const local = store.tasks[0]
    const text = JSON.stringify({
      schemaVersion: 3,
      tasks: [
        {
          id: local?.id,
          title: '更新后的任务',
          status: 'todo',
          priority: 2,
          sortOrder: 1024,
          createdAt: local?.createdAt,
          updatedAt: '2099-01-01T00:00:00.000Z',
        },
        {
          id: 'new-1',
          title: '新增任务',
          status: 'todo',
          priority: 2,
          sortOrder: 2048,
          createdAt: '2026-10-01T00:00:00.000Z',
          updatedAt: '2026-10-01T00:00:00.000Z',
        },
      ],
    })

    await chooseFile(wrapper, text)
    await wrapper.find('input[value="merge"]').setValue(true)

    expect(wrapper.text()).toContain('新增')
    expect(wrapper.text()).toContain('更新')
    expect(wrapper.text()).toContain('保持')
    // 默认仍是覆盖模式，不会静默改成合并
    expect(buttonByText(wrapper, '确认合并导入')).toBeDefined()
  })

  it('确认合并后更新同 id 并新增其余任务', async () => {
    const { store, wrapper } = await setup()
    const local = store.tasks[0]
    const text = JSON.stringify({
      schemaVersion: 3,
      tasks: [
        {
          id: local?.id,
          title: '更新后的任务',
          status: 'todo',
          priority: 2,
          sortOrder: 1024,
          createdAt: local?.createdAt,
          updatedAt: '2099-01-01T00:00:00.000Z',
        },
        {
          id: 'new-1',
          title: '新增任务',
          status: 'todo',
          priority: 2,
          sortOrder: 2048,
          createdAt: '2026-10-01T00:00:00.000Z',
          updatedAt: '2026-10-01T00:00:00.000Z',
        },
      ],
    })

    await chooseFile(wrapper, text)
    await wrapper.find('input[value="merge"]').setValue(true)
    await buttonByText(wrapper, '确认合并导入')?.trigger('click')

    expect(store.activeTasks.map((task) => task.title).sort()).toEqual(
      ['更新后的任务', '新增任务'].sort(),
    )
    expect(wrapper.text()).toContain('已合并')
    expect(wrapper.text()).toContain('新增 1 个，更新 1 个')
  })

  it('合并不删除本地独有的任务', async () => {
    const { store, wrapper } = await setup()
    await chooseFile(wrapper, makePayload(['文件任务']))
    await wrapper.find('input[value="merge"]').setValue(true)
    await buttonByText(wrapper, '确认合并导入')?.trigger('click')

    expect(store.activeTasks.map((task) => task.title).sort()).toEqual(
      ['原有任务', '文件任务'].sort(),
    )
  })

  it('合并前自动写快照', async () => {
    const { store, wrapper } = await setup()
    expect(store.snapshots).toHaveLength(0)

    await chooseFile(wrapper, makePayload(['文件任务']))
    await wrapper.find('input[value="merge"]').setValue(true)
    await buttonByText(wrapper, '确认合并导入')?.trigger('click')

    expect(store.snapshots).toHaveLength(1)
  })
})

describe('BackupPanel 自动备份', () => {
  beforeEach(() => {
    setActivePinia(createPinia())
    vi.mocked(downloadText).mockClear()
  })

  it('启动时写入的快照会出现在列表中', async () => {
    const repository = createMemoryTaskRepository()

    // 第一次启动：看板为空，不产生快照
    setActivePinia(createPinia())
    const first = useTaskStore()
    first.init({ repository, crossTab: false })
    first.createTask({ title: '已有任务' })

    // 第二次启动：此时已有数据，写入启动快照
    const pinia = createPinia()
    setActivePinia(pinia)
    const store = useTaskStore()
    store.init({ repository, crossTab: false })
    expect(store.snapshots).toHaveLength(1)

    const wrapper = mount(BackupPanel, {
      props: { open: true },
      global: { plugins: [pinia], stubs: { teleport: true } },
    })
    expect(wrapper.text()).not.toContain('暂无自动备份')
    expect(buttonByText(wrapper, '恢复')).toBeDefined()
  })

  it('空看板不写快照，显示暂无备份', async () => {
    const pinia = createPinia()
    setActivePinia(pinia)
    const store = useTaskStore()
    store.init({ repository: createMemoryTaskRepository(), crossTab: false })

    const wrapper = mount(BackupPanel, {
      props: { open: true },
      global: { plugins: [pinia], stubs: { teleport: true } },
    })
    expect(wrapper.text()).toContain('暂无自动备份')
  })

  it('看板为空时仍会列出已有快照（数据丢失后要能恢复）', async () => {
    const repository = createMemoryTaskRepository()

    setActivePinia(createPinia())
    const first = useTaskStore()
    first.init({ repository, crossTab: false })
    first.createTask({ title: '快照里的任务' })

    // 第二次启动：写入快照
    setActivePinia(createPinia())
    const second = useTaskStore()
    second.init({ repository, crossTab: false })
    expect(second.snapshots).toHaveLength(1)

    // 清空数据后第三次启动：不能因为看板为空就丢掉快照列表
    second.replaceAll([])
    const pinia = createPinia()
    setActivePinia(pinia)
    const third = useTaskStore()
    third.init({ repository, crossTab: false })

    expect(third.tasks).toHaveLength(0)
    expect(third.snapshots).toHaveLength(1)

    const wrapper = mount(BackupPanel, {
      props: { open: true },
      global: { plugins: [pinia], stubs: { teleport: true } },
    })
    expect(wrapper.text()).not.toContain('暂无自动备份')
    expect(buttonByText(wrapper, '恢复')).toBeDefined()
  })

  it('点击恢复会用快照内容覆盖当前数据', async () => {
    const repository = createMemoryTaskRepository()

    setActivePinia(createPinia())
    const first = useTaskStore()
    first.init({ repository, crossTab: false })
    first.createTask({ title: '快照里的任务' })

    const pinia = createPinia()
    setActivePinia(pinia)
    const store = useTaskStore()
    store.init({ repository, crossTab: false })
    expect(store.snapshots).toHaveLength(1)

    // 模拟数据丢失
    store.replaceAll([])
    expect(store.tasks).toHaveLength(0)

    const wrapper = mount(BackupPanel, {
      props: { open: true },
      global: { plugins: [pinia], stubs: { teleport: true } },
    })
    await buttonByText(wrapper, '恢复')?.trigger('click')

    expect(store.tasks.map((task) => task.title)).toEqual(['快照里的任务'])
    expect(wrapper.text()).toContain('已从备份恢复 1 个任务')
  })
})