import { defineStore } from 'pinia'
import { ref, computed, watch } from 'vue'
import type { Board, Stage, Task, Category, Meta } from '~/types/schema'
import { uuid } from '~/utils/uuid'
import { diffBoards } from '~/utils/diff'

function nowIso() { return new Date().toISOString() }

function emptyBoard(): Board {
  return { categories: [], stages: [], tasks: [], layout: { columns: [] }, meta: makeMeta('') }
}
function makeMeta(actor: string): Meta {
  return { id: 'open-kanban', version: '1.0.0', createdAt: nowIso(), modifiedAt: nowIso(), actor, history: [] }
}

export const useBoardStore = defineStore('board', () => {
  const runtime = useRuntimeConfig().public
  const localKey = runtime.localStorageKey || 'open-kanban-board'

  const filename = ref('')
  const dirty = ref(false)
  const board = ref<Board>(emptyBoard())
  const lastLoadedSnapshot = ref<Board | null>(null)
  const selectedTaskId = ref<string | null>(null)

  function log(type: string, payload?: any) {
    if (!board.value.meta) board.value.meta = makeMeta('')
    const actor = board.value.meta.actor || ''
    board.value.meta.history.push({ id: uuid(), ts: nowIso(), actor, type, payload })
    board.value.meta.modifiedAt = nowIso()
    dirty.value = true
  }

  function setBoard(data: Board, name = '') {
    if (!data.layout) data.layout = { columns: [] }
    if (!data.meta) data.meta = makeMeta(board.value.meta?.actor || '')
    filename.value = name
    board.value = data
    dirty.value = false
    lastLoadedSnapshot.value = JSON.parse(JSON.stringify(data))
  }

  function setActor(name: string) {
    if (!board.value.meta) board.value.meta = makeMeta('')
    board.value.meta.actor = name
    dirty.value = true
  }

  // LocalStorage persistence
  function saveToLocal() {
    localStorage.setItem(localKey, JSON.stringify(board.value))
    dirty.value = false
  }
  function loadFromLocal(): boolean {
    const raw = localStorage.getItem(localKey)
    if (!raw) return false
    try {
      const data = JSON.parse(raw)
      setBoard(data, '(localStorage)')
      log('load-local', {})
      return true
    } catch (e) {
      console.error(e)
      return false
    }
  }
  function clearLocal() {
    localStorage.removeItem(localKey)
  }

  // Import/Export
  function toJSON(pretty = true) {
    return JSON.stringify(board.value, null, pretty ? 2 : 0)
  }
  function downloadCurrent() {
    const name = filename.value || runtime.defaultFilename || 'kanban.json'
    const blob = new Blob([toJSON(true)], { type: 'application/json' })
    const a = document.createElement('a')
    a.href = URL.createObjectURL(blob)
    a.download = name
    a.click()
    URL.revokeObjectURL(a.href)
    dirty.value = false
  }
  function applyMerge(imported: Board, policy: 'prefer-import' | 'prefer-current', removeMissing: boolean) {
    const cur = board.value
    // cats
    const cMap = Object.fromEntries(cur.categories.map(c => [c.uuid, c]))
    const iMap = Object.fromEntries(imported.categories.map(c => [c.uuid, c]))
    imported.categories.forEach(c => { if (!cMap[c.uuid]) cur.categories.push(structuredClone(c)) })
    cur.categories.forEach(c => { const ic = iMap[c.uuid]; if (!ic) return; if (policy === 'prefer-import') { c.title = ic.title; c.color = ic.color } })
    if (removeMissing) cur.categories = cur.categories.filter(c => !!iMap[c.uuid])
    // tasks
    const tMap = Object.fromEntries(cur.tasks.map(t => [t.uuid, t]))
    const itMap = Object.fromEntries(imported.tasks.map(t => [t.uuid, t]))
    imported.tasks.forEach(t => { if (!tMap[t.uuid]) cur.tasks.push(structuredClone(t)) })
    cur.tasks.forEach(t => { const it = itMap[t.uuid]; if (!it) return; if (policy === 'prefer-import') { t.title = it.title; t.description = it.description; t.category = it.category; t.steps = structuredClone(it.steps || []) } })
    if (removeMissing) cur.tasks = cur.tasks.filter(t => !!itMap[t.uuid])
    // stages
    const sMap = Object.fromEntries(cur.stages.map(s => [s.uuid, s]))
    const isMap = Object.fromEntries(imported.stages.map(s => [s.uuid, s]))
    imported.stages.forEach(s => { if (!sMap[s.uuid]) cur.stages.push(structuredClone(s)) })
    cur.stages.forEach(s => { const is = isMap[s.uuid]; if (!is) return; if (policy === 'prefer-import') { s.title = is.title; s.tasks = structuredClone(is.tasks || []) } })
    if (removeMissing) cur.stages = cur.stages.filter(s => !!isMap[s.uuid])
    // layout
    if (policy === 'prefer-import') cur.layout = structuredClone(imported.layout || { columns: [] })
    dirty.value = true
    log('merge-apply', { policy, removeMissing })
  }

  // Operations
  const taskById = (id: string) => board.value.tasks.find(t => t.uuid === id)
  const stageById = (id: string) => board.value.stages.find(s => s.uuid === id)
  const categoryById = (id: string) => board.value.categories.find(c => c.uuid === id)

  function addCategory(title: string, color: string) {
    const c: Category = { uuid: uuid(), title, color }
    board.value.categories.push(c)
    log('category-add', { id: c.uuid, title, color })
    return c
  }
  function updateCategory(id: string, patch: Partial<Category>) {
    const c = categoryById(id)
    if (!c) return false
    const before = JSON.parse(JSON.stringify(c))
    Object.assign(c, patch)
    log('category-update', { id, before, after: c })
    return true
  }
  function removeCategory(id: string) {
    const used = board.value.tasks.some(t => t.category === id)
    if (used) return false
    board.value.categories = board.value.categories.filter(c => c.uuid !== id)
    log('category-delete', { id })
    return true
  }

  function addStage(title: string, colIndex = 0) {
    const s: Stage = { uuid: uuid(), title, tasks: [] }
    board.value.stages.push(s)
    if (!board.value.layout.columns.length) board.value.layout.columns.push([])
    board.value.layout.columns[Math.max(0, Math.min(colIndex, board.value.layout.columns.length - 1))].push(s.uuid)
    dirty.value = true
    log('stage-add', { id: s.uuid, title, colIndex })
    return s
  }
  function renameStage(id: string, title: string) {
    const s = stageById(id); if (!s) return
    const from = s.title; s.title = title; dirty.value = true; log('stage-rename', { id, from, to: title })
  }
  function deleteStage(id: string) {
    const s = stageById(id); if (!s) return false
    if (s.tasks?.length) return false
    board.value.stages = board.value.stages.filter(x => x.uuid !== id)
    board.value.layout.columns = board.value.layout.columns.map(col => col.filter(x => x !== id))
    dirty.value = true
    log('stage-delete', { id })
    return true
  }
  function addTask(stageId: string) {
    const t: Task = { uuid: uuid(), title: '新任务', description: '', category: null, steps: [] }
    board.value.tasks.push(t)
    const s = stageById(stageId)
    if (s) s.tasks.push(t.uuid)
    dirty.value = true
    log('task-add', { task: t.uuid, stage: stageId })
    return t
  }
  function removeTask(id: string) {
    board.value.stages.forEach(s => s.tasks = s.tasks.filter(tid => tid !== id))
    const prev = taskById(id)
    board.value.tasks = board.value.tasks.filter(t => t.uuid !== id)
    dirty.value = true
    log('task-delete', { id, task: prev })
  }
  function editTask(id: string, patch: Partial<Task>) {
    const t = taskById(id); if (!t) return
    const before = JSON.parse(JSON.stringify(t))
    Object.assign(t, patch)
    dirty.value = true
    log('task-edit', { id, before, after: t })
  }
  function moveTask(taskId: string, toStageId: string, toIndex: number) {
    const fromStage = board.value.stages.find(s => s.tasks.includes(taskId))
    const toStage = stageById(toStageId); if (!toStage) return
    if (fromStage && fromStage.uuid === toStage.uuid) {
      const arr = fromStage.tasks
      const old = arr.indexOf(taskId)
      arr.splice(old, 1)
      arr.splice(toIndex > old ? toIndex - 1 : toIndex, 0, taskId)
      dirty.value = true
      log('task-reorder', { stage: toStageId, task: taskId, toIndex })
      return
    }
    if (fromStage) fromStage.tasks = fromStage.tasks.filter(x => x !== taskId)
    toStage.tasks.splice(Math.max(0, Math.min(toIndex, toStage.tasks.length)), 0, taskId)
    dirty.value = true
    log('task-move', { task: taskId, from: fromStage?.uuid || null, to: toStageId, toIndex })
  }

  // Autosave to LocalStorage (throttled)
  let saveTimer: any
  watch(board, () => {
    clearTimeout(saveTimer)
    saveTimer = setTimeout(() => { saveToLocal() }, 500)
  }, { deep: true })

  return {
    filename, dirty, board, lastLoadedSnapshot, selectedTaskId,
    setBoard, setActor, log, saveToLocal, loadFromLocal, clearLocal,
    toJSON, downloadCurrent, applyMerge,
    addStage, renameStage, deleteStage, addTask, removeTask, editTask, moveTask,
    addCategory, updateCategory, removeCategory,
    taskById, stageById, categoryById,
    diffBoards
  }
})