import { acceptHMRUpdate, defineStore } from 'pinia'
import {
  disposeClipartItems,
  isFileSystemAccessSupported,
  listClipart,
  loadStoredClipartFolders,
  pickClipartFolder,
  saveClipartFolders,
  type ClipartItem,
} from '@/lib/clipartLibrary'

interface State {
  /** Root folders the user has added. Order matches display order. */
  handles: FileSystemDirectoryHandle[]
  /** Which root folder is being viewed. `null` means "root overview"
   *  (folder tiles, only used when `handles.length > 1`). With a single
   *  root the drawer auto-drills into it — callers should check
   *  `inOverview` rather than this field directly. */
  activeHandleIndex: number | null
  /** Current view's items — folder tiles in overview mode, files in
   *  in-folder mode. Consumers iterate this directly. */
  items: ClipartItem[]
  open: boolean
  loading: boolean
  error: string | null
  supported: boolean
  initialized: boolean
}

const DRAWER_OPEN_KEY = 'animatr:clipartDrawerOpen'

function readDrawerOpen(): boolean {
  try {
    return localStorage.getItem(DRAWER_OPEN_KEY) === '1'
  } catch {
    return false
  }
}

function writeDrawerOpen(open: boolean) {
  try {
    localStorage.setItem(DRAWER_OPEN_KEY, open ? '1' : '0')
  } catch {
    /* noop */
  }
}

export const useClipartStore = defineStore('clipart', {
  state: (): State => ({
    handles: [],
    activeHandleIndex: null,
    items: [],
    open: readDrawerOpen(),
    loading: false,
    error: null,
    supported: isFileSystemAccessSupported(),
    initialized: false,
  }),
  getters: {
    /** Active root handle (either the explicitly-entered one or the
     *  sole-folder auto-drill). `null` when the drawer sits on the
     *  overview. */
    activeHandle(state): FileSystemDirectoryHandle | null {
      if (state.activeHandleIndex !== null) {
        return state.handles[state.activeHandleIndex] ?? null
      }
      if (state.handles.length === 1) return state.handles[0]
      return null
    },
    /** True when the drawer should render folder tiles instead of
     *  files. Only possible with 2+ roots. */
    inOverview(state): boolean {
      return state.handles.length > 1 && state.activeHandleIndex === null
    },
    /** Current folder's display name, or null in overview / empty. */
    folderName(): string | null {
      return this.activeHandle?.name ?? null
    },
    /** True when there's any folder configured at all. Drives the
     *  header-controls visibility in the drawer. */
    hasAnyFolder(state): boolean {
      return state.handles.length > 0
    },
    /** Back button is shown whenever the user can exit to the overview
     *  (requires an explicit active index AND multiple roots). */
    canGoBack(state): boolean {
      return state.activeHandleIndex !== null && state.handles.length > 1
    },
  },
  actions: {
    async initialize() {
      if (!this.supported) {
        this.initialized = true
        return
      }
      if (this.handles.length > 0) {
        this.initialized = true
        return
      }
      const handles = await loadStoredClipartFolders()
      this.initialized = true
      if (handles.length === 0) return
      this.handles = handles
      try {
        await this.refresh()
      } catch {
        /* permission may require a user gesture; items will populate
           on next open */
      }
    },
    /** Prompt the user for a folder and append it to the root list.
     *  Single-folder installs keep the auto-drill behaviour; adding a
     *  second root pops the drawer back to the overview so both roots
     *  are visible. */
    async addFolder() {
      this.error = null
      try {
        const handle = await pickClipartFolder()
        if (!handle) return
        const wasEmpty = this.handles.length === 0
        this.handles = [...this.handles, handle]
        await saveClipartFolders(this.handles)
        if (wasEmpty) {
          // First folder — auto-drill via the getter. Nothing to do.
        } else {
          // Adding a 2nd+ folder: show the overview so the user sees
          // every root at once.
          this.activeHandleIndex = null
        }
        await this.refresh()
      } catch (err) {
        this.error = (err as Error).message ?? 'Failed to pick folder'
      }
    },
    /** Legacy alias — early callers (DocumentSettings, tests) still
     *  invoke pickFolder. Keeps the same semantics as addFolder. */
    async pickFolder() {
      await this.addFolder()
    },
    enterFolder(index: number) {
      if (index < 0 || index >= this.handles.length) return
      this.activeHandleIndex = index
      void this.refresh()
    },
    /** Pop to the overview. No-op with only one root (the drawer stays
     *  auto-drilled). */
    exitFolder() {
      if (this.handles.length <= 1) return
      this.activeHandleIndex = null
      void this.refresh()
    },
    async removeFolder(index: number) {
      if (index < 0 || index >= this.handles.length) return
      this.handles = this.handles.filter((_, i) => i !== index)
      // Adjust the active pointer so it still points at the intended
      // folder (or drops to overview when the active one was removed).
      if (this.activeHandleIndex === index) {
        this.activeHandleIndex = null
      } else if (
        this.activeHandleIndex !== null &&
        this.activeHandleIndex > index
      ) {
        this.activeHandleIndex -= 1
      }
      await saveClipartFolders(this.handles)
      await this.refresh()
    },
    async clearFolder() {
      this.disposeItems()
      this.handles = []
      this.activeHandleIndex = null
      this.items = []
      this.error = null
      await saveClipartFolders([])
    },
    async refresh() {
      if (this.handles.length === 0) {
        this.disposeItems()
        this.items = []
        return
      }
      this.loading = true
      this.error = null
      try {
        const active = this.activeHandle
        if (active) {
          // In-folder view: list files; strip subdirectory entries so
          // drilling stays one-level-deep (matches the pre-multi-root
          // behaviour).
          const next = await listClipart(active)
          this.disposeItems()
          this.items = next.filter((it) => it.kind !== 'folder')
        } else {
          // Overview: synthesize a folder tile per root. These items
          // have no URLs to revoke, so disposeItems is cheap.
          this.disposeItems()
          this.items = this.handles.map((h) => ({
            kind: 'folder' as const,
            name: h.name,
            handle: h,
          }))
        }
      } catch (err) {
        this.error = (err as Error).message ?? 'Failed to read folder'
      } finally {
        this.loading = false
      }
    },
    disposeItems() {
      disposeClipartItems(this.items)
    },
    setOpen(v: boolean) {
      this.open = v
      writeDrawerOpen(v)
      if (
        v &&
        this.handles.length > 0 &&
        this.items.length === 0 &&
        !this.loading
      ) {
        // User gesture opens the drawer — good moment to (re-)request
        // directory permission or recover from a cold-boot skip.
        void this.refresh()
      }
    },
    toggle() {
      this.setOpen(!this.open)
    },
  },
})

// Let Vite's HMR swap the store definition in place instead of leaving
// the initial (stale) state + getters behind — without this, edits to
// `State` or the getter surface only land after a full page reload.
if (import.meta.hot) {
  import.meta.hot.accept(acceptHMRUpdate(useClipartStore, import.meta.hot))
}