import { computed, ref } from 'vue';
import { useDebounceFn } from '@vueuse/core';
import { type WorkbenchColumnId, type WorkbenchModuleKey, useWorkbenchModules } from './use-workbench-modules';
import { buildDefaultLayout } from './workbench-layout-default';
import type { LayoutStorage } from './layout-storage';
import { LocalStorageAdapter } from './layout-storage-local';
import { reconcileLayout } from './workbench-layout-reconcile';
import { WORKBENCH_LAYOUT_VERSION, type WorkbenchLayout } from './workbench-layout-types';

export type WorkbenchMode = 'normal' | 'editing';

interface UseWorkbenchLayoutOptions {
  userId: string;
  storage?: LayoutStorage;
}

export function useWorkbenchLayout(options: UseWorkbenchLayoutOptions) {
  const { getAllModules } = useWorkbenchModules();
  const storage = options.storage ?? new LocalStorageAdapter();

  const layout = ref<WorkbenchLayout>(buildDefaultLayout(getAllModules()));
  const mode = ref<WorkbenchMode>('normal');
  const dirty = ref(false);
  const saving = ref(false);
  const error = ref<Error | null>(null);

  let snapshotBeforeEdit: WorkbenchLayout | null = null;

  async function load() {
    const fromStorage = await storage.load(options.userId);
    if (fromStorage && fromStorage.version === WORKBENCH_LAYOUT_VERSION) {
      layout.value = reconcileLayout(fromStorage, getAllModules());
      return;
    }
    // 版本不匹配 / 无存储：走新默认布局；旧 settings 迁移过来，避免用户偏好（如 shortcut.menuKeys）被 version bump 清空
    const fresh = buildDefaultLayout(getAllModules());
    if (fromStorage?.settings) {
      fresh.settings = { ...fromStorage.settings };
    }
    layout.value = fresh;
  }

  const persist = useDebounceFn(async () => {
    saving.value = true;
    error.value = null;
    try {
      await storage.save(options.userId, layout.value);
    } catch (err) {
      error.value = err as Error;
    } finally {
      saving.value = false;
    }
  }, 500);

  function markDirty() {
    if (mode.value === 'editing') {
      dirty.value = true;
    } else {
      // 非编辑态写（如折叠）直接落盘
      persist();
    }
  }

  function enterEditing() {
    snapshotBeforeEdit = JSON.parse(JSON.stringify(layout.value));
    mode.value = 'editing';
    dirty.value = false;
  }

  async function saveEditing() {
    saving.value = true;
    try {
      await storage.save(options.userId, layout.value);
      mode.value = 'normal';
      dirty.value = false;
      snapshotBeforeEdit = null;
    } catch (err) {
      error.value = err as Error;
    } finally {
      saving.value = false;
    }
  }

  function cancelEditing() {
    if (snapshotBeforeEdit) {
      layout.value = snapshotBeforeEdit;
    }
    mode.value = 'normal';
    dirty.value = false;
    snapshotBeforeEdit = null;
  }

  function hideModule(key: WorkbenchModuleKey) {
    for (const col of layout.value.columns) {
      col.modules = col.modules.filter(k => k !== key);
    }
    if (!layout.value.hidden.includes(key)) layout.value.hidden.push(key);
    markDirty();
  }

  function showModule(key: WorkbenchModuleKey, columnId: WorkbenchColumnId = 'left') {
    layout.value.hidden = layout.value.hidden.filter(k => k !== key);
    const target = layout.value.columns.find(c => c.id === columnId);
    if (target && !target.modules.includes(key)) target.modules.push(key);
    markDirty();
  }

  function setColumnModules(columnId: WorkbenchColumnId, modules: WorkbenchModuleKey[]) {
    const target = layout.value.columns.find(c => c.id === columnId);
    if (target) target.modules = modules;
    markDirty();
  }

  function toggleCollapse(key: WorkbenchModuleKey) {
    if (layout.value.collapsed.includes(key)) {
      layout.value.collapsed = layout.value.collapsed.filter(k => k !== key);
    } else {
      layout.value.collapsed.push(key);
    }
    markDirty();
  }

  function updateModuleSettings<K extends keyof WorkbenchLayout['settings']>(
    key: K,
    value: WorkbenchLayout['settings'][K]
  ) {
    layout.value.settings = { ...layout.value.settings, [key]: value };
    markDirty();
  }

  async function resetToDefault() {
    layout.value = buildDefaultLayout(getAllModules());
    mode.value = 'normal';
    dirty.value = false;
    snapshotBeforeEdit = null;
    await storage.save(options.userId, layout.value);
  }

  const isCollapsed = (key: WorkbenchModuleKey) => layout.value.collapsed.includes(key);

  const hiddenMetas = computed(() => {
    const allMeta = getAllModules();
    return layout.value.hidden
      .map(k => allMeta.find(m => m.key === k))
      .filter((m): m is NonNullable<typeof m> => Boolean(m));
  });

  return {
    layout,
    mode,
    dirty,
    saving,
    error,
    hiddenMetas,
    isCollapsed,
    load,
    enterEditing,
    saveEditing,
    cancelEditing,
    hideModule,
    showModule,
    setColumnModules,
    toggleCollapse,
    updateModuleSettings,
    resetToDefault
  };
}