import { instantiate, Node } from 'cc';
import { BUNDLE_ID } from '@scripts/define/ResDefine';
import { getUIViewConfig, UIViewConfig, UIViewID } from '../../define/UIDefine';
import { ResourceManager } from '../resource/ResourceManager';
import { UICachePolicy, UICloseReason, UILayer, UIViewState } from './UILayer';
import { UIView } from './UIView';

interface UIViewRecord {
  config: UIViewConfig;
  state: UIViewState;
  view: UIView | null;
  ownerRoot: Node | null;
  generation: number;
  opening: Promise<UIView | null> | null;
  closing: Promise<boolean> | null;
  delayedDestroyTimer: ReturnType<typeof setTimeout> | null;
}

export class UIManager {
  private static readonly DELAYED_DESTROY_MS = 5000;

  private readonly records = new Map<UIViewID, UIViewRecord>();
  private readonly roots = new Map<UILayer, Node>();

  constructor(private readonly resources: ResourceManager) { }

  bindLayer(layer: UILayer, root: Node): void {
    this.roots.set(layer, root);
  }

  /**
   * 接管当前场景各 UI Layer 中预放置的 UIView。
   * 注册后的 View 先进入缓存态，之后仍由 open/close 统一驱动生命周期。
   */
  async registerSceneViews(): Promise<void> {
    for (const [layer, root] of this.roots) {
      if (!root.isValid) continue;

      const views = root.getComponentsInChildren(UIView);
      for (const view of views) {
        const viewId = view.getViewID();
        if (!viewId) {
          console.warn(`[UIManager] Scene UIView has no viewId: ${view.node.name}`);
          continue;
        }

        const config = getUIViewConfig(viewId);
        if (!config) {
          console.warn(`[UIManager] Scene UIView is not configured: ${viewId}`);
          continue;
        }
        if (config.layer !== layer) {
          console.warn(
            `[UIManager] Scene UIView is under the wrong layer: ${viewId}, expected=${config.layer}, actual=${layer}`,
          );
          continue;
        }

        const existing = this.records.get(viewId);
        if (existing?.view === view) continue;
        if (existing?.view?.node?.isValid) {
          console.warn(`[UIManager] Duplicate scene UIView ignored: ${viewId}`);
          continue;
        }
        if (existing) this.forgetRecord(existing);

        const record: UIViewRecord = {
          config,
          state: UIViewState.Creating,
          view,
          ownerRoot: root,
          generation: 1,
          opening: null,
          closing: null,
          delayedDestroyTimer: null,
        };
        this.records.set(viewId, record);
        view.node.active = false;

        try {
          await view.internalCreate();
          if (!view.node.isValid || this.records.get(viewId) !== record) {
            this.forgetRecord(record);
            continue;
          }
          record.state = UIViewState.Cached;
        } catch (error) {
          this.forgetRecord(record);
          throw error;
        }
      }
    }
  }

  clearSceneLayers(): void {
    const sceneRoots = new Set(this.roots.values());
    this.roots.clear();

    for (const record of [...this.records.values()]) {
      const node = record.view?.node;
      const belongsToSceneLayer = node?.isValid
        ? [...sceneRoots].some((root) => root.isValid && (node === root || node.isChildOf(root)))
        : record.ownerRoot !== null && sceneRoots.has(record.ownerRoot);

      if (!node?.isValid || belongsToSceneLayer) {
        this.forgetRecord(record);
      }
    }
  }

  get<TView extends UIView>(viewId: UIViewID): TView | null {
    const record = this.records.get(viewId);
    if (
      !record
      || !record.view?.node?.isValid
      || (record.state !== UIViewState.Opening && record.state !== UIViewState.Opened)
    ) {
      return null;
    }
    return record.view as TView | null;
  }

  isOpen(viewId: UIViewID): boolean {
    return this.get(viewId) !== null;
  }

  async open<TView extends UIView, TParams = unknown>(viewId: UIViewID, params?: TParams): Promise<TView | null> {
    let record = this.records.get(viewId);
    if (record?.view && !record.view.node.isValid) {
      this.forgetRecord(record);
      record = undefined;
    }
    if (record?.state === UIViewState.Opened) return record.view as TView;
    if (record?.opening) return record.opening as Promise<TView | null>;
    if (record?.closing) await record.closing;
    if (record) this.cancelDelayedDestroy(record);

    if (record?.state === UIViewState.Cached && record.view?.node.isValid) {
      await this.closeMutexViews(record.config);
      record.state = UIViewState.Opening;
      record.view.node.active = true;
      await record.view.internalOpen(params);
      record.state = UIViewState.Opened;
      return record.view as TView;
    }

    const config = getUIViewConfig(viewId);
    const root = this.roots.get(config.layer);
    if (!root?.isValid) throw new Error(`[UIManager] UILayer is not bound: ${config.layer}`);

    record = record ?? {
      config,
      state: UIViewState.None,
      view: null,
      ownerRoot: root,
      generation: 0,
      opening: null,
      closing: null,
      delayedDestroyTimer: null,
    };
    record.ownerRoot = root;
    this.records.set(viewId, record);

    const generation = ++record.generation;
    record.opening = this.performOpen(record, root, params, generation);
    try {
      return await record.opening as TView | null;
    } finally {
      if (record.generation === generation) record.opening = null;
    }
  }

  async close(viewIdOrInstance: UIViewID, reason = UICloseReason.User): Promise<boolean> {
    const record = typeof viewIdOrInstance === 'string'
      ? this.records.get(viewIdOrInstance)
      : [...this.records.values()].find((item) => item.view === viewIdOrInstance);
    if (!record) return false;
    if (record.closing) return record.closing;
    if (record.state === UIViewState.Cached) return true;

    ++record.generation;
    record.closing = this.performClose(record, reason);
    try {
      return await record.closing;
    } finally {
      record.closing = null;
    }
  }

  async closeAll(reason = UICloseReason.SceneChanged): Promise<void> {
    await Promise.all([...this.records.values()].map((record) => this.close(record.config.id, reason)));
  }

  private async performOpen(
    record: UIViewRecord,
    root: Node,
    params: unknown,
    generation: number,
  ): Promise<UIView | null> {
    record.state = UIViewState.Loading;
    const bundleName = record.config.bundle || BUNDLE_ID.Lobby;
    const prefab = await this.resources.loadPrefab(bundleName, record.config.prefabPath);
    if (generation !== record.generation) return null;

    record.state = UIViewState.Creating;
    const node = instantiate(prefab);
    root.addChild(node);
    const view = node.getComponent(UIView);
    if (!view) {
      node.destroy();
      throw new Error(`[UIManager] Prefab has no UIView component: ${record.config.id}`);
    }

    record.view = view;
    await view.internalCreate();
    if (generation !== record.generation || !node.isValid) {
      node.destroy();
      record.view = null;
      return null;
    }

    await this.closeMutexViews(record.config);
    record.state = UIViewState.Opening;
    node.active = true;
    await view.internalOpen(params);
    if (generation !== record.generation || !node.isValid) return null;

    record.state = UIViewState.Opened;
    return view;
  }

  private async performClose(record: UIViewRecord, reason: UICloseReason): Promise<boolean> {
    if (!record.view?.node?.isValid) {
      this.cancelDelayedDestroy(record);
      record.state = UIViewState.Disposed;
      record.view = null;
      this.records.delete(record.config.id);
      return false;
    }

    const allow = reason === UICloseReason.ForceDispose
      ? true
      : await record.view.internalBeforeClose(reason);
    if (!allow) return false;

    record.state = UIViewState.Closing;
    await record.view.internalClose(reason);

    const uiCache = record.config.cache || UICachePolicy.None;
    if (reason === UICloseReason.ForceDispose || uiCache === UICachePolicy.None) {
      this.disposeRecord(record);
      return true;
    }

    record.view.node.active = false;
    record.state = UIViewState.Cached;

    if (uiCache === UICachePolicy.Delayed) {
      this.scheduleDelayedDestroy(record);
    }
    return true;
  }

  private scheduleDelayedDestroy(record: UIViewRecord): void {
    this.cancelDelayedDestroy(record);
    const generation = record.generation;
    record.delayedDestroyTimer = setTimeout(() => {
      record.delayedDestroyTimer = null;
      if (
        record.generation === generation
        && record.state === UIViewState.Cached
      ) {
        this.disposeRecord(record);
      }
    }, UIManager.DELAYED_DESTROY_MS);
  }

  private cancelDelayedDestroy(record: UIViewRecord): void {
    if (record.delayedDestroyTimer === null) return;
    clearTimeout(record.delayedDestroyTimer);
    record.delayedDestroyTimer = null;
  }

  private disposeRecord(record: UIViewRecord): void {
    this.cancelDelayedDestroy(record);
    if (record.view?.node?.isValid) {
      record.view.internalDispose();
      record.view.node.destroy();
    }
    record.view = null;
    record.ownerRoot = null;
    record.state = UIViewState.Disposed;
    this.records.delete(record.config.id);
  }

  /** 从管理器中同步移除记录，不主动销毁正由场景释放的节点。 */
  private forgetRecord(record: UIViewRecord): void {
    ++record.generation;
    this.cancelDelayedDestroy(record);
    if (record.view?.node?.isValid) {
      record.view.internalDispose();
    }
    record.view = null;
    record.ownerRoot = null;
    record.opening = null;
    record.closing = null;
    record.state = UIViewState.Disposed;
    if (this.records.get(record.config.id) === record) {
      this.records.delete(record.config.id);
    }
  }

  private async closeMutexViews(config: UIViewConfig): Promise<void> {
    const tasks: Promise<boolean>[] = [];
    for (const record of this.records.values()) {
      if (!record.config.mutexGroup) continue;
      if (record.config.id !== config.id && record.config.mutexGroup === config.mutexGroup) {
        tasks.push(this.close(record.config.id, UICloseReason.Navigation));
      }
    }
    await Promise.all(tasks);
  }

  loading(active: boolean) {
    if (active) {
      this.open(UIViewID.LoadingView);
    } else {
      this.close(UIViewID.LoadingView);
    }
  }

  toast() {

  }

  dialog() {

  }
}