import { BlockSuiteError, ErrorCode } from '@blocksuite/global/exceptions';
import { DisposableGroup } from '@blocksuite/global/utils';

import { LifeCycleWatcher } from '../extension/index.js';
import { KeymapIdentifier } from '../identifier.js';
import { type BlockComponent, EditorHost } from '../view/index.js';
import {
  type UIEventHandler,
  UIEventState,
  UIEventStateContext,
} from './base.js';
import { ClipboardControl } from './control/clipboard.js';
import { KeyboardControl } from './control/keyboard.js';
import { PointerControl } from './control/pointer.js';
import { RangeControl } from './control/range.js';
import { EventScopeSourceType, EventSourceState } from './state/source.js';
import { toLowerCase } from './utils.js';

const bypassEventNames = [
  'beforeInput',

  'blur',
  'focus',
  'contextMenu',
  'wheel',
] as const;

const eventNames = [
  'click',
  'doubleClick',
  'tripleClick',

  'pointerDown',
  'pointerMove',
  'pointerUp',
  'pointerOut',

  'dragStart',
  'dragMove',
  'dragEnd',

  'pinch',
  'pan',

  'keyDown',
  'keyUp',

  'selectionChange',
  'compositionStart',
  'compositionUpdate',
  'compositionEnd',

  'cut',
  'copy',
  'paste',

  'nativeDragStart',
  'nativeDragMove',
  'nativeDragEnd',
  'nativeDrop',

  ...bypassEventNames,
] as const;

export type EventName = (typeof eventNames)[number];
export type EventOptions = {
  flavour?: string;
  blockId?: string;
};
export type EventHandlerRunner = {
  fn: UIEventHandler;
  flavour?: string;
  blockId?: string;
};

export class UIEventDispatcher extends LifeCycleWatcher {
  private static _activeDispatcher: UIEventDispatcher | null = null;

  static override readonly key = 'UIEventDispatcher';

  private _active = false;

  private readonly _clipboardControl: ClipboardControl;

  private _handlersMap = Object.fromEntries(
    eventNames.map((name): [EventName, Array<EventHandlerRunner>] => [name, []])
  ) as Record<EventName, Array<EventHandlerRunner>>;

  private readonly _keyboardControl: KeyboardControl;

  private readonly _pointerControl: PointerControl;

  private readonly _rangeControl: RangeControl;

  bindHotkey = (...args: Parameters<KeyboardControl['bindHotkey']>) =>
    this._keyboardControl.bindHotkey(...args);

  disposables = new DisposableGroup();

  private get _currentSelections() {
    return this.std.selection.value;
  }

  get active() {
    return this._active;
  }

  get host() {
    return this.std.host;
  }

  constructor(std: BlockSuite.Std) {
    super(std);
    this._pointerControl = new PointerControl(this);
    this._keyboardControl = new KeyboardControl(this);
    this._rangeControl = new RangeControl(this);
    this._clipboardControl = new ClipboardControl(this);
    this.disposables.add(this._pointerControl);
  }

  private _bindEvents() {
    bypassEventNames.forEach(eventName => {
      this.disposables.addFromEvent(
        this.host,
        toLowerCase(eventName),
        event => {
          this.run(
            eventName,
            UIEventStateContext.from(
              new UIEventState(event),
              new EventSourceState({
                event,
                sourceType: EventScopeSourceType.Selection,
              })
            )
          );
        },
        eventName === 'wheel'
          ? {
              passive: false,
            }
          : undefined
      );
    });

    this._pointerControl.listen();
    this._keyboardControl.listen();
    this._rangeControl.listen();
    this._clipboardControl.listen();

    let _dragging = false;
    this.disposables.addFromEvent(this.host, 'pointerdown', () => {
      _dragging = true;
      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'pointerup', () => {
      _dragging = false;
    });
    this.disposables.addFromEvent(this.host, 'click', () => {
      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'focusin', () => {
      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'focusout', e => {
      if (e.relatedTarget && !this.host.contains(e.relatedTarget as Node)) {
        this._setActive(false);
      }
    });
    this.disposables.addFromEvent(this.host, 'blur', () => {
      if (_dragging) {
        return;
      }

      this._setActive(false);
    });
    this.disposables.addFromEvent(this.host, 'dragover', () => {
      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'dragend', () => {
      this._setActive(false);
    });
    this.disposables.addFromEvent(this.host, 'drop', () => {
      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'pointerenter', () => {
      if (this._isActiveElementOutsideHost()) {
        return;
      }

      this._setActive(true);
    });
    this.disposables.addFromEvent(this.host, 'pointerleave', () => {
      if (
        (document.activeElement &&
          this.host.contains(document.activeElement)) ||
        _dragging
      ) {
        return;
      }

      this._setActive(false);
    });
  }

  private _buildEventScopeBySelection(name: EventName) {
    const handlers = this._handlersMap[name];
    if (!handlers) return;

    const selections = this._currentSelections;
    const ids = selections.map(selection => selection.blockId);

    return this.buildEventScope(name, ids);
  }

  private _buildEventScopeByTarget(name: EventName, target: Node) {
    const handlers = this._handlersMap[name];
    if (!handlers) return;

    // TODO(mirone/#6534): find a better way to get block element from a node
    const el = target instanceof Element ? target : target.parentElement;
    const block = el?.closest<BlockComponent>('[data-block-id]');

    const blockId = block?.blockId;
    if (!blockId) {
      return this._buildEventScopeBySelection(name);
    }

    return this.buildEventScope(name, [blockId]);
  }

  private _getDeepActiveElement(): Element | null {
    let active = document.activeElement;
    while (active && active.shadowRoot && active.shadowRoot.activeElement) {
      active = active.shadowRoot.activeElement;
    }
    return active;
  }

  private _getEventScope(name: EventName, state: EventSourceState) {
    const handlers = this._handlersMap[name];
    if (!handlers) return;

    let output: EventHandlerRunner[] | undefined;

    switch (state.sourceType) {
      case EventScopeSourceType.Selection: {
        output = this._buildEventScopeBySelection(name);
        break;
      }
      case EventScopeSourceType.Target: {
        output = this._buildEventScopeByTarget(
          name,
          state.event.target as Node
        );
        break;
      }
      default: {
        throw new BlockSuiteError(
          ErrorCode.EventDispatcherError,
          `Unknown event scope source: ${state.sourceType}`
        );
      }
    }

    return output;
  }

  private _isActiveElementOutsideHost(): boolean {
    const activeElement = this._getDeepActiveElement();
    return (
      activeElement !== null &&
      this._isEditableElementActive(activeElement) &&
      !this.host.contains(activeElement)
    );
  }

  private _isEditableElementActive(element: Element | null): boolean {
    if (!element) return false;
    return (
      element instanceof HTMLInputElement ||
      element instanceof HTMLTextAreaElement ||
      (element instanceof EditorHost && !element.doc.readonly) ||
      (element as HTMLElement).isContentEditable
    );
  }

  private _setActive(active: boolean) {
    if (active) {
      if (UIEventDispatcher._activeDispatcher !== this) {
        if (UIEventDispatcher._activeDispatcher) {
          UIEventDispatcher._activeDispatcher._active = false;
        }
        UIEventDispatcher._activeDispatcher = this;
      }
      this._active = true;
    } else {
      if (UIEventDispatcher._activeDispatcher === this) {
        UIEventDispatcher._activeDispatcher = null;
      }
      this._active = false;
    }
  }

  add(name: EventName, handler: UIEventHandler, options?: EventOptions) {
    const runner: EventHandlerRunner = {
      fn: handler,
      flavour: options?.flavour,
      blockId: options?.blockId,
    };
    this._handlersMap[name].unshift(runner);
    return () => {
      if (this._handlersMap[name].includes(runner)) {
        this._handlersMap[name] = this._handlersMap[name].filter(
          x => x !== runner
        );
      }
    };
  }

  buildEventScope(
    name: EventName,
    blocks: string[]
  ): EventHandlerRunner[] | undefined {
    const handlers = this._handlersMap[name];
    if (!handlers) return;

    const globalEvents = handlers.filter(
      handler => handler.flavour === undefined && handler.blockId === undefined
    );

    let blockIds: string[] = blocks;
    const events: EventHandlerRunner[] = [];
    const flavourSeen: Record<string, boolean> = {};
    while (blockIds.length > 0) {
      const idHandlers = handlers.filter(
        handler => handler.blockId && blockIds.includes(handler.blockId)
      );

      const flavourHandlers = blockIds
        .map(blockId => this.std.doc.getBlock(blockId)?.flavour)
        .filter((flavour): flavour is string => {
          if (!flavour) return false;
          if (flavourSeen[flavour]) return false;
          flavourSeen[flavour] = true;
          return true;
        })
        .flatMap(flavour => {
          return handlers.filter(handler => handler.flavour === flavour);
        });

      events.push(...idHandlers, ...flavourHandlers);
      blockIds = blockIds
        .map(blockId => {
          const parent = this.std.doc.getParent(blockId);
          return parent?.id;
        })
        .filter((id): id is string => !!id);
    }

    return events.concat(globalEvents);
  }

  override mounted() {
    if (this.disposables.disposed) {
      this.disposables = new DisposableGroup();
    }
    this._bindEvents();

    const std = this.std;
    this.std.provider
      .getAll(KeymapIdentifier)
      .forEach(({ getter, options }) => {
        this.bindHotkey(getter(std), options);
      });
  }

  run(
    name: EventName,
    context: UIEventStateContext,
    runners?: EventHandlerRunner[]
  ) {
    if (!this.active) return;

    const sourceState = context.get('sourceState');
    if (!runners) {
      runners = this._getEventScope(name, sourceState);
      if (!runners) {
        return;
      }
    }
    for (const runner of runners) {
      const { fn } = runner;
      const result = fn(context);
      if (result) {
        context.get('defaultState').event.stopPropagation();
        return;
      }
    }
  }

  override unmounted() {
    this.disposables.dispose();
  }
}