import { ClientWidgetApi } from 'matrix-widget-api';
import { EventEmitter } from 'events';
import { CallControlState } from './CallControlState';
import { ElementMediaStateDetail, ElementMediaStatePayload, ElementWidgetActions } from './types';

export enum CallControlEvent {
  StateUpdate = 'state_update',
}

export class CallControl extends EventEmitter implements CallControlState {
  private state: CallControlState;

  private call: ClientWidgetApi;

  private iframe: HTMLIFrameElement;

  private bodyMutationObserver: MutationObserver;

  private controlMutationObserver: MutationObserver;

  private _pipMode = false;

  private get document(): Document | undefined {
    return this.iframe.contentDocument ?? this.iframe.contentWindow?.document;
  }

  private get screenshareButton(): HTMLElement | undefined {
    const screenshareBtn = this.document?.querySelector(
      '[data-testid="incall_screenshare"]',
    ) as HTMLElement | null;

    return screenshareBtn ?? undefined;
  }

  private get leaveButton(): Element | undefined {
    const leaveBtn = this.document?.querySelector('[data-testid="incall_leave"]');

    return leaveBtn ?? undefined;
  }

  private get settingsButton(): HTMLElement | undefined {
    // EC 0.20.1: settings button moved to bottom-left; fall back to bottom-center.
    const settingsButtonLeft = this.document?.querySelector(
      '[data-testid="settings-bottom-left"]',
    ) as HTMLButtonElement | undefined;
    const settingsButtonCenter = this.document?.querySelector(
      '[data-testid="settings-bottom-center"]',
    ) as HTMLButtonElement | undefined;

    return settingsButtonLeft ?? settingsButtonCenter ?? undefined;
  }

  private get reactionsButton(): HTMLElement | undefined {
    // EC 0.20.1: reactions/raise-hand button sits just before the leave button.
    const reactionsButton = this.leaveButton?.previousElementSibling as HTMLElement | null;

    return reactionsButton ?? undefined;
  }

  private get spotlightButton(): HTMLInputElement | undefined {
    const spotlightButton = this.document?.querySelector(
      'input[value="spotlight"]',
    ) as HTMLInputElement | null;

    return spotlightButton ?? undefined;
  }

  private get gridButton(): HTMLInputElement | undefined {
    const gridButton = this.document?.querySelector(
      'input[value="grid"]',
    ) as HTMLInputElement | null;

    return gridButton ?? undefined;
  }

  constructor(state: CallControlState, call: ClientWidgetApi, iframe: HTMLIFrameElement) {
    super();

    this.state = state;
    this.call = call;
    this.iframe = iframe;

    this.bodyMutationObserver = new MutationObserver(this.onBodyMutation.bind(this));
    this.controlMutationObserver = new MutationObserver(this.onControlMutation.bind(this));
  }

  public getState(): CallControlState {
    return this.state;
  }

  public get microphone(): boolean {
    return this.state.microphone;
  }

  public get video(): boolean {
    return this.state.video;
  }

  public get sound(): boolean {
    return this.state.sound;
  }

  public get screenshare(): boolean {
    return this.state.screenshare;
  }

  public get spotlight(): boolean {
    return this.state.spotlight;
  }

  public get screenshareAudioMuted(): boolean {
    return this.state.screenshareAudioMuted;
  }

  public async applyState() {
    await this.setMediaState({
      audio_enabled: this.microphone,
      video_enabled: this.video,
    });
    this.setSound(this.sound);
    this.emitStateUpdate();
  }

  public async forceState(desired: CallControlState) {
    this.state = new CallControlState(
      desired.microphone,
      desired.video,
      desired.sound,
      this.screenshare,
      this.spotlight,
    );
    await this.applyState();
  }

  public startObserving() {
    if (!this.document) return;

    this.bodyMutationObserver.observe(this.document.body, {
      childList: true,
      subtree: false, // only direct children of body
    });
    this.onBodyMutation();
  }

  private onBodyMutation() {
    if (!this.document) return;

    this.document.body.style.setProperty('background', 'none', 'important');

    const controls = this.leaveButton?.parentElement?.parentElement;
    if (controls) {
      controls.style.setProperty('position', 'absolute');
      controls.style.setProperty('visibility', 'hidden');
    }

    this.observeControls();
  }

  private observeControls() {
    this.controlMutationObserver.disconnect();

    const screenshareBtn = this.screenshareButton;
    if (screenshareBtn) {
      this.controlMutationObserver.observe(screenshareBtn, {
        attributes: true,
        attributeFilter: ['data-kind'],
      });
    }
    const spotlightBtn = this.spotlightButton;
    if (spotlightBtn) {
      this.controlMutationObserver.observe(spotlightBtn, {
        attributes: true,
      });
    }

    this.onControlMutation();
  }

  public applySound() {
    this.setSound(this.sound);
  }

  private async setMediaState(state: ElementMediaStatePayload) {
    // transport.send resolves once EC has ACK'd the command, which is enough to
    // consider the mute applied. We deliberately do NOT gate completion on a
    // follow-up DeviceMute state-echo: EC may elide it (e.g. when the requested
    // state already matches its current state) or skip it during teardown,
    // which would strand this promise forever and block applyState(). The echo,
    // when it does arrive, is still handled authoritatively by onMediaState().
    return this.call.transport.send(ElementWidgetActions.DeviceMute, state);
  }

  private setSound(sound: boolean): void {
    const callDocument = this.iframe.contentDocument ?? this.iframe.contentWindow?.document;
    if (callDocument) {
      callDocument.querySelectorAll('audio').forEach((el) => {
        const isScreenshareAudio = el.getAttribute('data-lk-source') === 'screen_share_audio';
        el.muted = !sound || (isScreenshareAudio && this.screenshareAudioMuted);
      });
    }
  }

  private applyScreenshareAudioMuted(): void {
    if (!this.sound) return;
    const callDocument = this.iframe.contentDocument ?? this.iframe.contentWindow?.document;
    if (callDocument) {
      callDocument
        .querySelectorAll<HTMLAudioElement>('audio[data-lk-source="screen_share_audio"]')
        .forEach((el) => {
          el.muted = this.screenshareAudioMuted;
        });
    }
  }

  public onMediaState(evt: CustomEvent<ElementMediaStateDetail>) {
    const { data } = evt.detail;
    if (!data) return;

    const state = new CallControlState(
      data.audio_enabled ?? this.microphone,
      data.video_enabled ?? this.video,
      this.sound,
      this.screenshare,
      this.spotlight,
      this.screenshareAudioMuted,
    );

    this.state = state;
    this.emitStateUpdate();

    if (this.microphone && !this.sound) {
      this.toggleSound();
    }
  }

  private onControlMutation() {
    const screenshare: boolean = this.screenshareButton?.getAttribute('data-kind') === 'primary';
    const spotlight: boolean = this.spotlightButton?.checked ?? false;

    this.state = new CallControlState(
      this.microphone,
      this.video,
      this.sound,
      screenshare,
      spotlight,
      this.screenshareAudioMuted,
    );
    this.emitStateUpdate();
  }

  public setMicrophone(enabled: boolean) {
    const payload: ElementMediaStatePayload = {
      audio_enabled: enabled,
      video_enabled: this.video,
    };
    return this.setMediaState(payload);
  }

  public toggleMicrophone() {
    const payload: ElementMediaStatePayload = {
      audio_enabled: !this.microphone,
      video_enabled: this.video,
    };
    return this.setMediaState(payload);
  }

  public toggleVideo() {
    const payload: ElementMediaStatePayload = {
      audio_enabled: this.microphone,
      video_enabled: !this.video,
    };
    return this.setMediaState(payload);
  }

  public toggleSound() {
    const sound = !this.sound;

    this.setSound(sound);
    // After un-deafening, re-apply screenshare audio mute if active
    if (sound) this.applyScreenshareAudioMuted();

    const state = new CallControlState(
      this.microphone,
      this.video,
      sound,
      this.screenshare,
      this.spotlight,
      this.screenshareAudioMuted,
    );
    this.state = state;
    this.emitStateUpdate();

    if (!this.sound && this.microphone) {
      this.toggleMicrophone();
    }
  }

  public toggleScreenshareAudio() {
    const screenshareAudioMuted = !this.screenshareAudioMuted;
    this.state = new CallControlState(
      this.microphone,
      this.video,
      this.sound,
      this.screenshare,
      this.spotlight,
      screenshareAudioMuted,
    );
    this.emitStateUpdate();
    this.applyScreenshareAudioMuted();
  }

  public toggleScreenshare() {
    this.screenshareButton?.click();
  }

  public toggleSpotlight() {
    if (this.spotlight) {
      this.gridButton?.click();
      return;
    }
    this.spotlightButton?.click();
  }

  public setPipMode(pip: boolean) {
    this._pipMode = pip;
  }

  public toggleReactions() {
    this.reactionsButton?.click();
  }

  public toggleSettings() {
    this.settingsButton?.click();
  }

  /**
   * Focus a specific participant's camera tile in Element Call.
   *
   * EC renders video tiles as `[data-testid="videoTile"]`. Each tile wraps a
   * mute-status indicator with `aria-label` set to the participant's Matrix
   * user ID. We find the tile containing that user, switch to spotlight mode
   * if needed, then click the tile so EC's internal focus handler runs.
   *
   * Falls back to a plain spotlight toggle if the tile is not found (e.g. the
   * participant has their camera off and EC didn't render a video tile for
   * them yet).
   */
  public focusCameraParticipant(userId: string): void {
    const doc = this.document;
    if (!doc) return;

    // EC labels participant tiles inconsistently across versions — the user's
    // matrix id may be the full aria-label, a substring of it, or carried on a
    // data attribute (and sometimes the visible label is the display name, not
    // the id at all). Try several strategies before giving up, then walk up to
    // the enclosing video tile.
    const findTile = (): HTMLElement | undefined => {
      const escaped = CSS.escape(userId);
      const el =
        doc.querySelector<HTMLElement>(`[aria-label="${escaped}"]`) ??
        doc.querySelector<HTMLElement>(`[data-testid="videoTile"][aria-label*="${escaped}"]`) ??
        doc.querySelector<HTMLElement>(`[aria-label*="${escaped}"]`) ??
        doc.querySelector<HTMLElement>(`[data-member-id="${escaped}"]`) ??
        doc.querySelector<HTMLElement>(`[data-id="${escaped}"]`) ??
        undefined;
      return (
        el?.closest<HTMLElement>('[data-testid="videoTile"]') ??
        el?.closest<HTMLElement>('[data-video-fit]') ??
        el ??
        undefined
      );
    };

    const applyFocus = () => {
      const tile = findTile();
      if (tile) {
        tile.click();
      } else if (import.meta.env.DEV) {
        console.warn(`[CallControl] focusCameraParticipant: no tile matched ${userId}`);
      }
    };

    if (this.spotlight) {
      // Already in spotlight — pin immediately.
      applyFocus();
      return;
    }

    // Switching to spotlight re-renders EC's layout asynchronously; clicking the
    // tile in the same tick would land in the old (grid) DOM. A fixed frame
    // delay is unreliable (EC's React commit can exceed it on slow devices), so
    // watch the iframe DOM for a spotlight video tile to mount, then focus —
    // with a hard timeout so the click is always attempted at least once.
    this.spotlightButton?.click();

    const tileSelector = '[data-testid="videoTile"]';
    let settled = false;
    let observer: MutationObserver | undefined;
    let timer: ReturnType<typeof setTimeout> | undefined;
    const finish = () => {
      if (settled) return;
      settled = true;
      if (timer) clearTimeout(timer);
      observer?.disconnect();
      applyFocus();
    };
    observer = new MutationObserver(() => {
      if (doc.querySelector(tileSelector)) finish();
    });
    observer.observe(doc.body, { childList: true, subtree: true });
    timer = setTimeout(finish, 600);
    // A tile may already be present immediately after toggling spotlight.
    if (doc.querySelector(tileSelector)) finish();
  }

  public dispose() {
    this.bodyMutationObserver.disconnect();
    this.controlMutationObserver.disconnect();
  }

  private emitStateUpdate() {
    this.emit(CallControlEvent.StateUpdate);
  }
}