import { CommonModule } from '@angular/common';
import { Component, computed, effect, ElementRef, inject, NgZone, OnDestroy, signal, ViewChild } from '@angular/core';
import { toSignal } from '@angular/core/rxjs-interop';
import { FormsModule } from '@angular/forms';
import { ActivatedRoute, Router, RouterLink } from '@angular/router';

import { PeerCallModalComponent } from './peer-call-modal.component';
import { ChatSessionService } from './chat-session.service';
import { JsonFileViewerComponent } from './json-file-viewer.component';
import type { CallMode, ChatEntry, ConnectionState, PeerSummary } from './models';

@Component({
  selector: 'app-chat-page',
  imports: [
    CommonModule,
    FormsModule,
    RouterLink,
    JsonFileViewerComponent,
    PeerCallModalComponent,
  ],
  templateUrl: './chat-page.component.html',
  styleUrl: './chat-page.component.scss',
})
export class ChatPageComponent implements OnDestroy {
  private readonly graphemeSegmenter = typeof Intl !== 'undefined' && 'Segmenter' in Intl
    ? new Intl.Segmenter(undefined, { granularity: 'grapheme' })
    : null;
  private readonly route = inject(ActivatedRoute);
  private readonly router = inject(Router);
  private readonly ngZone = inject(NgZone);
  private readonly routeParamMap = toSignal(this.route.paramMap, {
    initialValue: this.route.snapshot.paramMap,
  });
  private composerSelectionStart = 0;
  private composerSelectionEnd = 0;
  private voiceRecorder: MediaRecorder | null = null;
  private voiceStream: MediaStream | null = null;
  private voiceChunks: Blob[] = [];
  private discardRecordedVoice = false;
  private recordingPeerId: string | null = null;
  private dictationRecorder: MediaRecorder | null = null;
  private dictationStream: MediaStream | null = null;
  private dictationChunks: Blob[] = [];
  private dictationBaseText = '';
  private discardRecordedDictation = false;
  private dictationCompletionPromise: Promise<void> | null = null;
  private resolveDictationCompletion: (() => void) | null = null;
  private dictationApplyToken = 0;
  private lastConversationSnapshot: { peerId: string; length: number; lastEntryId: string | null } | null = null;
  @ViewChild('callAudioElement')
  set callAudioElementRef(value: ElementRef<HTMLAudioElement> | undefined) {
    this.callAudioElement = value;
    this.syncCallAudioSource();
  }
  private callAudioElement?: ElementRef<HTMLAudioElement>;
  @ViewChild('conversationContainer')
  set conversationContainerRef(value: ElementRef<HTMLDivElement> | undefined) {
    this.conversationContainer = value;
  }
  private conversationContainer?: ElementRef<HTMLDivElement>;
  @ViewChild('fullscreenConversationContainer')
  set fullscreenConversationContainerRef(value: ElementRef<HTMLDivElement> | undefined) {
    this.fullscreenConversationContainer = value;
  }
  private fullscreenConversationContainer?: ElementRef<HTMLDivElement>;

  messageText = '';
  readonly forwardingEntryId = signal<string | null>(null);
  readonly callChoicePeerId = signal<string | null>(null);
  readonly conversationModalOpen = signal(false);
  readonly peerDropdownOpen = signal(false);
  readonly emojiPickerOpen = signal(false);
  readonly isRecordingVoice = signal(false);
  readonly isDictating = signal(false);
  readonly isTranscribingDictation = signal(false);
  readonly emojiOptions = [
    '😀', '😁', '😂', '🤣', '😊',
    '😉', '😍', '😘', '😎', '🤔',
    '😅', '😭', '😡', '😴', '🙃',
    '👍', '👎', '👏', '🙏', '🤝',
    '🎉', '🔥', '❤️', '💡', '✅',
    '🚀', '👀', '📹', '📎', '💬',
    '🌍', '⚡', '⭐', '🎵', '📷',
    '🗑️', '⏩', '🛑', '🙌', '👌',
  ];
  readonly peerId = computed(() => this.routeParamMap().get('peerId') ?? '');
  readonly peer = computed(() => this.session.peers().find((item) => item.id === this.peerId()) ?? null);
  readonly displayedPeer = computed(() => this.peer() ?? this.session.peers()[0] ?? null);
  readonly currentUser = computed(() => this.session.currentUser());
  readonly callModalPeerId = computed(() =>
    this.session.activeVoiceCallPeerId()
      ?? this.session.incomingVoiceCallPeerId()
      ?? this.session.outgoingVoiceCallPeerId()
      ?? null,
  );
  readonly callModalPeer = computed(() => {
    const peerId = this.callModalPeerId();

    return peerId ? this.session.peers().find((peer) => peer.id === peerId) ?? null : null;
  });
  readonly callChoicePeer = computed(() => {
    const peerId = this.callChoicePeerId();

    return peerId ? this.session.peers().find((peer) => peer.id === peerId) ?? null : null;
  });
  readonly conversation = computed(() =>
    this.session
      .messages()
      .filter((entry) => entry.peerId === this.peerId()),
  );
  readonly remoteCallAudioStream = computed(() =>
    this.session.remoteAudioStreamForPeer(this.callModalPeerId() ?? ''),
  );
  readonly callModalMode = computed<CallMode>(() => this.session.callModeForPeer(this.callModalPeerId() ?? '') ?? 'video');
  readonly localCallStream = computed(() => this.session.localCallStreamForPeer(this.callModalPeerId() ?? ''));
  readonly remoteCallVideoStream = computed(() => this.session.remoteVideoStreamForPeer(this.callModalPeerId() ?? ''));
  readonly callModalVisible = computed(() => !!this.callModalPeer());
  readonly callModalState = computed<'incoming' | 'outgoing' | 'active'>(() => {
    const peerId = this.callModalPeerId();

    if (!peerId) {
      return 'active';
    }

    if (this.session.incomingVoiceCallPeerId() === peerId) {
      return 'incoming';
    }

    if (this.session.outgoingVoiceCallPeerId() === peerId) {
      return 'outgoing';
    }

    return 'active';
  });
  readonly callModalStatusText = computed(() => {
    const peer = this.callModalPeer();

    if (!peer) {
      return '';
    }

    switch (this.callModalState()) {
      case 'incoming':
        return `${peer.displayName} is calling you${this.callModalMode() === 'audio' ? ' with audio only.' : '.'}`;
      case 'outgoing':
        return this.callModalMode() === 'audio'
          ? 'Calling… your microphone is ready.'
          : 'Calling… your camera and microphone are ready.';
      default:
        return this.callModalMode() === 'audio'
          ? 'Connected with live audio.'
          : 'Connected with live video and audio.';
    }
  });
  readonly selectedPeerVoiceCallState = computed<'idle' | 'incoming' | 'outgoing' | 'active'>(() => {
    const peerId = this.peerId();

    if (!peerId) {
      return 'idle';
    }

    if (this.session.activeVoiceCallPeerId() === peerId) {
      return 'active';
    }

    if (this.session.outgoingVoiceCallPeerId() === peerId) {
      return 'outgoing';
    }

    if (this.session.incomingVoiceCallPeerId() === peerId) {
      return 'incoming';
    }

    return 'idle';
  });
  readonly canStartSelectedVoiceCall = computed(() => {
    const selectedPeer = this.peer();

    if (!selectedPeer || selectedPeer.channelState !== 'open') {
      return false;
    }

    const activePeerId = this.session.activeVoiceCallPeerId();
    const outgoingPeerId = this.session.outgoingVoiceCallPeerId();
    const incomingPeerId = this.session.incomingVoiceCallPeerId();

    return !activePeerId && !outgoingPeerId && !incomingPeerId;
  });
  readonly canEndSelectedVoiceCall = computed(() => {
    const peerId = this.peerId();

    return !!peerId && (
      this.session.activeVoiceCallPeerId() === peerId ||
      this.session.outgoingVoiceCallPeerId() === peerId
    );
  });
  readonly webRtcState = computed<ConnectionState>(() => {
    const selectedPeer = this.peer();

    if (!selectedPeer) {
      return 'disconnected';
    }

    if (selectedPeer.channelState === 'open' || selectedPeer.connectionState === 'connected') {
      return 'connected';
    }

    if (selectedPeer.channelState === 'connecting' || selectedPeer.connectionState === 'connecting') {
      return 'connecting';
    }

    return 'disconnected';
  });

  constructor(readonly session: ChatSessionService) {
    if (!this.session.currentUser()) {
      void this.router.navigateByUrl('/');
    }

    effect(() => {
      const peerId = this.peerId();

      if (!peerId) {
        return;
      }

      this.session.selectPeer(peerId);
      void this.session.connectToPeer(peerId);
    });

    effect(() => {
      this.remoteCallAudioStream();
      this.syncCallAudioSource();
    });

    effect(() => {
      const peerId = this.peerId();
      const entries = this.conversation();
      const snapshot = {
        peerId,
        length: entries.length,
        lastEntryId: entries.at(-1)?.id ?? null,
      };
      const previousSnapshot = this.lastConversationSnapshot;

      this.lastConversationSnapshot = snapshot;

      if (!peerId || !previousSnapshot || previousSnapshot.peerId !== peerId) {
        return;
      }

      const hasNewTailEntry = snapshot.length > previousSnapshot.length
        || (snapshot.length > 0 && snapshot.lastEntryId !== previousSnapshot.lastEntryId);

      if (!hasNewTailEntry) {
        return;
      }

      this.scrollConversationToBottom();
    });
  }

  ngOnDestroy(): void {
    void this.stopDictation(true);
    this.stopVoiceRecording(true);
    this.detachCallAudioSource();
  }

  async ensureConnection(): Promise<void> {
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    this.session.selectPeer(peerId);
    await this.session.connectToPeer(peerId);
  }

  async sendMessage(): Promise<void> {
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    await this.stopDictation(false);
    await this.session.sendText(peerId, this.messageText);
    this.messageText = '';
    this.emojiPickerOpen.set(false);
    this.composerSelectionStart = 0;
    this.composerSelectionEnd = 0;
  }

  async requestGeneratedImage(): Promise<void> {
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    await this.stopDictation(false);
    const requested = await this.session.requestGeneratedImage(peerId, this.messageText);

    if (!requested) {
      return;
    }

    this.messageText = '';
    this.handleMessageTextChange('');
    this.emojiPickerOpen.set(false);
    this.composerSelectionStart = 0;
    this.composerSelectionEnd = 0;
  }

  handleComposerEnter(event: Event): void {
    if (!(event instanceof KeyboardEvent) || event.shiftKey) {
      return;
    }

    event.preventDefault();
    void this.sendMessage();
  }

  handleMessageTextChange(text: string): void {
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    this.session.notifyTypingActivity(peerId, text);
  }

  trackComposerSelection(textarea: HTMLTextAreaElement): void {
    this.composerSelectionStart = textarea.selectionStart ?? this.messageText.length;
    this.composerSelectionEnd = textarea.selectionEnd ?? this.composerSelectionStart;
  }

  toggleEmojiPicker(event?: Event): void {
    event?.stopPropagation();
    this.emojiPickerOpen.update((open) => !open);
  }

  insertEmoji(emoji: string, textarea: HTMLTextAreaElement): void {
    const selectionStart = textarea.selectionStart ?? this.composerSelectionStart;
    const selectionEnd = textarea.selectionEnd ?? this.composerSelectionEnd;
    const before = this.messageText.slice(0, selectionStart);
    const after = this.messageText.slice(selectionEnd);

    this.messageText = `${before}${emoji}${after}`;
    this.emojiPickerOpen.set(false);
    this.handleMessageTextChange(this.messageText);

    const nextSelection = selectionStart + emoji.length;
    this.composerSelectionStart = nextSelection;
    this.composerSelectionEnd = nextSelection;

    queueMicrotask(() => {
      textarea.focus();
      textarea.setSelectionRange(nextSelection, nextSelection);
      this.trackComposerSelection(textarea);
    });
  }

  openCallChoice(peerId: string): void {
    if (!peerId) {
      return;
    }

    this.callChoicePeerId.set(peerId);
  }

  closeCallChoice(): void {
    this.callChoicePeerId.set(null);
  }

  async startSelectedCall(mode: CallMode): Promise<void> {
    const peerId = this.callChoicePeerId() ?? this.peerId();

    if (!peerId) {
      return;
    }

    this.callChoicePeerId.set(null);
    await this.session.startVoiceCall(peerId, mode);
  }

  async sendFile(peerId: string, input: HTMLInputElement): Promise<void> {
    const file = input.files?.item(0);

    if (!file) {
      return;
    }

    await this.session.sendFile(peerId, file);
    input.value = '';
  }

  async toggleDictation(textarea: HTMLTextAreaElement): Promise<void> {
    if (this.isDictating()) {
      await this.stopDictation(false);
      return;
    }

    if (this.isTranscribingDictation()) {
      return;
    }
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    if (typeof MediaRecorder === 'undefined' || typeof navigator === 'undefined') {
      this.session.error.set('This browser does not support dictation recording.');
      return;
    }

    if (typeof navigator.mediaDevices?.getUserMedia !== 'function') {
      this.session.error.set('This browser cannot access the microphone for dictation.');
      return;
    }

    this.dictationBaseText = this.messageText;
    this.discardRecordedDictation = false;
    this.dictationApplyToken += 1;

    try {
      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
      const preferredMimeType = this.preferredVoiceMimeType();
      const recorder = preferredMimeType
        ? new MediaRecorder(stream, { mimeType: preferredMimeType })
        : new MediaRecorder(stream);
      const applyToken = this.dictationApplyToken;

      this.dictationChunks = [];
      this.dictationStream = stream;
      this.dictationRecorder = recorder;
      this.dictationCompletionPromise = new Promise<void>((resolve) => {
        this.resolveDictationCompletion = resolve;
      });

      recorder.ondataavailable = (event) => {
        if (event.data.size > 0) {
          this.dictationChunks.push(event.data);
        }
      };

      recorder.onerror = () => {
        this.ngZone.run(() => {
          this.session.error.set('Could not record dictation audio.');
          this.cleanupDictationRecorder();
          this.finishDictationCompletion();
        });
      };

      recorder.onstop = () => {
        const shouldDiscard = this.discardRecordedDictation;
        const mimeType = recorder.mimeType || preferredMimeType || 'audio/webm';
        const blob = new Blob(this.dictationChunks, { type: mimeType });

        this.ngZone.run(() => {
          this.cleanupDictationRecorder();

          if (shouldDiscard || blob.size === 0) {
            this.finishDictationCompletion();
            return;
          }

          this.isTranscribingDictation.set(true);
          void this.transcribeDictation(blob, textarea, applyToken);
        });
      };

      recorder.start();
      this.isDictating.set(true);
      this.session.error.set(null);
    } catch {
      this.session.error.set('Could not start dictation recording.');
      this.cleanupDictationRecorder();
      this.finishDictationCompletion();
    }
  }

  async toggleVoiceRecording(): Promise<void> {
    if (this.isRecordingVoice()) {
      this.stopVoiceRecording(false);
      return;
    }

    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    if (typeof MediaRecorder === 'undefined' || typeof navigator === 'undefined') {
      this.session.error.set('This browser does not support voice recording.');
      return;
    }

    if (typeof navigator.mediaDevices?.getUserMedia !== 'function') {
      this.session.error.set('This browser cannot access the microphone.');
      return;
    }

    try {
      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
      const preferredMimeType = this.preferredVoiceMimeType();
      const recorder = preferredMimeType
        ? new MediaRecorder(stream, { mimeType: preferredMimeType })
        : new MediaRecorder(stream);

      this.voiceChunks = [];
      this.discardRecordedVoice = false;
      this.recordingPeerId = peerId;
      this.voiceStream = stream;
      this.voiceRecorder = recorder;

      recorder.ondataavailable = (event) => {
        if (event.data.size > 0) {
          this.voiceChunks.push(event.data);
        }
      };

      recorder.onerror = () => {
        this.session.error.set('Could not record voice message.');
        this.cleanupVoiceRecording();
      };

      recorder.onstop = () => {
        const shouldDiscard = this.discardRecordedVoice;
        const targetPeerId = this.recordingPeerId;
        const mimeType = recorder.mimeType || preferredMimeType || 'audio/webm';
        const blob = new Blob(this.voiceChunks, { type: mimeType });

        this.cleanupVoiceRecording();

        if (shouldDiscard || !targetPeerId || blob.size === 0) {
          return;
        }

        void this.session.sendVoiceMessage(targetPeerId, blob, mimeType);
      };

      recorder.start();
      this.isRecordingVoice.set(true);
      this.session.error.set(null);
    } catch {
      this.session.error.set('Could not start microphone recording.');
      this.cleanupVoiceRecording();
    }
  }

  async deleteMessage(entry: ChatEntry): Promise<void> {
    await this.session.deleteMessage(entry);
  }

  isEmojiOnlyEntry(entry: ChatEntry): boolean {
    if (entry.kind !== 'text' || entry.direction === 'system' || !entry.text?.trim()) {
      return false;
    }

    return entry.text
      .trim()
      .split(/\s+/u)
      .every((token) => this.isEmojiToken(token));
  }

  async deleteConversation(peerId: string, event?: Event): Promise<void> {
    event?.stopPropagation();
    await this.session.deleteConversation(peerId);
  }

  toggleForwardMenu(entry: ChatEntry, event?: Event): void {
    event?.stopPropagation();

    if (entry.kind === 'system' || entry.direction === 'system' || this.forwardTargets(entry).length === 0) {
      this.forwardingEntryId.set(null);
      return;
    }

    this.forwardingEntryId.update((currentEntryId) => (currentEntryId === entry.id ? null : entry.id));
  }

  isForwardMenuOpen(entryId: string): boolean {
    return this.forwardingEntryId() === entryId;
  }

  forwardTargets(entry: ChatEntry): PeerSummary[] {
    if (entry.kind === 'system' || entry.direction === 'system') {
      return [];
    }

    return this.session.peers().filter((peer) => peer.id !== entry.peerId);
  }

  togglePeerDropdown(): void {
    if (this.session.peers().length === 0) {
      return;
    }

    this.peerDropdownOpen.update((open) => !open);
  }

  closePeerDropdown(): void {
    this.peerDropdownOpen.set(false);
  }

  openConversationModal(): void {
    this.closePeerDropdown();
    this.conversationModalOpen.set(true);
    this.scrollConversationToBottom();
  }

  closeConversationModal(): void {
    this.conversationModalOpen.set(false);
  }

  async selectPeerFromDropdown(peerId: string): Promise<void> {
    this.closePeerDropdown();
    await this.switchPeer(peerId);
  }

  async forwardEntry(entry: ChatEntry, targetPeerId: string, select: HTMLSelectElement): Promise<void> {
    if (!targetPeerId) {
      return;
    }

    await this.session.forwardMessage(targetPeerId, entry);
    select.value = '';
    this.forwardingEntryId.set(null);
  }

  async sendGeneratedImage(entry: ChatEntry): Promise<void> {
    const peerId = this.peerId();

    if (!peerId) {
      return;
    }

    await this.session.sendGeneratedImageToPeer(entry, peerId);
  }

  async endVoiceCall(peerId: string): Promise<void> {
    await this.session.endVoiceCall(peerId);
  }

  async acceptIncomingVoiceCall(peerId: string): Promise<void> {
    if (!peerId) {
      return;
    }

    await this.session.acceptVoiceCall(peerId);
  }

  rejectIncomingVoiceCall(peerId: string): void {
    if (!peerId) {
      return;
    }

    this.session.rejectVoiceCall(peerId);
  }

  isImageEntry(entry: ChatEntry): boolean {
    return entry.kind === 'file' && !!entry.downloadUrl && (entry.fileMimeType?.startsWith('image/') ?? false);
  }

  isGeneratedImageEntry(entry: ChatEntry): boolean {
    return this.isImageEntry(entry) && entry.generatedByAi === true;
  }

  isVideoEntry(entry: ChatEntry): boolean {
    if (entry.kind !== 'file' || !entry.downloadUrl) {
      return false;
    }

    if (entry.fileMimeType?.startsWith('video/')) {
      return true;
    }

    return /\.(mp4|webm|ogg|ogv|mov|m4v)$/i.test(entry.fileName ?? '');
  }

  isIncomingJsonFileEntry(entry: ChatEntry): boolean {
    return (
      entry.kind === 'file' &&
      entry.direction === 'incoming' &&
      !!entry.downloadUrl &&
      !!entry.fileName &&
      entry.fileName.toLowerCase().endsWith('.json')
    );
  }

  hasDocumentPreviewImage(entry: ChatEntry): boolean {
    return (
      entry.kind === 'file' &&
      !!entry.previewDownloadUrl &&
      (entry.previewMimeType?.startsWith('image/') ?? false)
    );
  }

  documentPreviewImageUrl(entry: ChatEntry): string | null {
    if (!this.hasDocumentPreviewImage(entry)) {
      return null;
    }

    return entry.previewDownloadUrl ?? null;
  }

  isPeerTyping(peerId: string): boolean {
    return this.session.typingPeerIds().includes(peerId);
  }

  isPeerUnread(peerId: string): boolean {
    return this.session.unreadPeerIds().includes(peerId);
  }

  indicatorTone(state: ConnectionState): 'ok' | 'connecting' | 'offline' {
    if (state === 'connected') {
      return 'ok';
    }

    if (state === 'connecting') {
      return 'connecting';
    }

    return 'offline';
  }

  canReconnectWebRtc(): boolean {
    return this.indicatorTone(this.webRtcState()) === 'offline';
  }

  async switchPeer(peerId: string): Promise<void> {
    if (!peerId || peerId === this.peerId()) {
      return;
    }

    await this.stopDictation(true);
    this.stopVoiceRecording(true);
    this.forwardingEntryId.set(null);
    this.callChoicePeerId.set(null);
    this.conversationModalOpen.set(false);
    this.peerDropdownOpen.set(false);
    this.emojiPickerOpen.set(false);
    this.session.selectPeer(peerId);
    await this.router.navigate(['/chat', peerId]);
  }

  private stopVoiceRecording(discard: boolean): void {
    const recorder = this.voiceRecorder;

    if (!recorder) {
      this.discardRecordedVoice = discard;
      this.cleanupVoiceRecording();
      return;
    }

    this.discardRecordedVoice = discard;

    if (recorder.state !== 'inactive') {
      recorder.stop();
      return;
    }

    this.cleanupVoiceRecording();
  }

  private cleanupVoiceRecording(): void {
    if (this.voiceStream) {
      for (const track of this.voiceStream.getTracks()) {
        track.stop();
      }
    }

    this.voiceRecorder = null;
    this.voiceStream = null;
    this.voiceChunks = [];
    this.recordingPeerId = null;
    this.isRecordingVoice.set(false);
  }

  private preferredVoiceMimeType(): string {
    if (typeof MediaRecorder === 'undefined' || typeof MediaRecorder.isTypeSupported !== 'function') {
      return '';
    }

    const candidates = ['audio/webm;codecs=opus', 'audio/webm', 'audio/ogg;codecs=opus', 'audio/ogg'];

    return candidates.find((candidate) => MediaRecorder.isTypeSupported(candidate)) ?? '';
  }

  private async stopDictation(discard: boolean): Promise<void> {
    const completion = this.dictationCompletionPromise;

    if (discard) {
      this.dictationApplyToken += 1;
      this.messageText = this.dictationBaseText || this.messageText;
      this.handleMessageTextChange(this.messageText);
      this.isTranscribingDictation.set(false);
    } else {
      this.dictationBaseText = this.messageText;
    }

    if (this.dictationRecorder) {
      this.discardRecordedDictation = discard;

      if (this.dictationRecorder.state !== 'inactive') {
        this.dictationRecorder.stop();
      } else {
        this.cleanupDictationRecorder();
        this.finishDictationCompletion();
      }
    } else if (!completion) {
      this.dictationBaseText = '';
    }

    if (completion) {
      await completion;
    }
  }

  private cleanupDictationRecorder(): void {
    if (this.dictationStream) {
      for (const track of this.dictationStream.getTracks()) {
        track.stop();
      }
    }

    this.dictationRecorder = null;
    this.dictationStream = null;
    this.dictationChunks = [];
    this.discardRecordedDictation = false;
    this.isDictating.set(false);
  }

  private finishDictationCompletion(): void {
    this.resolveDictationCompletion?.();
    this.resolveDictationCompletion = null;
    this.dictationCompletionPromise = null;
    this.dictationBaseText = '';
  }

  private async transcribeDictation(blob: Blob, textarea: HTMLTextAreaElement, applyToken: number): Promise<void> {
    try {
      const transcript = await this.session.requestSpeechTranscription(blob);

      if (applyToken !== this.dictationApplyToken) {
        return;
      }

      this.applyDictatedText(this.mergeDictatedText(this.dictationBaseText, transcript), textarea);
    } catch {
      if (applyToken === this.dictationApplyToken) {
        this.session.error.set('Dictation transcription failed.');
      }
    } finally {
      if (applyToken === this.dictationApplyToken) {
        this.isTranscribingDictation.set(false);
      }

      this.finishDictationCompletion();
    }
  }

  private mergeDictatedText(baseText: string, transcript: string): string {
    const trimmedTranscript = transcript.trim();

    if (!trimmedTranscript) {
      return baseText;
    }

    if (!baseText.trim()) {
      return trimmedTranscript;
    }

    return `${baseText.trimEnd()} ${trimmedTranscript}`;
  }

  private applyDictatedText(text: string, textarea: HTMLTextAreaElement): void {
    this.messageText = text;
    textarea.value = text;
    this.composerSelectionStart = text.length;
    this.composerSelectionEnd = text.length;
    this.handleMessageTextChange(text);

    queueMicrotask(() => {
      textarea.focus();
      textarea.setSelectionRange(text.length, text.length);
    });
  }

  private syncCallAudioSource(): void {
    const audio = this.callAudioElement?.nativeElement;

    if (!audio) {
      return;
    }

    const stream = this.remoteCallAudioStream();

    audio.srcObject = stream;

    if (stream) {
      void audio.play().catch(() => {
        // Autoplay may wait for a browser gesture.
      });
      return;
    }

    audio.pause();
  }

  private detachCallAudioSource(): void {
    const audio = this.callAudioElement?.nativeElement;

    if (!audio) {
      return;
    }

    audio.pause();
    audio.srcObject = null;
  }

  private scrollConversationToBottom(): void {
    queueMicrotask(() => {
      requestAnimationFrame(() => {
        for (const container of [
          this.conversationContainer?.nativeElement,
          this.fullscreenConversationContainer?.nativeElement,
        ]) {
          if (!container) {
            continue;
          }

          container.scrollTop = container.scrollHeight;
        }
      });
    });
  }

  private isEmojiToken(token: string): boolean {
    if (!token) {
      return false;
    }

    const graphemes = this.graphemeSegmenter
      ? Array.from(this.graphemeSegmenter.segment(token), ({ segment }) => segment)
      : [token];

    return graphemes.every((grapheme) =>
      /[\p{Emoji}\p{Extended_Pictographic}\u20E3]/u.test(grapheme)
      && /^[\p{Emoji}\p{Emoji_Component}\p{Extended_Pictographic}\u200D\uFE0F\u20E3]+$/u.test(grapheme),
    );
  }
}