/**
 * Initializes a new instance of the `DailyCallManager` class, creating
 * a Daily.co call object and setting initial states for camera and
 * microphone muting, as well as the current room URL. It then calls the
 * `initialize` method to set up event listeners and UI interactions.
 */
class DailyCallManager {
  constructor() {
    this.call = Daily.createCallObject();
    this.currentRoomUrl = null;
    this.initialize();
  }

  /**
   * Performs initial setup of event listeners and UI component interactions.
   */
  async initialize() {
    this.setupEventListeners();
    document
      .getElementById("toggle-camera")
      .addEventListener("click", () => this.toggleCamera());
    document
      .getElementById("toggle-mic")
      .addEventListener("click", () => this.toggleMicrophone());
  }

  /**
   * Configures event listeners for various call-related events.
   */
  setupEventListeners() {
    const events = {
      "active-speaker-change": this.handleActiveSpeakerChange.bind(this),
      error: this.handleError.bind(this),
      "joined-meeting": this.handleJoin.bind(this),
      "left-meeting": this.handleLeave.bind(this),
      "participant-joined": this.handleParticipantJoinedOrUpdated.bind(this),
      "participant-left": this.handleParticipantLeft.bind(this),
      "participant-updated": this.handleParticipantJoinedOrUpdated.bind(this),
    };

    Object.entries(events).forEach(([event, handler]) => {
      this.call.on(event, handler);
    });
  }

  /**
   * Handler for the local participant joining:
   * - Prints the room URL
   * - Enables the toggle camera, toggle mic, and leave buttons
   * - Gets the initial track states
   * - Sets up and enables the device selectors
   * @param {Object} event - The joined-meeting event object.
   */
  handleJoin(event) {
    const tracks = event.participants.local.tracks;

    console.log(`Successfully joined: ${this.currentRoomUrl}`);

    // Update the participant count
    this.updateAndDisplayParticipantCount();

    // Enable the leave button
    document.getElementById("leave-btn").disabled = false;

    // Enable the toggle camera and mic buttons and selectors
    document.getElementById("toggle-camera").disabled = false;
    document.getElementById("toggle-mic").disabled = false;
    document.getElementById("camera-selector").disabled = false;
    document.getElementById("mic-selector").disabled = false;

    // Set up the camera and mic selectors
    this.setupDeviceSelectors();

    // Initialize the camera and microphone states and UI for the local
    // participant
    Object.entries(tracks).forEach(([trackType, trackInfo]) => {
      this.updateUiForDevicesState(trackType, trackInfo);
    });
  }

  /**
   * Handler for participant leave events:
   * - Confirms leaving with a console message
   * - Disable the toggle camera and mic buttons
   * - Resets the camera and mic selectors
   * - Updates the call state in the UI
   * - Removes all video containers
   */
  handleLeave() {
    console.log("Successfully left the call");

    // Update the join and leave button states
    document.getElementById("leave-btn").disabled = true;
    document.getElementById("join-btn").disabled = false;

    // Disable the toggle camera and mic buttons
    document.getElementById("toggle-camera").disabled = true;
    document.getElementById("toggle-mic").disabled = true;

    // Reset and disable the camera and mic selectors
    const cameraSelector = document.getElementById("camera-selector");
    const micSelector = document.getElementById("mic-selector");
    cameraSelector.selectedIndex = 0;
    micSelector.selectedIndex = 0;
    cameraSelector.disabled = true;
    micSelector.disabled = true;

    // Update the call state in the UI
    document.getElementById("camera-state").textContent = "Camera: Off";
    document.getElementById("mic-state").textContent = "Mic: Off";
    document.getElementById(
      "participant-count"
    ).textContent = `Participants: 0`;
    document.getElementById(
      "active-speaker"
    ).textContent = `Active Speaker: None`;

    // Remove all video containers
    const videosDiv = document.getElementById("videos");
    while (videosDiv.firstChild) {
      videosDiv.removeChild(videosDiv.firstChild);
    }
  }

  /**
   * Handles fatal errors emitted from the Daily call object.
   * These errors result in the participant leaving the meeting. A
   * `left-meeting` event will also be sent, so we still rely on that event
   * for cleanup.
   * @param {Object} e - The error event object.
   */
  handleError(e) {
    console.error("DAILY SENT AN ERROR!", e.error ? e.error : e.errorMsg);
  }

  /**
   * Handles participant-left event:
   * - Cleans up the video and audio tracks for the participant
   * - Removes the related UI elements
   * @param {Object} event - The participant-left event object.
   */
  handleParticipantLeft(event) {
    const participantId = event.participant.session_id;

    // Clean up the video and audio tracks for the participant
    this.destroyTracks(["video", "audio"], participantId);

    // Now, remove the related video UI
    document.getElementById(`video-container-${participantId}`)?.remove();

    // Update the participant count
    this.updateAndDisplayParticipantCount();
  }

  /**
   * Handles participant-joined and participant-updated events:
   * - Updates the participant count
   * - Creates a video container for new participants
   * - Creates an audio element for new participants
   * - Manages video and audio tracks based on their current state
   * - Updates device states for the local participant
   * @param {Object} event - The participant-joined, participant-updated
   * event object.
   */
  handleParticipantJoinedOrUpdated(event) {
    const { participant } = event;
    const participantId = participant.session_id;
    const isLocal = participant.local;
    const tracks = participant.tracks;

    // Always update the participant count regardless of the event action
    this.updateAndDisplayParticipantCount();

    // Create a video container if one doesn't exist
    if (!document.getElementById(`video-container-${participantId}`)) {
      this.createVideoContainer(participantId);
    }

    // Create an audio element for non-local participants if one doesn't exist
    if (!document.getElementById(`audio-${participantId}`) && !isLocal) {
      this.createAudioElement(participantId);
    }

    Object.entries(tracks).forEach(([trackType, trackInfo]) => {
      // If a persistentTrack exists...
      if (trackInfo.persistentTrack) {
        // Check if this is the local participant's audio track.
        // If so, we will skip playing it, as it's already being played.
        // We'll start or update tracks in all other cases.
        if (!(isLocal && trackType === "audio")) {
          this.startOrUpdateTrack(trackType, trackInfo, participantId);
        }
      } else {
        // If the track is not available, remove the media element
        this.destroyTracks([trackType], participantId);
      }

      // Update the video UI based on the track's state
      if (trackType === "video") {
        this.updateVideoUi(trackInfo, participantId);
      }

      // Update the camera and microphone states for the local user based on
      // the track's state
      if (isLocal) {
        this.updateUiForDevicesState(trackType, trackInfo);
      }
    });
  }

  /**
   * Updates the UI with the current active speaker's identity.
   * @param {Object} event - The active speaker change event object.
   */
  handleActiveSpeakerChange(event) {
    document.getElementById(
      "active-speaker"
    ).textContent = `Active Speaker: ${event.activeSpeaker.peerId}`;
  }

  /**
   * Tries to join a call with provided room URL and optional join token.
   * @param {string} roomUrl - The URL of the room to join.
   * @param {string|null} joinToken - An optional token for joining the room.
   */
  async joinRoom(roomUrl, joinToken = null) {
    if (!roomUrl) {
      console.error("Room URL is required to join a room.");
      return;
    }

    this.currentRoomUrl = roomUrl;

    const joinOptions = { url: roomUrl };
    if (joinToken) {
      joinOptions.token = joinToken;
      console.log("Joining with a token.");
    } else {
      console.log("Joining without a token.");
    }

    try {
      // Disable the join button to prevent multiple attempts to join
      document.getElementById("join-btn").disabled = true;
      // Join the room
      await this.call.join(joinOptions);
    } catch (e) {
      console.error("Join failed:", e);
    }
  }

  /**
   * Creates and sets up a new video container for a specific participant. This
   * function dynamically generates a video element along with a container and
   * an overlay displaying the participant's ID. The newly created elements are
   * appended to a designated parent in the DOM, preparing them for video
   * streaming or playback related to the specified participant.
   *
   * @param {string} participantId - The unique identifier for the participant.
   */
  createVideoContainer(participantId) {
    // Create a video container for the participant
    const videoContainer = document.createElement("div");
    videoContainer.id = `video-container-${participantId}`;
    videoContainer.className = "video-container";
    document.getElementById("videos").appendChild(videoContainer);

    // Add an overlay to display the participant's session ID
    // const sessionIdOverlay = document.createElement("div");
    //  sessionIdOverlay.className = "session-id-overlay";
    //  sessionIdOverlay.textContent = participantId;
    //  videoContainer.appendChild(sessionIdOverlay);

    // Create a video element for the participant
    const videoEl = document.createElement("video");
    videoEl.className = "video-element";
    videoContainer.appendChild(videoEl);
  }

  /**
   * Creates an audio element for a particular participant. This function is
   * responsible for dynamically generating a standalone audio element that can
   * be used to play audio streams associated with the specified participant.
   * The audio element is appended directly to the document body or a relevant
   * container, thereby preparing it for playback of the participant's audio.
   *
   * @param {string} participantId - A unique identifier corresponding to the participant.
   */
  createAudioElement(participantId) {
    // Create an audio element for the participant
    const audioEl = document.createElement("audio");
    audioEl.id = `audio-${participantId}`;
    document.body.appendChild(audioEl);
  }

  /**
   * Updates the media track (audio or video) source for a specific participant
   * and plays the updated track. It checks if the source track needs to be
   * updated and performs the update if necessary, ensuring playback of the
   * media track.
   *
   * @param {string} trackType - Specifies the type of track to update ('audio'
   * or 'video'), allowing the function to dynamically adapt to the track being
   * processed.
   * @param {Object} track - Contains the media track data, including the
   * `persistentTrack` property which holds the actual MediaStreamTrack to be
   * played or updated.
   * @param {string} participantId - Identifies the participant whose media
   * track is being updated.
   */
  startOrUpdateTrack(trackType, track, participantId) {
    // Construct the selector string or ID based on the trackType.
    const selector =
      trackType === "video"
        ? `#video-container-${participantId} video.video-element`
        : `audio-${participantId}`;

    // Retrieve the specific media element from the DOM.
    const trackEl =
      trackType === "video"
        ? document.querySelector(selector)
        : document.getElementById(selector);

    // Error handling if the target media element does not exist.
    if (!trackEl) {
      console.error(
        `${trackType} element does not exist for participant: ${participantId}`
      );
      return;
    }

    // Check for the need to update the media source. This is determined by
    // checking whether the existing srcObject's tracks include the new
    // persistentTrack. If there are no existing tracks or the new track is not
    // among them, an update is necessary.
    const existingTracks = trackEl.srcObject?.getTracks();
    const needsUpdate = !existingTracks?.includes(track.persistentTrack);

    // Perform the media source update if needed by setting the srcObject of
    // the target element to a new MediaStream containing the provided
    // persistentTrack.
    if (needsUpdate) {
      trackEl.srcObject = new MediaStream([track.persistentTrack]);

      // Once the media metadata is loaded, attempts to play the track. Error
      // handling for play failures is included to catch and log issues such as
      // autoplay policies blocking playback.
      trackEl.onloadedmetadata = () => {
        trackEl
          .play()
          .catch((e) =>
            console.error(
              `Error playing ${trackType} for participant ${participantId}:`,
              e
            )
          );
      };
    }
  }

  /**
   * Shows or hides the video element for a participant, including managing
   * the visibility of the video based on the track state.
   * @param {Object} track - The video track object.
   * @param {string} participantId - The ID of the participant.
   */
  updateVideoUi(track, participantId) {
    let videoEl = document
      .getElementById(`video-container-${participantId}`)
      .querySelector("video.video-element");

    switch (track.state) {
      case "off":
      case "interrupted":
      case "blocked":
        videoEl.style.display = "none"; // Hide video but keep container
        break;
      case "playable":
      default:
        // Here we handle all other states the same as we handle 'playable'.
        // In your code, you may choose to handle them differently.
        videoEl.style.display = "";
        break;
    }
  }

  /**
   * Cleans up specified media track types (e.g., 'video', 'audio') for a given
   * participant by stopping the tracks and removing their corresponding
   * elements from the DOM. This is essential for properly managing resources
   * when participants leave or change their track states.
   * @param {Array} trackTypes - An array of track types to destroy, e.g.,
   * ['video', 'audio'].
   * @param {string} participantId - The ID of the participant.
   */
  destroyTracks(trackTypes, participantId) {
    trackTypes.forEach((trackType) => {
      const elementId = `${trackType}-${participantId}`;
      const element = document.getElementById(elementId);
      if (element) {
        element.srcObject = null; // Release media resources
        element.parentNode.removeChild(element); // Remove element from the DOM
      }
    });
  }

  /**
   * Toggles the local video track's mute state.
   */
  toggleCamera() {
    this.call.setLocalVideo(!this.call.localVideo());
  }

  /**
   * Toggles the local audio track's mute state.
   */
  toggleMicrophone() {
    this.call.setLocalAudio(!this.call.localAudio());
  }

  /**
   * Updates the UI to reflect the current states of the local participant's
   * camera and microphone.
   * @param {string} trackType - The type of track, either 'video' for cameras
   * or 'audio' for microphones.
   * @param {Object} trackInfo - The track object.
   */
  updateUiForDevicesState(trackType, trackInfo) {
    // For video, set the camera state
    if (trackType === "video") {
      document.getElementById("camera-state").textContent = `Camera: ${
        this.call.localVideo() ? "On" : "Off"
      }`;
    } else if (trackType === "audio") {
      // For audio, set the mic state
      document.getElementById("mic-state").textContent = `Mic: ${
        this.call.localAudio() ? "On" : "Off"
      }`;
    }
  }

  /**
   * Sets up device selectors for cameras and microphones by dynamically
   * populating them with available devices and attaching event listeners to
   * handle device selection changes.
   */
  async setupDeviceSelectors() {
    // Fetch current input devices settings and an array of available devices.
    const selectedDevices = await this.call.getInputDevices();
    const { devices: allDevices } = await this.call.enumerateDevices();

    // Element references for camera and microphone selectors.
    const selectors = {
      videoinput: document.getElementById("camera-selector"),
      audioinput: document.getElementById("mic-selector"),
    };

    // Prepare selectors by clearing existing options and adding a
    // non-selectable prompt.
    Object.values(selectors).forEach((selector) => {
      selector.innerHTML = "";
      const promptOption = new Option(
        `Select a ${selector.id.includes("camera") ? "camera" : "microphone"}`,
        "",
        true,
        true
      );
      promptOption.disabled = true;
      selector.appendChild(promptOption);
    });

    // Create and append options to the selectors based on available devices.
    allDevices.forEach((device) => {
      if (device.label && selectors[device.kind]) {
        const isSelected =
          selectedDevices[device.kind === "videoinput" ? "camera" : "mic"]
            .deviceId === device.deviceId;
        const option = new Option(
          device.label,
          device.deviceId,
          isSelected,
          isSelected
        );
        selectors[device.kind].appendChild(option);
      }
    });

    // Listen for user device change requests.
    Object.entries(selectors).forEach(([deviceKind, selector]) => {
      selector.addEventListener("change", async (e) => {
        const deviceId = e.target.value;
        const deviceOptions = {
          [deviceKind === "videoinput" ? "videoDeviceId" : "audioDeviceId"]:
            deviceId,
        };
        await this.call.setInputDevicesAsync(deviceOptions);
      });
    });
  }

  /**
   * Updates the UI with the current number of participants.
   * This method combines getting the participant count and updating the UI.
   */
  updateAndDisplayParticipantCount() {
    const participantCount =
      this.call.participantCounts().present +
      this.call.participantCounts().hidden;
    document.getElementById(
      "participant-count"
    ).textContent = `Participants: ${participantCount}`;
  }

  /**
   * Leaves the call and performs necessary cleanup operations like removing
   * video elements.
   */
  async leave() {
    try {
      await this.call.leave();
      document.querySelectorAll("#videos video, audio").forEach((el) => {
        el.srcObject = null; // Release media resources
        el.remove(); // Remove the element from the DOM
      });
    } catch (e) {
      console.error("Leaving failed", e);
    }
  }
}

/**
 * Main entry point: Setup and event listener bindings after the DOM is fully
 * loaded.
 */ /**
 * Main entry point: Setup and event listener bindings after the DOM is fully loaded.
 */

document.addEventListener("DOMContentLoaded", async () => {
  const dailyCallManager = new DailyCallManager();

  // Extract the room URL from query parameters if available
  const urlParams = new URLSearchParams(window.location.search);
  const roomUrlParam = urlParams.get("room_url");

  if (roomUrlParam) {
    document.getElementById("room-url").value = roomUrlParam.trim();
  }

  // Bind the join call action to the join button.
  document
    .getElementById("join-btn")
    .addEventListener("click", async function () {
      const roomUrl = document.getElementById("room-url").value.trim();
      const joinToken =
        document.getElementById("join-token").value.trim() || null;
      await dailyCallManager.joinRoom(roomUrl, joinToken);
    });

  // Bind the leave call action to the leave button.
  document.getElementById("leave-btn").addEventListener("click", function () {
    dailyCallManager.leave();
  });
});