class VideoRTC extends HTMLElement {
  constructor() {
    super();

    this.DISCONNECT_TIMEOUT = 5000;
    this.RECONNECT_TIMEOUT = 30000;

    this.CODECS = [
      "avc1.640029", // H.264 high 4.1 (Chromecast 1st and 2nd Gen)
      "avc1.64002A", // H.264 high 4.2 (Chromecast 3rd Gen)
      "avc1.640033", // H.264 high 5.1 (Chromecast with Google TV)
      "hvc1.1.6.L153.B0", // H.265 main 5.1 (Chromecast Ultra)
      "mp4a.40.2", // AAC LC
      "mp4a.40.5", // AAC HE
      "flac", // FLAC (PCM compatible)
      "opus", // OPUS Chrome, Firefox
    ];

    /**
     * [config] Supported modes (webrtc, mse, mp4, mjpeg).
     * @type {string}
     */
    this.mode = "webrtc,mse,mp4,mjpeg";

    /**
     * [config] Run stream when not displayed on the screen. Default `false`.
     * @type {boolean}
     */
    this.background = false;

    /**
     * [config] Run stream only when player in the viewport. Stop when user scroll out player.
     * Value is percentage of visibility from `0` (not visible) to `1` (full visible).
     * Default `0` - disable;
     * @type {number}
     */
    this.visibilityThreshold = 0;

    /**
     * [config] Run stream only when browser page on the screen. Stop when user change browser
     * tab or minimise browser windows.
     * @type {boolean}
     */
    this.visibilityCheck = true;

    /**
     * [config] WebRTC configuration
     * @type {RTCConfiguration}
     */
    this.pcConfig = {
      iceServers: [{ urls: "stun:stun.l.google.com:19302" }],
      sdpSemantics: "unified-plan", // important for Chromecast 1
    };

    /**
     * [info] WebSocket connection state. Values: CONNECTING, OPEN, CLOSED
     * @type {number}
     */
    this.wsState = WebSocket.CLOSED;

    /**
     * [info] WebRTC connection state.
     * @type {number}
     */
    this.pcState = WebSocket.CLOSED;

    /**
     * @type {HTMLVideoElement}
     */
    this.video = null;

    /**
     * @type {WebSocket}
     */
    this.ws = null;

    /**
     * @type {string|URL}
     */
    this.wsURL = "";

    /**
     * @type {RTCPeerConnection}
     */
    this.pc = null;

    /**
     * @type {number}
     */
    this.connectTS = 0;

    /**
     * @type {string}
     */
    this.mseCodecs = "";

    /**
     * [internal] Disconnect TimeoutID.
     * @type {number}
     */
    this.disconnectTID = 0;

    /**
     * [internal] Reconnect TimeoutID.
     * @type {number}
     */
    this.reconnectTID = 0;

    /**
     * [internal] Handler for receiving Binary from WebSocket.
     * @type {Function}
     */
    this.ondata = null;

    /**
     * [internal] Handlers list for receiving JSON from WebSocket
     * @type {Object.<string,Function>}}
     */
    this.onmessage = null;
  }

  /**
   * Set video source (WebSocket URL). Support relative path.
   * @param {string|URL} value
   */
  set src(value) {
    if (typeof value !== "string") value = value.toString();
    if (value.startsWith("http")) {
      value = `ws${value.substring(4)}`;
    } else if (value.startsWith("/")) {
      value = `ws${location.origin.substring(4)}${value}`;
    }

    this.wsURL = value;

    this.onconnect();
  }

  /**
   * Play video. Support automute when autoplay blocked.
   * https://developer.chrome.com/blog/autoplay/
   */
  play() {
    this.video.play().catch((er) => {
      if (er.name === "NotAllowedError" && !this.video.muted) {
        this.video.muted = true;
        this.video.play().catch(() => {});
      }
    });
  }

  /**
   * Send message to server via WebSocket
   * @param {Object} value
   */
  send(value) {
    if (this.ws) this.ws.send(JSON.stringify(value));
  }

  /** @param {Function} isSupported */
  codecs(isSupported) {
    return this.CODECS.filter((codec) =>
      isSupported(`video/mp4; codecs="${codec}"`)
    ).join();
  }

  /**
   * `CustomElement`. Invoked each time the custom element is appended into a
   * document-connected element.
   */
  connectedCallback() {
    if (this.disconnectTID) {
      clearTimeout(this.disconnectTID);
      this.disconnectTID = 0;
    }

    // because video autopause on disconnected from DOM
    if (this.video) {
      const seek = this.video.seekable;
      if (seek.length > 0) {
        this.video.currentTime = seek.end(seek.length - 1);
      }
      this.play();
    } else {
      this.oninit();
    }

    this.onconnect();
  }

  /**
   * `CustomElement`. Invoked each time the custom element is disconnected from the
   * document's DOM.
   */
  disconnectedCallback() {
    if (this.background || this.disconnectTID) return;
    if (this.wsState === WebSocket.CLOSED && this.pcState === WebSocket.CLOSED)
      return;

    this.disconnectTID = setTimeout(() => {
      if (this.reconnectTID) {
        clearTimeout(this.reconnectTID);
        this.reconnectTID = 0;
      }

      this.disconnectTID = 0;

      this.ondisconnect();
    }, this.DISCONNECT_TIMEOUT);
  }

  /**
   * Creates child DOM elements. Called automatically once on `connectedCallback`.
   */
  oninit() {
    this.video = document.createElement("video");
    this.video.controls = true;
    this.video.playsInline = true;
    this.video.preload = "auto";
    this.video.muted = true;

    this.video.style.display = "block"; // fix bottom margin 4px
    this.video.style.width = "100%";
    this.video.style.height = "100%";

    this.appendChild(this.video);

    if (this.background) return;

    if ("hidden" in document && this.visibilityCheck) {
      document.addEventListener("visibilitychange", () => {
        if (document.hidden) {
          this.disconnectedCallback();
        } else if (this.isConnected) {
          this.connectedCallback();
        }
      });
    }

    if ("IntersectionObserver" in window && this.visibilityThreshold) {
      const observer = new IntersectionObserver(
        (entries) => {
          entries.forEach((entry) => {
            if (!entry.isIntersecting) {
              this.disconnectedCallback();
            } else if (this.isConnected) {
              this.connectedCallback();
            }
          });
        },
        { threshold: this.visibilityThreshold }
      );
      observer.observe(this);
    }
  }

  /**
   * Connect to WebSocket. Called automatically on `connectedCallback`.
   * @return {boolean} true if the connection has started.
   */
  onconnect() {
    if (!this.isConnected || !this.wsURL || this.ws || this.pc) return false;

    // CLOSED or CONNECTING => CONNECTING
    this.wsState = WebSocket.CONNECTING;

    this.connectTS = Date.now();

    this.ws = new WebSocket(this.wsURL);
    this.ws.binaryType = "arraybuffer";
    this.ws.addEventListener("open", (ev) => this.onopen(ev));
    this.ws.addEventListener("close", (ev) => this.onclose(ev));

    return true;
  }

  ondisconnect() {
    this.wsState = WebSocket.CLOSED;
    if (this.ws) {
      this.ws.close();
      this.ws = null;
    }

    this.pcState = WebSocket.CLOSED;
    if (this.pc) {
      this.pc.close();
      this.pc = null;
    }
  }

  /**
   * @returns {Array.<string>} of modes (mse, webrtc, etc.)
   */
  onopen() {
    // CONNECTING => OPEN
    this.wsState = WebSocket.OPEN;

    this.ws.addEventListener("message", (ev) => {
      if (typeof ev.data === "string") {
        const msg = JSON.parse(ev.data);
        for (const mode in this.onmessage) {
          this.onmessage[mode](msg);
        }
      } else {
        this.ondata(ev.data);
      }
    });

    this.ondata = null;
    this.onmessage = {};

    const modes = [];

    if (
      this.mode.indexOf("mse") >= 0 &&
      ("MediaSource" in window || "ManagedMediaSource" in window)
    ) {
      // iPhone
      modes.push("mse");
      this.onmse();
    } else if (this.mode.indexOf("mp4") >= 0) {
      modes.push("mp4");
      this.onmp4();
    }

    if (this.mode.indexOf("webrtc") >= 0 && "RTCPeerConnection" in window) {
      // macOS Desktop app
      modes.push("webrtc");
      this.onwebrtc();
    }

    if (this.mode.indexOf("mjpeg") >= 0) {
      if (modes.length) {
        this.onmessage["mjpeg"] = (msg) => {
          if (msg.type !== "error" || msg.value.indexOf(modes[0]) !== 0) return;
          this.onmjpeg();
        };
      } else {
        modes.push("mjpeg");
        this.onmjpeg();
      }
    }

    return modes;
  }

  /**
   * @return {boolean} true if reconnection has started.
   */
  onclose() {
    if (this.wsState === WebSocket.CLOSED) return false;

    // CONNECTING, OPEN => CONNECTING
    this.wsState = WebSocket.CONNECTING;
    this.ws = null;

    // reconnect no more than once every X seconds
    const delay = Math.max(
      this.RECONNECT_TIMEOUT - (Date.now() - this.connectTS),
      0
    );

    this.reconnectTID = setTimeout(() => {
      this.reconnectTID = 0;
      this.onconnect();
    }, delay);

    return true;
  }

  onmse() {
    /** @type {MediaSource} */
    let ms;

    if ("ManagedMediaSource" in window) {
      const MediaSource = window.ManagedMediaSource;

      ms = new MediaSource();
      ms.addEventListener(
        "sourceopen",
        () => {
          this.send({
            type: "mse",
            value: this.codecs(MediaSource.isTypeSupported),
          });
        },
        { once: true }
      );

      this.video.disableRemotePlayback = true;
      this.video.srcObject = ms;
    } else {
      ms = new MediaSource();
      ms.addEventListener(
        "sourceopen",
        () => {
          URL.revokeObjectURL(this.video.src);
          this.send({
            type: "mse",
            value: this.codecs(MediaSource.isTypeSupported),
          });
        },
        { once: true }
      );

      this.video.src = URL.createObjectURL(ms);
      this.video.srcObject = null;
    }
    this.play();

    this.mseCodecs = "";

    this.onmessage["mse"] = (msg) => {
      if (msg.type !== "mse") return;

      this.mseCodecs = msg.value;

      const sb = ms.addSourceBuffer(msg.value);
      sb.mode = "segments"; // segments or sequence
      sb.addEventListener("updateend", () => {
        if (sb.updating) return;

        try {
          if (bufLen > 0) {
            const data = buf.slice(0, bufLen);
            bufLen = 0;
            sb.appendBuffer(data);
          } else if (sb.buffered && sb.buffered.length) {
            const end = sb.buffered.end(sb.buffered.length - 1) - 15;
            const start = sb.buffered.start(0);
            if (end > start) {
              sb.remove(start, end);
              ms.setLiveSeekableRange(end, end + 15);
            }
            // console.debug("VideoRTC.buffered", start, end);
          }
        } catch (e) {
          // console.debug(e);
        }
      });

      const buf = new Uint8Array(2 * 1024 * 1024);
      let bufLen = 0;

      this.ondata = (data) => {
        if (sb.updating || bufLen > 0) {
          const b = new Uint8Array(data);
          buf.set(b, bufLen);
          bufLen += b.byteLength;
          // console.debug("VideoRTC.buffer", b.byteLength, bufLen);
        } else {
          try {
            sb.appendBuffer(data);
          } catch (e) {
            // console.debug(e);
          }
        }
      };
    };
  }

  onwebrtc() {
    const pc = new RTCPeerConnection(this.pcConfig);

    /** @type {HTMLVideoElement} */
    const video2 = document.createElement("video");
    video2.addEventListener("loadeddata", (ev) => this.onpcvideo(ev), {
      once: true,
    });

    pc.addEventListener("icecandidate", (ev) => {
      const candidate = ev.candidate ? ev.candidate.toJSON().candidate : "";
      this.send({ type: "webrtc/candidate", value: candidate });
    });

    pc.addEventListener("track", (ev) => {
      // when stream already init
      if (video2.srcObject !== null) return;

      // when audio track not exist in Chrome
      if (ev.streams.length === 0) return;

      // when audio track not exist in Firefox
      if (ev.streams[0].id[0] === "{") return;

      video2.srcObject = ev.streams[0];
    });

    pc.addEventListener("connectionstatechange", () => {
      if (
        pc.connectionState === "failed" ||
        pc.connectionState === "disconnected"
      ) {
        pc.close(); // stop next events

        this.pcState = WebSocket.CLOSED;
        this.pc = null;

        this.onconnect();
      }
    });

    this.onmessage["webrtc"] = (msg) => {
      switch (msg.type) {
        case "webrtc/candidate":
          pc.addIceCandidate({
            candidate: msg.value,
            sdpMid: "0",
          }).catch(() => {});
          break;
        case "webrtc/answer":
          pc.setRemoteDescription({
            type: "answer",
            sdp: msg.value,
          }).catch(() => {});
          break;
        case "error":
          if (msg.value.indexOf("webrtc/offer") < 0) return;
          pc.close();
      }
    };

    // Safari doesn't support "offerToReceiveVideo"
    pc.addTransceiver("video", { direction: "recvonly" });
    pc.addTransceiver("audio", { direction: "recvonly" });

    pc.createOffer().then((offer) => {
      pc.setLocalDescription(offer).then(() => {
        this.send({ type: "webrtc/offer", value: offer.sdp });
      });
    });

    this.pcState = WebSocket.CONNECTING;
    this.pc = pc;
  }

  /**
   * @param ev {Event}
   */
  onpcvideo(ev) {
    if (!this.pc) return;

    /** @type {HTMLVideoElement} */
    const video2 = ev.target;
    const state = this.pc.connectionState;

    // Firefox doesn't support pc.connectionState
    if (state === "connected" || state === "connecting" || !state) {
      // Video+Audio > Video, H265 > H264, Video > Audio, WebRTC > MSE
      let rtcPriority = 0,
        msePriority = 0;

      /** @type {MediaStream} */
      const ms = video2.srcObject;
      if (ms.getVideoTracks().length > 0) rtcPriority += 0x220;
      if (ms.getAudioTracks().length > 0) rtcPriority += 0x102;

      if (this.mseCodecs.indexOf("hvc1.") >= 0) msePriority += 0x230;
      if (this.mseCodecs.indexOf("avc1.") >= 0) msePriority += 0x210;
      if (this.mseCodecs.indexOf("mp4a.") >= 0) msePriority += 0x101;

      if (rtcPriority >= msePriority) {
        this.video.srcObject = ms;
        this.play();

        this.pcState = WebSocket.OPEN;

        this.wsState = WebSocket.CLOSED;
        this.ws.close();
        this.ws = null;
      } else {
        this.pcState = WebSocket.CLOSED;
        this.pc.close();
        this.pc = null;
      }
    }

    video2.srcObject = null;
  }

  onmjpeg() {
    this.ondata = (data) => {
      this.video.controls = false;
      this.video.poster = `data:image/jpeg;base64,${VideoRTC.btoa(data)}`;
    };

    this.send({ type: "mjpeg" });
  }

  onmp4() {
    /** @type {HTMLCanvasElement} **/
    const canvas = document.createElement("canvas");
    /** @type {CanvasRenderingContext2D} */
    let context;

    /** @type {HTMLVideoElement} */
    const video2 = document.createElement("video");
    video2.autoplay = true;
    video2.playsInline = true;
    video2.muted = true;

    video2.addEventListener("loadeddata", (_) => {
      if (!context) {
        canvas.width = video2.videoWidth;
        canvas.height = video2.videoHeight;
        context = canvas.getContext("2d");
      }

      context.drawImage(video2, 0, 0, canvas.width, canvas.height);

      this.video.controls = false;
      this.video.poster = canvas.toDataURL("image/jpeg");
    });

    this.ondata = (data) => {
      video2.src = `data:video/mp4;base64,${VideoRTC.btoa(data)}`;
    };

    this.send({ type: "mp4", value: this.codecs(this.video.canPlayType) });
  }

  static btoa(buffer) {
    const bytes = new Uint8Array(buffer);
    const len = bytes.byteLength;
    let binary = "";
    for (let i = 0; i < len; i++) {
      binary += String.fromCharCode(bytes[i]);
    }
    return window.btoa(binary);
  }
}

class VideoStream extends VideoRTC {
  /**
   * Custom GUI
   */
  oninit() {
    super.oninit();
    const info = this.querySelector(".info");
    this.insertBefore(this.video, info);
  }

  onconnect() {
    const result = super.onconnect();
    if (result) this.divMode = "loading";
    return result;
  }

  ondisconnect() {
    super.ondisconnect();
  }

  onopen() {
    const result = super.onopen();

    this.onmessage["stream"] = (_) => {};

    return result;
  }

  onclose() {
    return super.onclose();
  }

  onpcvideo(ev) {
    super.onpcvideo(ev);

    if (this.pcState !== WebSocket.CLOSED) {
      this.divMode = "RTC";
    }
  }
}

customElements.define("video-stream", VideoStream);

export default function MsePlayer({ src }) {
  return <video-stream src={src} mode="mse" />;
}
