[WIP] Update around webrtc.

src/Components/Excalidraw/RightTopUI.tsx

@@ -5,13 +5,13 @@ import { SidebarVariant, SidebarVariantSchema } from './Sidebar';
 import { z } from 'zod';
 import { LiveCollaborationTrigger } from '@excalidraw/excalidraw';
 
-export const RightTopUIPropsScheme = z.object({
+export const RightTopUIPropsSchema = z.object({
   setSidebarVariant: z.function().args(SidebarVariantSchema).returns(z.void()),
   setToggleState: z.function().args(z.boolean()).returns(z.void()),
   toggleState: z.boolean(),
 });
 
-export type RightTopUIProps = z.infer<typeof RightTopUIPropsScheme> & {
+export type RightTopUIProps = z.infer<typeof RightTopUIPropsSchema> & {
   excalidrawAPI: ExcalidrawImperativeAPI;
 };
 

src/Components/Excalidraw/Sidebar/Collaboration.tsx

@@ -1,7 +1,16 @@
-import { FC } from 'react';
+import { FC, useCallback, useEffect, useState } from 'react';
 import { Button, SidebarHeader } from '@/Components/Utilities';
 import { z } from 'zod';
 import SidebarProviderBase, { SidebarBasePropsSchema } from './Base';
+import { startCollaboration } from '@/webrtc/collaboration';
+import {
+  SignalingData,
+  decodeSignalingData,
+  encodeSignalingData,
+} from '@/webrtc/utilities';
+import { Input, Link } from '@mui/material';
+import { fromUrl, toUrl } from '@/utilities/url';
+import { copyToClipboard } from '@/utilities/clipboard';
 
 export type CollaborationSidebarProps = z.infer<
   typeof CollaborationSidebarPropsSchema
@@ -12,10 +21,72 @@ export const CollaborationSidebarPropsSchema = z
   .merge(SidebarBasePropsSchema);
 
 const CollaborationSidebar: FC<CollaborationSidebarProps> = (props) => {
+  const signalingDataCallback = useCallback((data: SignalingData) => {
+    const encodedData = encodeSignalingData(data);
+    const url = toUrl({ signalingData: encodedData });
+
+    setCollaborationUrl(url);
+
+    console.log(data);
+  }, []);
+
+  const [collaborationUrl, setCollaborationUrl] = useState<URL | null>(null);
+  const [isCollaborationStarted, setIsCollaborationStarted] = useState(false);
+  const [providedCollaborationUrl, setProvidedCollaborationUrl] =
+    useState<URL | null>(null);
+
+  const onMessage = useCallback((event: MessageEvent) => {
+    console.log(event);
+  }, []);
+
+  const startCollaborationWrapper = useCallback(async () => {
+    console.log('start collaboration');
+
+    const signalingData = providedCollaborationUrl
+      ? decodeSignalingData(fromUrl(providedCollaborationUrl).signalingData!)
+      : undefined;
+
+    console.log(signalingData);
+
+    await startCollaboration(signalingData, signalingDataCallback, {
+      onMessage,
+    });
+  }, [signalingDataCallback, onMessage, providedCollaborationUrl]);
+
+  const copyCollaborationUrl = useCallback(async () => {
+    console.log('copy collaboration url');
+    console.log(collaborationUrl?.toString());
+    await copyToClipboard(collaborationUrl ? collaborationUrl?.toString() : '');
+  }, [collaborationUrl]);
+
+  useEffect(() => {
+    if (isCollaborationStarted || providedCollaborationUrl) {
+      startCollaborationWrapper().catch((error) => console.error(error));
+    }
+  }, [
+    isCollaborationStarted,
+    startCollaborationWrapper,
+    providedCollaborationUrl,
+  ]);
+
   return (
     <SidebarProviderBase onClose={props.onClose}>
-      <SidebarHeader>Collaboration Settings</SidebarHeader>
-      <Button>Button</Button>
+      <SidebarHeader>Collaboration</SidebarHeader>
+      <Button onClick={() => setIsCollaborationStarted(true)}>
+        Start Collaboration
+      </Button>
+      <Link>{collaborationUrl?.toString()}</Link>
+      <Button
+        onClick={() => {
+          copyCollaborationUrl().catch((e) => console.error(e));
+        }}
+      >
+        Copy
+      </Button>
+      <Input
+        value={providedCollaborationUrl ?? ''}
+        onChange={(e) => setProvidedCollaborationUrl(new URL(e.target.value))}
+      ></Input>
     </SidebarProviderBase>
   );
 };

src/utilities/clipboard.ts

@@ -0,0 +1,3 @@
+export const copyToClipboard = async (text: string) => {
+  await navigator.clipboard.writeText(text);
+};

src/utilities/url.ts

@@ -0,0 +1,25 @@
+import { z } from 'zod';
+
+export const AvailableURLParametersSchema = z.object({
+  signalingData: z.string().optional(),
+});
+
+export type AvailableURLParameters = z.infer<
+  typeof AvailableURLParametersSchema
+>;
+
+export const toUrl = (params: AvailableURLParameters) => {
+  const url = new URL(window.location.href);
+
+  Object.entries(params).forEach(([key, value]) => {
+    url.searchParams.set(key, value);
+  });
+
+  return url;
+};
+
+export const fromUrl = (url: URL): AvailableURLParameters => {
+  const params = Object.fromEntries(url.searchParams.entries());
+
+  return AvailableURLParametersSchema.parse(params);
+};

src/webrtc/collaboration.ts

@@ -0,0 +1,28 @@
+import establishConnection from './connection';
+import type { Connection, DataChannelCallbacks } from './connection';
+import type { SignalingData } from './utilities';
+
+export type SignalingDataCallback = (signalingData: SignalingData) => void;
+
+export type OnAnswerCallback = (answer: RTCSessionDescription) => void;
+export type OnOfferCallback = (offer: RTCSessionDescription) => void;
+
+export const startCollaboration = async (
+  signalingData: SignalingData | undefined,
+  onSignalingData: SignalingDataCallback,
+  dataChannelCallbacks: DataChannelCallbacks
+): Promise<void> => {
+  let connection: Connection = {
+    connectionState: 'noConnection',
+    dataChannelCallbacks,
+    signalingData,
+  };
+
+  while (connection?.connectionState !== 'established') {
+    connection = await establishConnection(connection);
+
+    if (connection.signalingData) {
+      onSignalingData(connection.signalingData);
+    }
+  }
+};

src/webrtc/connection.ts

@@ -0,0 +1,148 @@
+import { match } from 'ts-pattern';
+import { SignalingDataType, SignalingData } from './utilities';
+import { z } from 'zod';
+
+export const PeerConfiguration: RTCConfiguration = {
+  iceServers: [{ urls: 'stun:stun.l.google.com:19302' }],
+};
+
+export const EstablishingConnectionStateSchema = z.enum([
+  'noConnection',
+  'waiting',
+  'established',
+]);
+
+export type EstablishingConnectionState = z.infer<
+  typeof EstablishingConnectionStateSchema
+>;
+
+export type Connection = {
+  connectionState: EstablishingConnectionState;
+  signalingData?: SignalingData;
+  dataChannelCallbacks?: DataChannelCallbacks;
+};
+
+export const establishConnection = async ({
+  connectionState,
+  signalingData,
+  dataChannelCallbacks,
+}: Connection): Promise<Connection> => {
+  const peerConnection = createPeerConnection();
+
+  return await match(connectionState)
+    .with('noConnection', async () => {
+      const _signalingData = await createOffer(peerConnection);
+
+      return {
+        connectionState: 'waiting',
+        signalingData: _signalingData,
+        dataChannelCallbacks,
+      } as Connection;
+    })
+    .with('waiting', async () => {
+      if (!dataChannelCallbacks) {
+        throw new Error('Data channel callbacks are not set');
+      }
+      if (!signalingData) {
+        throw new Error('Signaling data is not set');
+      }
+
+      await peerConnection.setRemoteDescription(signalingData.sdp);
+
+      const connection: Connection = await match(signalingData.type)
+        .with('offer', async () => {
+          const answer = await createAnswer(peerConnection);
+          return {
+            connectionState: 'waiting',
+            signalingData: answer,
+            dataChannelCallbacks,
+          } as Connection;
+        })
+        .with('answer', () => {
+          return {
+            connectionState: 'established',
+            signalingData: undefined,
+            dataChannelCallbacks,
+          } as Connection;
+        })
+        .exhaustive();
+
+      dataChannelHandler(
+        signalingData.type,
+        peerConnection,
+        dataChannelCallbacks
+      );
+
+      return connection;
+    })
+    .with('established', () => {
+      throw new Error(
+        "Connection can't be established because it is already established"
+      );
+    })
+    .exhaustive();
+};
+
+export default establishConnection;
+
+export const createPeerConnection = () => {
+  const configuration = PeerConfiguration;
+
+  return new RTCPeerConnection(configuration);
+};
+
+export const createOffer = async (peerConnection: RTCPeerConnection) => {
+  const offer = await peerConnection.createOffer();
+  await peerConnection.setLocalDescription(offer);
+
+  if (peerConnection.localDescription) {
+    const signalingData: SignalingData = {
+      type: 'offer',
+      sdp: peerConnection.localDescription,
+    };
+
+    return signalingData;
+  } else {
+    throw new Error('Local description is not set');
+  }
+};
+
+export type DataChannelCallbacks = {
+  onMessage: (event: MessageEvent) => void;
+};
+
+export const dataChannelHandler = (
+  type: SignalingDataType,
+  peerConnection: RTCPeerConnection,
+  DataChannelCallbacks: DataChannelCallbacks
+) => {
+  const { onMessage } = DataChannelCallbacks;
+
+  match(type)
+    .with('offer', () => {
+      const dataChannel = peerConnection.createDataChannel('dataChannel');
+      dataChannel.onmessage = onMessage;
+    })
+    .with('answer', () => {
+      peerConnection.ondatachannel = (event) => {
+        event.channel.onmessage = onMessage;
+      };
+    })
+    .exhaustive();
+};
+
+export const createAnswer = async (peerConnection: RTCPeerConnection) => {
+  const answer = await peerConnection.createAnswer();
+  await peerConnection.setLocalDescription(answer);
+
+  if (peerConnection.localDescription) {
+    const signalingData: SignalingData = {
+      type: 'answer',
+      sdp: peerConnection.localDescription,
+    };
+
+    return signalingData;
+  } else {
+    throw new Error('Local description is not set');
+  }
+};

src/webrtc/utilities.ts

@@ -0,0 +1,24 @@
+import { z } from 'zod';
+
+export const encodeSignalingData = (
+  data: SignalingData
+): EncodedSignalingData => {
+  return encodeURIComponent(JSON.stringify(data));
+};
+
+export const decodeSignalingData = (encodedData: string) => {
+  return JSON.parse(decodeURIComponent(encodedData)) as SignalingData;
+};
+
+export const SignanlingDataTypeSchema = z.enum(['offer', 'answer']);
+
+export type SignalingDataType = z.infer<typeof SignanlingDataTypeSchema>;
+
+export type SignalingData = {
+  type: SignalingDataType;
+  sdp: RTCSessionDescription;
+};
+
+export const EncodedSignalingDataSchema = z.string();
+
+export type EncodedSignalingData = z.infer<typeof EncodedSignalingDataSchema>;