fallback for room avatar media repo (disabled by default)

app.js

@@ -21,7 +21,12 @@ let App = create({
   displayName: "App",
 
   getInitialState: function() {
-    return {rooms: []}
+    return {
+      rooms: [],
+      options: {
+        fallbackMediaRepos: []
+      }
+    }
   },
 
   componentDidMount: function() {
@@ -85,7 +90,7 @@ let App = create({
     }
     return (
       <>
-        <Sidebar client={this.state.client} rooms={this.state.rooms} selectRoom={(roomId) => {this.setState({roomId: roomId})}}/>
+        <Sidebar options={this.state.options} client={this.state.client} rooms={this.state.rooms} selectRoom={(roomId) => {this.setState({roomId: roomId})}}/>
         <Chat client={this.state.client} roomId={this.state.roomId}/>
       </>
     )

components/sidebar.js

@@ -14,7 +14,8 @@ let RoomListItem = create({
   getInitialState: function() {
     let room = this.props.content
     let client = this.props.properties.client
-    let avatar = <svg id="avatar" ref={this.jdenticonRef}/>
+    let jdenticon = <svg id="avatar" ref={this.jdenticonRef}/>
+    let avatarUrl
 
     let roomState = room.getLiveTimeline().getState('f')
     let avatarState = roomState.getStateEvents('m.room.avatar')
@@ -22,14 +23,19 @@ let RoomListItem = create({
       let event = avatarState[avatarState.length-1].event
       let hs = client.baseUrl
       let media_mxc = event.content.url.slice(6)
-      let url = `${hs}/_matrix/media/v1/thumbnail/${media_mxc}?width=128&height=128&method=scale`
-      avatar = <img id="avatar" src={url}></img>
+      let path = `/_matrix/media/v1/thumbnail/${media_mxc}?width=128&height=128&method=scale`
+      avatarUrl = {
+        hs: hs,
+        path: path
+      }
     }
 
     return {
       filterName: room.name.toUpperCase(),
       unread: Math.random() > 0.7,
-      avatar: avatar
+      avatarUrl: avatarUrl,
+      jdenticon: jdenticon,
+      tries: 0
     }
   },
 
@@ -37,6 +43,24 @@ let RoomListItem = create({
     jdenticon.update(ref, this.props.content.roomId)
   },
 
+  avatarFallback: function() {
+    // instead of falling back on jdenticon immediately, we can try
+    // a third-party homeserver's media repo
+    // this does come with trust issues, and is opt-in in settings
+    let fallbackMediaRepos = this.props.properties.options.fallbackMediaRepos
+
+    if (this.state.tries < fallbackMediaRepos.length) {
+      let avatarUrl = this.state.avatarUrl
+      avatarUrl.hs = fallbackMediaRepos[this.state.tries]
+      this.setState({
+        avatarUrl: avatarUrl,
+        tries: this.state.tries + 1
+      })
+    } else {
+      this.setState({avatarUrl: null, avatar: jdenticon})
+    }
+  },
+
   setRef: function(ref) {
     if (ref == null) {
       return
@@ -57,7 +81,11 @@ let RoomListItem = create({
       className += " unread"
     }
     return <div className={className} ref={this.setRef}>
-      {this.state.avatar}
+      {this.state.avatarUrl ?
+        <img id="avatar" src={`${this.state.avatarUrl.hs}${this.state.avatarUrl.path}`} onError={this.avatarFallback}></img>
+        :
+        this.state.jdenticon
+      }
       <span id="name">{this.props.content.name}</span>
     </div>
   }
@@ -80,7 +108,7 @@ let Sidebar = create({
 
   render: function() {
     return <div className="sidebar">
-      <FilterList items={this.props.rooms} properties={{client: this.props.client}} element={RoomListItem} callback={(roomId) => {this.props.selectRoom(roomId)}}/>
+      <FilterList items={this.props.rooms} properties={{client: this.props.client, options: this.props.options}} element={RoomListItem} callback={(roomId) => {this.props.selectRoom(roomId)}}/>
     </div>
   }
 })