Refactor sidebar

app/src/components/Sidebar/HistoryDrawer.tsx

@@ -34,6 +34,12 @@ class HistoryDrawer extends React.Component<Props, State> {
     this.setState({ collapsed: !this.state.collapsed })
   }
 
+  private createSelectionHandler = (index: number) => (event: React.MouseEvent) => {
+    this.props.onClick && this.props.onClick(index, event.target)
+    event.preventDefault()
+    event.stopPropagation()
+  }
+
   private handleCtrlA = selectTextWithCtrlA({ targetSelector: 'pre' })
 
   public renderHistory() {
@@ -51,7 +57,7 @@ class HistoryDrawer extends React.Component<Props, State> {
       <div
         key={element.key}
         style={style(element)}
-        onClick={(event: React.MouseEvent) => this.props.onClick && this.props.onClick(index, event.target)}
+        onClick={this.createSelectionHandler(index)}
         tabIndex={0}
         onKeyDown={this.handleCtrlA}
       >

app/src/components/Sidebar/NodeStats.tsx

@@ -4,7 +4,7 @@ import { TopicViewModel } from '../../model/TopicViewModel'
 import { Typography } from '@material-ui/core'
 
 interface Props {
-  node: q.TreeNode<TopicViewModel>
+  node?: q.TreeNode<TopicViewModel>
 }
 
 class NodeStats extends React.Component<Props, {}> {
@@ -14,6 +14,9 @@ class NodeStats extends React.Component<Props, {}> {
 
   public render() {
     const { node } = this.props
+    if (!node) {
+      return null
+    }
 
     return (
       <div>

app/src/components/Sidebar/Panel.tsx

@@ -0,0 +1,33 @@
+import React from 'react'
+import ExpandMore from '@material-ui/icons/ExpandMore'
+import { ExpansionPanel, ExpansionPanelDetails, ExpansionPanelSummary, Typography, Theme } from '@material-ui/core'
+import { withStyles } from '@material-ui/styles'
+
+const styles = (theme: Theme) => ({
+  summary: { minHeight: '0' },
+  details: { padding: '0px 16px 8px 8px', display: 'block' },
+  heading: {
+    fontSize: theme.typography.pxToRem(15),
+    fontWeight: theme.typography.fontWeightRegular,
+  },
+})
+
+const Panel = (props: {
+  classes: any
+  children: [React.ReactElement, React.ReactElement]
+  disabled?: boolean
+  detailsHidden?: boolean
+}) => {
+  return (
+    <ExpansionPanel defaultExpanded={true} disabled={props.disabled}>
+      <ExpansionPanelSummary expandIcon={<ExpandMore />} className={props.classes.summary}>
+        <Typography className={props.classes.heading}>{props.children[0]}</Typography>
+      </ExpansionPanelSummary>
+      {props.detailsHidden ? null : (
+        <ExpansionPanelDetails className={props.classes.detail}>{props.children[1]}</ExpansionPanelDetails>
+      )}
+    </ExpansionPanel>
+  )
+}
+
+export default withStyles(styles)(Panel)

app/src/components/Sidebar/Publish/Publish.tsx

@@ -1,30 +1,18 @@
-import * as React from 'react'
-import ClearAdornment from '../../helper/ClearAdornment'
 import Editor from './Editor'
 import FormatAlignLeft from '@material-ui/icons/FormatAlignLeft'
-import History from '../HistoryDrawer'
 import Message from './Model/Message'
 import Navigation from '@material-ui/icons/Navigation'
-import QosSelect from './QosSelect'
+import PublishHistory from './PublishHistory'
+import React, { useCallback, useState, useMemo } from 'react'
+import TopicInput from './TopicInput'
 import { AppState } from '../../../reducers'
 import { bindActionCreators } from 'redux'
+import { Button, Fab, Theme, Tooltip, withTheme } from '@material-ui/core'
 import { connect } from 'react-redux'
 import { EditorModeSelect } from './EditorModeSelect'
 import { globalActions, publishActions } from '../../../actions'
 import { KeyCodes } from '../../../utils/KeyCodes'
-import {
-  Button,
-  FormControlLabel,
-  FormControl,
-  InputLabel,
-  Input,
-  Checkbox,
-  Tooltip,
-  Fab,
-  Theme,
-  withTheme,
-} from '@material-ui/core'
-const sha1 = require('sha1')
+import RetainSwitch from './RetainSwitch'
 
 interface Props {
   connectionId?: string
@@ -37,108 +25,73 @@ interface Props {
   theme: Theme
 }
 
-interface State {
-  history: Array<Message>
+function useHistory(): [Array<Message>, (topic: string, payload?: string) => void] {
+  const [history, setHistory] = useState<Array<Message>>([])
+  const amendToHistory = useCallback(
+    (topic: string, payload?: string) => {
+      // Remove duplicates
+      let filteredHistory = history.filter(e => e.payload !== payload || e.topic !== topic)
+      filteredHistory = filteredHistory.slice(-7)
+      setHistory([...filteredHistory, { topic, payload, sent: new Date() }])
+    },
+    [history]
+  )
+
+  return [history, amendToHistory]
 }
 
-class Publish extends React.Component<Props, State> {
-  constructor(props: any) {
-    super(props)
-    this.state = { history: [] }
-  }
+function Publish(props: Props) {
+  console.log(props.connectionId)
+  const updatePayload = props.actions.setPayload
+  const [history, amendToHistory] = useHistory()
 
-  private updatePayload = (payload: string) => {
-    this.props.actions.setPayload(payload)
-  }
+  const updateMode = useCallback((e: React.ChangeEvent<{}>, value: string) => {
+    props.actions.setEditorMode(value)
+  }, [])
 
-  private updateTopic = (e: React.ChangeEvent<HTMLInputElement>) => {
-    this.props.actions.setTopic(e.target.value)
-  }
-
-  private updateMode = (e: React.ChangeEvent<{}>, value: string) => {
-    this.props.actions.setEditorMode(value)
-  }
-
-  private handleClickPublish = (e: React.MouseEvent) => {
-    e.stopPropagation()
-    this.publish()
-  }
-
-  private publish() {
-    if (!this.props.connectionId) {
+  const publish = useCallback(() => {
+    if (!props.connectionId) {
       return
     }
 
-    this.props.actions.publish(this.props.connectionId)
+    props.actions.publish(props.connectionId)
 
-    const topic = this.props.topic || ''
-    const payload = this.props.payload
-    if (this.props.connectionId && topic) {
-      this.addMessageToHistory(topic, payload)
+    const topic = props.topic || ''
+    const payload = props.payload
+    if (props.connectionId && topic) {
+      amendToHistory(topic, payload)
     }
-  }
+  }, [props, props.connectionId, props.topic, props.payload, amendToHistory])
 
-  private addMessageToHistory(topic: string, payload?: string) {
-    // Remove duplicates
-    let filteredHistory = this.state.history.filter(e => e.payload !== payload || e.topic !== topic)
-    filteredHistory = filteredHistory.slice(-7)
-    const history: Array<Message> = [...filteredHistory, { topic, payload, sent: new Date() }]
-    this.setState({ history })
-  }
-
-  private clearTopic = () => {
-    this.props.actions.setTopic('')
-  }
-
-  private topic() {
-    const topicStr = this.props.topic || ''
+  const handleClickPublish = useCallback(
+    (e: React.MouseEvent) => {
+      e.stopPropagation()
+      publish()
+    },
+    [publish]
+  )
 
+  const PublishButton = () => {
     return (
-      <div>
-        <FormControl style={{ width: '100%' }}>
-          <InputLabel htmlFor="publish-topic">Topic</InputLabel>
-          <Input
-            id="publish-topic"
-            value={topicStr}
-            startAdornment={<span />}
-            endAdornment={<ClearAdornment action={this.clearTopic} value={topicStr} />}
-            onBlur={this.onTopicBlur}
-            onChange={this.updateTopic}
-            multiline={true}
-            placeholder="example/topic"
-          />
-        </FormControl>
-      </div>
-    )
-  }
-
-  private onTopicBlur = (e: React.FocusEvent<HTMLInputElement>) => {
-    if (!e.target.value) {
-      this.props.actions.setTopic(undefined)
-    }
-  }
-
-  private publishButton() {
-    return (
-      <Button variant="contained" size="small" color="primary" onClick={this.handleClickPublish} id="publish-button">
+      <Button variant="contained" size="small" color="primary" onClick={handleClickPublish} id="publish-button">
         <Navigation style={{ marginRight: '8px' }} /> Publish
       </Button>
     )
   }
 
-  private formatJson = () => {
-    if (this.props.payload) {
+  const formatJson = () => {
+    if (props.payload) {
       try {
-        const str = JSON.stringify(JSON.parse(this.props.payload), undefined, '  ')
-        this.updatePayload(str)
+        const str = JSON.stringify(JSON.parse(props.payload), undefined, '  ')
+        updatePayload(str)
       } catch (error) {
-        this.props.globalActions.showError(`Format error: ${error.message}`)
+        props.globalActions.showError(`Format error: ${error.message}`)
       }
     }
   }
 
-  private renderFormatJson() {
-    if (this.props.editorMode !== 'json') {
+  const renderFormatJson = () => {
+    if (props.editorMode !== 'json') {
       return null
     }
 
@@ -146,7 +99,7 @@ class Publish extends React.Component<Props, State> {
       <Tooltip title="Format JSON">
         <Fab
           style={{ width: '36px', height: '36px', marginLeft: '8px' }}
-          onClick={this.formatJson}
+          onClick={formatJson}
           id="sidebar-publish-format-json"
         >
           <FormatAlignLeft style={{ fontSize: '20px' }} />
@@ -155,80 +108,45 @@ class Publish extends React.Component<Props, State> {
     )
   }
 
-  private editorMode() {
+  function EditorMode() {
     return (
       <div style={{ marginTop: '16px' }}>
         <div style={{ width: '100%', lineHeight: '64px' }}>
-          <EditorModeSelect value={this.props.editorMode} onChange={this.updateMode} />
-          {this.renderFormatJson()}
-          <div style={{ float: 'right', marginRight: '16px' }}>{this.publishButton()}</div>
+          <EditorModeSelect value={props.editorMode} onChange={updateMode} />
+          {renderFormatJson()}
+          <div style={{ float: 'right', marginRight: '16px' }}>
+            <PublishButton />
+          </div>
         </div>
       </div>
     )
   }
 
-  private publishMode() {
-    const labelStyle = { margin: '0 8px 0 8px' }
+  const handleSubmit = useCallback(
+    (e: React.KeyboardEvent) => {
+      if (e.keyCode === KeyCodes.enter && (e.metaKey || e.ctrlKey)) {
+        e.preventDefault()
+        e.stopPropagation()
+        publish()
+      }
+    },
+    [publish]
+  )
 
-    return (
-      <div style={{ marginTop: '8px', clear: 'both' }}>
-        <div style={{ width: '100%', textAlign: 'right' }}>
-          <FormControlLabel style={labelStyle} control={<QosSelect />} label="QoS" labelPlacement="start" />
-          <Tooltip
-            title="Retained messages only appear to be retained, when client subscribes after the initial publish."
-            placement="top"
-          >
-            <FormControlLabel
-              value="retain"
-              style={labelStyle}
-              control={
-                <Checkbox color="primary" checked={this.props.retain} onChange={this.props.actions.toggleRetain} />
-              }
-              label="retain"
-              labelPlacement="end"
-            />
-          </Tooltip>
-        </div>
-      </div>
-    )
-  }
-
-  private history() {
-    const items = [...this.state.history].reverse().map(message => ({
-      key: sha1(message.topic + message.payload),
-      title: message.topic,
-      value: message.payload || '',
-    }))
-    return <History items={items} onClick={this.didSelectHistoryEntry} />
-  }
-
-  private didSelectHistoryEntry = (index: number) => {
-    const message = this.state.history[index]
-    this.props.actions.setTopic(message.topic)
-    this.props.actions.setPayload(message.payload)
-  }
-
-  private handleSubmit = (e: React.KeyboardEvent) => {
-    if (e.keyCode === KeyCodes.enter && (e.metaKey || e.ctrlKey)) {
-      e.preventDefault()
-      e.stopPropagation()
-      this.publish()
-    }
-  }
-
-  public render() {
-    return (
-      <div style={{ flexGrow: 1, marginLeft: '8px' }} onKeyDown={this.handleSubmit}>
-        {this.topic()}
+  return useMemo(
+    () => (
+      <div style={{ flexGrow: 1, marginLeft: '8px' }} onKeyDown={handleSubmit}>
+        <TopicInput />
         <div style={{ width: '100%', display: 'block' }}>
-          {this.editorMode()}
-          <Editor value={this.props.payload} editorMode={this.props.editorMode} onChange={this.updatePayload} />
-          {this.publishMode()}
+          <EditorMode />
+          <Editor value={props.payload} editorMode={props.editorMode} onChange={updatePayload} />
+          <RetainSwitch />
         </div>
-        {this.history()}
+        <PublishHistory history={history} />
       </div>
-    )
-  }
+    ),
+    [props.payload, props.editorMode, history, handleSubmit, updatePayload]
+  )
 }
 
 const mapDispatchToProps = (dispatch: any) => {

app/src/components/Sidebar/Publish/PublishHistory.tsx

@@ -0,0 +1,40 @@
+import History from '../HistoryDrawer'
+import Message from './Model/Message'
+import React, { useCallback, useMemo } from 'react'
+import { bindActionCreators } from 'redux'
+import { connect } from 'react-redux'
+import { publishActions } from '../../../actions'
+const sha1 = require('sha1')
+
+function PublishHistory(props: { history: Array<Message>; actions: typeof publishActions }) {
+  const didSelectHistoryEntry = useCallback(
+    (index: number) => {
+      const items = [...props.history].reverse()
+      const message = items[index]
+      props.actions.setTopic(message.topic)
+      props.actions.setPayload(message.payload)
+    },
+    [props.history]
+  )
+
+  return useMemo(() => {
+    const items = [...props.history].reverse().map(message => ({
+      key: sha1(message.topic + message.payload),
+      title: message.topic,
+      value: message.payload || '',
+    }))
+
+    return <History items={items} onClick={didSelectHistoryEntry} />
+  }, [props.history])
+}
+
+const mapDispatchToProps = (dispatch: any) => {
+  return {
+    actions: bindActionCreators(publishActions, dispatch),
+  }
+}
+
+export default connect(
+  undefined,
+  mapDispatchToProps
+)(PublishHistory)

app/src/components/Sidebar/Publish/RetainSwitch.tsx

@@ -0,0 +1,47 @@
+import QosSelect from './QosSelect'
+import React from 'react'
+import { Checkbox, FormControlLabel, Tooltip } from '@material-ui/core'
+import { publishActions } from '../../../actions'
+import { bindActionCreators } from 'redux'
+import { AppState } from '../../../reducers'
+import { connect } from 'react-redux'
+
+export function RetainSwitch(props: { retain: boolean; actions: typeof publishActions }) {
+  const labelStyle = { margin: '0 8px 0 8px' }
+  return (
+    <div style={{ marginTop: '8px', clear: 'both' }}>
+      <div style={{ width: '100%', textAlign: 'right' }}>
+        <FormControlLabel style={labelStyle} control={<QosSelect />} label="QoS" labelPlacement="start" />
+        <Tooltip
+          title="Retained messages only appear to be retained, when client subscribes after the initial publish."
+          placement="top"
+        >
+          <FormControlLabel
+            value="retain"
+            style={labelStyle}
+            control={<Checkbox color="primary" checked={props.retain} onChange={props.actions.toggleRetain} />}
+            label="retain"
+            labelPlacement="end"
+          />
+        </Tooltip>
+      </div>
+    </div>
+  )
+}
+
+const mapDispatchToProps = (dispatch: any) => {
+  return {
+    actions: bindActionCreators(publishActions, dispatch),
+  }
+}
+
+const mapStateToProps = (state: AppState) => {
+  return {
+    retain: state.publish.retain,
+  }
+}
+
+export default connect(
+  mapStateToProps,
+  mapDispatchToProps
+)(RetainSwitch)

app/src/components/Sidebar/Publish/TopicInput.tsx

@@ -0,0 +1,60 @@
+import ClearAdornment from '../../helper/ClearAdornment'
+import React, { useCallback } from 'react'
+import { FormControl, Input, InputLabel } from '@material-ui/core'
+import { publishActions } from '../../../actions'
+import { bindActionCreators } from 'redux'
+import { AppState } from '../../../reducers'
+import { connect } from 'react-redux'
+
+function TopicInput(props: { actions: typeof publishActions; topic?: string }) {
+  console.log(props.topic)
+  const updateTopic = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
+    props.actions.setTopic(e.target.value)
+  }, [])
+
+  const clearTopic = useCallback(() => {
+    props.actions.setTopic('')
+  }, [])
+
+  const onTopicBlur = useCallback((e: React.FocusEvent<HTMLInputElement>) => {
+    if (!e.target.value) {
+      props.actions.setTopic(undefined)
+    }
+  }, [])
+
+  const topicStr = props.topic || ''
+  return (
+    <div>
+      <FormControl style={{ width: '100%' }}>
+        <InputLabel htmlFor="publish-topic">Topic</InputLabel>
+        <Input
+          id="publish-topic"
+          value={topicStr}
+          startAdornment={<span />}
+          endAdornment={<ClearAdornment action={clearTopic} value={topicStr} />}
+          onBlur={onTopicBlur}
+          onChange={updateTopic}
+          multiline={true}
+          placeholder="example/topic"
+        />
+      </FormControl>
+    </div>
+  )
+}
+
+const mapDispatchToProps = (dispatch: any) => {
+  return {
+    actions: bindActionCreators(publishActions, dispatch),
+  }
+}
+
+const mapStateToProps = (state: AppState) => {
+  return {
+    topic: state.publish.topic,
+  }
+}
+
+export default connect(
+  mapStateToProps,
+  mapDispatchToProps
+)(TopicInput)

app/src/components/Sidebar/Sidebar.tsx

@@ -1,11 +1,7 @@
 import * as q from '../../../../backend/src/Model'
-import * as React from 'react'
-import Copy from '../helper/Copy'
-import CustomIconButton from '../helper/CustomIconButton'
-import Delete from '@material-ui/icons/Delete'
+import React, { useState, useEffect, useCallback } from 'react'
 import ExpandMore from '@material-ui/icons/ExpandMore'
 import NodeStats from './NodeStats'
-import Topic from './Topic'
 import ValuePanel from './ValueRenderer/ValuePanel'
 import { AppState } from '../../reducers'
 import { Badge, ExpansionPanel, ExpansionPanelDetails, ExpansionPanelSummary, Typography } from '@material-ui/core'
@@ -14,6 +10,8 @@ import { connect } from 'react-redux'
 import { settingsActions, sidebarActions } from '../../actions'
 import { Theme, withStyles } from '@material-ui/core/styles'
 import { TopicViewModel } from '../../model/TopicViewModel'
+import TopicPanel from './TopicPanel/TopicPanel'
+import Panel from './Panel'
 
 const throttle = require('lodash.throttle')
 
@@ -27,148 +25,48 @@ interface Props {
   connectionId?: string
 }
 
-interface State {
-  compareMessage?: q.Message
-  valueRenderWidth: number
-}
+function Sidebar(props: Props) {
+  const { classes, node } = props
+  const [lastUpdate, setLastUpdate] = useState(0)
 
-class Sidebar extends React.Component<Props, State> {
-  private updateNode = throttle(() => {
-    this.setState(this.state)
-  }, 300)
+  const updateNode = useCallback(
+    throttle(() => {
+      setLastUpdate(node ? node.lastUpdate : 0)
+    }, 300),
+    [node]
+  )
 
-  private detailsStyle = { padding: '0px 16px 8px 8px', display: 'block' }
+  useEffect(() => {
+    const updateCallback = updateNode
+    node && node.onMerge.subscribe(updateCallback)
+    node && node.onMessage.subscribe(updateCallback)
 
-  constructor(props: any) {
-    super(props)
-    this.state = { valueRenderWidth: 300 }
-  }
-
-  private registerUpdateListener(node: q.TreeNode<TopicViewModel>) {
-    node.onMerge.subscribe(this.updateNode)
-    node.onMessage.subscribe(this.updateNode)
-  }
-
-  private removeUpdateListener(node: q.TreeNode<TopicViewModel>) {
-    node.onMerge.unsubscribe(this.updateNode)
-    node.onMessage.unsubscribe(this.updateNode)
-  }
-
-  private renderTopicDeleteButton() {
-    if (!this.props.node || (!this.props.node.message || !this.props.node.message.value)) {
-      return null
+    return function cleanup() {
+      node && node.onMerge.unsubscribe(updateCallback)
+      node && node.onMessage.unsubscribe(updateCallback)
     }
+  }, [node])
 
-    return (
-      <CustomIconButton onClick={() => this.deleteTopic(this.props.node)} tooltip="Clear this topic">
-        <Delete style={{ marginTop: '-3px' }} />
-      </CustomIconButton>
-    )
-  }
-
-  private renderRecursiveTopicDeleteButton() {
-    const deleteLimit = 50
-    const topicCount = this.props.node ? this.props.node.childTopicCount() : 0
-    if (!this.props.node || topicCount === 0 || (this.props.node.message && topicCount === 1)) {
-      return null
-    }
-
-    return (
-      <Badge
-        classes={{ badge: this.props.classes.badge }}
-        badgeContent={<span style={{ whiteSpace: 'nowrap' }}>{topicCount >= deleteLimit ? '50+' : topicCount}</span>}
-        color="secondary"
-      >
-        <CustomIconButton
-          onClick={() => this.deleteTopic(this.props.node, true, deleteLimit)}
-          tooltip={`Deletes up to ${deleteLimit} sub-topics with a single click`}
-        >
-          <Delete style={{ marginTop: '-3px' }} color="action" />
-        </CustomIconButton>
-      </Badge>
-    )
-  }
-
-  private deleteTopic = (topic?: q.TreeNode<TopicViewModel>, recursive: boolean = false, maxCount = 50) => {
-    if (!topic) {
-      return
-    }
-
-    this.props.actions.clearTopic(topic, recursive, maxCount)
-  }
-
-  private renderNode() {
-    const { classes, node } = this.props
-
-    const copyTopic = node ? <Copy value={node.path()} /> : null
-    const deleteTopic = this.renderTopicDeleteButton()
-    const deleteRecursiveTopic = this.renderRecursiveTopicDeleteButton()
-    const summaryStyle = { minHeight: '0' }
-    return (
+  return (
+    <div id="Sidebar" className={props.classes.drawer}>
       <div>
-        <ExpansionPanel key="topic" defaultExpanded={true} disabled={!Boolean(this.props.node)}>
-          <ExpansionPanelSummary expandIcon={<ExpandMore />} style={summaryStyle}>
-            <Typography className={classes.heading}>
-              Topic {copyTopic} {deleteTopic} {deleteRecursiveTopic}
-            </Typography>
-          </ExpansionPanelSummary>
-          <ExpansionPanelDetails style={this.detailsStyle}>
-            <Topic node={this.props.node} didSelectNode={this.updateNode} />
+        <TopicPanel node={node} updateNode={updateNode} />
+        <ValuePanel lastUpdate={node ? node.lastUpdate : 0} />
+        <Panel>
+          <span>Publish</span>
+          <React.Suspense fallback={<div>Loading...</div>}>
+            <Publish connectionId={props.connectionId} />
+          </React.Suspense>
+        </Panel>
+        <Panel detailsHidden={!node}>
+          <span>Stats</span>
+          <ExpansionPanelDetails className={props.classes.details}>
+            <NodeStats node={node} />
           </ExpansionPanelDetails>
-        </ExpansionPanel>
-        <ValuePanel lastUpdate={this.props.node ? this.props.node.lastUpdate : 0} />
-        <ExpansionPanel defaultExpanded={true}>
-          <ExpansionPanelSummary expandIcon={<ExpandMore />} style={summaryStyle}>
-            <Typography className={classes.heading}>Publish</Typography>
-          </ExpansionPanelSummary>
-          <ExpansionPanelDetails style={this.detailsStyle}>
-            <React.Suspense fallback={<div>Loading...</div>}>
-              <Publish connectionId={this.props.connectionId} />
-            </React.Suspense>
-          </ExpansionPanelDetails>
-        </ExpansionPanel>
-        <ExpansionPanel defaultExpanded={Boolean(this.props.node)}>
-          <ExpansionPanelSummary expandIcon={<ExpandMore />} style={summaryStyle}>
-            <Typography className={classes.heading}>Stats</Typography>
-          </ExpansionPanelSummary>
-          {this.renderNodeStats()}
-        </ExpansionPanel>
+        </Panel>
       </div>
-    )
-  }
-
-  private renderNodeStats() {
-    if (!this.props.node) {
-      return null
-    }
-
-    return (
-      <ExpansionPanelDetails style={this.detailsStyle}>
-        <NodeStats node={this.props.node} />
-      </ExpansionPanelDetails>
-    )
-  }
-
-  public componentWillReceiveProps(nextProps: Props) {
-    this.props.node && this.removeUpdateListener(this.props.node)
-    nextProps.node && this.registerUpdateListener(nextProps.node)
-
-    if (this.props.node !== nextProps.node) {
-      this.setState({ compareMessage: undefined })
-    }
-  }
-
-  public componentWillUnmount() {
-    this.props.node && this.removeUpdateListener(this.props.node)
-  }
-
-  public render() {
-    return (
-      <div id="Sidebar" className={this.props.classes.drawer}>
-        {this.renderNode()}
-      </div>
-    )
-  }
+    </div>
+  )
 }
 
 const mapStateToProps = (state: AppState) => {
@@ -188,13 +86,11 @@ const styles = (theme: Theme) => ({
   drawer: {
     display: 'block' as 'block',
   },
-  badge: {
-    top: '3px',
-    right: '3px',
-  },
   valuePaper: {
     margin: theme.spacing(1),
   },
+  summary: { minHeight: '0' },
+  details: { padding: '0px 16px 8px 8px', display: 'block' },
   heading: {
     fontSize: theme.typography.pxToRem(15),
     fontWeight: theme.typography.fontWeightRegular,

app/src/components/Sidebar/TopicPanel/RecursiveTopicDeleteButton.tsx

@@ -0,0 +1,38 @@
+import * as q from '../../../../../backend/src/Model'
+import CustomIconButton from '../../helper/CustomIconButton'
+import Delete from '@material-ui/icons/Delete'
+import React, { useCallback } from 'react'
+import { Badge } from '@material-ui/core'
+
+export const RecursiveTopicDeleteButton = (props: {
+  node?: q.TreeNode<any>
+  deleteTopicAction: (node: q.TreeNode<any>, a: boolean, limit: number) => void
+}) => {
+  const onClick = useCallback(() => {
+    if (props.node) {
+      props.deleteTopicAction(props.node, true, deleteLimit)
+    }
+  }, [props.node])
+  if (!props.node) {
+    return null
+  }
+  const deleteLimit = 50
+  const topicCount = props.node ? props.node.childTopicCount() : 0
+  if (topicCount === 0 || (props.node.message && topicCount === 1)) {
+    return null
+  }
+  return (
+    <Badge
+      style={{
+        top: '3px',
+        right: '3px',
+      }}
+      badgeContent={<span style={{ whiteSpace: 'nowrap' }}>{topicCount >= deleteLimit ? '50+' : topicCount}</span>}
+      color="secondary"
+    >
+      <CustomIconButton onClick={onClick} tooltip={`Deletes up to ${deleteLimit} sub-topics with a single click`}>
+        <Delete style={{ marginTop: '-3px' }} color="action" />
+      </CustomIconButton>
+    </Badge>
+  )
+}

app/src/components/Sidebar/TopicPanel/Topic.tsx

@@ -1,11 +1,11 @@
-import * as React from 'react'
-import * as q from '../../../../backend/src/Model'
+import React from 'react'
+import * as q from '../../../../../backend/src/Model'
 import Button from '@material-ui/core/Button'
 import { withStyles, Theme } from '@material-ui/core/styles'
-import { treeActions } from '../../actions'
+import { treeActions } from '../../../actions'
 import { bindActionCreators } from 'redux'
 import { connect } from 'react-redux'
-import { TopicViewModel } from '../../model/TopicViewModel'
+import { TopicViewModel } from '../../../model/TopicViewModel'
 
 interface Props {
   classes: any

app/src/components/Sidebar/TopicPanel/TopicDeleteButton.tsx

@@ -0,0 +1,19 @@
+import * as q from '../../../../../backend/src/Model'
+import CustomIconButton from '../../helper/CustomIconButton'
+import Delete from '@material-ui/icons/Delete'
+import React from 'react'
+
+export const TopicDeleteButton = (props: {
+  node?: q.TreeNode<any>
+  deleteTopicAction: (node: q.TreeNode<any>) => void
+}) => {
+  const { node } = props
+  if (!node || !node.message || !node.message.value) {
+    return null
+  }
+  return (
+    <CustomIconButton onClick={() => props.deleteTopicAction(node)} tooltip="Clear this topic">
+      <Delete style={{ marginTop: '-3px' }} />
+    </CustomIconButton>
+  )
+}

app/src/components/Sidebar/TopicPanel/TopicPanel.tsx

@@ -0,0 +1,48 @@
+import * as q from '../../../../../backend/src/Model'
+import Copy from '../../helper/Copy'
+import Panel from '../Panel'
+import React, { useMemo } from 'react'
+import Topic from './Topic'
+import { bindActionCreators } from 'redux'
+import { connect } from 'react-redux'
+import { RecursiveTopicDeleteButton } from './RecursiveTopicDeleteButton'
+import { sidebarActions } from '../../../actions'
+import { TopicDeleteButton } from './TopicDeleteButton'
+
+const TopicPanel = (props: { node?: q.TreeNode<any>; actions: typeof sidebarActions; updateNode: () => void }) => {
+  const { node, updateNode } = props
+  const copyTopic = node ? <Copy value={node.path()} /> : null
+
+  const deleteTopic = (topic?: q.TreeNode<any>, recursive: boolean = false, maxCount = 50) => {
+    if (!topic) {
+      return
+    }
+
+    props.actions.clearTopic(topic, recursive, maxCount)
+  }
+
+  return useMemo(
+    () => (
+      <Panel disabled={!Boolean(node)}>
+        <span>
+          Topic {copyTopic}
+          <TopicDeleteButton node={node} deleteTopicAction={deleteTopic} />
+          <RecursiveTopicDeleteButton node={node} deleteTopicAction={deleteTopic} />
+        </span>
+        <Topic node={node} didSelectNode={updateNode} />
+      </Panel>
+    ),
+    [node, node && node.childTopicCount()]
+  )
+}
+
+const mapDispatchToProps = (dispatch: any) => {
+  return {
+    actions: bindActionCreators(sidebarActions, dispatch),
+  }
+}
+
+export default connect(
+  undefined,
+  mapDispatchToProps
+)(TopicPanel)

app/src/components/Tree/TreeNode/TreeNodeSubnodes.tsx

@@ -63,7 +63,7 @@ function TreeNodeSubnodes(props: Props) {
     })
 
     return <span className={props.classes.list}>{listItems}</span>
-  }, [alreadyAdded, props.lastUpdate, props.theme])
+  }, [alreadyAdded, props.treeNode.lastUpdate, props.theme])
 }
 
 const styles = (theme: Theme) => ({

app/src/components/Tree/TreeNode/index.tsx

@@ -133,7 +133,7 @@ function TreeNodeComponent(props: Props) {
         {renderNodes()}
       </div>
     )
-  }, [lastUpdate, treeNode, name, isCollapsed, selected, theme])
+  }, [treeNode.lastUpdate, treeNode, name, isCollapsed, selected, theme])
 }
 
 export default withStyles(styles, { withTheme: true })(TreeNodeComponent)

app/src/components/Tree/index.tsx

@@ -99,8 +99,8 @@ class TreeComponent extends React.PureComponent<Props, State> {
           this.updateTimer = undefined
           this.renderTime = performance.now()
 
-          if (!this.props.paused) {
-            this.props.tree && this.props.tree.applyUnmergedChanges()
+          if (!this.props.paused && this.props.tree) {
+            this.props.tree.applyUnmergedChanges()
           }
           window.requestIdleCallback(
             () => {