fix(highlight-code): handle mousewheel events properly

SyntaxHighlighter component doesn't support ref. We had
to use different approach to finds it's DOM Node using
ref of the root Node of the render tree for HighlightCode
component.

Refs #7497

src/core/components/highlight-code.jsx

@@ -1,47 +1,40 @@
-import React, { Component } from "react"
+import React, { useRef, useEffect } from "react"
 import PropTypes from "prop-types"
+import cx from "classnames"
 import {SyntaxHighlighter, getStyle} from "core/syntax-highlighting"
 import get from "lodash/get"
+import isFunction from "lodash/isFunction"
 import saveAs from "js-file-download"
 import { CopyToClipboard } from "react-copy-to-clipboard"
 
-export default class HighlightCode extends Component {
-  static propTypes = {
-    value: PropTypes.string.isRequired,
-    getConfigs: PropTypes.func.isRequired,
-    className: PropTypes.string,
-    downloadable: PropTypes.bool,
-    fileName: PropTypes.string,
-    language: PropTypes.string,
-    canCopy: PropTypes.bool
-  }
+const HighlightCode = ({value, fileName, className, downloadable, getConfigs, canCopy, language}) => {
+  const config = isFunction(getConfigs) ? getConfigs() : null
+  const canSyntaxHighlight = get(config, "syntaxHighlight.activated", true)
+  const highlighterStyle = getStyle(get(config, "syntaxHighlight.theme", "agate"))
+  const rootRef = useRef(null)
 
-  #childNodes
+  useEffect(() => {
+    const childNodes = Array
+      .from(rootRef.current.childNodes)
+      .filter(node => !!node.nodeType && node.classList.contains("microlight"))
 
-  downloadText = () => {
-    saveAs(this.props.value, this.props.fileName || "response.txt")
-  }
+    // eslint-disable-next-line no-use-before-define
+    childNodes.forEach(node => node.addEventListener("mousewheel", handlePreventYScrollingBeyondElement, { passive: false }))
 
-  handleRootRef = (node) => {
-    if (node === null) {
-      this.#childNodes = node
-    } else {
-      this.#childNodes = Array
-        .from(node.childNodes)
-        .filter(node => !!node.nodeType && node.classList.contains("microlight"))
+    return () => {
+      // eslint-disable-next-line no-use-before-define
+      childNodes.forEach(node => node.removeEventListener("mousewheel", handlePreventYScrollingBeyondElement))
     }
+  }, [value, className, language])
+
+  const handleDownload = () => {
+    saveAs(value, fileName)
   }
 
-  preventYScrollingBeyondElement = (e) => {
-    const target = e.target
-
-    var deltaY = e.deltaY
-    var contentHeight = target.scrollHeight
-    var visibleHeight = target.offsetHeight
-    var scrollTop = target.scrollTop
-
+  const handlePreventYScrollingBeyondElement = (e) => {
+    const { target, deltaY }  = e
+    const { scrollHeight: contentHeight, offsetHeight: visibleHeight, scrollTop } = target
     const scrollOffset = visibleHeight + scrollTop
-
     const isElementScrollable = contentHeight > visibleHeight
     const isScrollingPastTop = scrollTop === 0 && deltaY < 0
     const isScrollingPastBottom = scrollOffset >= contentHeight && deltaY > 0
@@ -51,49 +44,47 @@ export default class HighlightCode extends Component {
     }
   }
 
-  UNSAFE_componentDidMount() {
-    [this.#syntaxHighlighter, this.#pre]
-    .map(element => element?.addEventListener("mousewheel", this.preventYScrollingBeyondElement, { passive: false }))
-  }
+  return (
+    <div className="highlight-code" ref={rootRef}>
+      {!downloadable ? null :
+        <div className="download-contents" onClick={handleDownload}>
+          Download
+        </div>
+      }
 
-  UNSAFE_componentWillUnmount() {
-    [this.#syntaxHighlighter, this.#pre]
-    .map(element => element?.removeEventListener("mousewheel", this.preventYScrollingBeyondElement))
-  }
+      {canCopy && (
+        <div className="copy-to-clipboard">
+          <CopyToClipboard text={value}><button/></CopyToClipboard>
+        </div>
+      )}
 
-  render () {
-    let { value, className, downloadable, getConfigs, canCopy, language } = this.props
-
-    const config = getConfigs ? getConfigs() : {syntaxHighlight: {activated: true, theme: "agate"}}
-
-    className = className || ""
-
-    const codeBlock = get(config, "syntaxHighlight.activated")
-      ? <SyntaxHighlighter
+      {canSyntaxHighlight
+        ? <SyntaxHighlighter
           language={language}
-          className={className + " microlight"}
-          style={getStyle(get(config, "syntaxHighlight.theme"))}
-          >
+          className={cx(className, "microlight")}
+          style={highlighterStyle}
+        >
           {value}
         </SyntaxHighlighter>
-      : <pre className={className + " microlight"}>{value}</pre>
+        : <pre className={cx(className + "microlight")}>{value}</pre>
+      }
 
-    return (
-      <div className="highlight-code" ref={this.handleRootRef}>
-        { !downloadable ? null :
-          <div className="download-contents" onClick={this.downloadText}>
-            Download
-          </div>
-        }
-
-        { !canCopy ? null :
-          <div className="copy-to-clipboard">
-            <CopyToClipboard text={value}><button/></CopyToClipboard>
-          </div>
-        }
-
-        { codeBlock }
-      </div>
-    )
-  }
+    </div>
+  )
 }
+
+HighlightCode.propTypes = {
+  value: PropTypes.string.isRequired,
+  getConfigs: PropTypes.func.isRequired,
+  className: PropTypes.string,
+  downloadable: PropTypes.bool,
+  fileName: PropTypes.string,
+  language: PropTypes.string,
+  canCopy: PropTypes.bool
+}
+
+HighlightCode.defaultProps = {
+  fileName: "response.txt"
+}
+
+export default HighlightCode