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 {
+const HighlightCode = ({value, fileName, className, downloadable, getConfigs, canCopy, language}) => {
-  static propTypes = {
+  const config = isFunction(getConfigs) ? getConfigs() : null
-    value: PropTypes.string.isRequired,
+  const canSyntaxHighlight = get(config, "syntaxHighlight.activated", true)
-    getConfigs: PropTypes.func.isRequired,
+  const highlighterStyle = getStyle(get(config, "syntaxHighlight.theme", "agate"))
-    className: PropTypes.string,
+  const rootRef = useRef(null)
-    downloadable: PropTypes.bool,
-    fileName: PropTypes.string,
-    language: PropTypes.string,
-    canCopy: PropTypes.bool
-  }
 
-  #childNodes
+  useEffect(() => {
-
+    const childNodes = Array
-  downloadText = () => {
+      .from(rootRef.current.childNodes)
-    saveAs(this.props.value, this.props.fileName || "response.txt")
-  }
-
-  handleRootRef = (node) => {
-    if (node === null) {
-      this.#childNodes = node
-    } else {
-      this.#childNodes = Array
-        .from(node.childNodes)
       .filter(node => !!node.nodeType && node.classList.contains("microlight"))
+
+    // eslint-disable-next-line no-use-before-define
+    childNodes.forEach(node => node.addEventListener("mousewheel", handlePreventYScrollingBeyondElement, { passive: false }))
+
+    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 handlePreventYScrollingBeyondElement = (e) => {
-    const target = e.target
+    const { target, deltaY }  = e
-
+    const { scrollHeight: contentHeight, offsetHeight: visibleHeight, scrollTop } = target
-    var deltaY = e.deltaY
-    var contentHeight = target.scrollHeight
-    var visibleHeight = target.offsetHeight
-    var scrollTop = target.scrollTop
-
     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 }))
-  }
-
-  UNSAFE_componentWillUnmount() {
-    [this.#syntaxHighlighter, this.#pre]
-    .map(element => element?.removeEventListener("mousewheel", this.preventYScrollingBeyondElement))
-  }
-
-  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
-          language={language}
-          className={className + " microlight"}
-          style={getStyle(get(config, "syntaxHighlight.theme"))}
-          >
-          {value}
-        </SyntaxHighlighter>
-      : <pre className={className + " microlight"}>{value}</pre>
-
   return (
-      <div className="highlight-code" ref={this.handleRootRef}>
+    <div className="highlight-code" ref={rootRef}>
-        { !downloadable ? null :
+      {!downloadable ? null :
-          <div className="download-contents" onClick={this.downloadText}>
+        <div className="download-contents" onClick={handleDownload}>
           Download
         </div>
       }
 
-        { !canCopy ? null :
+      {canCopy && (
         <div className="copy-to-clipboard">
           <CopyToClipboard text={value}><button/></CopyToClipboard>
         </div>
+      )}
+
+      {canSyntaxHighlight
+        ? <SyntaxHighlighter
+          language={language}
+          className={cx(className, "microlight")}
+          style={highlighterStyle}
+        >
+          {value}
+        </SyntaxHighlighter>
+        : <pre className={cx(className + "microlight")}>{value}</pre>
       }
 
-        { codeBlock }
     </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