src/Linkifier.ts

   1 /**
   2  * The time to wait after a row is changed before it is linkified. This prevents
   3  * the costly operation of searching every row multiple times, pntentially a
   4  * huge aount of times.
   5  */
   6 const TIME_BEFORE_LINKIFY = 200;
   7
   8 const protocolClause = '(https?:\\/\\/)';
   9 const domainCharacterSet = '[\\da-z\\.-]+';
  10 const negatedDomainCharacterSet = '[^\\da-z\\.-]+';
  11 const domainBodyClause = '(' + domainCharacterSet + ')';
  12 const tldClause = '([a-z\\.]{2,6})';
  13 const ipClause = '((\\d{1,3}\\.){3}\\d{1,3})';
  14 const portClause = '(:\\d{1,5})';
  15 const hostClause = '((' + domainBodyClause + '\\.' + tldClause + ')|' + ipClause + ')' + portClause + '?';
  16 const pathClause = '(\\/[\\/\\w\\.-]*)*';
  17 const negatedPathCharacterSet = '[^\\/\\w\\.-]+';
  18 const bodyClause = hostClause + pathClause;
  19 const start = '(?:^|' + negatedDomainCharacterSet + ')(';
  20 const end = ')($|' + negatedPathCharacterSet + ')';
  21 const strictUrlRegex = new RegExp(start + protocolClause + bodyClause + end);
  22
  23 export type LinkHandler = (uri: string) => void;
  24
  25 /**
  26  * The Linkifier applies links to rows shortly after they have been refreshed.
  27  */
  28 export class Linkifier {
  29   private _rows: HTMLElement[];
  30   private _rowTimeoutIds: number[];
  31   private _hypertextLinkHandler: LinkHandler;
  32
  33   constructor(rows: HTMLElement[]) {
  34     this._rows = rows;
  35     this._rowTimeoutIds = [];
  36   }
  37
  38   /**
  39    * Queues a row for linkification.
  40    * @param {number} rowIndex The index of the row to linkify.
  41    */
  42   public linkifyRow(rowIndex: number): void {
  43     const timeoutId = this._rowTimeoutIds[rowIndex];
  44     if (timeoutId) {
  45       clearTimeout(timeoutId);
  46     }
  47     this._rowTimeoutIds[rowIndex] = setTimeout(this._linkifyRow.bind(this, rowIndex), TIME_BEFORE_LINKIFY);
  48   }
  49
  50   // TODO: Support local links
  51   public attachHypertextLinkHandler(handler: LinkHandler): void {
  52     this._hypertextLinkHandler = handler;
  53   }
  54
  55   /**
  56    * Linkifies a row.
  57    * @param {number} rowIndex The index of the row to linkify.
  58    */
  59   private _linkifyRow(rowIndex: number): void {
  60     const rowHtml = this._rows[rowIndex].innerHTML;
  61     const uri = this._findLinkMatch(rowHtml);
  62     if (!uri) {
  63       return;
  64     }
  65
  66     // Iterate over nodes as we want to consider text nodes
  67     const nodes = this._rows[rowIndex].childNodes;
  68     for (let i = 0; i < nodes.length; i++) {
  69       const node = nodes[i];
  70       const searchIndex = node.textContent.indexOf(uri);
  71       if (searchIndex >= 0) {
  72         if (node.childNodes.length > 0) {
  73           // This row has already been linkified
  74           return;
  75         }
  76
  77         const linkElement = this._createAnchorElement(uri);
  78         // TODO: Check if childNodes check is needed
  79         if (node.textContent.trim().length === uri.length) {
  80           // Matches entire string
  81           if (node.nodeType === Node.TEXT_NODE) {
  82             this._replaceNode(node, linkElement);
  83           } else {
  84             const element = (<HTMLElement>node);
  85             element.innerHTML = '';
  86             element.appendChild(linkElement);
  87           }
  88         } else {
  89           // Matches part of string
  90           this._replaceNodeSubstringWithNode(node, linkElement, uri, searchIndex);
  91         }
  92       }
  93     }
  94   }
  95
  96   /**
  97    * Finds a link match in a piece of HTML.
  98    * @param {string} html The HTML to search.
  99    * @return {string} The matching URI or null if not found.
 100    */
 101   private _findLinkMatch(html: string): string {
 102     const match = html.match(strictUrlRegex);
 103     if (!match || match.length === 0) {
 104       return null;
 105     }
 106     return match[1];
 107   }
 108
 109   /**
 110    * Creates a link anchor element.
 111    * @param {string} uri The uri of the link.
 112    * @return {HTMLAnchorElement} The link.
 113    */
 114   private _createAnchorElement(uri: string): HTMLAnchorElement {
 115     const element = document.createElement('a');
 116     element.textContent = uri;
 117     if (this._hypertextLinkHandler) {
 118       element.addEventListener('click', () => this._hypertextLinkHandler(uri));
 119     } else {
 120       element.href = uri;
 121       // Force link on another tab so work is not lost
 122       element.target = '_blank';
 123     }
 124     return element;
 125   }
 126
 127   /**
 128    * Replace a node with 1 or more other nodes.
 129    * @param {Node} oldNode The node to replace.
 130    * @param {Node[]} newNodes The new nodes to insert in order.
 131    */
 132   private _replaceNode(oldNode: Node, ...newNodes: Node[]): void {
 133     const parent = oldNode.parentNode;
 134     for (let i = 0; i < newNodes.length; i++) {
 135       parent.insertBefore(newNodes[i], oldNode);
 136     }
 137     parent.removeChild(oldNode);
 138   }
 139
 140   /**
 141    * Replace a substring within a node with a new node.
 142    * @param {Node} targetNode The target node; either a text node or a <span>
 143    * containing a single text node.
 144    * @param {Node} newNode The new node to insert.
 145    * @param {string} substring The substring to replace.
 146    * @param {number} substringIndex The index of the substring within the string.
 147    */
 148   private _replaceNodeSubstringWithNode(targetNode: Node, newNode: Node, substring: string, substringIndex: number): void {
 149     let node = targetNode;
 150     if (node.nodeType !== Node.TEXT_NODE) {
 151       node = node.childNodes[0];
 152     }
 153
 154     // The targetNode will be either a text node or a <span>. The text node
 155     // (targetNode or its only-child) needs to be replaced with newNode plus new
 156     // text nodes potentially on either side.
 157     if (node.childNodes.length === 0 && node.nodeType !== Node.TEXT_NODE) {
 158       throw new Error('targetNode must be a text node or only contain a single text node');
 159     }
 160
 161     const fullText = node.textContent;
 162
 163     if (substringIndex === 0) {
 164       // Replace with <newNode><textnode>
 165       const rightText = fullText.substring(substring.length);
 166       const rightTextNode = document.createTextNode(rightText);
 167       this._replaceNode(node, newNode, rightTextNode);
 168     } else if (substringIndex === targetNode.textContent.length - substring.length) {
 169       // Replace with <textnode><newNode>
 170       const leftText = fullText.substring(0, substringIndex);
 171       const leftTextNode = document.createTextNode(leftText);
 172       this._replaceNode(node, leftTextNode, newNode);
 173     } else {
 174       // Replace with <textnode><newNode><textnode>
 175       const leftText = fullText.substring(0, substringIndex);
 176       const leftTextNode = document.createTextNode(leftText);
 177       const rightText = fullText.substring(substringIndex + substring.length);
 178       const rightTextNode = document.createTextNode(rightText);
 179       this._replaceNode(node, leftTextNode, newNode, rightTextNode);
 180     }
 181   }
 182 }