Hover text description of GCodes

.gitignore

@@ -0,0 +1 @@
+node_modules/

client/extension.js

@@ -0,0 +1,100 @@
+const vscode = require('vscode');
+var fetch = require("node-fetch");
+
+var urlLookup;
+
+function activate(context) {
+
+    console.log('GCode hover text is active');
+
+    if (urlLookup == null)
+    {
+        console.debug('Fetching cache of documentation');
+        urlLookup = new Object();
+        fetch(`https://api.github.com/repos/MarlinFirmware/MarlinDocumentation/contents/_gcode`)
+        .then(res => res.json())
+        .then(body => parseRepoContents(body))
+        .catch((error) => console.log(error));
+    }
+
+    disposable = vscode.languages.registerHoverProvider('gcode', {
+        async provideHover(document, position, token) {
+            const range = document.getWordRangeAtPosition(position);
+            const word = document.getText(range);
+
+            // format the word correctly
+            const regex = /\s*([A-Za-z])(\d+)\s*/
+            const matches = word.match(regex);
+            // If the second part is a number then search the lookup for the documentation
+            if(!isNaN(matches[2]))
+            {
+                // Format the string correctly (i.e. with leading zeros)
+                const gcode = matches[1] + matches[2].padStart(3,"0");
+                return new vscode.Hover(await getHoverText(gcode));
+            }
+        }
+    });    
+
+    context.subscriptions.push(disposable);
+}
+
+function deactivate() { }
+
+async function getHoverText(gcode)
+{
+    if (urlLookup[gcode].hoverText == null)
+    {
+        // Can we generate the info?
+        if (urlLookup[gcode].download_url != null)
+        {
+            const rawInfoUrl = urlLookup[gcode].download_url;
+            if (rawInfoUrl != null)
+            {
+                try {
+                    const response = await fetch(rawInfoUrl);
+                    const json = await response.text();
+                    const docs = parseDocs(json);
+                    urlLookup[gcode].hoverText = `**${docs.title}** \n\n ${docs.brief} \n\n <${urlLookup[gcode].docs_url}>`
+                } catch (error) {
+                    console.log(error);
+                }
+            }
+        }
+
+    }
+    return urlLookup[gcode].hoverText;
+}
+
+function parseRepoContents(json)
+{
+    json.forEach(element => {
+        const filename = element.name.split(".")[0];
+        const download_url = element.download_url;
+        const docs_url = `https://marlinfw.org/docs/gcode/${filename}.html`;
+
+        const regex = /([A-Za-z])(\d+)(?:-([A-Za-z])(\d+))?/;
+        const matches = filename.match(regex);
+
+        // remove the global match
+        matches.shift();
+
+        for (i = 0; i <= matches.length/2; i+=2) {
+            urlLookup[matches[i] + matches[i+1]] = {
+                download_url: download_url,
+                docs_url: docs_url,
+            };
+        }
+    });
+}
+
+function parseDocs(text) 
+{
+    return {
+        title:text.match(/title: ([^\n]*)/)[1],
+        brief:text.match(/brief: ([^\n]*)/)[1]};
+}
+
+module.exports = {
+    activate,
+    deactivate
+}

package.json

@@ -2,7 +2,7 @@
     "name": "nc-gcode",
     "displayName": "nc-gcode",
     "description": "G-code syntax highlighter",
-    "version": "0.14.1",
+    "version": "0.14.2",
     "publisher": "ML2",
     "author": {
         "name": "Milys",
@@ -11,11 +11,18 @@
     "maintainers": [{
         "name": "scottmwyant",
         "url": "https://github.com/scottmwyant"
+    },
+    {
+        "name": "Stevil Knevil",
+        "url": "https://github.com/StevilKnevil"
     }],
     "scripts": {
         "pack": "vsce package"
     },
     "preview": true,
+    "activationEvents": [
+        "onLanguage:gcode"
+     ],    
     "engines": {
         "vscode": "^1.19.0"
     },
@@ -32,7 +39,11 @@
         "color": "#E4F2FF",
         "theme": "light"
     },
+    "main": "./client/extension.js",
     "contributes": {
+        "capabilities": {
+            "hoverProvider": "true"
+        },
         "languages": [{
             "id": "gcode",
             "aliases": [
@@ -88,5 +99,7 @@
             "scopeName": "source.gcode",
             "path": "./gcode.tmLanguage.json"
         }]
-    }
+    },
+    "dependencies" :
+        { "node-fetch" : ">2.6.0" }
 }