Update svglint ignore list, add ignore list updater (#3433)

This updates the ignore list as per #3250 and embeds code for updating
the ignore file when the environment variable `SI_UPDATE_IGNORE=true`
is set and the linter is run like so `SI_UPDATE_IGNORE=true npm run svglint`
-- running this command will display all remaining linting failures and
use these to update the ignore file.

This also:

* Normalises the top-level object key in the ignore file to match each
  linter name
* Sorts the ignore output on top-level key and icon name value to
  make output consistent
* Speeds up icon center checking if ignored
* Ignores icons in size linter if icon is otherwise ignored

.svglintrc.js

@@ -1,3 +1,5 @@
+const fs = require('fs');
+
 const data = require("./_data/simple-icons.json");
 const { htmlFriendlyToTitle } = require("./scripts/utils.js");
 const getBounds = require("svg-path-bounding-box");
@@ -8,7 +10,58 @@ const svgRegexp = /^<svg( [^\s]*=".*"){3}><title>.*<\/title><path d=".*"\/><\/sv
 const iconSize = 24;
 const iconFloatPrecision = 3;
 const iconTolerance = 0.001;
-const iconIgnored = require("./.svglint-ignored.json");
+
+// set env SI_UPDATE_IGNORE to recreate the ignore file
+const updateIgnoreFile = process.env.SI_UPDATE_IGNORE === 'true'
+const ignoreFile = "./.svglint-ignored.json";
+const iconIgnored = !updateIgnoreFile ? require(ignoreFile) : {};
+
+function sortObjectByKey(obj) {
+  return Object
+    .keys(obj)
+    .sort()
+    .reduce((r, k) => Object.assign(r, { [k]: obj[k] }), {});
+}
+
+function sortObjectByValue(obj) {
+  return Object
+    .keys(obj)
+    .sort((a, b) => ('' + obj[a]).localeCompare(obj[b]))
+    .reduce((r, k) => Object.assign(r, { [k]: obj[k] }), {});
+}
+
+if (updateIgnoreFile) {
+  process.on('exit', () => {
+    // ensure object output order is consistent due to async svglint processing
+    const sorted = sortObjectByKey(iconIgnored)
+    for (const linterName in sorted) {
+      sorted[linterName] = sortObjectByValue(sorted[linterName])
+    }
+
+    fs.writeFileSync(
+      ignoreFile,
+      JSON.stringify(sorted, null, 2) + '\n',
+      {flag: 'w'}
+    );
+  });
+}
+
+function isIgnored(linterName, path) {
+  return iconIgnored[linterName]
+    .map(ignored => ignored.hasOwnProperty(path))
+    .some(v => v === true);
+}
+
+function ignoreIcon(linterName, path, $) {
+  if (!iconIgnored[linterName]) {
+    iconIgnored[linterName] = {};
+  }
+
+  const title = $.find("title").text().replace(/(.*) icon/, '$1');
+  const iconName = htmlFriendlyToTitle(title);
+
+  iconIgnored[linterName][path] = iconName;
+}
 
 module.exports = {
     rules: {
@@ -23,7 +76,6 @@ module.exports = {
                 "role": "img",
                 "viewBox": `0 0 ${iconSize} ${iconSize}`,
                 "xmlns": "http://www.w3.org/2000/svg",
-
                 "rule::selector": "svg",
                 "rule::whitelist": true,
             },
@@ -59,7 +111,7 @@ module.exports = {
             reporter.name = "icon-size";
 
             const iconPath = $.find("path").attr("d");
-            if (iconIgnored.size.hasOwnProperty(iconPath)) {
+            if (!updateIgnoreFile && isIgnored(reporter.name, iconPath)) {
               return;
             }
 
@@ -69,8 +121,14 @@ module.exports = {
 
             if (width === 0 && height === 0) {
               reporter.error("Path bounds were reported as 0 x 0; check if the path is valid");
+              if (updateIgnoreFile) {
+                ignoreIcon(reporter.name, iconPath, $);
+              }
             } else if (width !== iconSize && height !== iconSize) {
               reporter.error(`Size of <path> must be exactly ${iconSize} in one dimension; the size is currently ${width} x ${height}`);
+              if (updateIgnoreFile) {
+                ignoreIcon(reporter.name, iconPath, $);
+              }
             }
           },
           function(reporter, $, ast) {
@@ -83,16 +141,13 @@ module.exports = {
           },
           function(reporter, $, ast) {
             reporter.name = "icon-centered";
-            const iconPath = $.find("path").attr("d");
-            const bounds = getBounds(iconPath);
 
-            if (
-              iconIgnored.size.hasOwnProperty(iconPath) ||
-              iconIgnored.center.hasOwnProperty(iconPath)
-            ) {
+            const iconPath = $.find("path").attr("d");
+            if (!updateIgnoreFile && isIgnored(reporter.name, iconPath)) {
               return;
             }
 
+            const bounds = getBounds(iconPath);
             const targetCenter = iconSize / 2;
             const centerX = +((bounds.minX + bounds.maxX) / 2).toFixed(iconFloatPrecision);
             const devianceX = centerX - targetCenter;
@@ -104,6 +159,9 @@ module.exports = {
               Math.abs(devianceY) > iconTolerance
             ) {
               reporter.error(`<path> must be centered at (${targetCenter}, ${targetCenter}); the center is currently (${centerX}, ${centerY})`);
+              if (updateIgnoreFile) {
+                ignoreIcon(reporter.name, iconPath, $);
+              }
             }
           }
         ]