produce asset hashed icons

scripts/build-plugins/rollup-plugin-build-themes.js

@@ -14,10 +14,10 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 const path = require('path').posix;
+const {optimize} = require('svgo');
 
 async function readCSSSource(location) {
     const fs = require("fs").promises;
-    const path = require("path");
     const resolvedLocation = path.resolve(__dirname, "../../", `${location}/theme.css`);
     const data = await fs.readFile(resolvedLocation);
     return data;
@@ -43,6 +43,28 @@ function addThemesToConfig(bundle, manifestLocations, defaultThemes) {
     }
 }
 
+/**
+ * Returns an object where keys are the svg file names and the values
+ * are the svg code (optimized)
+ * @param {*} icons Object where keys are css variable names and values are locations of the svg
+ * @param {*} manifestLocation Location of manifest used for resolving path 
+ */
+async function generateIconSourceMap(icons, manifestLocation) {
+    const sources = {};
+    const fs = require("fs").promises;
+    for (const icon of Object.values(icons)) {
+        const [location] = icon.split("?");
+        const resolvedLocation = path.resolve(__dirname, "../../", manifestLocation, location);
+        const iconData = await fs.readFile(resolvedLocation);
+        const svgString = iconData.toString();
+        const result = optimize(svgString);
+        const optimizedSvgString = result.data;
+        const fileName = path.basename(resolvedLocation);
+        sources[fileName] = optimizedSvgString;
+    }
+    return sources;
+}
+
 /**
  * Returns a mapping from location (of manifest file) to an array containing all the chunks (of css files) generated from that location.
  * To understand what chunk means in this context, see https://rollupjs.org/guide/en/#generatebundle.
@@ -283,7 +305,7 @@ module.exports = function buildThemes(options) {
             ];
 },
 
-        generateBundle(_, bundle) {
+        async generateBundle(_, bundle) {
             const assetMap = getMappingFromFileNameToAssetInfo(bundle);
             const chunkMap = getMappingFromLocationToChunkArray(bundle);
             const runtimeThemeChunkMap = getMappingFromLocationToRuntimeChunk(bundle);
@@ -304,13 +326,28 @@ module.exports = function buildThemes(options) {
                     const locationRelativeToManifest = path.relative(manifestLocation, locationRelativeToBuildRoot);
                     builtAssets[`${name}-${variant}`] = locationRelativeToManifest;
                 }
+                // Emit the base svg icons as asset
+                const nameToAssetHashedLocation = [];
+                const nameToSource = await generateIconSourceMap(icon, location);
+                for (const [name, source] of Object.entries(nameToSource)) {
+                    const ref = this.emitFile({ type: "asset", name, source });
+                    const assetHashedName = this.getFileName(ref);
+                    nameToAssetHashedLocation[name] = assetHashedName;
+                }
+                for (const [variable, location] of Object.entries(icon)) {
+                    const [locationWithoutQueryParameters, queryParameters] = location.split("?");
+                    const name = path.basename(locationWithoutQueryParameters);
+                    const locationRelativeToBuildRoot = nameToAssetHashedLocation[name];
+                    const locationRelativeToManifest = path.relative(manifestLocation, locationRelativeToBuildRoot);
+                    icon[variable] = `${locationRelativeToManifest}?${queryParameters}`;
+                }
                 const runtimeThemeChunk = runtimeThemeChunkMap.get(location);
                 const runtimeAssetLocation = path.relative(manifestLocation, assetMap.get(runtimeThemeChunk.fileName).fileName); 
                 manifest.source = {
                     "built-assets": builtAssets,
                     "runtime-asset": runtimeAssetLocation,
                     "derived-variables": derivedVariables,
-                    "icon": icon
+                    "icon": icon,
                 };
                 const name = `theme-${themeKey}.json`;
                 manifestLocations.push(`${manifestLocation}/${name}`);