Update brew content merging functionality and add it to downloads/page source views

#1838

server/utils/brew.js

@@ -0,0 +1,41 @@
+const yaml = require('js-yaml');
+
+module.exports = {
+	mergeBrewText : (brew, { style, metadata, fullMetadata })=>{
+		let text = brew.text;
+		if(style) {
+			text = `\`\`\`css\n` +
+                `${brew.style || ''}\n` +
+                `\`\`\`\n\n` +
+                `${text}`;
+		}
+		if(metadata) {
+			let metadata = {
+				title       : brew.title,
+				description : brew.description,
+				tags        : brew.tags,
+				systems     : brew.systems,
+				renderer    : brew.renderer,
+				authors     : brew.authors,
+				published   : brew.published
+			};
+			if(fullMetadata) {
+				metadata = {
+					...metadata,
+					shareId    : brew.shareId,
+					pageCount  : brew.pageCount,
+					createdAt  : brew.createdAt,
+					updatedAt  : brew.updatedAt,
+					lastViewed : brew.lastViewed,
+					views      : brew.views,
+					version    : brew.version
+				};
+			}
+			text = `\`\`\`metadata\n` +
+                `${yaml.dump(metadata)}\n` +
+                `\`\`\`\n\n` +
+                `${text}`;
+		}
+		return text;
+	}
+};