[FEATURE] Add option to use hash signatures in cachebuster info file

- There are situations where using timestamps may not be reliable
  (ex: CI environments)
- Provide two different signature type to be used: time and hash
- Read configuration parameter from ui5.yaml file, keeping time as default one

lib/tasks/generateCachebusterInfo.js

@@ -1,4 +1,31 @@
 const resourceFactory = require("@ui5/fs").resourceFactory;
+const crypto = require("crypto");
+
+async function signByTime(resource) {
+	return resource.getStatInfo().mtime.getTime();
+}
+
+async function signByHash(resource) {
+	const hasher = crypto.createHash("sha1");
+	const buffer = await resource.getBuffer();
+
+	hasher.update(buffer.toString("binary"));
+	return hasher.digest("hex");
+}
+
+function getSigner(type) {
+	type = type || "time";
+
+	switch (type) {
+	case "time":
+		return signByTime;
+	case "hash":
+		return signByHash;
+
+	default:
+		throw new Error(`Invalid signature type: '${type}'. Valid ones are: 'time' or 'hash'`);
+	}
+}
 
 /**
  * Task to generate the application cachebuster info file.
@@ -10,17 +37,20 @@ const resourceFactory = require("@ui5/fs").resourceFactory;
  * @param {module:@ui5/fs.AbstractReader} parameters.dependencies Reader or Collection to read dependency files
  * @param {Object} parameters.options Options
  * @param {string} parameters.options.namespace Namespace of the application
+ * @param {string} [parameters.options.signatureType='time'] Type of signature to be used ('time' or 'hash')
  * @returns {Promise<undefined>} Promise resolving with <code>undefined</code> once data has been written
  */
 module.exports = function({workspace, dependencies, options}) {
 	return workspace.byGlob(`/resources/${options.namespace}/**/*`)
 		.then(async (resources) => {
 			const cachebusterInfo = {};
 			const regex = new RegExp(`^/resources/${options.namespace}/`);
-			resources.forEach((resource) => {
+			const signer = getSigner(options.signatureType);
+
+			await Promise.all(resources.map(async (resource) => {
 				const normalizedPath = resource.getPath().replace(regex, "");
-				cachebusterInfo[normalizedPath] = resource.getStatInfo().mtime.getTime();
-			});
+				cachebusterInfo[normalizedPath] = await signer(resource);
+			}));
 			const cachebusterInfoResource = resourceFactory.createResource({
 				path: `/resources/${options.namespace}/sap-ui-cachebuster-info.json`,
 				string: JSON.stringify(cachebusterInfo, null, 2)

lib/types/application/ApplicationBuilder.js

@@ -171,7 +171,10 @@ class ApplicationBuilder extends AbstractBuilder {
 					workspace: resourceCollections.workspace,
 					dependencies: resourceCollections.dependencies,
 					options: {
-						namespace: project.metadata.namespace
+						namespace: project.metadata.namespace,
+						signatureType: project.builder
+							&& project.builder.cachebuster
+							&& project.builder.cachebuster.signatureType,
 					}
 				});
 			});

test/lib/tasks/generateCachebusterInfo.js

@@ -57,6 +57,39 @@ test("integration: Build application.g with manifestBundler", (t) => {
 	});
 });
 
+test("integration: Build application.g with manifestBundler and cachebuster using hashes", (t) => {
+	const destPath = path.join("test", "tmp", "build", "application.g", "cachebuster_hash");
+	const expectedPath = path.join("test", "expected", "build", "application.g", "cachebuster");
+	const excludedTasks = ["generateVersionInfo"];
+	const includedTasks = ["generateCachebusterInfo"];
+
+	return builder.build({
+		tree: applicationGTreeWithCachebusterHash,
+		destPath,
+		excludedTasks,
+		includedTasks
+	}).then(() => {
+		return findFiles(expectedPath);
+	}).then((expectedFiles) => {
+		// Check for all directories and files
+		assert.directoryDeepEqual(destPath, expectedPath);
+
+		// Check for all file contents
+		expectedFiles.forEach((expectedFile) => {
+			const relativeFile = path.relative(expectedPath, expectedFile);
+			const destFile = path.join(destPath, relativeFile);
+			if (expectedFile.endsWith("sap-ui-cachebuster-info.json")) {
+				const currentContent = JSON.parse(fs.readFileSync(destFile, "utf-8").replace(/(:\s+)("[^"]+")/g, ": \"\""));
+				const expectedContent = JSON.parse(fs.readFileSync(expectedFile, "utf-8").replace(/(:\s+)(\d+)/g, ": \"\""));
+				assert.deepEqual(currentContent, expectedContent);
+			} else {
+				assert.fileEqual(destFile, expectedFile);
+			}
+		});
+		t.pass();
+	});
+});
+
 const applicationGTree = {
 	"id": "application.g",
 	"version": "1.0.0",
@@ -82,3 +115,33 @@ const applicationGTree = {
 		}
 	}
 };
+
+const applicationGTreeWithCachebusterHash = {
+	"id": "application.g",
+	"version": "1.0.0",
+	"path": applicationGPath,
+	"dependencies": [],
+	"builder": {
+		"cachebuster": {
+			"signatureType": "hash"
+		}
+	},
+	"_level": 0,
+	"specVersion": "0.1",
+	"type": "application",
+	"metadata": {
+		"name": "application.g",
+		"namespace": "application.g",
+		"copyright": "Some fancy copyright"
+	},
+	"resources": {
+		"configuration": {
+			"paths": {
+				"webapp": "webapp"
+			}
+		},
+		"pathMappings": {
+			"/": "webapp"
+		}
+	}
+};