feat(sys): add sys.generateFileHash() for more efficient file hashing

src/declarations/stencil-public-compiler.ts

@@ -892,9 +892,13 @@ export interface CompilerSystem {
    */
   fetch?(input: string | any, init?: any): Promise<any>;
   /**
-   * Generates a MD5 digest encoded as HEX
+   * Generates a sha1 digest encoded as HEX
    */
   generateContentHash?(content: string | any, length?: number): Promise<string>;
+  /**
+   * Generates a sha1 digest encoded as HEX from a file path
+   */
+  generateFileHash?(filePath: string | any, length?: number): Promise<string>;
   /**
    * Get the current directory.
    */

src/sys/node/node-sys.ts

@@ -525,12 +525,26 @@ export function createNodeSys(c: { process?: any } = {}) {
     },
     generateContentHash(content, length) {
       let hash = createHash('sha1').update(content).digest('hex').toLowerCase();
-
       if (typeof length === 'number') {
         hash = hash.substr(0, length);
       }
       return Promise.resolve(hash);
     },
+    generateFileHash(filePath, length) {
+      return new Promise((resolve, reject) => {
+        const h = createHash('sha1');
+        fs.createReadStream(filePath)
+          .on('error', err => reject(err))
+          .on('data', data => h.update(data))
+          .on('end', () => {
+            let hash = h.digest('hex').toLowerCase();
+            if (typeof length === 'number') {
+              hash = hash.substr(0, length);
+            }
+            resolve(hash);
+          });
+      });
+    },
     copy: nodeCopyTasks,
     details: {
       cpuModel: (Array.isArray(sysCpus) && sysCpus.length > 0 ? sysCpus[0] && sysCpus[0].model : '') || '',