Rollup for proper CLI

cli/lib/asset-plugin.js

@@ -0,0 +1,75 @@
+/**
+ * Copyright 2020 Google Inc. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { promises as fs } from 'fs';
+import { basename } from 'path';
+
+const defaultOpts = {
+  prefix: 'asset-url',
+};
+
+export default function assetPlugin(opts) {
+  opts = Object.assign({}, defaultOpts, opts);
+
+  /** @type {Map<string, Buffer>} */
+  let assetIdToSourceBuffer;
+
+  const prefix = opts.prefix + ':';
+  return {
+    name: 'asset-plugin',
+    buildStart() {
+      assetIdToSourceBuffer = new Map();
+    },
+    augmentChunkHash(info) {
+      // Get the sources for all assets imported by this chunk.
+      const buffers = Object.keys(info.modules)
+        .map(moduleId => assetIdToSourceBuffer.get(moduleId))
+        .filter(Boolean);
+
+      if (buffers.length === 0) return;
+
+      for (const moduleId of Object.keys(info.modules)) {
+        const buffer = assetIdToSourceBuffer.get(moduleId);
+        if (buffer) buffers.push(buffer);
+      }
+
+      const combinedBuffer =
+        buffers.length === 1 ? buffers[0] : Buffer.concat(buffers);
+
+      return combinedBuffer;
+    },
+    async resolveId(id, importer) {
+      if (!id.startsWith(prefix)) return;
+      const realId = id.slice(prefix.length);
+      const resolveResult = await this.resolve(realId, importer);
+
+      if (!resolveResult) {
+        throw Error(`Cannot find ${realId}`);
+      }
+      // Add an additional .js to the end so it ends up with .js at the end in the _virtual folder.
+      return prefix + resolveResult.id + '.js';
+    },
+    async load(id) {
+      if (!id.startsWith(prefix)) return;
+      const realId = id.slice(prefix.length, -'.js'.length);
+      const source = await fs.readFile(realId);
+      assetIdToSourceBuffer.set(id, source);
+      this.addWatchFile(realId);
+
+      return `export default import.meta.ROLLUP_FILE_URL_${this.emitFile({
+        type: 'asset',
+        source,
+        name: basename(realId),
+      })}`;
+    },
+  };
+}