Initial commit.

lib/hostr-file-stream.js

@@ -0,0 +1,36 @@
+import fs from 'fs';
+import path from 'path';
+import createError from 'http-errors';
+import { get as getFile } from './s3';
+
+import debugname from 'debug';
+const debug = debugname('hostr:file-stream');
+
+export default function* hostrFileStream(localPath, remotePath) {
+  const localRead = fs.createReadStream(localPath);
+  return new Promise((resolve, reject) => {
+    localRead.once('error', () => {
+      debug('local error');
+      const remoteRead = getFile(remotePath);
+
+      remoteRead.once('readable', () => {
+        debug('remote readable');
+        const localWrite = fs.createWriteStream(localPath);
+        localWrite.once('finish', () => {
+          debug('local write end');
+          resolve(fs.createReadStream(localPath));
+        });
+        remoteRead.pipe(localWrite);
+      });
+
+      remoteRead.once('error', () => {
+        debug('remote error');
+        reject(createError(404));
+      });
+    });
+    localRead.once('readable', () => {
+      debug('local readable');
+      resolve(localRead);
+    });
+  });
+}