From 0d03cc0f9ae09da0826bef636e05e3489e50f9c2 Mon Sep 17 00:00:00 2001
From: Joel Einbinder <joel.einbinder@gmail.com>
Date: Thu, 20 Aug 2020 09:27:04 -0700
Subject: [PATCH] feat(utils): add a script for watching various builds (#3545)

Watches our main typescript compilation, webpacks, type generation, and rpc channel generation.
---
 package.json   |  2 +-
 utils/watch.js | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 utils/watch.js

diff --git a/package.json b/package.json
index 699f12adeb..d7adb95a34 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
     "clean": "rimraf lib && rimraf types",
     "prepare": "node install-from-github.js",
     "build": "node utils/runWebpack.js --mode='development' && tsc -p . && npm run generate-types",
-    "watch": "node utils/runWebpack.js --mode='development' --watch --silent | tsc -w -p .",
+    "watch": "node utils/watch.js",
     "test-types": "npm run generate-types && npx -p typescript@3.7.5 tsc -p utils/generate_types/test/tsconfig.json && npm run typecheck-tests",
     "generate-types": "node utils/generate_types/",
     "generate-channels": "node utils/generate_channels.js",
diff --git a/utils/watch.js b/utils/watch.js
new file mode 100644
index 0000000000..756dd915eb
--- /dev/null
+++ b/utils/watch.js
@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * 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.
+ */
+
+const child_process = require('child_process');
+const path = require('path');
+const fs = require('fs');
+
+const spawns = [
+  child_process.spawn('node', [path.join(__dirname, 'runWebpack.js'), '--mode="development"', '--watch', '--silent'], { stdio: 'inherit', shell: true }),
+  child_process.spawn('npx', ['tsc', '-w', '--preserveWatchOutput', '-p', path.join(__dirname, '..')], { stdio: 'inherit', shell: true }),
+];
+process.on('exit', () => spawns.forEach(s => s.kill()));
+
+runOnChanges(['src/rpc/protocol.yml'], 'utils/generate_channels.js');
+runOnChanges(['docs/api.md', 'utils/generate_types/overrides.d.ts', 'utils/generate_types/exported.json'], 'utils/generate_types/index.js');
+
+/**
+ * @param {string[][]} paths 
+ * @param {string} nodeFile
+ */
+function runOnChanges(paths, nodeFile) {
+  for (const p of [...paths, nodeFile]) {
+    const filePath = path.join(__dirname, '..', ...p.split('/'));
+    if (!fs.existsSync(filePath)) {
+      console.error('could not find file', filePath);
+      process.exit(1);
+    }
+    fs.watchFile(filePath, callback);
+  }
+  
+  callback();
+  
+  function callback() {
+    child_process.spawnSync('node', [path.join(__dirname, '..', ...nodeFile.split('/'))]);
+  }
+}
\ No newline at end of file