tools/serve.py: build, serve and rebuild on change (t9)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/serve.py

@@ -0,0 +1,86 @@
+#!/usr/bin/env python3
+"""Build, serve and rebuild when sources change: python3 tools/serve.py [--port 8000]."""
+import argparse, errno, http.server, pathlib, subprocess, sys, threading, time
+
+ROOT = pathlib.Path(__file__).resolve().parent.parent
+DIST = ROOT / 'dist'
+
+
+class Handler(http.server.SimpleHTTPRequestHandler):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, directory=str(DIST), **kwargs)
+
+    def end_headers(self):
+        self.send_header('Cache-Control', 'no-store')
+        super().end_headers()
+
+    def log_message(self, format, *args):
+        pass
+
+
+def build(first=False):
+    result = subprocess.run([sys.executable, str(ROOT / 'build.py')], cwd=ROOT,
+                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
+    if result.returncode:
+        print('build failed:\n' + result.stdout, flush=True)
+    elif first:
+        print(result.stdout, end='', flush=True)
+    else:
+        print(time.strftime('rebuilt %H:%M:%S'), flush=True)
+
+
+def mtimes():
+    files = [ROOT / 'build.py', *(ROOT / 'src').rglob('*')]
+    stamps = {}
+    for path in files:
+        try:
+            if path.is_file(): stamps[path] = path.stat().st_mtime_ns
+        except FileNotFoundError:
+            pass
+    return stamps
+
+
+def watch(stopped, previous):
+    while not stopped.wait(0.5):
+        current = mtimes()
+        if current != previous:
+            previous = current
+            build()
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--port', type=int, default=8000)
+    args = parser.parse_args()
+    if not 1 <= args.port <= 65525:
+        parser.error('--port must be between 1 and 65525 (leaves room for ten retries)')
+    previous = mtimes()
+    build(first=True)
+    if not (DIST / 'index.html').is_file():
+        sys.exit('Cannot serve: dist/index.html does not exist. Fix the build and try again.')
+    for port in range(args.port, args.port + 11):
+        try:
+            server = http.server.ThreadingHTTPServer(('127.0.0.1', port), Handler)
+            break
+        except OSError as error:
+            if error.errno != errno.EADDRINUSE:
+                sys.exit(f'Cannot serve on port {port}: {error}')
+    else:
+        sys.exit(f'Cannot serve: ports {args.port}-{args.port + 10} are all busy.')
+    if port != args.port:
+        print(f'Port {args.port} was busy; using {port}.', flush=True)
+    print(f'Serving dist/ at http://localhost:{port}  (Ctrl+C to stop)', flush=True)
+    stopped = threading.Event()
+    threading.Thread(target=watch, args=(stopped, previous), daemon=True).start()
+    try:
+        with server:
+            server.serve_forever()
+    finally:
+        stopped.set()
+
+
+if __name__ == '__main__':
+    try:
+        main()
+    except KeyboardInterrupt:
+        print('\nServer stopped.', flush=True)