Add Windows HTTP frontend

Author: mearvk

src/windows/WindowsHttpFrontend.java

@@ -0,0 +1,35 @@
+package windows;
+
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpHandler;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+/** Minimal HTTP boundary for the Windows execution model. */
+public final class WindowsHttpFrontend implements HttpHandler {
+    private final WindowsFrontendAdapter adapter;
+
+    public WindowsHttpFrontend(WindowsFrontendAdapter adapter) {
+        this.adapter = Objects.requireNonNull(adapter, "adapter");
+    }
+
+    @Override
+    public void handle(HttpExchange exchange) throws IOException {
+        if (!"POST".equalsIgnoreCase(exchange.getRequestMethod())) {
+            exchange.sendResponseHeaders(405, -1);
+            return;
+        }
+
+        String body = new String(exchange.getRequestBody().readAllBytes(), StandardCharsets.UTF_8);
+        WindowsCall call = WindowsCall.parse(body);
+        WindowsExecution.Result result = adapter.accept(call).toCompletableFuture().join();
+        byte[] response = result.toJson().getBytes(StandardCharsets.UTF_8);
+        exchange.getResponseHeaders().set("Content-Type", "application/json; charset=utf-8");
+        exchange.sendResponseHeaders(result.exitCode(), response.length);
+        try (var output = exchange.getResponseBody()) {
+            output.write(response);
+        }
+    }
+}