Initial http implementation

src/http_handler.hpp

@@ -0,0 +1,92 @@
+#pragma once
+
+#include "connection.hpp"
+#include "connection_handler.hpp"
+#include <llhttp.h>
+#include <memory>
+#include <string_view>
+
+/**
+ * HTTP routes supported by WeaselDB server.
+ * Using enum for efficient switch-based routing.
+ */
+enum class HttpRoute {
+  GET_version,
+  POST_commit,
+  GET_subscribe,
+  GET_status,
+  PUT_retention,
+  GET_retention,
+  DELETE_retention,
+  GET_metrics,
+  NotFound
+};
+
+/**
+ * HTTP connection state stored in Connection::user_data.
+ * Manages llhttp parser state and request data.
+ */
+struct HttpConnectionState {
+  llhttp_t parser;
+  llhttp_settings_t settings;
+
+  // Current request data (arena-allocated)
+  std::string_view method;
+  std::string_view url;
+  std::string_view body;
+
+  // Parse state
+  bool headers_complete = false;
+  bool message_complete = false;
+  HttpRoute route = HttpRoute::NotFound;
+
+  explicit HttpConnectionState(ArenaAllocator &arena);
+};
+
+/**
+ * HTTP/1.1 server implementation using llhttp for parsing.
+ * Supports the WeaselDB REST API endpoints with enum-based routing.
+ */
+class HttpHandler : public ConnectionHandler {
+public:
+  HttpHandler() = default;
+
+  void on_connection_established(Connection &conn) override;
+  void on_connection_closed(Connection &conn) override;
+  void on_data_arrived(std::string_view data,
+                       std::unique_ptr<Connection> &conn_ptr) override;
+  void on_write_progress(std::unique_ptr<Connection> &conn_ptr) override;
+
+  // Route parsing (public for testing)
+  static HttpRoute parseRoute(std::string_view method, std::string_view url);
+
+  // llhttp callbacks (public for HttpConnectionState access)
+  static int onUrl(llhttp_t *parser, const char *at, size_t length);
+  static int onHeaderField(llhttp_t *parser, const char *at, size_t length);
+  static int onHeaderValue(llhttp_t *parser, const char *at, size_t length);
+  static int onHeadersComplete(llhttp_t *parser);
+  static int onBody(llhttp_t *parser, const char *at, size_t length);
+  static int onMessageComplete(llhttp_t *parser);
+
+private:
+  // Route handlers
+  void handleGetVersion(Connection &conn, const HttpConnectionState &state);
+  void handlePostCommit(Connection &conn, const HttpConnectionState &state);
+  void handleGetSubscribe(Connection &conn, const HttpConnectionState &state);
+  void handleGetStatus(Connection &conn, const HttpConnectionState &state);
+  void handlePutRetention(Connection &conn, const HttpConnectionState &state);
+  void handleGetRetention(Connection &conn, const HttpConnectionState &state);
+  void handleDeleteRetention(Connection &conn,
+                             const HttpConnectionState &state);
+  void handleGetMetrics(Connection &conn, const HttpConnectionState &state);
+  void handleNotFound(Connection &conn, const HttpConnectionState &state);
+
+  // HTTP utilities
+  static void sendResponse(Connection &conn, int status_code,
+                           std::string_view content_type,
+                           std::string_view body);
+  static void sendJsonResponse(Connection &conn, int status_code,
+                               std::string_view json);
+  static void sendErrorResponse(Connection &conn, int status_code,
+                                std::string_view message);
+};