add new http module

tooling/pipeline/CMakeLists.txt

@@ -1,3 +1,4 @@
+# CMakeLists.txt (project root)
 cmake_minimum_required(VERSION 3.31)
 project(biergarten-pipeline)
 
@@ -46,10 +47,15 @@ set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG}   -Og -g")
 
 # 4. Dependencies
 include(FetchContent)
+
+# DEPRECATED: libcurl — to be removed once all usages are migrated to cpp-httplib.
+# Tracked in: web_client/curl_web_client_get.cc, web_client/curl_web_client_url_encode.cc,
+#             web_client/curl_global_state.cc
 find_package(CURL QUIET)
 if (NOT CURL_FOUND)
     message(FATAL_ERROR "[biergarten] libcurl not found. Install it (e.g. 'sudo dnf install libcurl-devel').")
 endif ()
+
 find_package(Boost REQUIRED COMPONENTS json program_options)
 
 # SQLite amalgamation
@@ -95,6 +101,22 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(spdlog)
 
+# cpp-httplib — replaces direct libcurl usage in web_client.
+# OpenSSL is required for HTTPS (Wikipedia). find_package is called first so
+# CMake can locate libssl/libcrypto; cpp-httplib itself is header-only so the
+# CPPHTTPLIB_OPENSSL_SUPPORT compile definition is propagated via the target.
+find_package(OpenSSL REQUIRED)
+
+FetchContent_Declare(
+        cpp-httplib
+        GIT_REPOSITORY https://github.com/yhirose/cpp-httplib.git
+        GIT_TAG v0.41.0
+        GIT_SHALLOW TRUE
+        SYSTEM
+)
+set(HTTPLIB_REQUIRE_OPENSSL ON CACHE BOOL "Require OpenSSL for cpp-httplib" FORCE)
+FetchContent_MakeAvailable(cpp-httplib)
+
 # 5. Executable & Sources
 add_executable(${PROJECT_NAME})
 
@@ -123,12 +145,17 @@ target_sources(${PROJECT_NAME} PRIVATE
 )
 
 # --- web_client ---
+# DEPRECATED: curl_web_client_* — to be replaced with cpp-httplib equivalents.
 target_sources(${PROJECT_NAME} PRIVATE
         src/web_client/curl_web_client_url_encode.cc
         src/web_client/curl_web_client_get.cc
         src/web_client/curl_global_state.cc
 )
 
+target_sources(${PROJECT_NAME} PRIVATE
+        src/web_client/http_web_client.cc
+)
+
 # --- data_generation: prompt_formatting ---
 target_sources(${PROJECT_NAME} PRIVATE
         src/data_generation/prompt_formatting/gemma4_jinja_prompt_formatter.cc
@@ -189,7 +216,10 @@ target_link_libraries(${PROJECT_NAME} PRIVATE
         Boost::program_options
         spdlog::spdlog
         sqlite3
-        CURL::libcurl
+        httplib::httplib
+        OpenSSL::SSL
+        OpenSSL::Crypto
+        CURL::libcurl          # DEPRECATED: remove once web_client is migrated to cpp-httplib
 )
 
 if (BIERGARTEN_MOCK_ONLY)

tooling/pipeline/includes/web_client/http_web_client.h

@@ -0,0 +1,49 @@
+/**
+* @file web_client/http_web_client.h
+* @brief cpp-httplib implementation of the WebClient interface.
+*/
+
+#ifndef BIERGARTEN_PIPELINE_INCLUDES_HTTP_WEB_CLIENT_CURL_WEB_CLIENT_H_
+#define BIERGARTEN_PIPELINE_INCLUDES_HTTP_WEB_CLIENT_CURL_WEB_CLIENT_H_
+
+
+#include "web_client/web_client.h"
+
+#include <string>
+
+/**
+ * @brief WebClient implementation backed by cpp-httplib.
+ *
+ * Supports HTTP and HTTPS (requires
+ * OpenSSL; see HTTPLIB_USE_OPENSSL_IF_AVAILABLE in CMakeLists.txt).
+ *
+ * URL parsing splits a full URL into scheme + host and path + query so that
+ * httplib::Client can be constructed correctly. A new client instance is
+ * created per request; th  is is intentional given the low call volume in the
+ * pipeline (Wikipedia enrichment, near-100 % cache hits).
+ */
+class HttpWebClient final : public WebClient {
+public:
+  HttpWebClient() = default;
+  ~HttpWebClient() override = default;
+
+  /**
+   * @brief Executes a blocking HTTP/HTTPS GET request against a full URL.
+   *
+   * @param url Fully-qualified URL, e.g. "https://en.wikipedia.org/api/rest_v1/page/summary/Berlin"
+   * @return Response body on HTTP 2xx; throws std::runtime_error otherwise.
+   */
+  std::string Get(const std::string& url) override;
+
+  /**
+   * @brief Percent-encodes a single URI component (query parameter value or
+   *        path segment). Delegates to httplib::encode_uri_component().
+   *
+   * @param value Raw string to encode.
+   * @return Percent-encoded string safe for use in a URL.
+   */
+  std::string UrlEncode(const std::string& value) override;
+};
+
+
+#endif

tooling/pipeline/src/web_client/http_web_client.cc

@@ -0,0 +1,61 @@
+/**
+* @file web_client/http_web_client.cc
+ * @brief cpp-httplib implementation of WebClient.
+ */
+
+#include "web_client/http_web_client.h"
+
+#include <httplib.h>
+
+#include <regex>
+#include <stdexcept>
+#include <string>
+#include <utility>
+
+namespace {
+constexpr time_t kConnectionTimeoutSeconds = 5;
+constexpr time_t kReadTimeoutSeconds = 10;
+
+constexpr int kSuccessMin = 200;
+constexpr int kSuccessMax = 300;
+const std::regex kUrlRegex(
+    R"(^(https?://[^/?#]+)(/[^?#]*(?:\?[^#]*)?(?:#.*)?)?)");
+
+std::pair<std::string, std::string> SplitUrl(const std::string& url) {
+  std::smatch match;
+  if (!std::regex_match(url, match, kUrlRegex)) {
+    throw std::invalid_argument("[HttpWebClient] Malformed URL: " + url);
+  }
+
+  return {match[1].str(), match[2].matched ? match[2].str() : "/"};
+}
+} // namespace
+
+std::string HttpWebClient::Get(const std::string& url) {
+  const auto [origin, path] = SplitUrl(url);
+
+  httplib::Client client(origin);
+  client.set_follow_location(true);
+  client.set_connection_timeout(kConnectionTimeoutSeconds);
+  client.set_read_timeout(kReadTimeoutSeconds);
+
+  const auto result = client.Get(path);
+
+  if (!result) {
+    throw std::runtime_error(
+        "[HttpWebClient] Request failed for URL: " + url +
+        " — " + httplib::to_string(result.error()));
+  }
+
+  if (result->status < kSuccessMin || result->status >= kSuccessMax) {
+    throw std::runtime_error(
+        "[HttpWebClient] HTTP " + std::to_string(result->status) +
+        " for URL: " + url);
+  }
+
+  return result->body;
+}
+
+std::string HttpWebClient::UrlEncode(const std::string& value) {
+  return httplib::encode_uri_component(value);
+}