Implement first version of http_server

components/http_server/include/http/server.h

@@ -0,0 +1,147 @@
+#pragma once
+
+#include <algorithm>
+#include <stdexcept>
+
+#include <esp_http_server.h>
+
+#include <util/inplace_function.h>
+
+
+#define RESPONSE_BUFFER_LEN 512
+
+//
+//
+// Types
+//
+//
+
+
+namespace http {
+
+
+enum class Method { get = HTTP_GET, post = HTTP_POST };
+
+struct response_t {
+    response_t() = default;
+    response_t(const char* str) {
+        std::size_t respLen =
+            std::min(strlen(str), static_cast<unsigned>(RESPONSE_BUFFER_LEN));
+        std::copy(str, str + respLen, text.begin());
+    }
+
+    std::array<char, RESPONSE_BUFFER_LEN> text = {0};
+};
+
+struct handler_t {
+    Method                         method;
+    const char*                    path;
+    inplace_function<response_t()> handler;
+};
+
+struct server_settings_t {
+    int                      port         = 80;
+    inplace_function<void()> on_error     = [] {};
+    inplace_function<void()> on_not_found = [] {};
+};
+
+
+} // namespace http
+
+
+//
+//
+// Implementation details
+//
+//
+
+
+namespace http::detail {
+
+
+inline auto& get_server() {
+    static httpd_handle_t server = nullptr;
+    return server;
+}
+
+template <std::size_t N>
+inline auto& get_handler_storage() {
+    static std::array<inplace_function<response_t()>, N> handlers;
+    return handlers;
+}
+
+template <std::size_t N>
+inline auto& get_esp_uri_storage() {
+    static std::array<httpd_uri_t, N> uris;
+    return uris;
+}
+
+
+// TODO: Currently, the set handler is only valid for GET requests
+template <std::size_t N, std::size_t I>
+inline void set_handlers_impl(const handler_t (&handlers)[N]) {
+    auto& uriStorage = get_esp_uri_storage<N>();
+
+    uriStorage[I] = httpd_uri_t{
+        .uri    = handlers[I].path,
+        .method = static_cast<httpd_method_t>(handlers[I].method),
+        .handler =
+            [](httpd_req_t* req) {
+                auto resp = get_handler_storage<N>()[I]();
+                httpd_resp_send(req, resp.text.data(), HTTPD_RESP_USE_STRLEN);
+                return ESP_OK;
+            },
+        .user_ctx = nullptr,
+    };
+
+    httpd_register_uri_handler(get_server(), &(uriStorage[I]));
+
+    if constexpr (I < N - 1) set_handlers_impl<N, I + 1>(handlers);
+}
+
+
+} // namespace http::detail
+
+
+//
+//
+// Public API
+//
+//
+
+
+namespace http {
+
+
+// TODO: Give request information to handlers
+template <std::size_t N>
+inline void set_handlers(const handler_t (&handlers)[N]) {
+    auto& handlerStorage = detail::get_handler_storage<N>();
+    std::transform(handlers, handlers + N, handlerStorage.begin(),
+                   [](const auto& handler) {
+                       return handler.handler;
+                   });
+
+    detail::set_handlers_impl<N, 0>(handlers);
+}
+
+inline void start_server(server_settings_t settings) {
+    httpd_config_t config = HTTPD_DEFAULT_CONFIG();
+    config.server_port    = settings.port;
+
+    if (httpd_start(&detail::get_server(), &config) != ESP_OK) {
+        throw std::runtime_error("Failed to start server");
+    }
+
+    // TODO: Set error and not found handlers
+}
+
+
+inline void stop_server() {
+    if (httpd_stop(detail::get_server()) != ESP_OK) {
+        throw std::runtime_error("Failed to stop server");
+    }
+}
+
+
+} // namespace http