feat: implement HttpHandler and WifiHandler classes for HTTP client management

main/common/constants.h

@@ -13,4 +13,5 @@
 //
 #define DISPLAY_READY_BIT       (1 << 1)
 #define TOUCH_CALIBRATED_BIT    (1 << 2)
-#define STORAGE_READY_BIT       (1 << 3)
+#define STORAGE_READY_BIT       (1 << 3)
+#define NETWORK_READY_BIT       (1 << 4)

main/network/http_handler.h

@@ -0,0 +1,55 @@
+#pragma once
+#include <memory>
+#include "esp_http_client.h"
+#include "network/wifi_handler.h"
+
+// forward declare NetworkHandler to avoid circular include with network.h
+class NetworkHandler;
+
+// default config values for esp_http_client_config_t
+// disable Wmissing-field-initializers warning for these structs
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+static const inline esp_http_client_config_t DEFAULT_HTTP_CLIENT_CONFIG = {
+  .timeout_ms = 10000,
+};
+
+static const inline esp_http_client_config_t DEFAULT_HTTP_CLIENT_CONFIG_HTTPS = {
+  .transport_type = HTTP_TRANSPORT_OVER_SSL,
+  //
+  .use_global_ca_store = true,
+  .skip_cert_common_name_check = false,
+};
+#pragma GCC diagnostic pop
+
+// esp http client wrapper with automatic initialization and cleanup
+class HttpHandler {
+public:
+  ~HttpHandler();
+
+  esp_err_t set_method(esp_http_client_method_t method);
+  esp_err_t set_header(const char* header, const char* value);
+  esp_err_t set_post_field(const char* field, size_t len);
+  //
+  esp_err_t perform_request();
+  // buffer is allocated inside the method, caller must free it
+  void get_body(
+    char*& buffer,
+    int& total_len
+  );
+
+
+  // only NetworkHandler can create HttpHandler instances
+  friend class NetworkHandler;
+  // disable copy constructor and assignment operator
+  HttpHandler(const HttpHandler&) = delete;
+  HttpHandler& operator=(const HttpHandler&) = delete;
+
+private:
+  // private constructor, only NetworkHandler can create instances
+  HttpHandler(const esp_http_client_config_t&& config, WifiHandler* wifiHandler);
+
+  esp_http_client_handle_t client;
+  // backreference to WifiHandler to ensure WiFi is connected, DO NOT DELETE
+  WifiHandler* wifiHandler;
+};

main/network/network.h

@@ -0,0 +1,27 @@
+#pragma once
+#include <memory>
+#include "freertos/FreeRTOS.h"
+#include "esp_system.h"
+#include "network/wifi_handler.h"
+#include "esp_http_client.h"
+
+// forward declare HttpHandler to avoid circular include with http_handler.h
+class HttpHandler;
+
+class NetworkHandler {
+public:
+  NetworkHandler(
+    WifiHandler&& wifiHandler
+  );
+  ~NetworkHandler();
+
+  void init(EventGroupHandle_t system_event_group);
+  WifiHandler& get_wifi_handler();
+  // factory method to create HttpHandler instances
+  std::unique_ptr<HttpHandler> get_http_handler(const esp_http_client_config_t&& config);
+
+
+private:
+  WifiHandler wifiHandler;
+  bool initialized = false;
+};

main/network/wifi_handler.h

@@ -0,0 +1,54 @@
+#pragma once
+#include "io/io.h"
+#include "esp_wifi.h"
+#include "freertos/event_groups.h"
+
+#define WIFI_CONNECTED_BIT (1 << 0)
+
+class WifiHandler {
+public:
+  WifiHandler(
+    // this handler is used to store/retrieve WiFi credentials
+    // should have a unique namespace for WiFi credentials
+    // it will be owned by WifiHandler and deleted in its destructor
+    KVStorageHandler* kvs
+  );
+  ~WifiHandler();
+
+  // move semantics
+  WifiHandler(WifiHandler&& other) noexcept;
+
+  void init();
+  esp_err_t connect(const char* ssid, const char* password);
+  esp_err_t connect(const char* ssid); // connect using stored password
+  esp_err_t reconnect(); // reconnect to current SSID
+  void disconnect();
+  EventBits_t wait_for_connection(TickType_t ticks_to_wait);
+  // returns list of available networks, caller is responsible for freeing the returned memory
+  // returns nullptr if scan failed
+  esp_err_t scan_networks(
+    wifi_ap_record_t*& ap_records,
+    uint16_t& ap_count
+  );
+
+  static void wifi_event_handler(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data);
+
+private:
+  // prevent copying
+  WifiHandler(const WifiHandler&) = delete;
+  WifiHandler& operator=(const WifiHandler&) = delete;
+
+  char* build_password_key(const char* ssid);
+  void get_wifi_credentials(char*& ssid, char*& password);
+
+  bool initialized = false;
+  KVStorageHandler* kvs = nullptr;
+  EventGroupHandle_t s_wifi_event_group = 0;
+  SemaphoreHandle_t scan_mutex = nullptr;
+  SemaphoreHandle_t connection_mutex = nullptr;
+  // current connected / preferred SSID
+  char* current_ssid = nullptr;
+  // prevent auto-reconnect on expected disconnection, e.g. when user calls disconnect()
+  // should be reset to false after connect()
+  bool expect_disconnected = false;
+};