PR review fixes (#384)

Tactility/Include/Tactility/network/EspHttpClient.h

@@ -11,7 +11,7 @@ class EspHttpClient {
     static constexpr auto* TAG = "EspHttpClient";
 
     std::unique_ptr<esp_http_client_config_t> config = nullptr;
-    esp_http_client_handle_t client;
+    esp_http_client_handle_t client = nullptr;
     bool isOpen = false;
 
 public:
@@ -87,11 +87,15 @@ public:
     bool close() {
         assert(client != nullptr);
         TT_LOG_I(TAG, "close()");
-        return esp_http_client_close(client) == ESP_OK;
+        if (esp_http_client_close(client) == ESP_OK) {
+            isOpen = false;
+        }
+        return !isOpen;
     }
 
     bool cleanup() {
         assert(client != nullptr);
+        assert(!isOpen);
         TT_LOG_I(TAG, "cleanup()");
         const auto result = esp_http_client_cleanup(client);
         client = nullptr;

Tactility/Include/Tactility/network/Http.h

@@ -1,10 +1,19 @@
 #pragma once
 
 #include <string>
+#include <functional>
 
 namespace tt::network::http {
-
-void download(
+    /**
+     * Download a file from a URL.
+     * The server must send the Content-Length header.
+     * @param url download source URL
+     * @param certFilePath the path to the .pem file
+     * @param downloadFilePath The path to downloadd the file to. The parent directories must exist.
+     * @param onSuccess the success result callback
+     * @param onError the error result callback
+     */
+    void download(
     const std::string& url,
     const std::string& certFilePath,
     const std::string &downloadFilePath,