added JSON support to select the services

src/json_settings.cpp

@@ -0,0 +1,54 @@
+#include <fstream>
+#include <format>
+#include "json.hpp"
+#include "json_settings.h"
+
+using namespace std;
+using json = nlohmann::json;
+
+expected<AppSettings, string> AppSettings::loadAppSettings() {
+    constexpr char settings_file[] = "static/settings.json";
+    ifstream file(settings_file);
+    if (!file.is_open()) {
+        return unexpected(format("Failed to open {}",settings_file));
+    }
+
+    // Parse the JSON
+    json j;
+    try {
+        file >> j;
+    } catch (const json::parse_error& e) {
+        return unexpected(format("Failed to parse JSON {}",e.what()));
+    }
+
+    if (!j.contains("services") || !j["services"].is_array()) {
+        return unexpected("JSON does not contain an array called 'services'");
+    }
+
+    AppSettings settings;
+
+    for (const auto& item : j["services"]) {
+        if (item.is_array() && item.size() == 2) { 
+            Service service = {
+                item[0].get<std::string>(), 
+                item[1].get<std::string>()
+            };
+            settings.services.push_back(service);
+        }
+    }
+
+    if (settings.services.empty()){
+        return unexpected("'services' array in JSON file is empty");
+    }
+
+    return settings;
+}
+
+optional<const std::string&> AppSettings::getId(string_view name){
+    for (auto& service : services) {
+        if(service.name == name) {
+            return service.service;
+        }
+    }
+    return {};
+}