Show error message if we fail to parse the config JSON (#534)

Closes #516

lang/1033.json

@@ -210,6 +210,8 @@
         "active_downloads": "Active downloads",
         "active_seeds": "Active seeds",
         "added_on": "Added on",
-        "completed_on": "Completed on"
+        "completed_on": "Completed on",
+        "config_error_s": "Failed to parse configuration file. Default configuration has been loaded.\n---\n%s",
+        "config_error_title": "Config error"
     }
 }

src/picotorrent/application.cpp

@@ -82,8 +82,10 @@ bool Application::OnInit()
         return false;
     }
 
+    std::string configurationError;
+
     auto env = std::make_shared<Environment>();
-    auto cfg = Configuration::Load(env);
+    auto cfg = Configuration::Load(env, configurationError);
     auto translator = Translator::Load(GetModuleHandle(NULL), cfg);
 
     MainFrame* mainFrame = new MainFrame(
@@ -122,6 +124,19 @@ bool Application::OnInit()
         break;
     }
 
+    if (!configurationError.empty())
+    {
+        wxString text = wxString::Format(
+            i18n(translator, "config_error_s"),
+            configurationError.c_str());
+
+        wxMessageBox(
+            text,
+            i18n(translator, "config_error_title"),
+            wxOK | wxICON_ERROR,
+            mainFrame);
+    }
+
     mainFrame->HandleOptions(m_options);
 
     return true;

src/picotorrent/config.cpp

@@ -8,7 +8,7 @@
 
 using pt::Configuration;
 
-std::shared_ptr<Configuration> Configuration::Load(std::shared_ptr<pt::Environment> env)
+std::shared_ptr<Configuration> Configuration::Load(std::shared_ptr<pt::Environment> env, std::string& error)
 {
     fs::path path = env->GetApplicationDataPath() / "PicoTorrent.json";
 
@@ -21,7 +21,7 @@ std::shared_ptr<Configuration> Configuration::Load(std::shared_ptr<pt::Environme
     std::ifstream cfg_stream(path, std::ios::binary);
 
     picojson::value val;
-    picojson::parse(val, cfg_stream);
+    error = picojson::parse(val, cfg_stream);
 
     if (!val.is<picojson::object>())
     {

src/picotorrent/config.hpp

@@ -110,7 +110,7 @@ namespace pt
             using Section::Section;
         };
 
-        static std::shared_ptr<Configuration> Load(std::shared_ptr<Environment> env);
+        static std::shared_ptr<Configuration> Load(std::shared_ptr<Environment> env, std::string& error);
         static void Save(std::shared_ptr<Environment> env, std::shared_ptr<Configuration> config);
 
         std::shared_ptr<SessionSection> Session();