Add recently-used file list to the welcome screen

ChangeLog

@@ -1,6 +1,8 @@
 ## [17.0.0-beta.2] - unreleased
 
 ### Added
+- The "Open existing game" button on the GUI's welcome screen now has a dropdown listing the most
+  recently opened games.  (#1108)
 - Details on bifurcations found and actions taken to resolve them (by perturbation) are now reported
   by `nash.logit_solve` (and related functions)  (#186)
 

src/gui/app.cc

@@ -26,6 +26,7 @@
 #endif // WX_PRECOMP
 #include <wx/artprov.h>
 #include <wx/display.h>
+#include <wx/filename.h>
 #include <wx/image.h>
 
 #include "games.h"
@@ -183,9 +184,17 @@ AppLoadResult Application::LoadFile(const wxString &p_filename, wxWindow *p_pare
 
   switch (result) {
   case GameDocument::LoadResult::OpenFailed:
-    FileErrorDialog(p_parent, _("Unable to open file"),
-                    _("Gambit could not open this file for reading."), p_filename)
-        .ShowModal();
+    if (!wxFileName::FileExists(p_filename) && ForgetRecentFile(p_filename)) {
+      FileErrorDialog(p_parent, _("File not found"), _("This file no longer exists."),
+                      p_filename + "\n\n" +
+                          _("It has been removed from the list of recent games."))
+          .ShowModal();
+    }
+    else {
+      FileErrorDialog(p_parent, _("Unable to open file"),
+                      _("Gambit could not open this file for reading."), p_filename)
+          .ShowModal();
+    }
     return AppLoadResult::OpenFailed;
 
   case GameDocument::LoadResult::ParseFailed:
@@ -210,6 +219,27 @@ AppLoadResult Application::LoadFile(const wxString &p_filename, wxWindow *p_pare
   }
 }
 
+std::vector<wxString> Application::GetRecentFiles() const
+{
+  std::vector<wxString> files;
+  for (size_t i = 0; i < m_fileHistory.GetCount(); i++) {
+    files.push_back(m_fileHistory.GetHistoryFile(i));
+  }
+  return files;
+}
+
+bool Application::ForgetRecentFile(const wxString &p_filename)
+{
+  for (size_t i = 0; i < m_fileHistory.GetCount(); i++) {
+    if (m_fileHistory.GetHistoryFile(i) == p_filename) {
+      m_fileHistory.RemoveFileFromHistory(i);
+      m_fileHistory.Save(*wxConfigBase::Get());
+      return true;
+    }
+  }
+  return false;
+}
+
 void Application::SetCurrentDir(const wxString &p_dir)
 {
   m_currentDir = p_dir;

src/gui/app.h

@@ -23,6 +23,8 @@
 #ifndef GAMBIT_GUI_APP_H
 #define GAMBIT_GUI_APP_H
 
+#include <vector>
+
 #include <wx/wx.h>
 #include <wx/config.h>  // for wxConfig
 #include <wx/docview.h> // for wxFileHistory
@@ -50,6 +52,8 @@ class Application final : public wxApp {
   bool OnInit() override;
   void DismissSplash();
   void OnSplashDismissTimer(wxTimerEvent &) { DismissSplash(); }
+  //! Drop `p_filename` from the recently-used list; returns whether it was there.
+  bool ForgetRecentFile(const wxString &p_filename);
 
   wxDECLARE_EVENT_TABLE();
 
@@ -61,6 +65,8 @@ class Application final : public wxApp {
   void SetCurrentDir(const wxString &p_dir);
 
   wxString GetHistoryFile(int index) const { return m_fileHistory.GetHistoryFile(index); }
+  //! The recently-used files, most recent first.
+  std::vector<wxString> GetRecentFiles() const;
   void AddMenu(wxMenu *p_menu)
   {
     m_fileHistory.UseMenu(p_menu);