From 368d066cc7e3de4ce8c7bfc5990227a6bc6221e0 Mon Sep 17 00:00:00 2001
From: Josh Yelon <jyelon@gmail.com>
Date: Sun, 7 Feb 2021 17:26:48 -0500
Subject: [PATCH] Added code to probe 'interface'

---
 luprex/cpp/luastack.cpp |  7 +++++-
 luprex/cpp/luastack.hpp | 10 +++++++++
 luprex/cpp/viewer.cpp   | 10 ++-------
 luprex/cpp/world.cpp    | 50 +++++++++++++++++++++++++++++++++++++++++
 luprex/cpp/world.hpp    |  5 +++++
 5 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/luprex/cpp/luastack.cpp b/luprex/cpp/luastack.cpp
index 0c4fee30..fbfe1772 100644
--- a/luprex/cpp/luastack.cpp
+++ b/luprex/cpp/luastack.cpp
@@ -8,6 +8,11 @@ LuaNilMarker LuaNil;
 LuaNewTableMarker LuaNewTable;
 LuaDiscardMarker LuaDiscard;
 
+void LuaStack::clear_tagged_pointer(LuaSlot target) {
+    TaggedPointer *tp = (TaggedPointer*)lua_touserdata(L_, target.index());
+    tp->ptr = 0;
+}
+
 void LuaStack::make_tagged_pointer(LuaSlot target, void *ptr, LuaTypeTag tag, LuaDeleterFn del) {
     TaggedPointer *tp = (TaggedPointer*)lua_newuserdata(L_, sizeof(TaggedPointer));
     tp->ptr = ptr;
@@ -21,7 +26,7 @@ void LuaStack::make_tagged_pointer(LuaSlot target, void *ptr, LuaTypeTag tag, Lu
 }
 
 int LuaStack::collect_tagged_pointer(lua_State *L) {
-    LuaStack::TaggedPointer *p = (LuaStack::TaggedPointer*)lua_touserdata(L, 1);
+    TaggedPointer *p = (TaggedPointer*)lua_touserdata(L, 1);
     if (p==0) {
         luaL_error(L, "lua deleter function received a non-userdata");
     }
diff --git a/luprex/cpp/luastack.hpp b/luprex/cpp/luastack.hpp
index 039e43dc..066cdfcb 100644
--- a/luprex/cpp/luastack.hpp
+++ b/luprex/cpp/luastack.hpp
@@ -372,6 +372,7 @@ private:
     };
     static int collect_tagged_pointer(lua_State *L);
     void make_tagged_pointer(LuaSlot target, void *ptr, LuaTypeTag tag, LuaDeleterFn del);
+    void clear_tagged_pointer(LuaSlot target);
 
     template<typename T>
     static void delete_pointer(void *p) { delete (T*)p; }
@@ -449,6 +450,8 @@ public:
         return (T*)(tp->ptr);
     }
 
+    void clearuserdata(LuaSlot target) { clear_tagged_pointer(target); }
+
     int next(LuaSlot tab, LuaSlot key, LuaSlot value) const;
     bool isemptytable(LuaSlot s) const;
 
@@ -462,6 +465,13 @@ public:
         pop_any_value(target);
     }
 
+    template<typename RT, typename KT>
+    void gettable(RT &target, LuaSlot tab, KT key) const {
+        push_any_value(key);
+        lua_gettable(L_, tab);
+        pop_any_value(target);
+    }
+
     template<typename RT, typename KT>
     void rawget(RT &target, LuaSlot tab, KT key) const {
         push_any_value(key);
diff --git a/luprex/cpp/viewer.cpp b/luprex/cpp/viewer.cpp
index ad51b51b..0be28186 100644
--- a/luprex/cpp/viewer.cpp
+++ b/luprex/cpp/viewer.cpp
@@ -13,13 +13,7 @@ int64_t Viewer::get_player_id() {
     return 1;
 }
 
-void Viewer::update_gui(int64_t id, Gui *gui) {
-    gui->clear();
-    gui->add_menu_item("north", "north");
-    gui->add_menu_item("south", "south");
-    gui->add_menu_item("east", "east");
-    gui->add_menu_item("west", "west");
-    gui->add_menu_item("build", "build");
-    gui->add_menu_item("destroy", "destroy");
+void Viewer::update_gui(int64_t place, Gui *gui) {
+    world_->update_gui(get_player_id(), place, gui);
 }
 
diff --git a/luprex/cpp/world.cpp b/luprex/cpp/world.cpp
index a401fe3f..85381153 100644
--- a/luprex/cpp/world.cpp
+++ b/luprex/cpp/world.cpp
@@ -2,6 +2,8 @@
 #include "world.hpp"
 #include "idalloc.hpp"
 #include "animqueue.hpp"
+#include "gui.hpp"
+#include "traceback.hpp"
 #include <iostream>
 
 LuaDefineType(World);
@@ -131,6 +133,54 @@ World *World::fetch(lua_State *L) {
     return w;
 }
 
+void World::update_gui(int64_t actor_id, int64_t place_id, Gui *gui) {
+    gui->clear();
+    lua_State *L = get_lua_state();
+
+    LuaVar actor, place, ugui, func, tangibles;
+    LuaStack LS(L, actor, place, ugui, func, tangibles);
+
+    // Get the actor and place.
+    LS.getfield(tangibles, LuaRegistry, "tangibles");
+    LS.rawget(actor, tangibles, actor_id);
+    LS.rawget(place, tangibles, place_id);
+    if (!LS.istable(actor) || !LS.istable(place)) {
+        LS.result();
+        return;
+    }
+
+    // Get the interface closure.
+    LS.getfield(func, place, "interface");
+    if (!LS.isfunction(func)) {
+        LS.result();
+        return;
+    }
+
+    // Construct the userdata with the GUI pointer.
+    LS.newpointer<Gui>(ugui, gui, false);
+
+    // Call the interface function.
+    lua_pushvalue(L, func.index());
+    lua_pushvalue(L, actor.index());
+    lua_pushvalue(L, place.index());
+    lua_pushvalue(L, ugui.index());
+    int status = traceback_pcall(L, 3, 0);
+    if (status != 0) {
+        gui->clear();
+        std::cerr << lua_tostring(L, -1);
+        LS.result();
+        return;
+    }
+    
+    // Nuke the userdata, in case somebody saved a pointer to it.
+    LS.clearuserdata(ugui);
+
+    // And we're done.
+    LS.result();
+}
+    
+
+
 LuaDefine(tangible_get, "c") {
     LuaArg id;
     LuaRet database;
diff --git a/luprex/cpp/world.hpp b/luprex/cpp/world.hpp
index fbc4786a..45a03f72 100644
--- a/luprex/cpp/world.hpp
+++ b/luprex/cpp/world.hpp
@@ -7,6 +7,7 @@
 #include "idalloc.hpp"
 #include "animqueue.hpp"
 #include "source.hpp"
+#include "gui.hpp"
 #include <memory>
 #include <unordered_map>
 
@@ -106,6 +107,10 @@ public:
     //
     void tangible_del(int64_t id);
 
+    // Probe the 'interface' function of the specified sprite.
+    //
+    void update_gui(int64_t actor_id, int64_t place_id, Gui *gui);
+
     // fetch
     //
     // Given a lua state, fetch the world model associated with