6 files changed, 392 insertions, 17 deletions

diff --git a/src/Bindings/LuaChunkStay.cpp b/src/Bindings/LuaChunkStay.cpp
new file mode 100644
index 000000000..0e982637f
--- /dev/null
+++ b/src/Bindings/LuaChunkStay.cpp
@@ -0,0 +1,173 @@
+
+// LuaChunkStay.cpp
+
+// Implements the cLuaChunkStay class representing a cChunkStay binding for plugins, used by cWorld:ChunkStay() Lua API
+
+#include "Globals.h"
+#include "LuaChunkStay.h"
+#include "PluginLua.h"
+#include "../World.h"
+
+
+
+
+
+cLuaChunkStay::cLuaChunkStay(cPluginLua & a_Plugin) :
+	m_Plugin(a_Plugin),
+	m_LuaState(NULL)
+{
+}
+
+
+
+
+
+bool cLuaChunkStay::AddChunks(int a_ChunkCoordTableStackPos)
+{
+	// This function is expected to be called just once, with all the coords in a table
+	ASSERT(m_Chunks.empty());
+	
+	cPluginLua::cOperation Op(m_Plugin);
+	cLuaState & L = Op();
+	
+	// Check that we got a table:
+	if (!lua_istable(L, a_ChunkCoordTableStackPos))
+	{
+		LOGWARNING("%s: The parameter is not a table of coords (got %s). Ignoring the call.",
+			__FUNCTION__, lua_typename(L, lua_type(L, a_ChunkCoordTableStackPos))
+		);
+		L.LogStackTrace();
+		return false;
+	}
+	
+	// Add each set of coords:
+	int NumChunks = luaL_getn(L, a_ChunkCoordTableStackPos);
+	m_Chunks.reserve(NumChunks);
+	for (int idx = 1; idx <= NumChunks; idx++)
+	{
+		// Push the idx-th element of the array onto stack top, check that it's a table:
+		lua_rawgeti(L, a_ChunkCoordTableStackPos, idx);
+		if (!lua_istable(L, -1))
+		{
+			LOGWARNING("%s: Element #%d is not a table (got %s). Ignoring the element.",
+				__FUNCTION__, idx, lua_typename(L, -1)
+			);
+			L.LogStackTrace();
+			lua_pop(L, 1);
+			continue;
+		}
+		AddChunkCoord(L, idx);
+		lua_pop(L, 1);
+	}
+	
+	// If there are no chunks, log a warning and return failure:
+	if (m_Chunks.empty())
+	{
+		LOGWARNING("%s: Zero chunks to stay.", __FUNCTION__);
+		L.LogStackTrace();
+		return false;
+	}
+	
+	// All ok
+	return true;
+}
+
+
+
+
+
+void cLuaChunkStay::AddChunkCoord(cLuaState & L, int a_Index)		
+{
+	// Check that the element has 2 coords:
+	int NumCoords = luaL_getn(L, -1);
+	if (NumCoords != 2)
+	{
+		LOGWARNING("%s: Element #%d doesn't contain 2 coords (got %d). Ignoring the element.",
+			__FUNCTION__, a_Index, NumCoords
+		);
+		return;
+	}
+	
+	// Read the two coords from the element:
+	lua_rawgeti(L, -1, 1);
+	lua_rawgeti(L, -2, 2);
+	int ChunkX = luaL_checkint(L, -2);
+	int ChunkZ = luaL_checkint(L, -1);
+	lua_pop(L, 2);
+	
+	// Check that a coord is not yet present:
+	for (cChunkCoordsVector::iterator itr = m_Chunks.begin(), end = m_Chunks.end(); itr != end; ++itr)
+	{
+		if ((itr->m_ChunkX == ChunkX) && (itr->m_ChunkZ == ChunkZ))
+		{
+			LOGWARNING("%s: Element #%d is a duplicate, ignoring it.",
+				__FUNCTION__, a_Index
+			);
+			return;
+		}
+	}  // for itr - m_Chunks[]
+	
+	m_Chunks.push_back(cChunkCoords(ChunkX, ZERO_CHUNK_Y, ChunkZ));
+}
+
+
+
+
+
+void cLuaChunkStay::Enable(cChunkMap & a_ChunkMap, int a_OnChunkAvailableStackPos, int a_OnAllChunksAvailableStackPos)
+{
+	// Get the references to the callback functions:
+	m_LuaState = &m_Plugin.GetLuaState();
+	m_OnChunkAvailable.RefStack(*m_LuaState, a_OnChunkAvailableStackPos);
+	m_OnAllChunksAvailable.RefStack(*m_LuaState, a_OnAllChunksAvailableStackPos);
+	
+	// Enable the ChunkStay:
+	super::Enable(a_ChunkMap);
+}
+
+
+
+
+
+void cLuaChunkStay::OnChunkAvailable(int a_ChunkX, int a_ChunkZ)
+{
+	// DEBUG:
+	LOGD("LuaChunkStay: Chunk [%d, %d] is now available, calling the callback...", a_ChunkX, a_ChunkZ);
+	
+	cPluginLua::cOperation Op(m_Plugin);
+	Op().Call((int)m_OnChunkAvailable, a_ChunkX, a_ChunkZ);
+}
+
+
+
+
+
+bool cLuaChunkStay::OnAllChunksAvailable(void)
+{
+	{
+		// Call the callback:
+		cPluginLua::cOperation Op(m_Plugin);
+		Op().Call((int)m_OnAllChunksAvailable);
+		
+		// Remove the callback references - they won't be needed anymore
+		m_OnChunkAvailable.UnRef();
+		m_OnAllChunksAvailable.UnRef();
+	}
+	
+	// Disable the ChunkStay by returning true
+	return true;
+}
+
+
+
+
+
+void cLuaChunkStay::OnDisabled(void)
+{
+	// This object is no longer needed, delete it
+	delete this;
+}
+
+
+
+
diff --git a/src/Bindings/LuaChunkStay.h b/src/Bindings/LuaChunkStay.h
new file mode 100644
index 000000000..49ab9a0ad
--- /dev/null
+++ b/src/Bindings/LuaChunkStay.h
@@ -0,0 +1,73 @@
+
+// LuaChunkStay.h
+
+// Declares the cLuaChunkStay class representing a cChunkStay binding for plugins, used by cWorld:ChunkStay() Lua API
+
+
+
+
+
+#pragma once
+
+#include "LuaState.h"
+#include "../ChunkStay.h"
+
+
+
+
+
+// fwd:
+class cPluginLua;
+
+
+
+
+
+class cLuaChunkStay
+	: public cChunkStay
+{
+	typedef cChunkStay super;
+	
+public:
+	cLuaChunkStay(cPluginLua & a_Plugin);
+	
+	~cLuaChunkStay() { }
+
+	/** Adds chunks in the specified on-stack Lua table.
+	Returns true if any chunk added, false (plus log warning) if none. */
+	bool AddChunks(int a_ChunkCoordTableStackPos);
+	
+	/** Enables the ChunkStay for the specified chunkmap, with the specified Lua callbacks. */
+	void Enable(cChunkMap & a_ChunkMap, int a_OnChunkAvailableStackPos, int a_OnAllChunksAvailableStackPos);
+	
+protected:
+	/** The plugin which has created the ChunkStay, via cWorld:ChunkStay() binding method.  */
+	cPluginLua & m_Plugin;
+	
+	/** The Lua state associated with the callbacks. Only valid when enabled. */
+	cLuaState * m_LuaState;
+	
+	/** The Lua function to call in OnChunkAvailable. Only valid when enabled. */
+	cLuaState::cRef m_OnChunkAvailable;
+	
+	/** The Lua function to call in OnAllChunksAvailable. Only valid when enabled. */
+	cLuaState::cRef m_OnAllChunksAvailable;
+	
+	
+	// cChunkStay overrides:
+	virtual void OnChunkAvailable(int a_ChunkX, int a_ChunkZ) override;
+	virtual bool OnAllChunksAvailable(void) override;
+	virtual void OnDisabled(void) override;
+	
+	/** Adds a single chunk coord from the table at the top of the Lua stack.
+	Expects the top element to be a table, checks that it contains two numbers.
+	Uses those two numbers as chunk coords appended to m_Chunks.
+	If the coords are already present, gives a warning and ignores the pair.
+	The a_Index parameter is only for the error messages. */
+	void AddChunkCoord(cLuaState & a_LuaState, int a_Index);
+} ;
+
+
+
+
+
diff --git a/src/Bindings/LuaState.cpp b/src/Bindings/LuaState.cpp
index ac5ce47e1..24e64d9b2 100644
--- a/src/Bindings/LuaState.cpp
+++ b/src/Bindings/LuaState.cpp
@@ -735,17 +735,20 @@ bool cLuaState::CallFunction(int a_NumResults)
 	ASSERT(lua_isfunction(m_LuaState, -m_NumCurrentFunctionArgs - 1));  // The function to call
 	ASSERT(lua_isfunction(m_LuaState, -m_NumCurrentFunctionArgs - 2));  // The error handler
 	
-	int s = lua_pcall(m_LuaState, m_NumCurrentFunctionArgs, a_NumResults, -m_NumCurrentFunctionArgs - 2);
+	// Save the current "stack" state and reset, in case the callback calls another function:
+	AString CurrentFunctionName;
+	std::swap(m_CurrentFunctionName, CurrentFunctionName);
+	int NumArgs = m_NumCurrentFunctionArgs;
+	m_NumCurrentFunctionArgs = -1;
+	
+	// Call the function:
+	int s = lua_pcall(m_LuaState, NumArgs, a_NumResults, -NumArgs - 2);
 	if (s != 0)
 	{
 		// The error has already been printed together with the stacktrace
-		LOGWARNING("Error in %s calling function %s()", m_SubsystemName.c_str(), m_CurrentFunctionName.c_str());
-		m_NumCurrentFunctionArgs = -1;
-		m_CurrentFunctionName.clear();
+		LOGWARNING("Error in %s calling function %s()", m_SubsystemName.c_str(), CurrentFunctionName.c_str());
 		return false;
 	}
-	m_NumCurrentFunctionArgs = -1;
-	m_CurrentFunctionName.clear();
 	
 	// Remove the error handler from the stack:
 	lua_remove(m_LuaState, -a_NumResults - 1);
@@ -1206,7 +1209,7 @@ void cLuaState::LogStack(const char * a_Header)
 void cLuaState::LogStack(lua_State * a_LuaState, const char * a_Header)
 {
 	LOGD((a_Header != NULL) ? a_Header : "Lua C API Stack contents:");
-	for (int i = lua_gettop(a_LuaState); i >= 0; i--)
+	for (int i = lua_gettop(a_LuaState); i > 0; i--)
 	{
 		AString Value;
 		int Type = lua_type(a_LuaState, i);
@@ -1240,13 +1243,21 @@ int cLuaState::ReportFnCallErrors(lua_State * a_LuaState)
 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 // cLuaState::cRef:
 
+cLuaState::cRef::cRef(void) :
+	m_LuaState(NULL),
+	m_Ref(LUA_REFNIL)
+{
+}
+
+
+
+
+
 cLuaState::cRef::cRef(cLuaState & a_LuaState, int a_StackPos) :
-	m_LuaState(a_LuaState)
+	m_LuaState(NULL),
+	m_Ref(LUA_REFNIL)
 {
-	ASSERT(m_LuaState.IsValid());
-	
-	lua_pushvalue(m_LuaState, a_StackPos);  // Push a copy of the value at a_StackPos onto the stack
-	m_Ref = luaL_ref(m_LuaState, LUA_REGISTRYINDEX);
+	RefStack(a_LuaState, a_StackPos);
 }
 
 
@@ -1255,12 +1266,42 @@ cLuaState::cRef::cRef(cLuaState & a_LuaState, int a_StackPos) :
 
 cLuaState::cRef::~cRef()
 {
-	ASSERT(m_LuaState.IsValid());
+	if (m_LuaState != NULL)
+	{
+		UnRef();
+	}
+}
+
+
+
+
+
+void cLuaState::cRef::RefStack(cLuaState & a_LuaState, int a_StackPos)
+{
+	ASSERT(a_LuaState.IsValid());
+	if (m_LuaState != NULL)
+	{
+		UnRef();
+	}
+	m_LuaState = &a_LuaState;
+	lua_pushvalue(a_LuaState, a_StackPos);  // Push a copy of the value at a_StackPos onto the stack
+	m_Ref = luaL_ref(a_LuaState, LUA_REGISTRYINDEX);
+}
+
+
+
+
+
+void cLuaState::cRef::UnRef(void)
+{
+	ASSERT(m_LuaState->IsValid());  // The reference should be destroyed before destroying the LuaState
 	
 	if (IsValid())
 	{
-		luaL_unref(m_LuaState, LUA_REGISTRYINDEX, m_Ref);
+		luaL_unref(*m_LuaState, LUA_REGISTRYINDEX, m_Ref);
 	}
+	m_LuaState = NULL;
+	m_Ref = LUA_REFNIL;
 }
 
 
diff --git a/src/Bindings/LuaState.h b/src/Bindings/LuaState.h
index dda45bb28..1c9c99e69 100644
--- a/src/Bindings/LuaState.h
+++ b/src/Bindings/LuaState.h
@@ -65,14 +65,27 @@ class cLuaState
 {
 public:
 
-	/** Used for storing references to object in the global registry */
+	/** Used for storing references to object in the global registry.
+	Can be bound (contains a reference) or unbound (doesn't contain reference).
+	The reference can also be reset by calling RefStack(). */
 	class cRef
 	{
 	public:
+		/** Creates an unbound reference object. */
+		cRef(void);
+		
 		/** Creates a reference in the specified LuaState for object at the specified StackPos */
 		cRef(cLuaState & a_LuaState, int a_StackPos);
+		
 		~cRef();
 		
+		/** Creates a reference to Lua object at the specified stack pos, binds this object to it.
+		Calls UnRef() first if previously bound to another reference. */
+		void RefStack(cLuaState & a_LuaState, int a_StackPos);
+		
+		/** Removes the bound reference, resets the object to Unbound state. */
+		void UnRef(void);
+		
 		/** Returns true if the reference is valid */
 		bool IsValid(void) const {return (m_Ref != LUA_REFNIL); }
 		
@@ -80,7 +93,7 @@ public:
 		operator int(void) const { return m_Ref; }
 		
 	protected:
-		cLuaState & m_LuaState;
+		cLuaState * m_LuaState;
 		int m_Ref;
 	} ;
 	
diff --git a/src/Bindings/ManualBindings.cpp b/src/Bindings/ManualBindings.cpp
index 841ec5cf2..f0bad92e8 100644
--- a/src/Bindings/ManualBindings.cpp
+++ b/src/Bindings/ManualBindings.cpp
@@ -8,6 +8,7 @@
 #include "PluginLua.h"
 #include "PluginManager.h"
 #include "LuaWindow.h"
+#include "LuaChunkStay.h"
 #include "../Root.h"
 #include "../World.h"
 #include "../Entities/Player.h"
@@ -1638,6 +1639,53 @@ static int tolua_cPluginManager_CallPlugin(lua_State * tolua_S)
 
 
 
+static int tolua_cWorld_ChunkStay(lua_State * tolua_S)
+{
+	/* Function signature:
+	World:ChunkStay(ChunkCoordTable, OnChunkAvailable, OnAllChunksAvailable)
+	ChunkCoordTable == { {Chunk1x, Chunk1z}, {Chunk2x, Chunk2z}, ... }
+	*/
+	
+	cLuaState L(tolua_S);
+	if (
+		!L.CheckParamUserType(1, "cWorld") ||
+		!L.CheckParamTable   (2) ||
+		!L.CheckParamFunction(3, 4)
+	)
+	{
+		return 0;
+	}
+	
+	cPluginLua * Plugin = GetLuaPlugin(tolua_S);
+	if (Plugin == NULL)
+	{
+		return 0;
+	}
+	cLuaChunkStay * ChunkStay = new cLuaChunkStay(*Plugin);
+	
+	// Read the params:
+	cWorld * World = (cWorld *)tolua_tousertype(tolua_S, 1, NULL);
+	if (World == NULL)
+	{
+		LOGWARNING("World:ChunkStay(): invalid world parameter");
+		L.LogStackTrace();
+		return 0;
+	}
+	L.LogStack("Before AddChunks()");
+	if (!ChunkStay->AddChunks(2))
+	{
+		return 0;
+	}
+	L.LogStack("After params read");
+
+	ChunkStay->Enable(*World->GetChunkMap(), 3, 4);
+	return 0;
+}
+
+
+
+
+
 static int tolua_cPlayer_GetGroups(lua_State* tolua_S)
 {
 	cPlayer* self = (cPlayer*)  tolua_tousertype(tolua_S,1,0);
@@ -2360,6 +2408,7 @@ void ManualBindings::Bind(lua_State * tolua_S)
 		tolua_endmodule(tolua_S);
 		
 		tolua_beginmodule(tolua_S, "cWorld");
+			tolua_function(tolua_S, "ChunkStay",                 tolua_cWorld_ChunkStay);
 			tolua_function(tolua_S, "DoWithBlockEntityAt",       tolua_DoWithXYZ<cWorld, cBlockEntity,        &cWorld::DoWithBlockEntityAt>);
 			tolua_function(tolua_S, "DoWithChestAt",             tolua_DoWithXYZ<cWorld, cChestEntity,        &cWorld::DoWithChestAt>);
 			tolua_function(tolua_S, "DoWithDispenserAt",         tolua_DoWithXYZ<cWorld, cDispenserEntity,    &cWorld::DoWithDispenserAt>);
diff --git a/src/Bindings/PluginLua.h b/src/Bindings/PluginLua.h
index ad0cfbe5a..a177f5288 100644
--- a/src/Bindings/PluginLua.h
+++ b/src/Bindings/PluginLua.h
@@ -35,7 +35,33 @@ class cPluginLua :
 public:
 	// tolua_end
 	
-	cPluginLua( const AString & a_PluginDirectory );
+	/** A RAII-style mutex lock for accessing the internal LuaState.
+	This will be the only way to retrieve the plugin's LuaState;
+	therefore it directly supports accessing the LuaState of the locked plugin.
+	Usage:
+		cPluginLua::cOperation Op(SomePlugin);
+		Op().Call(...)  // Call a function in the plugin's LuaState
+	*/
+	class cOperation
+	{
+	public:
+		cOperation(cPluginLua & a_Plugin) :
+			m_Plugin(a_Plugin),
+			m_Lock(a_Plugin.m_CriticalSection)
+		{
+		}
+
+		cLuaState & operator ()(void) { return m_Plugin.m_LuaState; }
+		
+	protected:
+		cPluginLua & m_Plugin;
+		
+		/** RAII lock for m_Plugin.m_CriticalSection */
+		cCSLock m_Lock;
+	} ;
+	
+	
+	cPluginLua(const AString & a_PluginDirectory);
 	~cPluginLua();
 
 	virtual void OnDisable(void) override;