#include "common/GMLuaModule.h" // Include the header for the required GMod Lua module definitions

GMOD_MODULE( Open, Close ); // State the functions we want to be called when the module loads and unloads

LUA_FUNCTION( PlayerInitialSpawnCallback ) // Declare our callback function that will be passed to hook.Add as the 3rd argument
{
    Lua()->CheckType( 1, GLua::TYPE_ENTITY ); // Ensure the first argument is type "Entity" - we can just assume its a player

    int playerRef = Lua()->GetReference( 1 ); // Get a reference to the player for later use (using GetUserData results in garbage collection, causing errors elsewhere)

    if ( playerRef != -1 ) // Make sure our reference is valid
    {
        ILuaObject *playerMeta = Lua()->GetMetaTable( "Player", GLua::TYPE_ENTITY ); // Retrieve the "Player" metatable, equivalent to "playerMeta = _R.Player"

        if ( playerMeta ) // Make sure the result is valid
        {
            if ( playerMeta->isTable() ) // Check that our reference is a table
            {
                ILuaObject *playerChatPrint = playerMeta->GetMember( "ChatPrint" ); // Lookup _R.Player.ChatPrint

                if ( playerChatPrint ) // Does _R.Player.ChatPrint exist?
                {
                    if ( playerChatPrint->isFunction() ) // Is _R.Player.ChatPrint a function?
                    {
                        // To call a meta function, we need to push it onto the stack using ILuaInterface::Push
                        // The meta function must be pushed first, followed by the userdata, followed by its arguments

                        Lua()->Push( playerChatPrint ); // Push the meta function
                        Lua()->PushReference( playerRef ); // Push the player object (userdata)
                        Lua()->Push( "You've just spawned!" ); // Push the argument

                        // We've pushed 2 arguments and don't care about any return values
                        Lua()->Call( 2, 0 );
                    }

                    playerChatPrint->UnReference(); // The function has been called, we can unreference
                }
            }

            playerMeta->UnReference(); // We're done, unreference
        }

        Lua()->FreeReference( playerRef ); // Free our player object reference, it isn't needed anymore
    }

    return 0; // Zero return values
}

int Open( lua_State *L ) // Declare the function we want to be called when the module loads
{
    ILuaObject *hookTable = Lua()->GetGlobal( "hook" ); // Find the global "hook", equivalent of "hookTable = hook", or "hookTable = _G.hook" in Lua

    if ( hookTable ) // If hook wasn't found then GetGlobal returns NULL; we make sure it was successful before continuing
    {
        if ( hookTable->isTable() ) // Hook may have been found, but we should check that it's a table
        {
            ILuaObject *hookAdd = hookTable->GetMember( "Add" ); // Hook appears to be a valid table so we lookup its "Add" member ( "hookAdd = hook.Add" in Lua )

            if ( hookAdd ) // Was hook.Add successfully retrieved?
            {
                if ( hookAdd->isFunction() ) // Is hook.Add a function?
                {
                    // To call a function, we need to push it onto the stack using ILuaInterface::Push
                    // The function must be pushed first, followed by its arguments

                    Lua()->Push( hookAdd ); // hookAdd is now the equivalent to the "hook.Add" function in Lua, so we push it onto the Lua stack
                    Lua()->Push( "PlayerInitialSpawn" ); // hook.Add takes the hook type as its first argument
                    Lua()->Push( "hookname" ); // The next argument is the unique hook name
                    Lua()->Push( PlayerInitialSpawnCallback ); // Push our callback function which will be called when PlayerInitialSpawn is triggered

                    // We've pushed 3 arguments and don't care about any return values
                    Lua()->Call( 3, 0 );
                }

                hookAdd->UnReference(); // We've added our hook and no longer need access to the "hook.Add" function, unreference it
            }
        }

        hookTable->UnReference(); // The hook table isn't required any further, unreference it
    }

    return 0;
}

int Close( lua_State *L ) // Declare the function we want to be called when the module unloads
{
    // You need to remove the hook here because the callback function will become invalid
    // Hopefully after reading through this, you'll be able to do it yourself

    return 0;
}