#ifndef LuaFunction_H
#define LuaFunction_H
#pragma once

#include "LuaConvert.h"
#include "LuaValue.h"
#include "LuaTable.h"

#include <vector>
#include <string>
#include <functional>


namespace luacpp {
typedef std::vector<LuaValue> LuaValueList;
class LuaFunction;

/**
 * @brief A reference to lua code.
 *
 * Wraps a Lua-function value which can be called as a function from C++ code into Lua code.
 * Provides ways to set arguments and get return values.
 *
 * @see luacpp::convert
 */
class LuaFunction: public LuaValue {
 public:
	/**
     * @brief Compile lua code and return the function.
     * The specified code is compiled into a lua functions which can then be called with the returned class.
     *
     * @param L The lua state
     * @param code The actual function code
     * @param name The name of the function, for debugging
     * @return luacpp::LuaFunction The function object which can be used for calling that lua function
     *
     * @exception LuaException Thrown when the compilation fails with the error as the execption message.
     */
	static LuaFunction createFromCode(lua_State* L, const std::string& code, const std::string& name = "");

	/**
     * @brief Creates a function object from a lua_CFunction
     *
     * @param L The lua state
     * @param function The function pointer
     * @return luacpp::LuaFunction
     */
	static LuaFunction createFromCFunction(lua_State* L, lua_CFunction function, const LuaValueList& upvalues = LuaValueList());

	/**
     * @brief Default constructor
     */
	LuaFunction();

	/**
     * @brief Copy-constructor
     *
     * Copies the reference of the other function and sets it as the reference of this object.
     *
     * @param other The other function.
     */
	LuaFunction(const LuaFunction& other);

	/**
     * @brief Frees the reference to the function if it exists.
     */
	virtual ~LuaFunction();

	/**
     * @brief Sets the function environment.
     *
     * @param environment The table which will be the new environment of the function.
     * @return `true` when successful, `false` otherwise
     */
	bool setEnvironment(const LuaTable& environment);

	/**
     * @brief Sets the function called when an error occurs
     * This lua_Cfunction will be called by lua if an error occus while executing this function
     *
     * @return void
     */
	void setErrorFunction(const LuaFunction& errorFunc) {
		_errorFunction = errorFunc.getReference();
	}

	/**
     * @brief Sets a new reference.
     * This overload checks if the passed reference is a function
     *
     * @param ref The new reference
     * @return void
     */
	void setReference(LuaReference ref) override;

	/**
     * @brief Calls the function.
     *
     * The parameters in the value list should be in the same order as they appear in the parameter list of the function.
     *
     * @details This function first pushes the error function onto the stack if one was set, then
     * the arguments and then the function. After that the function is called with lua_pcall
     * and the return values are converted into a LuaValueList.
     *
     * @param arguments The arguments passed to the functions. Defaults to none
     * @return luacpp::LuaValueList The values returned by the function call
     *
     * @exception LuaException If an error occurs while executing the function an exception is thrown
     * 	with the message of the error.
     */
	LuaValueList call(const LuaValueList& arguments = LuaValueList());

	/**
     * @brief Calls the function. See call().
     * @return Same as call().
     */
	LuaValueList operator()(const LuaValueList& arguments = LuaValueList());
 private:
	LuaReference _errorFunction;
};

namespace convert {

template<>
inline LuaFunction popValue<LuaFunction>(lua_State* luaState, int stackposition, bool remove) {
	if (!isValidIndex(luaState, stackposition)) {
		throw LuaException("Specified stack position is not valid!");
	}

	if (!lua_isfunction(luaState, stackposition)) {
		throw LuaException("Specified index is no function!");
	} else {
		LuaFunction target;
		target.setReference(UniqueLuaReference::create(luaState, stackposition));

		if (remove) {
			lua_remove(luaState, stackposition);
		}

		return target;
	}
}

}
}

#endif