// The MIT License (MIT)

// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_COROUTINE_HPP
#define SOL_COROUTINE_HPP

#include "reference.hpp"
#include "stack.hpp"
#include "function_result.hpp"
#include "thread.hpp"

namespace sol {
class coroutine : public reference {
private:
    call_status stats = call_status::yielded;

    void luacall(std::ptrdiff_t argcount, std::ptrdiff_t) {
#if SOL_LUA_VERSION < 502
        stats = static_cast<call_status>(lua_resume(lua_state(), static_cast<int>(argcount)));
#else
        stats = static_cast<call_status>(lua_resume(lua_state(), nullptr, static_cast<int>(argcount)));
#endif // Lua 5.1 compat
    }

    template<std::size_t... I, typename... Ret>
    auto invoke( types<Ret...>, std::index_sequence<I...>, std::ptrdiff_t n ) {
        luacall(n, sizeof...(Ret));
        int stacksize = lua_gettop(lua_state());
        int firstreturn = std::max(1, stacksize - static_cast<int>(sizeof...(Ret)) + 1);
        auto r = stack::get<std::tuple<Ret...>>(lua_state(), firstreturn);
        lua_pop(lua_state(), static_cast<int>(sizeof...(Ret)));
        return r;
    }

    template<std::size_t I, typename Ret>
    Ret invoke(types<Ret>, std::index_sequence<I>, std::ptrdiff_t n) {
        luacall(n, 1);
        return stack::pop<Ret>(lua_state());
    }

    template <std::size_t I>
    void invoke(types<void>, std::index_sequence<I>, std::ptrdiff_t n) {
        luacall(n, 0);
    }

    protected_function_result invoke(types<>, std::index_sequence<>, std::ptrdiff_t n) {
        int stacksize = lua_gettop( lua_state() );
        int firstreturn = std::max( 1, stacksize - static_cast<int>( n ) );
        luacall(n, LUA_MULTRET);
        int poststacksize = lua_gettop(lua_state());
        int returncount = poststacksize - (firstreturn - 1);
        return protected_function_result( lua_state( ), firstreturn, returncount, returncount, status() );
    }

public:
    coroutine(lua_State* L, int index = -1) : reference(L, index) {}
    coroutine() = default;
    coroutine(const coroutine&) = default;
    coroutine& operator=(const coroutine&) = default;

    call_status status() const {
        return stats;
    }

    bool error() const {
        call_status cs = status();
        return cs != call_status::ok && cs != call_status::yielded;
    }

    bool runnable () const {
        return valid() 
            && (status() == call_status::yielded);
    }

    explicit operator bool() const {
        return runnable();
    }

    template<typename... Args>
    protected_function_result operator()( Args&&... args ) {
        return call<>( std::forward<Args>( args )... );
    }

    template<typename... Ret, typename... Args>
    decltype(auto) operator()( types<Ret...>, Args&&... args ) {
        return call<Ret...>( std::forward<Args>( args )... );
    }

    template<typename... Ret, typename... Args>
    decltype(auto) call( Args&&... args ) {
        push();
        int pushcount = stack::push_args( lua_state(), std::forward<Args>( args )... );
        return invoke( types<Ret...>( ), std::index_sequence_for<Ret...>(), pushcount );
    }
};
}
#endif // SOL_COUROUTINE_HPP