/*
** $Id: lcorolib.c,v 1.5.1.1 2013/04/12 18:48:47 roberto Exp $
** Coroutine Library
** See Copyright Notice in lua.h
*/

#include <stdlib.h>

#define lcorolib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

static int auxresume(lua_State *L, lua_State *co, int narg)
{
	int status;
	if (!lua_checkstack(co, narg))
	{
		lua_pushliteral(L, "too many arguments to resume");
		return -1; /* error flag */
	}
	if (lua_status(co) == LUA_OK && lua_gettop(co) == 0)
	{
		lua_pushliteral(L, "cannot resume dead coroutine");
		return -1; /* error flag */
	}
	lua_xmove(L, co, narg);
	status = lua_resume(co, L, narg);
	if (status == LUA_OK || status == LUA_YIELD)
	{
		int nres = lua_gettop(co);
		if (!lua_checkstack(L, nres + 1))
		{
			lua_pop(co, nres); /* remove results anyway */
			lua_pushliteral(L, "too many results to resume");
			return -1; /* error flag */
		}
		lua_xmove(co, L, nres); /* move yielded values */
		return nres;
	}
	else
	{
		lua_xmove(co, L, 1); /* move error message */
		return -1;           /* error flag */
	}
}

static int luaB_coresume(lua_State *L)
{
	lua_State *co = lua_tothread(L, 1);
	int r;
	luaL_argcheck(L, co, 1, "coroutine expected");
	r = auxresume(L, co, lua_gettop(L) - 1);
	if (r < 0)
	{
		lua_pushboolean(L, 0);
		lua_insert(L, -2);
		return 2; /* return false + error message */
	}
	else
	{
		lua_pushboolean(L, 1);
		lua_insert(L, -(r + 1));
		return r + 1; /* return true + `resume' returns */
	}
}

static int luaB_auxwrap(lua_State *L)
{
	lua_State *co = lua_tothread(L, lua_upvalueindex(1));
	int r = auxresume(L, co, lua_gettop(L));
	if (r < 0)
	{
		if (lua_isstring(L, -1))
		{                     /* error object is a string? */
			luaL_where(L, 1); /* add extra info */
			lua_insert(L, -2);
			lua_concat(L, 2);
		}
		return lua_error(L); /* propagate error */
	}
	return r;
}

static int luaB_cocreate(lua_State *L)
{
	lua_State *NL;
	luaL_checktype(L, 1, LUA_TFUNCTION);
	NL = lua_newthread(L);
	lua_pushvalue(L, 1); /* move function to top */
	lua_xmove(L, NL, 1); /* move function from L to NL */
	return 1;
}

static int luaB_cowrap(lua_State *L)
{
	luaB_cocreate(L);
	lua_pushcclosure(L, luaB_auxwrap, 1);
	return 1;
}

static int luaB_yield(lua_State *L)
{
	return lua_yield(L, lua_gettop(L));
}

static int luaB_costatus(lua_State *L)
{
	lua_State *co = lua_tothread(L, 1);
	luaL_argcheck(L, co, 1, "coroutine expected");
	if (L == co)
		lua_pushliteral(L, "running");
	else
	{
		switch (lua_status(co))
		{
			case LUA_YIELD:
				lua_pushliteral(L, "suspended");
				break;
			case LUA_OK:
			{
				lua_Debug ar;
				if (lua_getstack(co, 0, &ar) > 0) /* does it have frames? */
					lua_pushliteral(L, "normal"); /* it is running */
				else if (lua_gettop(co) == 0)
					lua_pushliteral(L, "dead");
				else
					lua_pushliteral(L, "suspended"); /* initial state */
				break;
			}
			default: /* some error occurred */
				lua_pushliteral(L, "dead");
				break;
		}
	}
	return 1;
}

static int luaB_corunning(lua_State *L)
{
	int ismain = lua_pushthread(L);
	lua_pushboolean(L, ismain);
	return 2;
}

static const luaL_Reg co_funcs[] = {
	{"create", luaB_cocreate},
	{"resume", luaB_coresume},
	{"running", luaB_corunning},
	{"status", luaB_costatus},
	{"wrap", luaB_cowrap},
	{"yield", luaB_yield},
	{NULL, NULL}};

LUAMOD_API int luaopen_coroutine(lua_State *L)
{
	luaL_newlib(L, co_funcs);
	return 1;
}
