#include "lua_func.h"
#include "error.h"

#include <lua5.1/lauxlib.h>

/**
 * Pushes onto the stack the value at t[i]
 */
static void lua_getindex (lua_State *L, int t, int i)
{
    lua_pushinteger(L, i);
    lua_gettable(L, t);
}

/**
 * Pushes onto the stack either:
 *  * the value at t[name]
 *  * the value at t[index]
 *
 *  Returns the new index, or 0, if neither could be found
 */
static int lua_arg_lookup (lua_State *L, int t, const char *name, int index)
{
    // try name
    lua_getfield(L, t, name);

    if (!lua_isnil(L, -1))
        return lua_gettop(L);
    else
        lua_pop(L, 1);
    
    // try index
    lua_getindex(L, t, index);
    
    if (!lua_isnil(L, -1))
        return lua_gettop(L);

    else
        lua_pop(L, 1);
    
    // not found
    return 0;
}

static const char *_lua_arg_string (lua_State *L, int index, const char *name, const char *def)
{
    const char *value;

    // use default?
    if (lua_isnoneornil(L, index) && def != (const char *) LUA_ARG_REQUIRED)
        return def;
    
    // value given?
    if ((value = lua_tostring(L, index)))
        return value;
   
    // error
    luaL_error(L, "missing value for required string argument <%d:%s>", index, name); return NULL;
}

static bool _lua_arg_bool (lua_State *L, int index, const char *name, int def)
{
    (void) name;

    // use default?
    if (lua_isnoneornil(L, index) && def != LUA_ARG_REQUIRED)
        return def;
   
    // value given
    return lua_toboolean(L, index);
}

static long _lua_arg_int (lua_State *L, int index, const char *name, long def)
{
    (void) name;

    // use default?
    if (lua_isnoneornil(L, index) && def != LUA_ARG_REQUIRED)
        return def;
   
    // conver to integer
    // XXX: check compatibility?
    return lua_tointeger(L, index);
}

static void * _lua_arg_obj (lua_State *L, int index, const struct lua_type *type, bool optional)
{
    // not given?
    if (!lua_isnoneornil(L, index))
        return lua_type_get(L, type, index);

    if (optional)
        return NULL;
    
    luaL_error(L, "missing value for required object argument <%d:%s>", index, type->name);
    return NULL;
}

/**
 * Look up the arg index to use for the given index/name.
 *
 * If no value is found for the corresponding index, returns zero.
 */
static int lua_arg_index (lua_State *L, int nargs, int index, const char *name)
{
    // lookup from table?
    if (nargs == 2 && lua_istable(L, 2) && name) {
        // push the value from the named field onto the stack
        lua_getfield(L, 2, name);
        
        // no named field?
        if (lua_isnil(L, -1)) {
            lua_pop(L, 1);

            lua_getindex(L, 2, index - 1);
        }

        // no index field?
        if (lua_isnil(L, -1)) {
            lua_pop(L, 1);

            return 0;
        }
        
        // found either a named or indexed arg
        return lua_gettop(L);

    } else if (index <= nargs) {
        // use the same index
        return index;

    } else {
        // no index
        return 0;
    }
}

const char *lua_arg_string (lua_State *L, int nargs, int index, const char *name, const char *def)
{
    return _lua_arg_string(L, lua_arg_index(L, nargs, index, name), name, def);
}

bool lua_arg_bool (lua_State *L, int nargs, int index, const char *name, int def)
{
    return _lua_arg_bool(L, lua_arg_index(L, nargs, index, name), name, def);    
}

void* lua_arg_obj (lua_State *L, int nargs, int index, const struct lua_type *type, bool optional)
{
    return _lua_arg_obj(L, lua_arg_index(L, nargs, index, NULL), type, optional);
}

long lua_arg_int (lua_State *L, int nargs, int index, const char *name, long def)
{
    return _lua_arg_int(L, lua_arg_index(L, nargs, index, name), name, def);
}

void lua_args_parse (lua_State *L, const struct lua_func *func, void **obj_ptr, ...)
{
    int argidx = 1, argtbl = 0, idx;
    const struct lua_func_arg *arg;
    va_list vargs;

    // first, the obj argument
    if (func->type)
        *obj_ptr = lua_type_get(L, func->type, argidx++);

    // were we given a table of arguments?
    if (lua_istable(L, argidx))
        argtbl = argidx++;

    // parse the args
    va_start(vargs, obj_ptr);

    for (arg = func->args, idx = 1; arg->name && arg->type; arg++, idx++) {
        int index;

        // map index
        if (!argtbl)
            // direct
            index = argidx++;
        
        else
            // lookup from table
            index = lua_arg_lookup(L, argtbl, arg->name, idx);
        
        // apply
        switch (arg->type) {
            case LUA_ARG_STRING:
                *va_arg(vargs, const char **) = _lua_arg_string(L, index, arg->name, arg->def.string);
                break;

            case LUA_ARG_BOOL:
                *va_arg(vargs, bool *) = _lua_arg_bool(L, index, arg->name, arg->def.boolean);
                break;
            
            case LUA_ARG_INT:
                *va_arg(vargs, long *) = _lua_arg_int(L, index, arg->name, arg->def.integer);
                break;

            default:
                NOT_REACHED();
        };
    }

    va_end(vargs);
}