/**
 * mds — A micro-display server
 * Copyright © 2014, 2015, 2016, 2017  Mattias Andrée (m@maandree.se)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "builtin-functions.h"

#include "variables.h"

#include <libmdsserver/macros.h>

#include <stdlib.h>
#include <string.h>



/**
 * Define useful data for built-in function with 2 parameters
 */
#define define_2\
	const char32_t *restrict a = *args++;\
	const char32_t *restrict b = *args++;\
	size_t an = string_length(a);\
	size_t bn = string_length(b);\
	size_t i, n = an > bn ? an : bn;\
	char32_t *restrict rc;\
	fail_if (xmalloc(rc, n + 1, char32_t));\
	rc[n] = -1

/**
 * Define useful data for built-in function with 1 parameter
 */
#define define_1\
	const char32_t* restrict a = *args++;\
	size_t i, n = string_length(a);\
	char32_t *restrict rc;\
	fail_if (xmalloc(rc, n + 1, char32_t));\
	rc[n] = -1

/**
 * Return a value, or if there was a failure somewhere, return `NULL`
 * 
 * @param  v:void*  The value to return on success
 */
#define return(v)\
	return v;\
fail:\
	return NULL;


/**
 * Definition of the built-in function add/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_add_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] + b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function sub/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_sub_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] - b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function mul/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_mul_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] * b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function div/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_div_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] / b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function mod/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_mod_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] % b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function rsh/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_rsh_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] >> b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function lsh/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_lsh_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] << b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function or/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_or_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] | b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function and/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_and_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] & b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function xor/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_xor_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] ^ b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function not/1
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_not_1(const char32_t **restrict args)
{
	define_1;
	for (i = 0; i < n; i++)
		rc[i] = !a[i];
	return(rc);
}


/**
 * Definition of the built-in function equals/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_equals_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] == b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function greater/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_greater_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] > b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function less/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_less_2(const char32_t **restrict args)
{
	define_2;
	for (i = 0; i < n; i++)
		rc[i] = a[i % an] < b[i % bn];
	return(rc);
}


/**
 * Definition of the built-in function get/2
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_get_2(const char32_t **restrict args)
{
	const char32_t *restrict a = *args++;
	const char32_t *restrict b = *args++;
	char32_t *restrict rc;
	size_t n = (size_t)*b;
	mds_kbdc_tree_t *value = variables_get((size_t)*a)->array.elements;
	while (n--)
		value = value->next;
	fail_if (rc = string_dup(value->compiled_string.string), rc == NULL);
	return(rc);
}


/**
 * Definition of the built-in function set/3
 * 
 * @param   args  The arguments passed to the function
 * @return        The return value of the function, `NULL` on error
 */
static char32_t *
builtin_function_set_3(const char32_t **restrict args)
{
	const char32_t *restrict a = *args++;
	const char32_t *restrict b = *args++;
	const char32_t *restrict c = *args++;
	char32_t *restrict rc;
	size_t n = (size_t)*b;
	mds_kbdc_tree_t *value = variables_get((size_t)*a)->array.elements;
	while (n--)
		value = value->next;
	free(value->compiled_string.string);
	value->compiled_string.string = string_dup(c);
	fail_if (!value->compiled_string.string);
	fail_if (!(rc = string_dup(c)));
	return(rc);
}


#undef define_1
#undef define_2
#undef return


/**
 * Check whether a function is a builtin function
 * 
 * @param   name       The name of the function
 * @param   arg_count  The number of arguments to pass to the function
 * @return             Whether the described function is a builtin function
 */
int
builtin_function_defined(const char *restrict name, size_t arg_count)
{
	size_t i;
	static const char* const BUILTIN_FUNCTIONS_2[] = {
		"add", "sub", "mul", "div", "mod", "rsh", "lsh", "or",
		"and", "xor", "equals", "greater", "less", "get", NULL
	};

	if (arg_count == 1) {
		return !strcmp(name, "not");
	} else if (arg_count == 2) {
		for (i = 0; BUILTIN_FUNCTIONS_2[i]; i++)
			if (!strcmp(name, BUILTIN_FUNCTIONS_2[i]))
				return 1;
	} else if (arg_count == 3) {
		return !strcmp(name, "set");
	}

	return 0;
}


/**
 * Invoke a builtin function
 * 
 * The function will abort if an non-builtin function is addressed
 * 
 * Before invoking set/3 or get/2, please check the arguments,
 * please also check that either all or none of the arguments
 * are empty string for any of the other builtin functions
 * 
 * @param   name       The name of the function
 * @param   arg_count  The number of arguments to pass to the function
 * @param   args       The arguments to pass
 * @return             The return value of the function, `NULL` on error
 */
char32_t *
builtin_function_invoke(const char *restrict name, size_t arg_count, const char32_t **restrict args)
{
#define t(f) do { fail_if (rc = builtin_function_##f(args), rc == NULL); return rc; } while (0)
	char32_t *rc;

	if (arg_count == 3 && !strcmp(name, "set"))  t (set_3);
	if (arg_count == 1 && !strcmp(name, "not"))  t (not_1);

	if (arg_count != 2)
		abort();

	if (!strcmp(name, "add"))     t (add_2);
	if (!strcmp(name, "sub"))     t (sub_2);
	if (!strcmp(name, "mul"))     t (mul_2);
	if (!strcmp(name, "div"))     t (div_2);
	if (!strcmp(name, "mod"))     t (mod_2);
	if (!strcmp(name, "rsh"))     t (rsh_2);
	if (!strcmp(name, "lsh"))     t (lsh_2);
	if (!strcmp(name, "or"))      t (or_2);
	if (!strcmp(name, "and"))     t (and_2);
	if (!strcmp(name, "xor"))     t (xor_2);
	if (!strcmp(name, "equals"))  t (equals_2);
	if (!strcmp(name, "greater")) t (greater_2);
	if (!strcmp(name, "less"))    t (less_2);
	if (!strcmp(name, "get"))     t (get_2);

	abort();
fail:
	return NULL;
#undef t
}