/*
 *  SPL - The SPL Programming Language
 *  Copyright (C) 2004, 2005  Clifford Wolf <clifford@clifford.at>
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  builtins.c: Collection of some useful CLIB functions
 */

#include <sys/types.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <assert.h>

#ifdef ENABLE_READLINE_SUPPORT
#  include <readline/readline.h>
#  include <readline/history.h>
#endif

#ifdef ENABLE_GETTEXT_SUPPORT
#  include <locale.h>
#  include <libintl.h>
#endif

#include "spl.h"
#include "compat.h"

/**
 * This module contains the SPL 'standard' builtin functions. It does not
 * need to be loaded explicitely, most SPL runtimes load it automatically
 * for you.
 */


/**
 * Write the text passed as argument to standard ouput. Some SPL runtimes
 * replace this function with their own output function.
 *
 * If the output should not be UTF-8 encoded, the encoding must be specified
 * with a 2nd parameter. Valid encodings are the same as for the '#encoding'
 * compiler pragma (see 'SPL Language Reference' for a list).
 */
// builtin write(text, encoding)
struct spl_node *spl_builtin_write(struct spl_task *task, void UNUSED(*data))
{
	char *text = spl_clib_get_string(task);
	char *encoding = spl_clib_get_string(task);

	if (*encoding) {
		char *old_text = text;
		text = spl_utf8_export(text, encoding);

		if ( !text ) {
			text = old_text;
			encoding = "";
		}
	}

	printf("%s", text);
	fflush(stdout);

	if (*encoding)
		free(text);

	return 0;
}


/**
 * Read a line from the standard input. Some SPL runtimes replace this
 * function with their own input function. The read text (or undef on
 * end-of-file) is returned.
 *
 * The fist parameter can be used to specify a prompt to be displayed for
 * reading the line.
 *
 * If the output is not UTF-8 encoded, the encoding must be specified with a
 * 2nd parameter. Valid encodings are the same as for the '#encoding' compiler
 * pragma (see 'SPL Language Reference' for a list).
 *
 * If UTF-8 encoding is expected but the output fails to pass the UTF-8 test,
 * the output is assumed to be latin1 encoded.
 */
// builtin read(prompt, encoding)
struct spl_node *spl_builtin_read(struct spl_task *task, void UNUSED(*data))
{
	char *prompt = spl_clib_get_string(task);
	char *encoding = spl_clib_get_string(task);
	char *input;

#ifdef ENABLE_READLINE_SUPPORT
	if (isatty(0))
	{
		static int did_run_using_history = 0;
		if (!did_run_using_history) {
			using_history();
			did_run_using_history = 1;
		}

		input = readline(prompt);

		if (!input) {
			if (*prompt) { printf("\n"); fflush(stdout); }
			return 0;
		}

		add_history(input);
	}
	else
#endif
	{
		printf("%s", prompt);
		fflush(stdout);

		char input_buffer[4096];
		char *rc = fgets(input_buffer, 4096, stdin);

		if (!rc) {
			if (*prompt) { printf("\n"); fflush(stdout); }
			return 0;
		}

		input = strdup(input_buffer);
	}

	if (*encoding) {
		char *old_input = input;
		input = spl_utf8_import(old_input, encoding);

		if (!input)
			input = old_input;
		else
			free(old_input);
	}

	if (spl_utf8_check(input)) {
		char *old_input = input;
		input = spl_utf8_import(old_input, "latin_1");
		free(old_input);

		/* this should never happen */
		if (!input) input = strdup("");
	}

	return SPL_NEW_STRING(input);
}


/**
 * Create a (unicode) charater from the number passed as argument.
 */
// builtin chr(number)
struct spl_node *spl_builtin_chr(struct spl_task *task, void UNUSED(*data))
{
	int number = spl_clib_get_int(task);
	char text[5] = { 0, 0, 0, 0, 0 };

#define OUT(bits, pos) ((number >> pos) & (0xff >> (8-bits)))

	if ( number <= 0x00007F ) {
		text[0] = number;
		return SPL_NEW_STRING_DUP(text);
	}

	if ( number <= 0x0007FF ) {
		text[0] = 0xC0 | OUT(5, 6);
		text[1] = 0x80 | OUT(6, 0);
		return SPL_NEW_STRING_DUP(text);
	}

	if ( number <= 0x00FFFF ) {
		text[0] = 0xE0 | OUT(4, 12);
		text[1] = 0x80 | OUT(6, 6);
		text[2] = 0x80 | OUT(6, 0);
		return SPL_NEW_STRING_DUP(text);
	}

	if ( number <= 0x10FFFF ) {
		text[0] = 0xF0 | OUT(3, 18);
		text[1] = 0x80 | OUT(6, 12);
		text[2] = 0x80 | OUT(6, 6);
		text[3] = 0x80 | OUT(6, 0);
		return SPL_NEW_STRING_DUP(text);
	}

#undef OUT

	/* Input is to big for beeing UTF-8 encoded. */
	return 0;
}

/**
 * Return the unicode character number of the first character in the text.
 */
// builtin ord(text)
struct spl_node *spl_builtin_ord(struct spl_task *task, void UNUSED(*data))
{
	char *t = spl_clib_get_string(task);

#define IN(off, mask, value) ((t[off] & (mask)) == (value))
#define OUT(off, bits, pos) ((t[off] & (0xff >> (8-bits))) << pos)

	if (IN(0, 0x80, 0x00))
		return SPL_NEW_INT(t[0]);

	if (IN(0, 0xE0, 0xC0) &&
	    IN(1, 0xC0, 0x80))
		return SPL_NEW_INT(OUT(0, 5, 6) | OUT(1, 6, 0));

	if (IN(0, 0xF0, 0xE0) &&
	    IN(1, 0xC0, 0x80) &&
	    IN(2, 0xC0, 0x80))
		return SPL_NEW_INT(OUT(0, 4, 12) |
				OUT(1, 6, 6) | OUT(2, 6, 0));

	if (IN(0, 0xF8, 0xF0) &&
	    IN(1, 0xC0, 0x80) &&
	    IN(2, 0xC0, 0x80) &&
	    IN(3, 0xC0, 0x80))
		return SPL_NEW_INT(OUT(0, 3, 18) |
				OUT(1, 6, 12) | OUT(2, 6, 6) | OUT(3, 6, 0));

#undef OUT
#undef IN

	/* Input is not UTF-8. This should not happen.. */
	return 0;
}

/**
 * Convert a string holding a hexadezimal number to an integer value. A
 * leading "0x" or "0X" is ignored. Zero is returned if there is no
 * hexadezimal number in the string.
 */
// builtin hex(text)
struct spl_node *spl_builtin_hex(struct spl_task *task, void UNUSED(*data))
{
	char *text = spl_clib_get_string(task);
	int ret = 0;

	while (*text == ' ' || *text == '\t') text++;
	if (!strncmp(text, "0x", 2) || !strncmp(text, "0X", 2)) text+=2;

	ret = strtol(text, 0, 16);
	return SPL_NEW_INT(ret);
}

/**
 * Convert a string holding an octal number to an integer value. A
 * leading "0o" or "0O" is ignored. Zero is returned if there is no
 * octal number in the string.
 */
// builtin oct(text)
struct spl_node *spl_builtin_oct(struct spl_task *task, void UNUSED(*data))
{
	char *text = spl_clib_get_string(task);
	int ret = 0;

	while (*text == ' ' || *text == '\t') text++;
	if (!strncmp(text, "0o", 2) || !strncmp(text, "0O", 2)) text+=2;

	ret = strtol(text, 0, 8);
	return SPL_NEW_INT(ret);
}

/**
 * Convert a string holding a binary number to an integer value. A
 * leading "0b" or "0B" is ignored. Zero is returned if there is no
 * binary number in the string.
 */
// builtin bin(text)
struct spl_node *spl_builtin_bin(struct spl_task *task, void UNUSED(*data))
{
	char *text = spl_clib_get_string(task);
	int ret = 0;

	while (*text == ' ' || *text == '\t') text++;
	if (!strncmp(text, "0b", 2) || !strncmp(text, "0B", 2)) text+=2;

	ret = strtol(text, 0, 2);
	return SPL_NEW_INT(ret);
}

/**
 * A C printf()-like format function. The formatted string is returned.
 * The following special sequences are supported:
 *
 *	%%	A '%' character
 *	%s	A string
 *	%d	A decimal integer
 *	%x	A hexadecimal integer (lowercase letters)
 *	%X	A hexadecimal integer (uppercase letters)
 *	%o	An octal integer
 *	%b	A binary integer
 *	%f	A floating point number
 *
 * The field width and precision format of printf() is also supported. But
 * currently there is no support for 'N$' argument specifications.
 */
// builtin fmt(text, @args)
struct spl_node *spl_builtin_fmt(struct spl_task *task, void UNUSED(*data))
{
	static const char num_to_char_lowercase[] = "0123456789abcdef";
	static const char num_to_char_uppercase[] = "0123456789ABCDEF";

	char *format = spl_clib_get_string(task);
	struct spl_string *output = 0;

	while (*format)
	{
		if (*format != '%') {
			int text_len = strcspn(format, "%");
			output = spl_string_new(SPL_STRING_NOAUTOGET, output,
					0, my_strndup(format, text_len), 0);
			format += text_len;
			continue;
		}

		int format_len = strspn(++format, "-01233456789.*");
		char *format_end = format + format_len;

		if (format[format_len] == 0) {
			output = spl_string_new(SPL_STRING_NOAUTOGET, output,
					0, strdup("(format_string_error:EOT)"), 0);
			break;
		}

		int got_width = 0, width = 0;
		int got_prec = 0, prec = 0;

		int left_adjust = 0;
		while (*format == '-') { format++; left_adjust=1; }

		int zero_padding = 0;
		while (*format == '0') { format++; zero_padding=1; }

		{
			char *width_format = 0;

			if (*format == '*') {
				width_format = strdup(spl_clib_get_string(task));
				format++;
			} else {
				int width_len = strspn(format, "-01233456789");
				if (width_len) width_format = my_strndup(format, width_len);
				format += width_len;
			}

			if (width_format) {
				char *tmp = width_format;
				if (*tmp == '-') { tmp++; left_adjust=1; }
				if (*tmp) {
					width = atoi(tmp);
					got_width = 1;
				}
			}

			if (width_format)
				free(width_format);
		}

		if (*format == '.')
		{
			char *prec_format = 0;
			format++;

			if (*format == '*') {
				prec_format = strdup(spl_clib_get_string(task));
				format++;
			} else {
				int prec_len = strspn(format, "-01233456789");
				if (prec_len) prec_format = my_strndup(format, prec_len);
				format += prec_len;
			}

			if (prec_format && *prec_format) {
				prec = atoi(prec_format);
				got_prec = 1;
			}

			if (prec_format)
				free(prec_format);
		}

		char *insert = 0;

		int base = 10;
		const char *num_to_char = num_to_char_lowercase;

		switch (*format_end)
		{
			case '%':
				insert = strdup("%");
				break;

			case 's': {
				char *arg = spl_clib_get_string(task);
				int arg_len = strlen(arg);
				int format_width = got_width ? width : arg_len;
				int format_prec  = got_prec ? prec : arg_len;
				if (format_width > format_prec && !got_width)
					format_width = format_prec;
				if (left_adjust) format_width *= -1;
				my_asprintf(&insert, "%*.*s",
					format_width, format_prec, arg);
				break;
			}

			// a little bit ugly but still legal C ..
			if (0) { case 'x': base = 16; }
			if (0) { case 'X': base = 16;
					num_to_char = num_to_char_uppercase; }
			if (0) { case 'o': base = 8; }
			if (0) { case 'b': base = 2; }

			case 'd': {
				int arg = spl_clib_get_int(task);

				int myprec = 1;
				int mywidth = width;
				if (got_prec) myprec = prec;

				int buffer_len = (myprec < 64 ? 64 : myprec);
				if (got_width && buffer_len < width) buffer_len = width;

				char buffer_data[buffer_len + 8];
				char *buffer = buffer_data + buffer_len + 7;

				int isneg = arg < 0;
				if (isneg) { arg *= -1; myprec--; mywidth--; }

				*buffer = 0;
				while (myprec > 0 || arg) {
					int rest = arg % base;
					arg = arg / base;
					*(--buffer) = num_to_char[rest];
					myprec--; mywidth--;
				}

				if (zero_padding)
					while (mywidth > 0) {
						*(--buffer) = '0';
						mywidth--;
					}

				if (isneg) *(--buffer) = '-';

				if (got_width && left_adjust) {
					my_asprintf(&insert, "%-*s", width, buffer);
					break;
				}

				if (!zero_padding)
					while (mywidth > 0) {
						*(--buffer) = ' ';
						mywidth--;
					}

				insert = strdup(buffer);
				break;
			}

			case 'f': {
				double arg = spl_clib_get_float(task);
				int format_prec  = got_prec ? prec : 6;

				if (got_width) {
					char *fmt_string = "%*.*f";
					if (zero_padding) fmt_string = "%0*.*f";
					if (left_adjust) fmt_string = "%-*.*f";
					my_asprintf(&insert, fmt_string,
						width, format_prec, arg);
				} else
					my_asprintf(&insert, "%.*f",
						format_prec, arg);
				break;
			}

			default:
				spl_put(task->vm, spl_clib_get_node(task));
				my_asprintf(&insert, "(format_string_error:%c)", *format_end);
		}

		if (insert) {
			output = spl_string_new(SPL_STRING_NOAUTOGET,
					output, 0, insert, 0);
		}

		format = format_end + 1;
	}

	return SPL_NEW_SPL_STRING(output);
}

static int rand_seeded = 0;

/**
 * Returns a random integer number, larger then or equal to zero and smaller
 * then the 'max' argument.
 *
 * When the argument is 0 or missing, the return value is a floating point
 * number between 0 and 1. When the argument is -1, the return value is an
 * integer between 0 and RAND_MAX.
 */
// builtin rand(max)
static struct spl_node *spl_builtin_rand(struct spl_task *task, void UNUSED(*data))
{
	int max = spl_clib_get_int(task);

	if (!rand_seeded) {
		unsigned int seed = (getpid() << 16) ^ time(0);
		int fd = open("/dev/urandom", O_RDONLY);
		if (fd >= 0) {
			read(fd, &seed, sizeof(unsigned int));
			close(fd);
		}
		srand(seed);
		rand_seeded = 1;
	}

	if (max == 0)
		return SPL_NEW_FLOAT((double)rand() / (double)RAND_MAX);

	if (max < 0)
		return SPL_NEW_INT(rand());

	return SPL_NEW_INT(rand() % max);
}

/**
 * Seeds the random number generater. When called with no argument a seed
 * is autogenerated from /dev/urandom. This is also done automatically when
 * rand() is called without calling srand() before.
 */
// builtin srand(seed)
static struct spl_node *spl_builtin_srand(struct spl_task *task, void UNUSED(*data))
{
	unsigned int seed = spl_clib_get_int(task);

	if (!seed) {
		seed = (getpid() << 16) ^ time(0);
		int fd = open("/dev/urandom", O_RDONLY);
		if (fd >= 0) {
			read(fd, &seed, sizeof(unsigned int));
			close(fd);
		}
	}

	srand(seed);
	rand_seeded = 1;

	return 0;
}

/**
 * Returns 1 if the specified builtin function is declared and 0 otherwise.
 */
// builtin declared_builtin(function_name)
static struct spl_node *spl_builtin_declared_builtin(struct spl_task *task, void UNUSED(*data))
{
	char *fname = spl_clib_get_string(task);
	return SPL_NEW_INT(spl_clib_check(task->vm, fname));
}

/**
 * Returns the section of given string
 * starting at offset with length number of characters.
 *
 * If length is 0 or out of range (offset + length > total length),
 * then the length is adjusted to include the entire string starting
 * at given offset.
 *
 * TODO: check if this causes memory leaks.
 *
 * TODO: this does not work with strings containing UTF-8 characters.
 */ 
// builting substring(string,offset,length)
static struct spl_node *spl_builtin_substring(struct spl_task *task, void UNUSED(*data))
{
	char *text = spl_clib_get_string(task);
	int offset = spl_clib_get_int(task);
	int length = spl_clib_get_int(task);

	struct spl_string *original = spl_string_printf(0,0,0,"%s",text);

	//printf("substring settings: original text: %s; offset: %d; length: %d\n",original->text,offset,length);
	
	if (offset < 0 || length <= 0 || (unsigned int)offset > original->total_len)
	{
		//printf("invalid range settings, returning empty string\n");
		return SPL_NEW_STRING_DUP("");
	}
	else
	{
		if ((unsigned int)offset + (unsigned int)length > original->total_len)
			length = original->total_len - offset;
		struct spl_string *substr = spl_string_split(original,offset,length);
		//printf("spl substring: %s\n",substr->text);
		struct spl_node *result = spl_get(0);
		spl_set_spl_string(result,substr);
		//printf("result value: %s\n",result->value_string->text);
		return result;
	}
}

/**
 * The setlocale() function is used to set or query the program's current locale.
 *
 * This is a simple wrapper for the C setlocale() function. The 'category'
 * argument is passed as string. E.g.:
 *
 *	setlocale("LC_ALL", "C");
 */
// builtin setlocale(category, locale)
static struct spl_node *spl_builtin_setlocale(struct spl_task UNUSED(*task), void UNUSED(*data))
{
#ifdef ENABLE_GETTEXT_SUPPORT
	char *category = spl_clib_get_string(task);
	char *locale = spl_clib_get_string(task);
	char *retval = 0;

	if (!strcmp(category, "LC_ALL"))
		retval = setlocale(LC_ALL, locale);
	else
	if (!strcmp(category, "LC_COLLATE"))
		retval = setlocale(LC_COLLATE, locale);
	else
	if (!strcmp(category, "LC_CTYPE"))
		retval = setlocale(LC_CTYPE, locale);
	else
	if (!strcmp(category, "LC_MESSAGES"))
		retval = setlocale(LC_MESSAGES, locale);
	else
	if (!strcmp(category, "LC_MONETARY"))
		retval = setlocale(LC_MONETARY, locale);
	else
	if (!strcmp(category, "LC_NUMERIC"))
		retval = setlocale(LC_NUMERIC, locale);
	else
	if (!strcmp(category, "LC_TIME"))
		retval = setlocale(LC_TIME, locale);

	return retval ? SPL_NEW_STRING_DUP(retval) : 0;
#else
	return 0;
#endif
}

/**
 * The bindtextdomain() function sets the base directory of the hierarchy
 * containing message catalogs for a given message domain.
 *
 * This is a simple wrapper for the C bindtextdomain() function.
 */
// builtin bindtextdomain(domain, directory)
static struct spl_node *spl_builtin_bindtextdomain(struct spl_task UNUSED(*task), void UNUSED(*data))
{
#ifdef ENABLE_GETTEXT_SUPPORT
	char *domain = spl_clib_get_string(task);
	char *newdirectory = spl_clib_get_string(task);
	if (!newdirectory || !*newdirectory) newdirectory = 0;

	char *retval = bindtextdomain(domain, newdirectory);
	return retval ? SPL_NEW_STRING_DUP(retval) : 0;
#else
	return 0;
#endif
}

/**
 * The textdomain() function sets or retrieves the current message domain.
 *
 * This is a simple wrapper for the C textdomain() function.
 */
// builtin textdomain(domain)
static struct spl_node *spl_builtin_textdomain(struct spl_task UNUSED(*task), void UNUSED(*data))
{
#ifdef ENABLE_GETTEXT_SUPPORT
	char *newdomain = spl_clib_get_string(task);
	if (!newdomain || !*newdomain) newdomain = 0;

	char *retval = textdomain(newdomain);
	return retval ? SPL_NEW_STRING_DUP(retval) : 0;
#else
	return 0;
#endif
}

/**
 * The gettext() function attempts to translate a text string into the user's
 * native language, by looking up the translation in a message catalog.
 *
 * This is a simple wrapper for the C gettext() function.
 */
// builtin gettext(message)
static struct spl_node *spl_builtin_gettext(struct spl_task *task, void UNUSED(*data))
{
#ifdef ENABLE_GETTEXT_SUPPORT
	char *message = spl_clib_get_string(task);
	char *retval = gettext(message);
	return retval ? SPL_NEW_STRING_DUP(retval) : 0;
#else
	char *message = spl_clib_get_string(task);
	return SPL_NEW_STRING_DUP(message);
#endif
}

/**
 * The dgettext() function attempts to translate a text string into the user's
 * native language, by looking up the translation in a message catalog.
 *
 * This is a simple wrapper for the C gettext() function.
 */
// builtin dgettext(domain, message)
static struct spl_node *spl_builtin_dgettext(struct spl_task *task, void UNUSED(*data))
{
#ifdef ENABLE_GETTEXT_SUPPORT
	char *domain = spl_clib_get_string(task);
	char *message = spl_clib_get_string(task);
	char *retval = dgettext(domain && *domain ? domain : 0, message);
	return retval ? SPL_NEW_STRING_DUP(retval) : 0;
#else
	spl_clib_get_string(task);
	char *message = spl_clib_get_string(task);
	return SPL_NEW_STRING_DUP(message);
#endif
}

/**
 * This function is implementing the backend functionality of the SPL
 * translation prefix for strings (_).
 *
 * It translates the message using the [[gettext()]] function and then
 * substitutes '{N}' with the strings passed as additional arguments (N
 * beeing the index in @args) and '{}' with a simple '{'.
 */
// builtin _(message, domain, @args)
static struct spl_node *spl_builtin_underscore(struct spl_task *task, void UNUSED(*data))
{
	char *message = spl_clib_get_string(task);
#ifdef ENABLE_GETTEXT_SUPPORT
	char *domain = spl_clib_get_string(task);
#else
	spl_clib_get_string(task);
#endif
	int args_counter = spl_clib_get_argc(task);

	char *args[args_counter];
	int args_len[args_counter];

	for (int i=0; i<args_counter; i++) {
		args[i] = spl_clib_get_string(task);
		args_len[i] = strlen(args[i]);
	}

	char *translation;
	int retval_len = 0;

#ifdef ENABLE_GETTEXT_SUPPORT
	translation = dgettext(domain && *domain ? domain : 0, message);
#else
	translation = message;
#endif

	for (int i=0; translation[i]; i++)
	{
		if (translation[i] == '{' && translation[i+1] == '}')
			continue;

		if (translation[i] == '{')
		{
			int j = i+1;
			int arg = 0;

			for (; translation[j] != '}'; j++) {
				if (translation[j] < '0' || translation[j] > '9')
					goto skip_format_error_A;
				arg = arg*10 + (translation[j] - '0');
			}

			if (arg >= args_counter)
				goto skip_format_error_A;

			i = j;
			retval_len += args_len[arg];
			continue;
		}

skip_format_error_A:
		retval_len++;
	}

	char *retval = malloc(retval_len+1);
	char *retval_p = retval;

	for (int i=0; translation[i]; i++)
	{
		if (translation[i] == '{' && translation[i+1] == '}') {
			*(retval_p++) = '{'; i++;
			continue;
		}

		if (translation[i] == '{')
		{
			int j = i+1;
			int arg = 0;

			for (; translation[j] != '}'; j++) {
				if (translation[j] < '0' || translation[j] > '9')
					goto skip_format_error_B;
				arg = arg*10 + (translation[j] - '0');
			}

			if (arg >= args_counter)
				goto skip_format_error_B;

			i = j;
			memcpy(retval_p, args[arg], args_len[arg]);
			retval_p += args_len[arg];
			continue;
		}

skip_format_error_B:
		*(retval_p++) = translation[i];
	}

	*retval_p = 0;
	assert(retval_p == retval + retval_len);

	return SPL_NEW_STRING(retval);
}

#define MATH1(x) spl_clib_reg(vm, #x, spl_builtin_math1_wrapper, x)
struct spl_node *spl_builtin_math1_wrapper(struct spl_task *task, void UNUSED(*data))
{
	double (*mlib_func)(double) = data;
	double arg1 = spl_clib_get_float(task);
	return SPL_NEW_FLOAT(mlib_func(arg1));
}

#define MATH2(x) spl_clib_reg(vm, #x, spl_builtin_math2_wrapper, x)
struct spl_node *spl_builtin_math2_wrapper(struct spl_task *task, void UNUSED(*data))
{
	double (*mlib_func)(double, double) = data;
	double arg1 = spl_clib_get_float(task);
	double arg2 = spl_clib_get_float(task);
	return SPL_NEW_FLOAT(mlib_func(arg1, arg2));
}

// round() and rint() are C99 functions and not provided by C89 libs
static double my_round(double x)
{
	return x > 0 ? floor (x + 0.5) : ceil (x - 0.5);
}

void spl_builtin_register_all(struct spl_vm *vm)
{
	spl_clib_reg(vm, "write", spl_builtin_write, 0);
	spl_clib_reg(vm, "read", spl_builtin_read, 0);

	spl_clib_reg(vm, "chr", spl_builtin_chr, 0);
	spl_clib_reg(vm, "ord", spl_builtin_ord, 0);

	spl_clib_reg(vm, "hex", spl_builtin_hex, 0);
	spl_clib_reg(vm, "oct", spl_builtin_oct, 0);
	spl_clib_reg(vm, "bin", spl_builtin_bin, 0);
	spl_clib_reg(vm, "fmt", spl_builtin_fmt, 0);

	spl_clib_reg(vm, "rand", spl_builtin_rand, 0);
	spl_clib_reg(vm, "srand", spl_builtin_srand, 0);
	spl_clib_reg(vm, "declared_builtin", spl_builtin_declared_builtin, 0);

	spl_clib_reg(vm, "substring", spl_builtin_substring, 0);

	spl_clib_reg(vm, "setlocale", spl_builtin_setlocale, 0);
	spl_clib_reg(vm, "bindtextdomain", spl_builtin_bindtextdomain, 0);
	spl_clib_reg(vm, "textdomain", spl_builtin_textdomain, 0);
	spl_clib_reg(vm, "gettext", spl_builtin_gettext, 0);
	spl_clib_reg(vm, "dgettext", spl_builtin_dgettext, 0);
	spl_clib_reg(vm, "_", spl_builtin_underscore, 0);

	/**
	 * arc cosine function
	 */
	// builtin acos(x)
	MATH1(acos);

	/**
	 * arc sine function
	 */
	// builtin asin)
	MATH1(asin);

	/**
	 * arc tangent function
	 */
	// builtin atan(x)
	MATH1(atan);

	/**
	 * arc tangent function of two variables
	 */
	// builtin atan2(x, y)
	MATH2(atan2);

	/**
	 * cosine function
	 */
	// builtin cos(x)
	MATH1(cos);

	/**
	 * sine function
	 */
	// builtin sin(x)
	MATH1(sin);

	/**
	 * tangent function
	 */
	// builtin tan(x)
	MATH1(tan);

	/**
	 * square root function
	 */
	// builtin sqrt(x)
	MATH1(sqrt);

	/**
	 * round to nearest integer
	 */
	// builtin round(x)
	spl_clib_reg(vm, "round", spl_builtin_math1_wrapper, my_round);

	/**
	 * smallest integral value not less than argument
	 */
	// builtin ceil(x)
	MATH1(ceil);

	/**
	 * largest integral value not greater than argument
	 */
	// builtin floor(x)
	MATH1(floor);
}