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/** @file
	Parser: @b math parser class.

	Copyright(c) 2001, 2003 ArtLebedev Group(http://www.artlebedev.com)
	Author: Alexandr Petrosian <paf@design.ru>(http://paf.design.ru)
*/

static const char* IDENT_MATH_C="$Date: 2003/01/21 15:51:07 $";

#include "pa_common.h"
#include "pa_vint.h"
#include "pa_vmath.h"
#include "pa_request.h"
#include "pa_md5.h"

#ifdef WIN32
// for threadID
#	include <windows.h>
#endif

#ifdef HAVE_CRYPT_H
#include <crypt.h>
#endif

// defines

#define PI 3.1415926535
#define MAX_SALT 8

// class

class MMath : public Methoded {
public:
	MMath(Pool& pool);
	void configure_admin(Request& r);

public: // Methoded
	bool used_directly() { return false; }
};

// methods
static unsigned int randomizer=0;
static inline int _random(uint top) {
	return (int)(((double)((randomizer=rand())% RAND_MAX)) / RAND_MAX * top );
}
static void _random(Request& r, const String& method_name, MethodParams *params) {
	Pool& pool=r.pool();

	Value& range=params->as_junction(0, "range must be expression");
    double top=r.process_to_value(range).as_double();
    if(top<=1)
		throw Exception("parser.runtime",
			&method_name,
			"top must be above 1(%g)", top);
	
	r.write_no_lang(*new(pool) VInt(pool, _random(uint(top))));
}


typedef double(*math1_func_ptr)(double);
static double frac(double param) { return param-trunc(param); }
static double degrees(double param) { return param /PI *180; }
static double radians(double param) { return param /180 *PI; }

static void math1(Request& r, 
				  const String& method_name, MethodParams *params,
				  math1_func_ptr func) {
	Pool& pool=r.pool();
	Value& param=params->as_junction(0, "parameter must be expression");

	double result=(*func)(r.process_to_value(param).as_double());
	r.write_no_lang(*new(pool) VDouble(pool, result));
}

#define MATH1(name) \
	static void _##name(Request& r, const String& method_name, MethodParams *params) {\
		math1(r, method_name, params, &name);\
	}
#define MATH1P(name_parser, name_c) \
	static void _##name_parser(Request& r, const String& method_name, MethodParams *params) {\
		math1(r, method_name, params, &name_c);\
	}
MATH1(round);	MATH1(floor);	MATH1P(ceiling, ceil);
MATH1(trunc);	MATH1(frac);
MATH1P(abs, fabs);	MATH1(sign);
MATH1(exp);	MATH1(log);	
MATH1(sin);	MATH1(asin);	
MATH1(cos);	MATH1(acos);	
MATH1(tan);	MATH1(atan);
MATH1(degrees);	MATH1(radians);
MATH1(sqrt);


typedef double (*math2_func_ptr)(double, double);
static void math2(Request& r, 
				  const String& method_name, MethodParams *params,
				  math2_func_ptr func) {
	Pool& pool=r.pool();
	Value& a=params->as_junction(0, "parameter must be expression");
	Value& b=params->as_junction(1, "parameter must be expression");

	double result=(*func)(
		r.process_to_value(a).as_double(),
		r.process_to_value(b).as_double());
	r.write_no_lang(*new(pool) VDouble(pool, result));
}

#define MATH2(name) \
	static void _##name(Request& r, const String& method_name, MethodParams *params) {\
		math2(r, method_name, params, &name);\
	}
MATH2(pow);

inline bool is_salt_body_char(int c) {
	return isalnum(c) || c == '.' || c=='/';
}
static size_t calc_prefix_size(const char *salt) {
	if(size_t salt_size=strlen(salt)) {
		if(!is_salt_body_char(salt[0])) { // $...  {...
			const char *cur=salt+1; // skip
			while(is_salt_body_char(*cur++)) // ...$  ...}
				;
			return cur-salt;
		} else
			return 0;
	} else
		return 0;
}
static void _crypt(Request& r, const String& method_name, MethodParams *params) {
	Pool& pool=r.pool();
	const char *password=params->as_string(0, "password must be string").cstr();
	const char *maybe_bodyless_salt=params->as_string(1, "salt must be string").cstr();

	size_t prefix_size=calc_prefix_size(maybe_bodyless_salt);
	const char *normal_salt;
	char normalize_buf[MAX_STRING];
	if(prefix_size==strlen(maybe_bodyless_salt)) { // bodyless?
		strncpy(normalize_buf, maybe_bodyless_salt, MAX_STRING-MAX_SALT-1);
		char *cur=normalize_buf+strlen(normalize_buf);
		// sould add up MAX_SALT random chars
		static unsigned char itoa64[] =         /* 0 ... 63 => ASCII - 64 */
		"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
		for(int i=0; i<MAX_SALT; i++)
			*cur++=itoa64[_random(64)];
		*cur=0;
		normal_salt=normalize_buf;
	} else
		normal_salt=maybe_bodyless_salt;

    /* FreeBSD style MD5 string 
     */
    if(strncmp(normal_salt, PA_MD5PW_ID, PA_MD5PW_IDLEN) == 0) {
		const size_t sample_size=120;
		char *sample_buf=(char *)pool.malloc(sample_size);
		pa_MD5Encode((const unsigned char *)password,
				(const unsigned char *)normal_salt, sample_buf, sample_size);
		r.write_pass_lang(*new(pool) String(pool, sample_buf));
    } else {
#ifdef HAVE_CRYPT
		const char *sample_buf=crypt(password, normal_salt);
		if(!sample_buf  // nothing generated
			|| !sample_buf[0] // generated nothing
			|| strncmp(sample_buf, normal_salt, prefix_size)!=0) // salt prefix not preserved
			throw Exception("parser.runtime",
				&method_name,
				"on this platform does not support '%.*s' salt prefix", prefix_size, normal_salt);
		
		r.write_pass_lang(*new(pool) String(pool, sample_buf));
#else
		throw Exception("parser.runtime",
			&method_name,
			"salt must start with '" PA_MD5PW_ID "'");
#endif
	}
}

// constructor

MMath::MMath(Pool& apool) : Methoded(apool, "math") {
	// ^FUNC(expr)	
#define ADD1(name) \
	add_native_method(#name, Method::CT_STATIC, _##name, 1, 1)

	ADD1(round);	ADD1(floor);	ADD1(ceiling);
	ADD1(trunc);	ADD1(frac);
	ADD1(abs);	ADD1(sign);
	ADD1(exp);	ADD1(log);	
	ADD1(sin);	ADD1(asin);	
	ADD1(cos);	ADD1(acos);	
	ADD1(tan);	ADD1(atan);
	ADD1(degrees);	ADD1(radians);
	ADD1(sqrt);
	ADD1(random);

#define ADD2(name) \
	add_native_method(#name, Method::CT_STATIC, _##name, 2, 2)

	// ^pow(x;y)
	ADD2(pow);

	// ^crypt[password;salt]
	ADD2(crypt);
}

// in MSVC each thread has it's own pseudo-random sequence
// in win32 apache each thread can handle multiple requests
// so to get proper randoms we remember random generated in one thread
void MMath::configure_admin(Request&) {
	// setting seed
	srand(
		randomizer
#ifdef WIN32
		^ GetCurrentThreadId()
#else
		^ getpid()
#endif
		^(unsigned int)time(NULL)
	);
	if(!randomizer)
		randomizer=rand();
}

// global variables

Methoded *math_base_class;
Hash *math_consts;

// creator

Methoded *MMath_create(Pool& pool) {
	math_consts=new(pool) Hash(pool);
	math_consts->put(
		*new(pool) String(pool, "PI"), 
		new(pool) VDouble(pool, PI));

	return math_base_class=new(pool) MMath(pool);
}