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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: 2003/02/17 07:18:57 $";

#include "pa_vmethod_frame.h"

#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 MAX_SALT 8

// class

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

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

// global variables

MethodedPtr math_class(0); // fictive
MethodedPtr math_base_class(new MMath);

// 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, StringPtr method_name, MethodParams& params) {
	Pool& pool=r.pool();

	ValuePtr 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(ValuePtr(new VInt(_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, 
				  StringPtr method_name, MethodParams& params,
				  math1_func_ptr func) {
	ValuePtr param=params.as_junction(0, "parameter must be expression");

	double result=func(r.process_to_value(param)->as_double());
	r.write_no_lang(ValuePtr(new VDouble(result)));
}

#define MATH1(name) \
	static void _##name(Request& r, StringPtr method_name, MethodParams& params) {\
		math1(r, method_name, params, &name);\
	}
#define MATH1P(name_parser, name_c) \
	static void _##name_parser(Request& r, StringPtr 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, 
				  StringPtr method_name, MethodParams& params,
				  math2_func_ptr func) {
	ValuePtr a=params.as_junction(0, "parameter must be expression");
	ValuePtr 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(ValuePtr(new VDouble(result)));
}

#define MATH2(name) \
	static void _##name(Request& r, StringPtr 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, StringPtr method_name, MethodParams& params) {
	Pool& pool=r.pool();
	CharPtr password=params.as_string(0, "password must be string")->cstr();
	CharPtr 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=new(pool) char[sample_size];
		pa_MD5Encode((const unsigned char *)password.get(),
				(const unsigned char *)normal_salt, sample_buf, sample_size);
		String sample(sample_buf);
		r.write_pass_lang(sample);
    } else {
#ifdef HAVE_CRYPT
		const char* static_sample_buf=crypt(password, normal_salt);
		if(!static_sample_buf  // nothing generated
			|| !static_sample_buf[0] // generated nothing
			|| strncmp(static_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(StringPtr(new String(pool.copy(static_sample_buf))));
#else
		throw Exception("parser.runtime",
			method_name,
			"salt must start with '" PA_MD5PW_ID "'");
#endif
	}
}

// constructor

MMath::MMath(): Methoded("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();
}