/**
 * Copyright (c) 2013, James Nutaro
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met: 
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation are those
 * of the authors and should not be interpreted as representing official policies, 
 * either expressed or implied, of the FreeBSD Project.
 *
 * Bugs, comments, and questions can be sent to nutaro@gmail.com
 */
#ifndef __adevs_rand_h_
#define __adevs_rand_h_
#include "adevs.h"
#include <cstdlib>

namespace adevs
{

/**
 * The random_seq class is an abstract interface to a random sequence
 * generator.
 */
class random_seq 
{
	public:
		/// Set the seed for the random number generator
		virtual void set_seed(unsigned long seed) = 0;
		/// Get the next double uniformly distributed in [0, 1]
		virtual double next_dbl() = 0;
		/// Copy the random number generator
		virtual random_seq* copy() const = 0;
		/// Get the next unsigned long
		virtual unsigned long next_long() = 0;
		/// Destructor
		virtual ~random_seq(){}
};

/**
 * The crand class provides random number sequences using the standard
 * C rand_r() function. Each instance of crand generates its own random
 * number sequence, and the clone method saves the state of the random
 * number generator. This class can be used in parallel simulations. 
 */
class crand: public random_seq 
{
	public:
		/// Create a generator with the default seed
		crand():seedp(0){}
		/// Copy constructor
		crand(const crand& src):seedp(src.seedp){}
		/// Create a generator with the given seed
		crand(unsigned long seed):seedp((unsigned int)seed){}
		/// Set the seed for the random number generator
		void set_seed(unsigned long seed) { seedp = (unsigned int)seed; }
		/// Get the next double uniformly distributed in [0, 1]
		double next_dbl()
		{
			#ifdef _WIN32
			return ((double)next_long()/(double)UINT_MAX);
			#else
			return ((double)next_long()/(double)RAND_MAX);
			#endif
		}
		/// Get the next unsigned long
		unsigned long next_long();
		/// Copy the random number generator
		random_seq* copy() const { return new crand(*this); }
		/// Destructor
		~crand(){}
	private:
		unsigned int seedp;
};

/**
 * <p>The rv class provides a random variable based on a selectable
 * implementation.  By default, this implementation is crand.
 * I recommend that you find a modern random variate generator,
 * such as the ones included in the new C++ standards,
 * rather than use the one here.</p>
 * <p>The assortment of random variable types was contributed by
 * Alex Cave (who, at the time, was with the Intelligent 
 * Systems Automation Group in the School of Engineering at
 * Deakin University).</p>
 */
class rv 
{
	public:
		/// Create a random variable with the default implementation.
		rv (unsigned long seed = 1);
		/**
		 * Create a random variable with the desired implementation.  The
		 * implementation class is adopted by the rv.
		 */
		rv(random_seq* rand);
		/// Copy constructor relies on copy method of underlying stream.
		rv(const rv& src);
		/// Assignment operator relies on copy method of underlying stream.
		const rv& operator=(const rv& src);
		/// See the random number generator implementation
		void set_seed(unsigned long seed);
		/// Get a raw value from the underlying random number generator
		unsigned long next_long();
		/// Sample a triangular distribution with minimum a, maximum b,
		/// and mode c.
		double triangular(double a, double b, double c);
		/// Sample a uniform distribution in the range [a, b]
		double uniform(double a, double b);
		/**
		 * Sample a normally distributed random variable with mean m and 
		 * standard deviation s.
		 */
		double normal(double m, double s);
		/**
		 * return a negative exponentially distributed random number with
		 * the mean as parameter
		 */
		double exponential(double a);
		/**
		 * return a hyperexponentially distributed random number with
		 * the means as parameters to two exponentially distributed variates,
		 * the first with a chance of p of being generated, the second with a
		 * chance of 1-p.
		 */
		double hyperexponential(double p,double a,double b);
		/// Return a laplace number with the given parameter
		double laplace(double a);
		/// Sample a chisquare random variable with n degrees of freedom
		double chisquare(unsigned int n);
		/// Sample a student-t random variable
		double student(unsigned int n);
		/// Sample a lognormal random variable
		double lognormal(double a,double b);
		/// Sample an erlang distribution
		double erlang(unsigned int n,double a);
		/// Sample a gamma random variable
		double gamma(double a,double b);
		/// Sample a beta random variable
		double beta(double a,double b);
		/// Sample a F-distributed random variable
		double fdistribution(unsigned int n,unsigned int m);
		/// Sample a Poisson random variable
		double poisson(double a);
		/// Sample a geometric random variable with event probability p
		double geometric(double p);
		/**
		 * return a variate from the hypergeometric distribution with m the
		 * population, p the chance on success and n the number of items drawn
		 */
		double hypergeometric(unsigned int m,unsigned int n,double p);
		/// Sample a weibull random variable
		double weibull(double a,double b);
		/**
		 *  An event count for a binomial distribution with event
		 *  probability p and n the number of trials
		 */ 
		double binomial(double p,unsigned int n);
		/**
		 * return a random variable with probabilty of success equal to p
		 * and n as the number of successes
		 */
		double negativebinomial(double p,unsigned int n);
		/// Sample a triangular random variable
		double triangular(double a);
		/// return TRUE with probability p and FALSE with probability 1-p
		bool probability(double p);
		/// Sample a lognormal gamma random variable
		double lngamma(double xx);
		/// Destructor
		~rv();
	private:	
		random_seq* _impl;
		typedef enum 
		{
			NDURATION,
			NCOUNT,
			EMPTY,
			NDELAY,
			ADDTOQ,
			EMPTYQ,
			HNCLMS,
			HMODE,
			PROBVAL,
			ERRUNIFORM,
			ERRNORMAL,
			ERRLOGNORM,
			ERRTRIANG,
			ERRGAMMA,
			ERRBETA,
			ERREXPONENT,
			ERRERLANG,
			ERRHYPGEO,
			NULLEV,
			NOHISTO,
			INITERR,
			AMODE,
			HFORM,
			ERRFILE,
			SAMPLE,
			FRACTION,
			LEVEL,
			SCAN,
			SUPPRESS,
			SEED
		} errorType;

		void err(errorType n);
};

} // end of namespace

#endif