// RandomGenerator.h

#ifndef RandomGenerator_H
#define RandomGenerator_H

// A generator produces objects with random parameters.
//
// This class is abstract and contains the interface for
// the random number generator.  Each instance will maintain
// its own sequence of random numbers.
//
// We use the default CLHEP random number generator.
//
// The calls to rand are encapsulated so that we can keep count of
// the number of calls to reproduce the state.

#include <iosfwd>
#include <CLHEP/Random/RanluxEngine.h>

class RandomGenerator {

private:  // attributes

  // Random number generator.
  RanluxEngine _rand;

  // Number of calls since seed was set.
  int _ncall;

private:  // methods

  // Hide assignment operator.
  RandomGenerator& operator=(const RandomGenerator& rhs);

  // Set the state = seed and number of calls.
  void set_state(long seed, int ncall);

protected:

  // Return a flat value in range (min.max).
  double flat(double min, double max);

  // Return according to Gaussian distribution with sigma = 1.0.
  double gauss();

  // Output stream.
  virtual void ostr(std::ostream& stream) const;

  // Raw output stream.
  // Does not include begin and end object delimiters.
  virtual void raw_ostr(std::ostream& stream) const;

public:

  // Default constructor.
  RandomGenerator();

  // Constructor from seed.
  RandomGenerator(long seed);

  // Copy constructor.
  // The new generator is independent from the original and is in the
  // same state.
  RandomGenerator(const RandomGenerator& rhs);

  // Destructor.
  virtual ~RandomGenerator();

  // Set the seed.
  // Generator is positioned at the beginning of the sequence.
  void set_seed(long seed);

  // Set the state (seed + ncall) to be the same as that of the argument.
  void set_state(const RandomGenerator& gen);

  // output stream
  friend std::ostream&
  operator<<(std::ostream& stream, const RandomGenerator& rgen);

};

#endif