#ifndef __JGRIDBOUNDS__
#define __JGRIDBOUNDS__

#include "JLang/JException.hh"
#include "JTools/JMultiKey.hh"


namespace JTOOLS {


  namespace {
    using JLANG::JValueOutOfRange;
  }


  /**
   * Abstract interface to specify boundary conditions of an equidistant collection of elements.
   * This abstract class provides for the methods getPosition() and getKey().
   * Note that the method getKey() returns the lower (upper) limit for argument values 
   * (0) and (number of keys - 1), respectively.
   */
  template<class JKey_t>
  class JAbstractGridBounds {
  public:    
    /**
     * Virtual destructor.
     */
    virtual ~JAbstractGridBounds()
    {}
    
    
    /**
     * Get number of keys.
     *
     * \return            number of keys
     */
    virtual unsigned int getNumberOfKeys() const = 0;
    

    /**
     * Get lower limit.
     *
     * \return            lower key
     */
    virtual JKey_t getLowerKey() const = 0;


    /**
     * Get upper limit.
     *
     * \return            upper key
     */
    virtual JKey_t getUpperKey() const = 0;
    
     
    /**
     * Get bin position (starting at 0).
     * The bin position could be less than zero or larger than the number of keys.
     *
     * \param  x          key 
     * \return            index
     */
    virtual int getPosition(const JKey_t x) const
    {
      return (int) ((getNumberOfKeys() - 1) * (x - getLowerKey()) / (getUpperKey() - getLowerKey()));
    }
    
     
    /**
     * Get index of bin (starting at 0).
     * The index is larger or equal zero and less than the number of keys.
     *
     * \param  x          key 
     * \return            index
     */
    virtual int getIndex(const JKey_t x) const
    {
      const int min = 0;
      const int max = getNumberOfKeys() - 1;
      const int pos = getPosition(x);

      if (pos < min) return min;
      if (pos > max) return max;

      return pos;
    }


    /**
     * Get lower edge of bin.
     *
     * \param  index      index of bin
     * \return            key
     */
    virtual JKey_t getKey(const int index) const 
    { 
      return getLowerKey()  +  index * ((getUpperKey() - getLowerKey()) / (getNumberOfKeys() - 1));
    }


    /**
     * Get bin width.
     *
     * \return            bin width
     */
    virtual JKey_t getBinWidth() const 
    { 
      return (getUpperKey() - getLowerKey()) / (getNumberOfKeys() - 1);
    }
  };

  
  /**
   * Data structure that implements the JAbstractGridBounds<> interface.
   */
  template<class JKey_t>
  class JGridBounds : public JAbstractGridBounds<JKey_t> {
  public:
    /**
     * Default constructor.
     */
    JGridBounds() :
      JAbstractGridBounds<JKey_t>(),
      number_of_keys(0),
      lower_key(),
      upper_key()
    {}


    /**
     * Constructor.
     *
     * \param  bounds         (abstract) grid bounds
     */
    JGridBounds(const JAbstractGridBounds<JKey_t>& bounds) :
      JAbstractGridBounds<JKey_t>(),
      number_of_keys(bounds.getNumberOfKeys()),
      lower_key     (bounds.getLowerKey()),
      upper_key     (bounds.getUpperKey())
    {}


    /**
     * Constructor.
     *
     * \param  numberOfKeys   number of keys
     * \param  lowerKey       lower key
     * \param  upperKey       upper key
     */
    JGridBounds(const unsigned int numberOfKeys,
		const JKey_t       lowerKey,
		const JKey_t       upperKey) :
      JAbstractGridBounds<JKey_t>(),
      number_of_keys(numberOfKeys),
      lower_key(lowerKey),
      upper_key(upperKey)
    {
      if (number_of_keys == 1)
	throw JValueOutOfRange("JGridBounds()");
      if (lower_key == upper_key)
	throw JValueOutOfRange("JGridBounds()");
    }


    virtual unsigned int getNumberOfKeys() const { return number_of_keys; }

    virtual JKey_t getLowerKey() const { return lower_key; }
    virtual JKey_t getUpperKey() const { return upper_key; }
    
  protected:
    unsigned int number_of_keys;
    JKey_t lower_key;
    JKey_t upper_key;
  };


  /**
   * Abstract interface for configuring of multi-dimensional grid.
   */
  template<unsigned int N, class JKey_t>
  class JAbstractMultiGridBounds {
  public:
    /**
     * Virtual destructor.
     */
    virtual ~JAbstractMultiGridBounds()
    {}


    /**
     * Evaluate grid bounds as a function of composite key.
     * 
     * \param  key           composite key
     * \return               grid bounds
     */
    virtual JGridBounds<JKey_t> operator()(const JMultiKey<N, JKey_t>& key) const = 0;
  };


  /**
   * Template specialisation of abstract interface for configuring of upper- of multi-dimensional grid.
   */
  template<class JKey_t>
  class JAbstractMultiGridBounds<0, JKey_t> 
  {
  public:
    /**
     * Virtual destructor.
     */
    virtual ~JAbstractMultiGridBounds()
    {}


    /**
     * Evaluate grid bounds.
     * 
     * \return               grid bounds
     */
    virtual JGridBounds<JKey_t> operator()() const = 0;
  };


  /**
   * Data structure that implements the JAbstractMultiGridBounds<> interface.
   */
  template<unsigned int N, class JKey_t>
  class JMultiGridBounds :
    public JAbstractMultiGridBounds<N, JKey_t> 
  {
  public:
    /**
     * Constructor.
     *
     * \param  numberOfKeys   number of keys
     * \param  lowerKey       lower key
     * \param  upperKey       upper key
     */
    JMultiGridBounds(const unsigned int& numberOfKeys,
		     const JKey_t&       lowerKey,
		     const JKey_t&       upperKey) :
      bounds(numberOfKeys, lowerKey, upperKey)
    {}
    

    /**
     * Evaluate grid bounds as a function of composite key.
     * 
     * \param  key           composite key
     * \return               grid bounds
     */
    JGridBounds<JKey_t> operator()(const JMultiKey<N, JKey_t>& key) const 
    {
      return bounds;
    }

  protected:
    JGridBounds<JKey_t> bounds;
  };


  /**
   * Data structure that implements the JAbstractMultiGridBounds<> interface.
   */
  template<class JKey_t>
  class JMultiGridBounds<0, JKey_t> :
    public JAbstractMultiGridBounds<0, JKey_t>
  {
  public:
    /**
     * Constructor.
     *
     * \param  numberOfKeys   number of keys
     * \param  lowerKey       lower key
     * \param  upperKey       upper key
     */
    JMultiGridBounds(const unsigned int& numberOfKeys,
		     const JKey_t&       lowerKey,
		     const JKey_t&       upperKey) :
      bounds(numberOfKeys, lowerKey, upperKey)
    {}
    

    /**
     * Evaluate grid bounds.
     * 
     * \return               grid bounds
     */
    JGridBounds<JKey_t> operator()() const 
    {
      return bounds;
    }

  protected:
    JGridBounds<JKey_t> bounds;
  };


  /**
   * Helper method for JGridBounds.
   *
   * \param  number_of_keys number of keys
   * \param  lower_key      lower key
   * \param  upper_key      upper key
   * \return                JGridBounds<>
   */
  template<class JKey_t>
  inline JGridBounds<JKey_t> make_grid_bounds(const unsigned int& number_of_keys,
					      const JKey_t&       lower_key,
					      const JKey_t&       upper_key)
  {
    return JGridBounds<JKey_t>(number_of_keys, lower_key, upper_key);
  }


  /**
   * Helper method for JMultiGridBounds.
   *
   * \param  number_of_keys number of keys
   * \param  lower_key      lower key
   * \param  upper_key      upper key
   * \return                JMultiGridBounds<>
   */
  template<unsigned int N, class JKey_t>
  inline JMultiGridBounds<N, JKey_t> make_multigrid_bounds(const unsigned int& number_of_keys,
							   const JKey_t&       lower_key,
							   const JKey_t&       upper_key)
  {
    return JMultiGridBounds<N, JKey_t>(number_of_keys, lower_key, upper_key);
  }
}

#endif