/**********************************************************************
  Bond - Bond class derived from the base Primitive class

  Copyright (C) 2007 Donald Ephraim Curtis
  Copyright (C) 2008 Marcus D. Hanwell

  This file is part of the Avogadro molecular editor project.
  For more information, see <http://avogadro.openmolecules.net/>

  Avogadro is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  Avogadro is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  02110-1301, USA.
 **********************************************************************/

#ifndef BOND_H
#define BOND_H

#include <avogadro/primitive.h>

namespace OpenBabel {
  class OBBond;
}

namespace Avogadro {

  /**
   * @class Bond bond.h <avogadro/bond.h>
   * @brief Representation of a chemical bond.
   * @author Marcus D. Hanwell
   *
   * The Bond class is a Primitive subclass that provides a Bond object.
   */
  class Atom;
  class Molecule;
  class BondPrivate;
  class A_EXPORT Bond : public Primitive
  {
  Q_OBJECT

  public:
    /**
     * Constructor
     *
     * @param parent the object parent.
     */
    Bond(QObject *parent=0);

    ~Bond();

    /** @name Set bonding information
     * These functions are used to set bonding information.
     * @{
     */

    /**
     * Set the unique ID of the first atom in the bond.
     */
    void setBegin(Atom* atom);

    /**
     * Set the unique ID of the second atom in the bond.
     */
    void setEnd(Atom* atom);

    /**
     * Set the unique ID of both atoms in the bond
     * @param atom1 First atom in the bond.
     * @param atom2 Second atom in the bond.
     * @param order Bond order (defaults to 1).
     */
    void setAtoms(unsigned long atom1, unsigned long atom2,
                  short order = 1);

    /**
     * Set the order of the bond.
     */
    void setOrder(short order) { m_order = order; }

    /**
     * Set the aromaticity of the bond.
     */
    void setAromaticity(bool isAromatic) const;
    /** @} */

    /** @name Get bonding information
     * These functions are used to get bonding information.
     * @{
     */

    /**
     * @return the unique ID of the first atom in the bond.
     */
    unsigned long beginAtomId() const { return m_beginAtomId; }

    /**
     * @return Pointer to the first atom in the bond.
     */
    Atom * beginAtom() const;

    /**
     * @return the unique ID of the second atom in the bond.
     */
    unsigned long endAtomId() const { return m_endAtomId; }

    /**
     * @return Pointer to the second atom in the bond.
     */
    Atom * endAtom() const;

    /**
     * @return The position of the start of the Bond.
     */
    const Eigen::Vector3d * beginPos() const;

    /**
     * @return The position of the mid-point of the Bond.
     */
    const Eigen::Vector3d * midPos() const;

    /**
     * @return The position of the end of the Bond.
     */
    const Eigen::Vector3d * endPos() const;

    /**
     * Get the unique id of the other atom in the bond.
     * @param atomId The unique id of the Atom.
     * @return The unique if of the other Atom in the bond.
     * @note This function does not perform checks to ensure the supplied
     * Atom is actually in the bond.
     */
    unsigned long otherAtom(unsigned long atomId) const;

    /**
     * @return the order of the bond - 1 = single, 2 = double etc.
     */
    short order() const { return m_order; }

    /**
     * @return True if the bond is aromatic.
     */
    bool isAromatic() const;

    /**
     * @return the length of the bond.
     */
    double length() const;
    /** @} */

    /** @name OpenBabel conversion functions
     * These functions are used convert between Avogadro and OpenBabel bonds.
     * @{
     */

    /**
     * Copy the data from an OpenBabel::OBBond to create a similar bond.
     */
    bool setOBBond(OpenBabel::OBBond *obbond);
    /** @} */

    /** @name Operators
     * Overloaded operators.
     * @{
     */
    Bond& operator=(const Bond& other);
    /** @} */

    friend class Molecule;

  private:
    unsigned long m_beginAtomId, m_endAtomId;
    short m_order;
    mutable bool m_isAromatic;
    mutable Eigen::Vector3d m_midPos;
    Molecule *m_molecule;
    /* shared d_ptr with Primitive */
    Q_DECLARE_PRIVATE(Bond)
  };

} // End namespace Avogadro

#endif