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/****************************************************************************
Copyright 2006, Colorado School of Mines and others.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
****************************************************************************/
package edu.mines.jtk.sgl;

import static java.lang.Math.max;
import static java.lang.Math.min;

import edu.mines.jtk.dsp.Sampling;

/**
 * A constraint for objects that must lie inside an axis-aligned box.
 * @author Dave Hale, Colorado School of Mines
 * @version 2006.05.25
 */
public class BoxConstraint {

  /**
   * Constructs a box constraint with specified bounding box.
   * Constrains objects to lie inside the bounding box.
   * @param box bounding box.
   */
  public BoxConstraint(BoundingBox box) {
    this(box.getMin(),box.getMax(),0.0,0.0,0.0);
  }

  /**
   * Constructs a box constraint with specified bounding box and min sizes.
   * Constrains objects to lie inside the bounding box.
   * @param box bounding box.
   * @param dxmin minimum size in x dimension.
   * @param dymin minimum size in y dimension.
   * @param dzmin minimum size in z dimension.
   */
  public BoxConstraint(BoundingBox box,
    double dxmin, double dymin, double dzmin) 
  {
    this(box.getMin(),box.getMax(),dxmin,dymin,dzmin);
  }

  /**
   * Constructs a box constraint with specified corner points.
   * Constrains objects to lie inside a box defined by the corner points.
   * @param p a corner point.
   * @param q a corner point.
   */
  public BoxConstraint(Point3 p, Point3 q) {
    this(p,q,0.0,0.0,0.0);
  }

  /**
   * Constructs a box constraint with specified corner points and min sizes.
   * Constrains objects to lie inside a box defined by the corner points.
   * @param p a corner point.
   * @param q a corner point.
   * @param dxmin minimum size in x dimension.
   * @param dymin minimum size in y dimension.
   * @param dzmin minimum size in z dimension.
   */
  public BoxConstraint(Point3 p, Point3 q,
    double dxmin, double dymin, double dzmin) 
  {
    _xmin = min(p.x,q.x);
    _ymin = min(p.y,q.y);
    _zmin = min(p.z,q.z);
    _xmax = max(p.x,q.x);
    _ymax = max(p.y,q.y);
    _zmax = max(p.z,q.z);
    _dxmin = dxmin;
    _dymin = dymin;
    _dzmin = dzmin;
    _sampled = false;
  }

  /**
   * Constructs a box constraint with specified samplings.
   * Constrains objects vertices to lie on the sampling grid.
   * @param sx sampling of x coordinate
   * @param sy sampling of y coordinate
   * @param sz sampling of z coordinate
   */
  public BoxConstraint(Sampling sx, Sampling sy, Sampling sz) {
    this(sx,sy,sz,0.0,0.0,0.0);
  }

  /**
   * Constructs a box constraint with specified samplings and min sizes.
   * Constrains object vertices to lie on the sampling grid.
   * @param sx sampling of x coordinate
   * @param sy sampling of y coordinate
   * @param sz sampling of z coordinate
   * @param dxmin minimum size in x dimension.
   * @param dymin minimum size in y dimension.
   * @param dzmin minimum size in z dimension.
   */
  public BoxConstraint(
    Sampling sx, Sampling sy, Sampling sz,
    double dxmin, double dymin, double dzmin) 
  {
    _xmin = sx.getFirst();
    _ymin = sy.getFirst();
    _zmin = sz.getFirst();
    _xmax = sx.getLast();
    _ymax = sy.getLast();
    _zmax = sz.getLast();
    _dxmin = dxmin;
    _dymin = dymin;
    _dzmin = dzmin;
    _sx = sx;
    _sy = sy;
    _sz = sz;
    _sampled = true;
  }

  /**
   * Gets the bounding box for this constraint.
   * @return the bounding box.
   */
  public BoundingBox getBoundingBox() {
    return new BoundingBox(_xmin,_ymin,_zmin,_xmax,_ymax,_zmax);
  }

  /**
   * Gets the bounding sphere for this constraint.
   * @return the bounding sphere.
   */
  public BoundingSphere getBoundingSphere() {
    BoundingSphere bs = new BoundingSphere();
    bs.expandBy(getBoundingBox());
    return bs;
  }

  /**
   * Determines whether this box constraint contains the specified point.
   * @param p the point
   * @return true, if this box contains the point; false, otherwise.
   */
  public boolean containsPoint(Point3 p) {
    return _xmin<=p.x && p.x<=_xmax &&
           _ymin<=p.y && p.y<=_ymax &&
           _zmin<=p.z && p.z<=_zmax;
  }

  /**
   * Constrains a specified point.
   * @param p the point.
   */
  public void constrainPoint(Point3 p) {
    p.x = max(_xmin,min(_xmax,p.x));
    p.y = max(_ymin,min(_ymax,p.y));
    p.z = max(_zmin,min(_zmax,p.z));
    if (_sampled) {
      p.x = _sx.valueOfNearest(p.x);
      p.y = _sy.valueOfNearest(p.y);
      p.z = _sz.valueOfNearest(p.z);
    }
  }

  /**
   * Constrains a box defined by two specified corner points. If necessary, 
   * modifies either or both of the points to satisfy this constraint.
   * @param p a corner point
   * @param q a corner point
   */
  public void constrainBox(Point3 p, Point3 q) {
    double ax = min(p.x,q.x);
    double bx = max(p.x,q.x);
    double dx = max(bx-ax,_dxmin);
    if (p.x<=q.x) {
      ax = max(_xmin,min(_xmax,ax));
      bx = min(_xmax,ax+dx);
      ax = max(_xmin,bx-dx);
    } else {
      bx = min(_xmax,max(_xmin,bx));
      ax = max(_xmin,bx-dx);
      bx = min(_xmax,ax+dx);
    }
    if (_sampled) {
      ax = _sx.valueOfNearest(ax);
      bx = _sx.valueOfNearest(bx);
    }
    if (p.x<=q.x) {
      p.x = ax;
      q.x = bx;
    } else {
      p.x = bx;
      q.x = ax;
    }
    double ay = min(p.y,q.y);
    double by = max(p.y,q.y);
    double dy = max(by-ay,_dymin);
    if (p.y<=q.y) {
      ay = max(_ymin,min(_ymax,ay));
      by = min(_ymax,ay+dy);
      ay = max(_ymin,by-dy);
    } else {
      by = min(_ymax,max(_ymin,by));
      ay = max(_ymin,by-dy);
      by = min(_ymax,ay+dy);
    }
    if (_sampled) {
      ay = _sy.valueOfNearest(ay);
      by = _sy.valueOfNearest(by);
    }
    if (p.y<=q.y) {
      p.y = ay;
      q.y = by;
    } else {
      p.y = by;
      q.y = ay;
    }
    double az = min(p.z,q.z);
    double bz = max(p.z,q.z);
    double dz = max(bz-az,_dzmin);
    if (p.z<=q.z) {
      az = max(_zmin,min(_zmax,az));
      bz = min(_zmax,az+dz);
      az = max(_zmin,bz-dz);
    } else {
      bz = min(_zmax,max(_zmin,bz));
      az = max(_zmin,bz-dz);
      bz = min(_zmax,az+dz);
    }
    if (_sampled) {
      az = _sz.valueOfNearest(az);
      bz = _sz.valueOfNearest(bz);
    }
    if (p.z<=q.z) {
      p.z = az;
      q.z = bz;
    } else {
      p.z = bz;
      q.z = az;
    }
  }

  private double _xmin,_ymin,_zmin;
  private double _xmax,_ymax,_zmax;
  private double _dxmin,_dymin,_dzmin;
  private Sampling _sx,_sy,_sz;
  private boolean _sampled;
}