/* Copyright 2000 Charles G. Wright
 * This software may be distributed under the terms of the
 * GNU General Public License.
 *
 * $Id: SOLorientation.java,v 1.1 2000-06-15 10:15:02-05 chuckles Exp chuckles $
 */

import java.math.*;
import java.util.*;

/** <p>This class represents the orientation of a surface exposed to
 * sunlight. Its class variables define the surface's position on Earth
 * (a SOLlocation object) and orientation. Its methods calculate
 * the angle of incidence of sunlight falling on it.
 * <p>Multiple surfaces with this orientation can be defined by
 * SOLsurface objects. All of these are contained in the "surfaces"
 * linked list attached to this SOLorientation object.
 * <p>The defining parameters of this object can be set using the
 * SOLorientationControl object, which provides a graphical interface.
 */

public class SOLorientation{

  /** The SOLlocation object that defines the location of this orientation.*/
  public SOLlocation location;

  // surface
  /** Azimuth of the surface, in degrees, measured from true south
   * (East is negative, West is positive). */
  public double surface_azimuth;
  /** Tilt angle of the surface, in degrees. Vertical surface is 90. */ 
  public double surface_tilt;
  /** Name of the orientation. For user interface purposes only. */
  public String name;
  /** Linked List of surfaces with this orientation. */
  public Vector surfaces;

  //--------------------  Constructors  -----------------------------
  /** <p>Create an SOLorientation object, which represents the orientation of 
   * a surface exposed to sunlight. The parameters defining the orientation
   * are:
   * <ul>
   * <li> a SOLlocation object, specifying the surface's location on Earth,
   * <li> surface azimuth(in degrees) -  measured from South, with Eastward deviation negative
   * and Westward deviation positive,
   * <li> and its surface tilt from the horizontal (in degrees).</ul>
  */

  public SOLorientation(SOLlocation location, double surface_azimuth, double surface_tilt, String name){
    this.location = location;
    //    location.orientations.add(this);
    this.surface_azimuth = surface_azimuth;
    this.surface_tilt = surface_tilt;
    this.name = name;
    surfaces = new Vector();
    //    System.out.println("[SOLorientation]: latitude = " + latitude + " longitude = " + longitude +
    //		       " time zone = " + time_zone + " surface_azimuth = " + surface_azimuth +
    //	       " surface_tilt = " + surface_tilt);
  }

  /** <p>Create an SOLorientation object, which represents the orientation of 
   * a surface exposed to sunlight. The parameters defining the orientation
   * are:
   * <ul>
   * <li> A TMYdata object (which includes an SOLlocation object),
   * <li> surface azimuth(in degrees) -  measured from South, with Eastward deviation negative
   * and Westward deviation positive,
   * <li> and its surface tilt from the horizontal (in degrees).</ul>*/

  public SOLorientation(TMYdata tmystuff, double surface_azimuth, double surface_tilt, String name){
    location = tmystuff.location;
    location.orientations.addElement(this);
    this.surface_azimuth = surface_azimuth;
    this.surface_tilt = surface_tilt;
    this.name = name;
    surfaces = new Vector();
  }

  //----------------------------- Cos of Angle of Incidence -------------
  /** Returns cosine of angle between solar radiation and normal to surface,
  * given solar time, in seconds, and day number. */

  public double getCosTheta(int daynum, int solar_time){
    double decl = location.getDeclination(daynum);
    double alt = location.getSolarAltitude(decl, solar_time);
    double azi = location.getSolarAzimuth(decl, solar_time);
    double rel_azi = azi - surface_azimuth;

    double cosIncidentAngle = (Math.cos(SOLlocation.toRadians(alt)) 
				 * Math.cos(SOLlocation.toRadians(rel_azi)) 
				 * Math.sin(SOLlocation.toRadians(surface_tilt)))
				 + (Math.sin(SOLlocation.toRadians(alt)) * Math.cos(SOLlocation.toRadians(surface_tilt)));
    //System.out.println("[getCosTheta]:decl:"+decl+" alt:"+alt+" azi:"+
    //azi+" rel_azi:"+rel_azi+" surface_tilt"+surface_tilt+"cos theta="+cosIncidentAngle);
    return(Math.max(0.0, cosIncidentAngle));
  }

  //----------------------------- Angle of Incidence ----------------------
  /** Returns angle between solar radiation and normal to surface,
  * given solar time, in seconds, and day number. */
  public double getTheta(int daynum, int solar_time){
    return(SOLlocation.toDegrees(Math.acos(getCosTheta(daynum, solar_time))));
  } 
} /* End of class SOLorientation */