/* Model3D.java  Representation of a 3D model as a wire frame of line
                 segments.

   History:

   12 Jun 2008  If an Exception is encountered while the model
                is being loaded, reset() before throwing or
                rethrowing the exception.
   10 Jun 2008  Extracted from ThreeD.java and JModel3D.java.
*/

import java.io.*;

/**
  The representation of a 3D model as a wire frame of line segments.
  */
public abstract class Model3D {
  /**
    Report problems with data file formatting.

    @param s description of the problem
    */
  public class FileFormatException extends Exception {
    public FileFormatException(String s) {
      super(s);
    }
  }

  /**
    Report problems with adding information to the model.

    @param s description of the problem
    */
  public class ModelException extends Exception {
    public ModelException(String s) {
      super(s);
    }
  }

  public Model3D() { }

  public Model3D(InputStream is)
    throws IOException, FileFormatException, ModelException
  { load(is); }

  /**
    Reset model to empty state.
   */
  public abstract void reset();

  /**
    Initialize the model geometry from data contained in a stream.
    If an exception occurs while the model is being loaded, the
    model is reset() back to empty.  The stream must fit the following
    format specification:

    <pre>
    # comment character
    v x_val y_val z_val
    l p1_val p2_val type

    x_val, y_val and z_val are floating-point values.
    p1_val and p2_val are zero-based indexes into the vertex array.
    type is a non-negative integer.  type % 8 == 1 indicates a strut.
    All the "v" specs must precede the "l" specs.
    </pre>

    @param is InputStream in the prescribed format.
    @exception java.io.IOException See exception documentation for reason.
    @exception FileFormatException See exception documentation for reason.
    @exception ModelException See exception documentation for reason.
    */
  public synchronized void load(InputStream is)
    throws IOException, FileFormatException, ModelException {
    reset();
    Reader r = new BufferedReader(new InputStreamReader(is));
    StreamTokenizer st = new StreamTokenizer(r);
    st.eolIsSignificant(true);
    st.commentChar('#');
    try {
      while (st.nextToken() != StreamTokenizer.TT_EOF)
        if (st.ttype == StreamTokenizer.TT_WORD) {
          if ("v".equals(st.sval)) { // v = "vertex"
	    // point
            double x = 0, y = 0, z = 0;
            if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
              x = st.nval;
              if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
                y = st.nval;
                if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
                  z = st.nval;
                }
                else fileFormatException(st.toString());
              }
              else fileFormatException(st.toString());
            }
            else fileFormatException(st.toString());
            addPoint(x, y, z);
          }
          else if ("l".equals(st.sval)) { // l = "line"
            // lineSegment
            int p1 = 0, p2 = 0, type = 0;
            if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
              p1 = (int)st.nval;
              if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
                p2 = (int)st.nval;
                if (st.nextToken() == StreamTokenizer.TT_NUMBER) {
                  type = (int)st.nval;
                }
                else throw new FileFormatException(st.toString());
              }
              else fileFormatException(st.toString());
            }
            else fileFormatException(st.toString());
            addLineSegment(p1, p2, type);
          }
        } // TT_WORD token
    }
    catch (IOException e) {
      reset();
      throw e;
    }
    catch (ModelException e) {
      reset();
      throw e;
    }
    computeBoundingSphere();
  }

  /**
   Handle a FileFormatException by emptying the model and then
   throwing said exception.

   @param tokenizerString string from tokenizer when bad format
                          encountered
   @exception FileFormatException See exception documentation for
                                  reason.
   */
  private void fileFormatException(String tokenizerString)
    throws FileFormatException {
    reset();
    throw new FileFormatException(tokenizerString);
  }

  /**
    Add a point to the model's geometry.

    @param x x coordinate of point
    @param y y coordinate of point
    @param z z coordinate of point
    */
  abstract void addPoint(double x, double y, double z)
    throws ModelException;

  /**
    Add a LineSegment with endpoints p1 and p2 to the model's geometry.

    @param p1 zero-based index of first endpoint
    @param p2 zero-based index of second endpoint
    @param type type value for this line segment
   */
  abstract void addLineSegment(int p1, int p2, int type)
    throws ModelException;

  /**
    Compute the bounding sphere for the model in its current state.
   */
  abstract void computeBoundingSphere();
}