import display.*;

public class CohenSutherland {

    public static final int LEFT = 1;
    public static final int RIGHT = 2;
    public static final int TOP = 4;
    public static final int BOTTOM = 8;
    
    /*
      Inputs: the original line from (x1,y1) to (x2,y2), and a
      viewport The viewport object has four public instance variables,
      which can be accessed by: 
      var1 = viewport.top; 
      var2 = viewport.bottom; 
      var3 = viewport.left; 
      var4 = viewport.right;

      Output: a LineSegment object 
            You can create a LineSegment object by making the call
			      LineSegment ls = new LineSegment()

            Having created it, you must set five values: 
	    x1, y1, x2, y2    the coordinates of each of the
                              endpoints of the clipped line You set
                              these values by including the line
                              ls.setEndPoints(x1, y1, x2, y2); 
			      or alternatively, by setting each of
                              the endpoints individually: 
			      ls.x1 = x1;
                              ls.y1 = y1; 
			      etc.

	    clipType          The clip type can be set to three
	                      values:

			      "internal" if the input line segment
			      falls entirely within the clip region,
			      otherwise:

                              "clipped" if it was determined that
                              some part of the input line segment does
                              fall within the boundaries defined by the
                              clip region, otherwise:

			      "external" if NO part of the input
			      line segment falls within the clip region
			      (i.e. the entire line was clipped.)
                              
			      You can set these values by including
			      the java statements:
                                    ls.setClipType("internal");
			      OR
                                    ls.setClipType("clipped");
                              OR
                                    ls.setClipType("external");
    
	NOTE: If you want to have any auxiliary methods (helpers), you
	must make sure to declare them "static" as well.
    */

    public static LineSegment ClipSegment(double x1, double y1, 
				       double x2, double y2, 
				       Viewport vp) {

	// ******* YOUR CODE HERE *********
	int code1, code2;
	double x, y;
	//for debugging:
	//System.out.println("Entering Cohen-Sutherland");
	LineSegment ls = new LineSegment();

	// if x1 > x2, exchange the coordinates of the two points
      	if (x1 > x2) {
	    x = x1;
	    x1 = x2;
	    x2 = x;
	    y = y1;
	    y1 = y2;
	    y2= y;
	}
	code1 = outcode(x1, y1, vp.top, vp.bottom, vp.left, vp.right);
	code2 = outcode(x2, y2, vp.top, vp.bottom, vp.left, vp.right);

	if (code1 == 0 && code2 == 0) {
	    ls.setClipType("internal");
	    ls.setEndPoints(x1, y1, x2, y2);
	    return ls;
	}

	// clip left
       	if (code1 % 2 == 1 && code2 % 2 == 0) {
	    y1 = y1 + (vp.left - x1) * (y2 - y1) / (x2 - x1);
	    x1 = vp.left;
	}
	// clip right
	code1 = outcode(x1, y1, vp.top, vp.bottom, vp.left, vp.right);
	code2 = outcode(x2, y2, vp.top, vp.bottom, vp.left, vp.right);
	if ((code1/2) % 2 == 0 && (code2/2) % 2 == 1) {
	    y2 = y1 + (vp.right - x1) * (y2 - y1) / (x2 - x1);
	    x2 = vp.right;
	}

	// if y1 > y2, exchange the coordinates of the two points
	if (y1 > y2) {
	    x = x1;
	    x1 = x2;
	    x2 = x;
	    y = y1;
	    y1 = y2;
	    y2= y;
	}

	// clip bottom
	code1 = outcode(x1, y1, vp.top, vp.bottom, vp.left, vp.right);
	code2 = outcode(x2, y2, vp.top, vp.bottom, vp.left, vp.right);
	if ((code1/8) % 2 == 1 && (code2/8) % 2 == 0) {
	    x1 = x1 + (vp.bottom - y1) * (x2 - x1) / (y2 - y1);
	    y1 = vp.bottom;
	}

	// clip top
	code1 = outcode(x1, y1, vp.top, vp.bottom, vp.left, vp.right);
	code2 = outcode(x2, y2, vp.top, vp.bottom, vp.left, vp.right);
	if ((code1/4) % 2 == 0 && (code2/4) % 2 == 1) {
	    x2 = x1 + (vp.top - y1) * (x2 - x1) / (y2 - y1);
	    y2 = vp.top;
	}	
	code1 = outcode(x1, y1, vp.top, vp.bottom, vp.left, vp.right);
	code2 = outcode(x2, y2, vp.top, vp.bottom, vp.left, vp.right);
	if ((code1 % 2 == 1 && code2 % 2 == 1) ||
	    ((code1/2) % 2 == 1 && (code2/2) % 2 == 1) ||
	    ((code1/4) % 2 == 1 && (code2/4) % 2 == 1) ||
	    ((code1/8) % 2 == 1 && (code2/8) % 2 == 1) )  {
	    ls.setClipType("external");
	}	
	else
	    ls.setClipType("clipped");

	ls.setEndPoints(x1, y1, x2, y2);
	return ls;
    }

    /*
      This method, given a point (x,y) and some clip region
      boundaries, should produce the binary clip codes for the
      Cohen-Sutherland algorithm.  
    */
    public static int outcode(double x, double y,
			      double top, double bottom, 
			      double left, double right) {

	int result = 0;
	if (y >= top)
	    result += TOP;
	if (y <= bottom)
	    result += BOTTOM;
	if (x >= right)
	    result += RIGHT;
	if (x <= left)
	    result += LEFT;
	return result;
    }	
}