/**
 * Write a description of class CornFields here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class CornField
{
    static final double L = 100.0;
    
    public static double getDirection(double angle){
        double d = Math.cos( Math.toRadians(angle));
        if(d >=0) return 1;
        return -1;
    }
    
    public static double computeAreaOfTrapezoid(double h, double a, double b){
        return h * ((a + b) / 2 );
    }
    
    public static double computeHeight(double l, double angle){
        double a = Math.toRadians(angle);
        if( angle >= 0 && angle <= 90){
            return l * Math.cos( a );
        }else if( angle > 90 && angle <= 180){
               return -l * Math.cos( Math.PI - a );
        }else if(angle > 180 && angle <= 270){
               return -l * Math.cos( a - Math.PI  ) ;
        }else{
               return l * Math.cos( 2* Math.PI  - a  );
        }
    }
    
    public static double computeFrontSide(double l, double h){
        return Math.sqrt(Math.pow(l,2) - Math.pow(h,2));
    }


    public static void printHeights(double[] ls, double[] angles){
        //    	accumulate the total areas of trapezoids
        double total = 0; 
        //   keep track of the hights of each trapezoids while moving
    	double rWidth = 0;
    	//this is the left side of the trapezoid
        double a = L;
        // this is the right side of the trapezoid
        double b = L;        
        
        for(int i=0;i<ls.length;i++){
            double h = computeHeight(ls[i],angles[i]);
            double ll = computeFrontSide(ls[i],h);
            if(angles[i] > 180){
                b -= ll;
            }else{
                b += ll;
            }

            double area = computeAreaOfTrapezoid(h,a,b);
            //System.out.println("h:" + h + " a :" + a + " b:" + b);
            //System.out.println("area:" + area);
            total+=area;
            rWidth +=h;
            
            a = b;  
        }
        
        //compute the distance between the first point and the last one.
        double rDistance = computeLastDistance(a,rWidth);
        
        //compute the area of the last remaining trapezoid that connect the last point
        // with the first one.
        double rArea = -1 * computeAreaOfTrapezoid(rWidth , a, L);
        
        //System.out.println("remaining area:"  + rArea);
        int ra = (int) ( ( rArea + total) * 10);
        rArea = (double)ra / 10;
        System.out.println("Area:" + rArea);
        //System.out.println("area:" + (total + rArea));
        
        //compute the perimeter of the polygram.
        //double peri = rDistance;
        //for(int i=0;i<ls.length;i++) peri+= ls[i];
        //System.out.println("perimeter:" + peri);
    }
    public static double computeLastDistance(double a, double rWidth){
    	double rDis = L - a;
    	return Math.sqrt( Math.pow(rDis,2)+  Math.pow(rWidth,2));
    }
    
    public static void main(String[] args){
        double[] ls = {50, 100, 50};
        double[] a = {45, 0, 225};
        printHeights(ls,a);
        double[] ls2 = {50,50,50,50,50};
        double[] a2 = {45, 0, 315,225,180};
        printHeights(ls2,a2);        
        double[] ls3 = {10,10,10,10,28.284};
        double[] a3 = {90,0,90,0,315};
        printHeights(ls3,a3);                
    }
}