import processing.core.PApplet;

public class Line {

    private float x1, x2, y1, y2;
    private double iX, iY;

    public Line(double x1, double y1, double x2, double y2)
    {
        this.x1 = (float)x1;
        this.y1 = (float)y1;
        this.x2 = (float)x2;
        this.y2 = (float)y2;
    }

    public void setPoint2(double x2, double y2)
    {
        this.x2 = (float)x2;
        this.y2 = (float)y2;
    }

    public void draw(PApplet drawer)
    {
        drawer.line(x1, y1, x2, y2);

//      drawer.line(50, 10, 100, 10); // horizontal parallel lines for testing intersecting
//      drawer.line(50, 40, 100, 40);

        drawer.ellipse((float)iX, (float)iY, 5, 5);
    }

    public boolean intersects(Line other)
    {
        if (((x1 - x2) * (other.y1 - other.y2)) - ((y1 - y2) * (other.x1 - other.x2)) == 0)
        {
            return false;
        } else
        {
            iX = ((x1 * y2 - y1 * x2) * (other.x1 - other.x2) - (x1 - x2) * (other.x1 * other.y2 - other.y1 * other.x2))
            /((x1 - x2) * (other.y1 - other.y2) - (y1 - y2) * (other.x1 - other.x2));
            iY = ((x1 * y2 - y1 * x2) * (other.y1 - other.y2) - (y1 - y2) * (other.x1 * other.y2 - other.y1 * other.x2))
            /((x1 - x2) * (other.y1 - other.y2) - (y1 - y2) * (other.x1 - other.x2));

            if (x1 < other.x1 && x2 < other.x2 && y1 < other.y1 && y2 < other.y2) // if red line is smaller
            {
                if (x1 > x2 && y1 > y2)
                {
                    if (iX <= x1 && iX >= x2 && iY <= y1 && iY >= y2)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (x2 > x1 && y1 > y2)
                {
                    if (iX <= x2 && iX >= x1 && iY <= y1 && iY >= y2)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (x1 > x2 && y2 > y1)
                {
                    if (iX <= x1 && iX >= x2 && iY <= y2 && iY >= y1)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (x2 > x1 && y2 > y1)
                {
                    if (iX <= x2 && iX >= x1 && iY <= y2 && iY >= y1)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else
                {
                    return false;
                }
            } else // if green line is smaller
            {
                if (other.x1 > other.x2 && other.y1 > other.y2)
                {
                    if (iX <= other.x1 && iX >= other.x2 && iY <= other.y1 && iY >= other.y2)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (other.x2 > other.x1 && other.y1 > other.y2)
                {
                    if (iX <= other.x2 && iX >= other.x1 && iY <= other.y1 && iY >= other.y2)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (other.x1 > other.x2 && other.y2 > other.y1)
                {
                    if (iX <= other.x1 && iX >= other.x2 && iY <= other.y2 && iY >= other.y1)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else if (other.x2 > other.x1 && other.y2 > other.y1)
                {
                    if (iX <= other.x2 && iX >= other.x1 && iY <= other.y2 && iY >= other.y1)
                    {
                        return true;
                    } else
                    {
                        return false;
                    }
                } else
                {
                    return false;
                }
            }
        }
    }
}