/**
 * @author Gaspar Guerra
 * Rocket.java
 * Project Assignment5
 */
public class Rocket {
   //Constant to convert from Feet to Meters
   public final static double FEET_TO_METERS = 0.3048;
   //Constant, Gravitational Force, in ft/s^2
   public final static double G = 32.152231;
   //Initial Velocity of Rocket
   private double v0;
   //Angle of launch of Rocket
   private double angle;
   
   public Rocket( double init, double ang ){
      //Initialize variables with given values
      v0 = init;
      angle = ang;
   }
   
   /*
    * Converts the given degrees to radians
    */
   public double degToRad( double deg ){
      return ( deg * Math.PI ) / 180.0;
   }
   
   /*
    * Returns the speed in Meters 
    */
   public double speedInMeters( ){
      return v0 * FEET_TO_METERS;
   }
   
   /*
    * Returns the horizontal component
    * of the initial velocity
    */
   public double horizontalComponent( ){
      return v0 * Math.cos( degToRad( angle ) );
   }
   
   /*
    * Returns the vertical component
    * of the initial velocity
    */
   public double verticalComponent( ){
      return v0 * Math.sin( degToRad( angle ) );
   }
   
   /*
    * Returns the state of this Rocket, at the given time
    */
   public CurrentState returnState( double time ){
      if( time <= 0.0 ){
             //If time is negative or zero, Rocket has not launched
         return new CurrentState( 0, 0, 0, 0 );
      }
      double vertical = verticalComponent( ) * time - 0.5 * G * time * time;
      if( vertical < 0.0 ){
         //If the Rocket's Y Position in the plane is negative, the 
         //Rocket has fallen to the ground. We calculate the time
         //When the Rocket fell, and return the state at that time
         time = 2 * ( verticalComponent( ) / G );
         return new CurrentState( horizontalComponent( ) * time, 0, 0, 0 );
      }
      //At this point, the Rocket has been determined to still be in the air
      //We return its position, and Velocity, as its State
      return new CurrentState( horizontalComponent( ) * time,
                        vertical,
                        horizontalComponent( ),
                        verticalComponent( ) - G * time );
   }
}