/*

The SwitchRail class.  A SwitchRail object has three ends, and a controller
which determines which ends are used.  If a Car moves on from the first end,
the switch determines which of the other two ends it leaves from.  If it moves
on from one of the other two ends, it automatically leaves by the first end.

*/

import java.awt.*;

abstract class SwitchRail extends Rail {
    
    // My line coordinates for drawing myself.
    protected double x1, y1, x2, y2, x3, y3;
    
    // Info for my corner portion.
    int startAngle;
    int arcAngle = 90;
        
    // (end1,end2) and (end1,end3) are the two pairs.
    // end1 and end2 are the straight directions (i.e., they are
    // opposite each other), and end1 and end3 form the corner.
    protected Direction end1, end2, end3;
    
    protected Rail neighbour1;  // The Rail in the direction end1.
    protected Rail neighbour2;  // The Rail in the direction end2.
    protected Rail neighbour3;  // The Rail in the direction end3.
    
    // Whether I am aligned to go straight.
    boolean goingStraight;
    
    public SwitchRail (Direction e1, Direction e2, Direction e3, GridLoc loc) {
        super(loc);
        color = Color.magenta;
        end1 = e1;
        end2 = e2;
        end3 = e3;
    }

    public SwitchRail (Direction e1, Direction e2, Direction e3) {
        super();
        color = Color.magenta;
        end1 = e1;
        end2 = e2;
        end3 = e3;
    }

    public boolean exitOK(Direction d) {
        return d.equals(end1) || d.equals(end2) || d.equals(end3);
    }

    // Return true if d is valid for this Rail, return false and
    // print an error otherwise.
    protected boolean validDir(Direction d) {
        if (!exitOK(d)) {
            System.err.print("exit(): Not a valid dir for this piece: ");
            System.err.println(end1.direction + " " + end2.direction + " " + d.direction);
            Exception e = new Exception();
            e.printStackTrace(System.out);
            return false;
        }
        return true;
    }
    
    // Register that r is adjacent to me from direction d.
    public void register(Rail r, Direction d) {
        if (validDir(d)) {
            if (d.equals(end1)) {
                neighbour1 = r;
            } else {
                neighbour2 = r;
            }
        }
    }
    

    public void unRegister(Direction d) {
        if (validDir(d)) {
            if (d.equals(end1)) {
                neighbour1 = null;
            } else if (d.equals(end2)) {
                neighbour2 = null;
            }
        }
    }

    // Given that d is the Direction from which a Car entered,
    // report where the Car will exit.
    // Note that if d is not end1's Direction, then it will have to
    // exit toward end1.
    public Direction exit(Direction d) {
        if (validDir(d)) {
            return d.equals(end1)
                ? end2
                : end1;
        }
        
        return null;
    }

    // d is the direction that I entered from, and must be one of end1, end2 and end3.
    // Return the Rail at the other end.
    public Rail nextRail(Direction d) {
        if (validDir(d)) {
            return d.equals(end1)
                ? neighbour2
                : neighbour1;
        }
        
        return null;
    }
    
    // Handle a mouse click.  This will toggle the direction of the switch.
    public boolean handleEvent (Event evt) {
        Object target = evt.target;
        
        if (evt.id == Event.MOUSE_DOWN && !occupied()) {
            goingStraight = !goingStraight;
            repaint();
            return true;
        }

        // If we get this far, I couldn't handle the event
        return false;
    }    

    // Redraw myself.
    public void draw(Graphics g) {

        super.draw(g);

        Rectangle b = bounds();
        
        // Draw current direction of the switch darker.
        if (goingStraight) {
            g.setColor(Color.lightGray);
            g.drawArc( (int)(x3*b.width), (int)(y3*b.height),
                       b.width, b.height, startAngle, arcAngle);
            g.setColor(color);
            g.drawLine( (int)(x1*b.width), (int)(y1*b.height),
                        (int)(x2*b.width), (int)(y2*b.height));                    
        } else {
            g.setColor(Color.lightGray);
            g.drawLine( (int)(x1*b.width), (int)(y1*b.height),
                        (int)(x2*b.width), (int)(y2*b.height));                    
            g.setColor(color);
            g.drawArc( (int)(x3*b.width), (int)(y3*b.height),
                       b.width, b.height, startAngle, arcAngle);
        }
    }
        
    public String toString() { return "SwitchRail"; };
}