#include <assert.h>
#include "dir.h"

bool isLegal( Dir d )
{
    return (d == NORTH) || (d == SOUTH) || (d == WEST) || (d == EAST);
}

Dir opposite( Dir d )
{
    assert( isLegal( d ) );

    switch( d ) {
    case NORTH: return SOUTH;
    case SOUTH: return NORTH;
    case WEST: return EAST;
    case EAST: default: return WEST;
    }
}

Dir nextCW( Dir d )
{
    assert( isLegal( d ) );

    switch( d ) {
    case NORTH: return EAST;
    case SOUTH: return WEST;
    case WEST: return NORTH;
    case EAST: default: return SOUTH;
    }
}

Dir nextCCW( Dir d )
{
    return nextCW( opposite( d ) );
}

ostream& operator <<( ostream& os, const Dir& d )
{
    assert( isLegal( d ) );

    switch( d ) {
    case NORTH: os << "NORTH"; break;
    case SOUTH: os << "SOUTH"; break;
    case WEST: os << "WEST";  break;
    case EAST: default:  os << "EAST";  break;
    }

    return os;
}