// Implementation of the Position class and Direction-related functions.
// CSE143 Spring '01
// Homework 6

#include "position.h"
#include <cassert>

// Returns true iff the direction is valid (one of the enum values)
bool validDir(Direction dir) {
	return (dir == North || dir == East || dir == South || dir == West);
}

// Returns the opposite direction, i.e. North for South, East for West, etc.
Direction oppositeDir(Direction dir) {
	assert (validDir(dir));
	switch (dir) {
	case North: return South;
	case East: return West;
	case South: return North;
	case West: return East;
	}
	return North; // for compiler's benefit: never get here.
}

// Returns the next direction clockwise (e.g. nextDir(North) = East).
Direction nextDir(Direction dir) {
	assert (validDir(dir));
	switch (dir) {
	case North: return East;
	case East: return South;
	case South: return West;
	case West: return North;
	}
	return North; // for compiler's benefit: never get here.
}


// Initialize the position at (0,0)
Position::Position() {
	x = 0;
	y = 0;
}

// Initialize the position to (x,y)
Position::Position(int x, int y) {
	this->x = x;
	this->y = y;
}

// Initialize the position to same as the other position
Position::Position(const Position& other) {
	x = other.x;
	y = other.y;
}

// Set the position to be the same as the other position
Position& Position::operator =(const Position& other) {
	x = other.x;
	y = other.y;
	return *this;
}

// = x coordinate of this position
int Position::getX() const {
	return x;
}

// = y coordinate of this position	
int Position::getY() const {
	return y;
}

// Move the position <distance> units in direction <dir>, where North
// is up the screen (bigger y's) and East is right on the screen (bigger
// x's).
void Position::move(Direction dir, int distance) {
	assert (validDir(dir));
	switch(dir) {
	case North:	y += distance; break;
	case East:	x += distance; break;
	case South:	y -= distance; break;
	case West:	x -= distance; break;
	}
}

// Rotate this position around <axis>, according to <dir>: rotate 90, 180,
// or 270 degrees clockwise, for <dir> = East, South or West, respectively.
// If <dir> = North, ignore. Returns the new position.
void Position::rotate(Position axis, Direction dir) {
	assert (validDir(dir));
	int dx = x - axis.x;
	int dy = y - axis.y;
	int temp;
	for (Direction cur = North; cur != dir; cur = nextDir(cur)) {
		temp = -dx;
		dx = dy;
		dy = temp;
	}
	x = axis.x + dx;
	y = axis.y + dy;
}