--[[
Allows a turtle to keep track of it's
location using a coordinate system.

Use the commands goForward(), goRight(),
goLeft(), goUp(), and goDown() to
control the turtle while adding to
the coordinates.

goHome() will send the turtle back to
it's origin and will point it north:
the direction it was originally facing.

A turtle always faces north when it is placed down
]]--

x = 0
y = 0
z = 0

saveX = 0
saveY = 0
saveZ = 0

ZX = 0
ZY = 0
ZZ = 0

saveDirection = NORTH

NORTH = 1
EAST = 2
SOUTH = 3
WEST = 4

UP = 5
DOWN = 6

RIGHT = 7
LEFT = 8

direction = NORTH

--[[sends a turtle forward 1 block
and adds to it's X coordinate]]--
function goForward()
  if turtle.forward() then
    addToCoords(direction)
    return true
  else return false
  end
end

--[[sends a turtle up 1 block
and adds to it's Z coordinate]]--
function goUp()
  if turtle.up() then
    addToCoords(UP)
    return true
  else return false
  end
end

--[[sends a turtle down 1 block
and subtracts from it's Z coordinate]]--
function goDown()
  if turtle.down() then
    addToCoords(DOWN)
    return true
  else return false
  end
end

--[[turns a turtle right and changes
it's direction accordingly]]--
function goRight()
  turtle.turnRight()
  changeDirection(RIGHT)
end

--[[turns a turtle left and changes
it's direction accordingly]]--
function goLeft()
  turtle.turnLeft()
  changeDirection(LEFT)
end

--[[moves a turtle forward a specified number of blocks]]--
function move(distance)
  for i=1,distance do
    goForward()
  end
end

--[[moves a turtle up a specified number of blocks]]--
function moveUp(distance)
  for i=1,distance do
    goUp()
  end
end

--[[moves a turtle down a specified number of blocks]]--
function moveDown(distance)
  for i=1,distance do
    goDown()
  end
end

--[[takes the direction of the turtle and adds 1
to the appropriate coordinate based on that direction]]--
function addToCoords(direction)
  if direction == NORTH then
    x = x+1
  elseif direction == EAST then
    y = y+1
  elseif direction == SOUTH then
    x = x-1
  elseif direction == WEST then
    y = y-1
  elseif direction == UP then
    z = z+1
  else
    z = z-1
  end
end

--[[takes a direction turned (right or left) and changes the
direction of the turtle to north, south, east, or west]]--
function changeDirection(turned)
  if turned == RIGHT then
    if direction == NORTH then
      direction = EAST
    elseif direction == EAST then
      direction = SOUTH
    elseif direction == SOUTH then
      direction = WEST
    else
      direction = NORTH
    end
  else
    if direction == NORTH then
      direction = WEST
    elseif direction == WEST then
      direction = SOUTH
    elseif direction == SOUTH then
      direction = EAST
    else
      direction = NORTH
    end
  end
end

--[[takes a direction (north, east, south, or west) and turns
the turtle in that direction]]--
function setDirection(newDirect)
  while true do
    if newDirect == direction then
      break
    end
    goRight()
  end
end

--[[This will solve a three dimensional maze]]--

WENT_DOWN = 20
WENT_UP = 21
LAST_MOVE = 0



function solve2D()
  if not goForward() then
    goLeft()
  end
end

function solve3D()
  if not goToZ() then
    solve2D()
  end
end

function goToZ(way)
  if way = UP
    goUp()
    LAST_MOVE = WENT_UP
  else
    goDown()
    LAST_MOVE = WENT_DOWN
  end
end