directions = {"north", "east", "south", "west"}

local position = {}
local direction = ""
function init(x, y, z, dir)
    position = to_pos(x, y, z)
    direction = dir
end

function forward()
    if turtle.forward() then
        forward_increment()
        print_pos()
    end
end

function back()
    if turtle.back() then
        backward_increment()
        print_pos()
    end
end

function up()
    if turtle.up() then
        position = {
            x = position.x,
            y = position.y + 1,
            z = position.z
        }
    end
end

function down()
    if turtle.down() then
        position = {
            x = position.x,
            y = position.y - 1,
            z = position.z
        }
    end
end

function turnLeft()
    if turtle.turnLeft() then
        if direction == "north" then
            direction = "west"
        elseif direction == "east" then
            direction = "north"
        elseif direction == "south" then
            direction = "east"
        elseif direction == "west" then
            direction = "south"
        end
    end
end

function turnRight()
    if turtle.turnRight() then
        if direction == "north" then
            direction = "east"
        elseif direction == "east" then
            direction = "south"
        elseif direction == "south" then
            direction = "west"
        elseif direction == "west" then
            direction = "north"
        end
    end
end
function forward_increment()
    if direction == directions[1] then
        position = {
            x = position.x,
            y = position.y,
            z = position.z - 1
        }
    elseif direction == directions[2] then
        position = {
            x = position.x + 1,
            y = position.y,
            z = position.z
        }
    elseif direction == directions[3] then
        position = {
            x = position.x,
            y = position.y,
            z = position.z + 1
        }
    elseif direction == directions[4] then
        position = {
            x = position.x - 1,
            y = position.y,
            z = position.z
        }
    end
end

function backward_increment()
    if direction == directions[1] then
        position = {
            x = position.x,
            y = position.y,
            z = position.z + 1
        }
    elseif direction == directions[2] then
        position = {
            x = position.x - 1,
            y = position.y,
            z = position.z
        }
    elseif direction == directions[3] then
        position = {
            x = position.x,
            y = position.y,
            z = position.z - 1
        }
    elseif direction == directions[4] then
        position = {
            x = position.x + 1,
            y = position.y,
            z = position.z
        }
    end
end

function to_pos(x1, y1, z1)
    return {x=x1, y=y1, z=z1}
end

function print_pos()
    print("Position: (" .. position.x .. ", " .. position.y .. ", " .. position.z .. ")")
end

function goto(position)
    -- nothing
end