impTurtle

if not turtle then
    error("impTurtle API requires device type 'turtle'.")
end

local moved = {
    north = vector.new( 0, 0,-1),
    east  = vector.new( 1, 0, 0),
    south = vector.new( 0, 0, 1),
    west  = vector.new(-1, 0, 0),
}

local faceName = {
    [0] = "north",
    [1] = "east",
    [2] = "south",
    [3] = "west",
}

local status = {
    bearing = nil,
    position = nil,
    fuel = turtle.getFuelLevel(),
}

local setup = function(bearing, posX, posY, posZ)
    bearing = string.lower(bearing or "")
    if bearing == "north" or bearing == "n" then
        status.bearing = 0
    elseif bearing == "east" or bearing == "e" then
        status.bearing = 1
    elseif bearing == "south" or bearing == "s" then
        status.bearing = 2
    elseif bearing == "west" or bearing == "w" then
        status.bearing = 3
    else
        error("Bad argument #1 setting up impTurtle. Expects string direction, e.g. 'north' or 'n'.")
    end
    if type(posX) == "number" and type(posY) == "number" and type(posZ) == "number" then
        status.position = vector.new(posX,posY,posZ)
    else
        status.bearing = nil
        error("Bad arguments #2 - #4 setting up impTurtle. Expects number for start co-ordinates, e.g. 0, 0, 0.")
    end
end

local getStatus = function(specified)
    local tmp = status.bearing
    status.bearing = faceName[tmp]
    gotStatus = textutils.serialise(status)
    status.bearing = tmp
    return textutils.unserialise(gotStatus)
end

local move = function(direction,times)
    local times = tonumber(times)
    local completed = 0
    if not times then times = 1 end
    for i = 1,times do
        if status.fuel == 0 then turtle.refuel() end
        if direction == "left" then
            turtle.turnLeft()
            if status.bearing then
                status.bearing = (status.bearing-1)%4
            end
        elseif direction == "right" then
            turtle.turnRight()
            if status.bearing then
                status.bearing = (status.bearing+1)%4
            end
        elseif direction == "up" then
            if turtle.up() then
                completed = completed + 1
                if status.position then
                    status.position.y = status.position.y + 1
                end
            else
                break
            end
        elseif direction == "down" then
            if turtle.down() then
                completed = completed + 1
                if status.position then
                    status.position.y = status.position.y - 1
                end
            else
                break
            end
        elseif direction == "forward" then
            if turtle.forward() then
                completed = completed + 1
                if status.position and status.bearing then
                    status.position = status.position + moved[faceName[status.bearing]]
                end
            else
                break
            end
        elseif direction == "back" then
            if turtle.back() then
                completed = completed + 1
                if status.position and status.bearing then
                    status.position = status.position - moved[faceName[status.bearing]]
                end
            else
                break
            end
        else
            return "Invalid Direction"
        end
        status.fuel = turtle.getFuelLevel()
    end
    return completed
end

local go = {
fd = function(times)
    return move("forward",times)
end,
bk = function(times)
    return move("back",times)
end,
lt = function(times)
    return move("left",times)
end,
rt = function(times)
    return move("right",times)
end,
up = function(times)
    return move("up",times)
end,
dn = function(times)
    return move("down",times)
end,
}

return {
left = go.lt,
right = go.rt,
up = go.up,
down = go.dn,
forward = go.fd,
back = go.bk,
status = getStatus,
setup = setup,
}