Turtle - Area miner

-- ********************************************************************************** --
-- **                                                                              ** --
-- **   Mining selected area turtle v1.5 by omr___                                 ** --
-- **   (Add support of negative height and width)                                 ** --
-- **   ----------------------------------------------------                       ** --
-- **                                                                              ** --
-- **   How to use:                                                                ** --
-- **     Download: rom/programs/http/pastebin get 0XqzVUPM dig                    ** --
-- **     !IMPORTANT! Place a chest above the turtle                               ** --
-- **     Start position: Bottom Left before area                                  ** --
-- **     Fuel slot: 16, Bottom Right                                              ** --
-- **                                                                              ** --
-- **  Change Log:                                                                 ** --
-- **    27th Aug 2018: [v1.5] Add support of negative height and width            ** --
-- **                   [v1.5] Fix items drop when no chest above                  ** --
-- **    26th Aug 2018: [v1.4] Type parameters after init                          ** --
-- **    26th Aug 2018: [v1.3] Unload items in chest when done                     ** --
-- **                   [v1.3] Return to start after finishing                     ** --
-- **    25th Aug 2018: [v1.2] Mining performance improvements                     ** --
-- **                   [v1.2] Fixed falling blocks issue                          ** --
-- **                                                                              ** --
-- **  TODO:                                                                       ** --
-- **    - Auto resume                                                             ** --
-- **    - Unload when full                                                        ** --
-- **    - Allow trash cobble                                                      ** --
-- **                                                                              ** --
-- ********************************************************************************** --

local args = { ... }
local direction = {FORWARD = 0, LEFT = 1, BACK = 2, RIGHT = 3, UP = 4, DOWN = 5}
local axis = {x = -1, y = -1}
local invertPos
local width
local height
local length

function rotate(invert)
    if invert == 1 then
        turtle.turnRight()
    else
        turtle.turnLeft()
    end
end

function turn(invert)
    if axis.x == 1 then
        rotate(invert)
    else
        rotate(-invert)
    end
end

function unloadToChest()
    for slot = 1, 16 do
        turtle.select(slot)
        if turtle.detectUp() then
            turtle.dropUp()
        end
    end
    turtle.select(1)
    print("Items were unloaded")
end

function returnToStart()
    if (axis.x == 1) and not (invertPos == true) then
        rotate()
        for i = 1, width - 1 do
            move(direction.FORWARD)
        end
        rotate(1)
    end
    if (axis.y == 1) and not (invertPos == true) then
        for i = 1, height - 1 do
            move(direction.DOWN)
        end
    end
    for i = 1, length do
        move(direction.BACK)
    end
    print("Return complete")
end

function verifyFuel()
    if turtle.getFuelLevel() < 10 then
        print("Fuel level is low, put fuel in slot 16")
        local selectedSlot = turtle.getSelectedSlot()
        turtle.select(16)
        turtle.refuel()
        turtle.select(selectedSlot)
    end
end

function dig(dir)
    function try(detectFn, digFn)
        while detectFn() do
            verifyFuel()
            digFn()
            os.sleep(0.5)
        end
    end

    if dir == direction.UP then
        try(turtle.detectUp, turtle.digUp)
    elseif dir == direction.DOWN then
        try(turtle.detectDown, turtle.digDown)
    elseif dir == direction.BACK then
        turtle.turnLeft()
        turtle.turnLeft()
        try(turtle.detect, turtle.dig)
        turtle.turnRight()
        turtle.turnRight()
    else
        try(turtle.detect, turtle.dig)
    end
end

function move(dir)
    function try(moveFn)
        dig(dir)
        moveFn()
    end

    if dir == direction.FORWARD then
        try(turtle.forward)
    elseif dir == direction.UP then
        try(turtle.up)
    elseif dir == direction.DOWN then
        try(turtle.down)
    elseif dir == direction.BACK then
        try(turtle.back)
    end
end

function digRow(w)
    turn(-1)
    for i = 1, w do
        dig()
        move(direction.FORWARD)
    end
    turn(1)
    axis.x = -axis.x
end

function digWall()
    for i = 1, height do
        digRow(width - 1)
        if (i < tonumber(height)) then
            if axis.y == 1 then
                dig(direction.DOWN)
                move(direction.DOWN)
            else
                dig(direction.UP)
                move(direction.UP)
            end
        end
    end
end

function digArea()
    local blocks = width * height * length
    print("Fuel level: "..turtle.getFuelLevel())
    print("Area size: "..width.."x"..height.."x"..length.." ("..blocks.." blocks)")

    for i = 1, length do
        dig()
        move(direction.FORWARD)
        digWall()
        axis.y = -axis.y
    end
end

if #args ~= 3 then
    print("Usage: dig <Length> <Width> <Height>")
    print("Length?")
    length = tonumber(read())
    print("Width?")
    width = tonumber(read())
    print("Height?")
    height = tonumber(read())
else
    length = tonumber(args[1])
    width = tonumber(args[2])
    height = tonumber(args[3])
end

if height < 0 then
    axis.y = 1
    height = -height
end

if width < 0 then
    axis.x = 1
    width = -width
    invertPos = true
end

if length < 1 then
    print("Length must be positive")
    return
end

digArea()
returnToStart()
unloadToChest()