xCoord = -164
zCoord = 195
yCoord = 72

xQuarry = 999
zQuarry = 999
yQuarry = 150

xProgress = 999
zProgress = 999
yProgress = 150

oProgress = 1

xHome = xCoord
zHome = zCoord
yHome = yCoord

yTravel = 85

orientation = 4
orientations = {"north", "east", "south", "west"}

zDiff = {-1, 0, 1, 0}
xDiff = {0, 1, 0, -1}

lineLength = 2
lines = 3

yMin = 999

function inventoryFull()
    turtle.select(9)
    full = turtle.getItemCount(9) > 0    -- I think this should be an if statement
    turtle.select(1)
    return full
    -- since full wont work (I think) you should do this
    if turtle.getItemCount(9) > 0 then
        turtle.select(1)
        return turtle.getItemCount(9)
    else
        return false
    end
end

function left()
    orientation = orientation - 1
    orientation = (orientation - 1) % 4
    orientation = orientation + 1

    turtle.turnLeft()
end

function right()
    orientation = orientation - 1
    orientation = (orientation + 1) % 4
    orientation = orientation + 1
    turtle.turnRight()
end

function moveForward()
    xCoord = xCoord + xDiff[orientation]
    zCoord = zCoord + zDiff[orientation]
    turtle.dig()
    moved = false
    while not(moved) do
        moved = turtle.forward()
    end
    -- I would write this function like so:
    xCoord = xCoord + xDiff[orientation]
    zCoord = zCoord + zDiff[orientation]
    move = turtle.forward()
    while not move do
        move = turtle.forward()
    end
end

function moveUp()
    yCoord = yCoord + 1
    turtle.digUp()
    moved = false
    while not(moved) do
        moved = turtle.up()
    end
    -- Look at the function above
end

function moveDown()
    yCoord = yCoord - 1
    turtle.digDown()
    moved = false
    while not(moved) do
        moved = turtle.down()
    end
    if yMin > yCoord then
        yMin = yCoord
    end
end

function look(direction)
    while direction ~= orientations[orientation] do
        right()
    end
    -- Not sure what this even does
end

function goto(xTarget, zTarget, yTarget)
    while yTarget < yCoord do
        moveDown()
    end
    while yTarget > yCoord do
        moveUp()
    end
    if xTarget < xCoord then
        look("west")
        while xTarget < xCoord do
            moveForward()
        end
    elseif xTarget > xCoord then
        look("east")
        while xTarget > xCoord do
            moveForward()
        end
    end
    if zTarget < zCoord then
        look("north")
        while zTarget < zCoord do
            moveForward()
        end
    end
    if zTarget > zCoord then
        look("south")
        while zTarget > zCoord do
            moveForward()
        end
    end
end

function returnItems()
    xProgress = xCoord
    zProgress = zCoord
    yProgress = yCoord
    oProgress = orientation
    goto(xHome, zHome, yTravel)
    goto(xHome, zHome, yHome)
    for i = 1,9 do
        turtle.select(i)
        turtle.drop()
    end
    turtle.select(1)
    goto(xProgress, zProgress, yTravel)
    goto(xProgress, zProgress, yProgress)
    look(orientations[oProgress])
end

function digLine()
    for i = 1,lineLength do
        if inventoryFull() then
            returnItems()
        end
        moveForward()
    end
end

function digLayer()
    for i = 1,lines do
        digLine()
        if (i%2) == 1 and i < lines then
            left()
            moveForward()
            left()
        elseif i < lines then
            right()
            moveForward()
            right()
        end
    end
    goto(xQuarry, zQuarry, yCoord)
    look("north")
    moveDown()
end

function digQuarry(xTarget, zTarget, yTarget)
    xQuarry = xTarget
    zQuarry = zTarget
    yQuarry = yTarget

    goto(xQuarry, zQuarry, yTravel)
    goto(xQuarry, zQuarry, yQuarry)

    look("north")
    while yMin > 7 do
        digLayer()
    end
    goto(xQuarry, zQuarry, yQuarry)
    yMin = 999
end

digQuarry(-170, 210, 70)