setup

local tArgs = { ... }

local depth = 0
local xPos,zPos = 0,0
local xDir,zDir = 0,1

local goTo

local count = 0
local chests = 0

local function amount(_name)
    tName = "minecraft:" .. _name
    local tCount = 0
    for i=1,16 do
        local item = turtle.getItemDetail(i)
        if item ~= nil then
            if item.count > 0 and item.name == tName then
                tCount = tCount + item.count
            end
        end
    end
    return tCount
end

local function turnLeft()
    turtle.turnLeft()
    xDir, zDir = -zDir, xDir
end

local function turnRight()
    turtle.turnRight()
    xDir, zDir = zDir, -xDir
end

function goTo( x, y, z, xd, zd )
    while depth > y do
        if turtle.up() then
            depth = depth - 1
        else
            turtle.digUp()
        end
    end

    if xPos > x then
        while xDir ~= -1 do
            turnLeft()
        end
        while xPos > x do
            if turtle.forward() then
                xPos = xPos - 1
            else
                turtle.dig()
            end
        end
    elseif xPos < x then
        while xDir ~= 1 do
            turnLeft()
        end
        while xPos < x do
            if turtle.forward() then
                xPos = xPos + 1
            else
                turtle.dig()
            end
        end
    end

    if zPos > z then
        while zDir ~= -1 do
            turnLeft()
        end
        while zPos > z do
            if turtle.forward() then
                zPos = zPos - 1
            else
                turtle.dig()
            end
        end
    elseif zPos < z then
        while zDir ~= 1 do
            turnLeft()
        end
        while zPos < z do
            if turtle.forward() then
                zPos = zPos + 1
            else
                turtle.dig()
            end
        end
    end

    while depth < y do
        if turtle.down() then
            depth = depth + 1
        else
            turtle.digDown()
        end
    end

    if zd ~= xd then
        while zDir ~= zd or xDir ~= xd do
            turnRight()
        end
    end
end

-- start --

count = amount("hopper")
chests = amount("chest")

if chests >= ((count * 2) + 2) then
    goTo(1, 1, -1, 0, -1)
    turtle.digUp() turtle.select(1) turtle.placeUp()
    goTo(0, 1, -1, 0, -1)
    turtle.digUp() turtle.placeUp()

    for i=1, count do
        goTo(0, (i+1), -2, 0, -1)
        turtle.digUp() turtle.placeUp()
    end
    goTo(0, (count+1), -1, 0, -1)
    goTo(0, 1, -1, 0, -1)
    goTo(1, 1, -1, 0, -1)
    for i=1, count do
        goTo(1, (i+1), -2, 0, -1)
        turtle.digUp() turtle.placeUp()
    end
    goTo(1, count+1, 0, 0, -1)
    goTo(1, 0, 0, 0, -1)
    for i=1, count do
        goTo(1, i, 0, 0, -1)
        turtle.dig() turtle.select(2) turtle.place()
    end
    goTo(0, 0, 0, 0, 1)
    turtle.select(1)

    print("Done!")

    if #tArgs > 0 then
        if tArgs[1] == "exf" then
            shell.run("exf 16")
        elseif tArgs[1] == "exc" then
            shell.run("excavate 16")
        end
    end
else
    print("Not enough chests!")
end