Quarry No Drops

local tArgs = { ... }
if #tArgs ~= 1 then
    print( "Usage: excavate <diameter>" )
    return
end

-- Mine in a quarry pattern until we hit something we can't dig
local size = tonumber( tArgs[1] )
if size < 1 then
    print( "Excavate diameter must be positive" )
    return
end

local depth = 0
local unloaded = 0
local collected = 0

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

local goTo -- Filled in further down
local refuel -- Filled in further down


function refuel( ammount )
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" then
        return true
    end

    if turtle.getFuelLevel() < 5000 then
        for dropar= 1,15 do
            turtle.select(dropar)
            turtle.drop()
        end
        turtle.select(16)
        turtle.placeUp()
        turtle.suckUp(1)
        turtle.refuel()
        turtle.dropUp()
        turtle.digUp()
        turtle.select(1)
        return false
    end

    return true
end

local function tryForwards()
    if not refuel() then
        print( "Not enough Fuel... Refuel in a Second" )
    end

    while not turtle.forward() do
        if turtle.detect() then
            if turtle.dig() then
                turtle.dropDown()
            else
                return false
            end
        end
    end

    xPos = xPos + xDir
    zPos = zPos + zDir
    return true
end

local function tryDown()

    while not turtle.down() do
        if turtle.detectDown() then
            if turtle.digDown() then
                turtle.dropUp()
            else
                return false
            end
        end
    end

    depth = depth + 1
    if math.fmod( depth, 10 ) == 0 then
        print( "Descended "..depth.." metres." )
    end

    return true
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
            sleep( 0.5 )
        end
    end

    if xPos > x then
        while xDir ~= -1 do
            turnLeft()
        end
        while xPos > x do
            if turtle.forward() then
                xPos = xPos - 1
            elseif turtle.dig() or turtle.attack() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    elseif xPos < x then
        while xDir ~= 1 do
            turnLeft()
        end
        while xPos < x do
            if turtle.forward() then
                xPos = xPos + 1
            elseif turtle.dig() or turtle.attack() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    end

    if zPos > z then
        while zDir ~= -1 do
            turnLeft()
        end
        while zPos > z do
            if turtle.forward() then
                zPos = zPos - 1
            elseif turtle.dig() or turtle.attack() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    elseif zPos < z then
        while zDir ~= 1 do
            turnLeft()
        end
        while zPos < z do
            if turtle.forward() then
                zPos = zPos + 1
            elseif turtle.dig() or turtle.attack() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    end

    while depth < y do
        if turtle.down() then
            depth = depth + 1
        elseif turtle.digDown() or turtle.attackDown() then
            collect()
        else
            sleep( 0.5 )
        end
    end

    while zDir ~= zd or xDir ~= xd do
        turnLeft()
    end
end

print( "Excavating..." )

local reseal = false
turtle.select(1)
if turtle.digDown() then
    reseal = true
end

local alternate = 0
local done = false
while not done do
    for n=1,size do
        for m=1,size-1 do
            if not tryForwards() then
                done = true
                break
            end
        end
        if done then
            break
        end
        if n<size then
            if math.fmod(n + alternate,2) == 0 then
                turnLeft()
                if not tryForwards() then
                    done = true
                    break
                end
                turnLeft()
            else
                turnRight()
                if not tryForwards() then
                    done = true
                    break
                end
                turnRight()
            end
        end
    end
    if done then
        break
    end

    if size > 1 then
        if math.fmod(size,2) == 0 then
            turnRight()
        else
            if alternate == 0 then
                turnLeft()
            else
                turnRight()
            end
            alternate = 1 - alternate
        end
    end

    if not tryDown() then
        done = true
        break
    end
end

print( "Returning to surface..." )

-- Return to where we started
goTo( 0,0,0,0,-1 )
unload( false )
goTo( 0,0,0,0,1 )

-- Seal the hole
if reseal then
    turtle.placeDown()
end

print( "Mined "..(collected + unloaded).." items total." )