-- Usage (program name) <Width> <Depth> <Length> <Direction>
-- Place a chest with enough space for what you are digging behind the turtle before beginning
-- Put any fuel in the first slot, if you don't want to have to refuel, use refuel<amount> before running this
-- Make sure you keep the chunk(s) the turtle is digging in loaded, otherwise it will break

rednet.open("left")

local tArgs = { ... }
if #tArgs ~= 4 then
    print( "Usage: excavate <Width> <Depth> <Length> <Direction>" )
    print( "Direction - 0 for down, 1 for up" )
    return
end


local size1    = tonumber( tArgs[1] )
local size2    = tonumber( tArgs[2] )
local size3    = tonumber( tArgs[3] )
local upordown = tonumber( tArgs[4] )
if size1 < 1 then
    print( "X size must be positive" )
    return
end
if size2 < 1 then
    print( "Depth must be positive" )
    return
end
if size3 < 1 then
    print( "Z size must be positive" )
    return
end
if upordown~=0 and upordown~=1 then
    print( "Invalid direction" )
    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

local function unload()
    rednet.send(38, "unloading")
    for n=2,16 do
        unloaded = unloaded + turtle.getItemCount(n)
        turtle.select(n)
        turtle.drop()
    end
    collected = 0
    turtle.select(1)
end

local function returnSupplies()
    local x,y,z,xd,zd = xPos,depth,zPos,xDir,zDir
    rednet.send(38, "surface")
    goTo( 0,0,0,0,-1 )

    local fuelNeeded = x+y+z + x+y+z + 1
    if not refuel( fuelNeeded ) then
        unload()
        print( "Waiting for fuel" )
        while not refuel( fuelNeeded ) do
            sleep(1)
        end
    else
        unload()
    end

    rednet.send(38, "mining")
    goTo( x,y,z,xd,zd )
end

local function collect()
    local bFull = true
    local nTotalItems = 0
    for n=1,16 do
        local nCount = turtle.getItemCount(n)
        if nCount == 0 then
            bFull = false
        end
        nTotalItems = nTotalItems + nCount
    end

    if nTotalItems > collected then
        collected = nTotalItems
        if math.fmod(collected + unloaded, 50) == 0 then
            print( "Mined "..(collected + unloaded).." items." )
        end
    end

    if bFull then
        print( "No empty slots left." )
        return false
    end
    return true
end

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

    local needed = ammount or (xPos + zPos + depth + 1)
    if turtle.getFuelLevel() < needed then
        local fueled = false
        for n=1,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    while turtle.getItemCount(n) > 0 and turtle.getFuelLevel() < needed do
                        turtle.refuel(1)
                    end
                    if turtle.getFuelLevel() >= needed then
                        turtle.select(1)
                        return true
                    end
                end
            end
        end
        turtle.select(1)
        return false
    end

    return true
end

local function tryForwards()
    if not refuel() then
        rednet.send(38, "Needs fuel")
        returnSupplies()
    end

    while not turtle.forward() do
        if turtle.detect() then
            if turtle.dig() then
                if not collect() then
                    returnSupplies()
                end
            else
                return false
            end
        elseif turtle.attack() then
            if not collect() then
                returnSupplies()
            end
        else
            sleep( 0.5 )
        end
    end

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

local function tryDown()
    if not refuel() then
        rednet.send(38, "Needs fuel")
        returnSupplies()
    end

    while not turtle.down() do
        if turtle.detectDown() then
            if turtle.digDown() then
                if not collect() then
                    returnSupplies()
                end
            else
                return false
            end
        elseif turtle.attackDown() then
            if not collect() then
                returnSupplies()
            end
        else
            sleep( 0.5 )
        end
    end

    depth = depth + 1

    return true
end

local function tryUp()
    if not refuel() then
        rednet.send(38,"Needs fuel")
        returnSupplies()
    end

    while not turtle.up() do
        if turtle.detectUp() then
            if turtle.digUp() then
                if not collect() then
                    returnSupplies()
                end
            else
                return false
            end
        elseif turtle.attackUp() then
            if not collect() then
                returnSupplies()
            end
        else
            sleep( 0.5 )
        end
    end

    depth = depth - 1

    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
        elseif turtle.digUp() or turtle.attackUp() then
            collect()
        else
            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

if not refuel() then
    rednet.send(38,"Out of fuel!")
    return
end

    rednet.send(38,"Mining")

local reseal = false
turtle.select(1)
if upordown == 0 then
    if turtle.digDown() then
    end
elseif upordown == 1 then
    if turtle.digUp() then
    end
end

local alternate = 0
local done = 0
while done~=size2 do
    for varx=1,size1 do
        for varz=1,size3-1 do
            if not tryForwards() then
                done = size2
                break
            end
        end
        if done==size2 then
            break
        end
        if varx<size1 then
            if math.fmod(varx + alternate,2) == 0 then
                turnLeft()
                if not tryForwards() then
                    done = size2
                    break
                end
                turnLeft()
            else
                turnRight()
                if not tryForwards() then
                    done = size2
                    break
                end
                turnRight()
            end
        end
    end
    if done==size2 then
        break
    end

    if size1 > 1 then
        goTo( 0,depth,0,0,1 )
    end
    if done ~= size2-1 then
        if upordown == 0 then
            if not tryDown() then
                done = size2
                break
            end
        elseif upordown == 1 then
            if not tryUp() then
                done = size2
                break
            end
        end
    end
    done = done + 1
end

rednet.send(38,"Returning to surface")

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

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

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