--~ Before usage:
--~ Make sure you have at least one piece of fuel in the first slot of the turtle.
--~ Preferably, try to refuel it a bit before starting the program, so that it won't have problem.

--~ Usage: there are 3 ways of launching the program:
--~ "mine"      will prompt the size
--~ "mine 16 32"    will make a quarry of 16 width and 32 long
--~ "mine 16 32 10"     will make the quarry start by going 10 times down, skipping the first layers

--~ How to place your base (side view) :
--~ _C
--~ C_T>
--~
--~ With C being chests, _ air and T the turtle, facing the > direction
--~ The chest at the top is the one that has to contain fuel,
--~ of the same type as the one put in the first slot of the turtle,
--~ so that the turtle will be able to refuel automatically.
--~ Charcoal is advised, being a renewable and reliable source of fuel,
--~ but you are free to use any fuel as long as it stays the same kind
--~ and is a valid fuel for turtles.

--~ As for the size (top view) :
--~ CTxxxxxxxxxxxxxxx
--~ _xxxxxxxxxxxxxxxx
--~ _xxxxxxxxxxxxxxxx
--~ _xxxxxxxxxxxxxxxx
--~
--~ this is the quarry for inputing "mine 4 16" (see above)

--~ The program is trying to log basic events, as via the function "log(text, alsoPrint)".
--~ If you do not wish for the log, comment (or delete) the log function and uncomment the second one.

--~ NOTE: it is a basic program, doesn't take much into account, and certainly not being shut down.
--~ As such, if the chuck unload, you will have to break the turtle and bring it back to the origin point before restarting it.

local x = 0
local y = 0
local h = 0
local dir = 0
local workX, workY, workH, workDir
local row = 0
local stop = false
local maxX, maxY
local args = {...}

local function log(text, alsoPrint)
    logName = "MiningLog.txt"
    local logFile = io.open(logName, "a")
    if logFile == nil then
        print("Error! ")
    else
        logFile:write(text.."\n")
        logFile:close()
    end
    if alsoPrint then
        print(text)
    end
end

--~ local function log(text, alsoPrint)
--~     if alsoPrint then
--~         print(text)
--~     end
--~ end

local function clearLog()
    logName = "MiningLog.txt"
    if fs.exists(logName) then
        fs.delete(logName)
    end
end

local function dig()
    local i = 0
    if turtle.detectUp() then
        turtle.digUp()
    end
    if turtle.detect() then
        turtle.dig()
    end
    if turtle.detectDown() then
        turtle.digDown()
    end
end

local function turn(direction)
    if direction == "left" then
        turtle.turnLeft()
        dir = (dir-1)%4
    elseif direction == "right" then
        turtle.turnRight()
        dir = (dir+1)%4
    end

    log("TURN "..direction.." x="..x.."  y="..y.." h="..h.." dir="..dir)
end

local function forward()
    local j=0
    while not turtle.forward() do
        if turtle.detect() then
            turtle.dig()
            j = j+1
            if j == 40 then
                stop = true
                return false
            end
        else
            turtle.attack()
        end
    end
    if dir == 0 then
        x = x+1
    elseif dir == 2 then
        x = x-1
    elseif dir == 1 then
        y = y+1
    elseif dir == 3 then
        y = y-1
    end
    return true
end

local function up()
    local j=0
    while not turtle.up() do
        if turtle.detectUp() then
            turtle.digUp()
            j = j+1
            if j == 40 then
                stop = true
                return false
            end
        else
            turtle.attackUp()
        end
    end
    h = h-1
    return true
end

local function down()
    local j=0
    while not turtle.down() do
        if turtle.detectDown() then
            turtle.digDown()
            j = j+1
            if j == 40 then
                stop = true
                return false
            end
        else
            turtle.attackDown()
        end
    end
    h = h+1
    return true
end

local function setDir(newDir)
    while not (newDir == dir) do
        turn("right")
    end
end

local function move()
    local locMin, locMax, locDirA, locDirB, directionA, directionB


    if row%2 == 0 then
        locMin = 0
        locMax = maxY
        directionA = "right"
        directionB = "left"
        locDir = 1
    else
        locMin = maxY
        locMax = 0
        directionA = "left"
        directionB = "right"
        locDir = 3
    end

    --Stopping the mining operation
    if x == locMax and y == 0 and turtle.detectDown() then
        stop = true
    --Going down to the next layer
    elseif x == 0 and y == locMax then

        for i=1,3 do
            local j=0
            down()
            if stop then
                break
            end
        end
        if not stop then
            row = row +1
        end
        log("DOWN  x="..x.."  y="..y.." h="..h.." dir="..dir)
    --Turning at end of a line
    elseif (x == maxX-1 and dir == 0) or (x == maxX and dir == locDir)then
        forward()
        turn(directionA)
    --Turning at the other end of the line
    elseif ((x == 1 and dir == 2) or (x==0 and dir == locDir)) and y ~= locMin and y ~= locMax  then
        forward()
        turn(directionB)
    elseif x==1 and y==locMax then
        forward()
        turn("right")
        turn("right")
    --In other cases, just go forward once
    else
        forward()
    end
end

local function returnHome()
    local curDir = dir
    local fuelCount
    log("Returning home: x="..x.."  y="..y.."  h="..h)


    for i=1,h do
        up()
    end

    setDir(3)
    for i=1, y do
        forward()
    end

    setDir(2)
    for i=1, x do
        forward()
    end
end

local function manageInventory()
    setDir(2)
    forward()

    local rowFuelNeed = maxX*maxY+h
    if turtle.getFuelLevel() < rowFuelNeed then
        turtle.select(1)
        turtle.suckUp()
        fuelCount = turtle.getItemCount(1) -1
        turtle.refuel(fuelCount)
        log("Refuelling...")
        if turtle.getFuelLevel() < rowFuelNeed then
            log("missing fuel")
            stop = true
        end
    end
    log("Dropping items")
    for i=2, 16 do
        turtle.select(i)
        turtle.drop()
    end

    turtle.select(1)
    setDir(0)

    forward()
end

local function returnPosition()

    log("Returning to work from : x="..x.."  y="..y.."  h="..h.." dir:"..dir)
    log("Returning to work to   : x="..workX.."  y="..workY.."  h="..workH.." dir:"..workDir)
    setDir(0)
    for i=x, workX-1 do
        forward()
    end

    setDir(1)
    for i=y, workY-1 do
        forward()
    end


    for i=h, workH-1 do
        down()
    end
    setDir(workDir)
end

local function inventoryCheck()
    local fuelLeft = turtle.getFuelLevel() -(x+y+h+1)
    if turtle.getItemCount(16) >0 or fuelLeft < 10 then
        workX = x
        workY = y
        workH = h
        workDir = dir
        returnHome()
        manageInventory()
        returnPosition()
        if(x == workX and y == workY and h == workH and dir == workDir) then
            log("Sucessfully returned at x="..x.."  y="..y.."  h="..h.."  dir="..dir)
        else
            log("For some reason, couldn't properly return, aborting...")
            stop = true
        end
    end
end

local function digLoop()
    while not stop do
        dig()
        inventoryCheck()
        move()
        if stop then
            returnHome()
            manageInventory()
            log("Your turtle has returned and stopped")
        end
    end
end

clearLog()
x=0
y=0
h=0
dir=0
if args[1] == nil then
    print("Size?")
    write("Width: ")
    maxY = read()
    maxY = maxY -1
    if maxY%2 == 0 then
        log("Width not a multiple of 2, adding 1", true)
        maxY =maxY+ 1
    end
    write("Length: ")
    maxX = read()
    maxX = maxX -1
    if maxX%2 == 0 then
        log("Length not a multiple of 2, adding 1", true)
        maxY =maxX+ 1
    end
else
    local var1, var2
    if args[2] == nil then
        var1 = args[1]-1
        if var1 == 0 then
            log("Not a multiple of 2, adding 1", true)
            var1 =var1+ 1
        end
        log(var1)
        maxX = var1
        maxY = var1
    else
        maxY = args[1]-1
        if maxY%2 == 0 then
            log("Width not a multiple of 2, adding 1", true)
            maxY =maxY+ 1
        end

        maxX = args[2]-1
        if maxX%2 == 0 then
            log("Length not a multiple of 2, adding 1", true)
            maxX =maxX+ 1
        end

        if args[3] ~= nill then
            workX = 0
            workY = 0
            workH = args[3]
            workDir = 0
            returnPosition()
        end
    end
end
log("Starting mining operation with dimensions "..(maxY+1).."x"..(maxX+1), true)

digLoop()