branch_miner

-- This work is licensed under a CC BY-NC-SA 3.0 license.
-- http://creativecommons.org/licenses/by-nc-sa/3.0/
--
-- by the Forlorn Hedgehog
--
-- Usage: branchMine <length>
-- Fuel goes in slot 1. Torches go in slot 2. Floor blocks (usually cobblestone) go in slot 3.
-- Mines a trunk <length> blocks long, with an 8 block long branch, on each side, every 3 blocks, starting 2 blocks in (n=3n-1)

-- If fuel level is less than 10, refuel
function fuel()
    if turtle.getFuelLevel() < 10 then
        turtle.select(1)
        if turtle.refuel(1) then
            return true
        end
        print("Refuelling failed.")
        return false
    end
end

-- Place floor block, if there is not already one.
function placeFloorBlock()
    if not turtle.detectDown() then
        turtle.select(3)
        if turtle.placeDown() then
            return true
        end
        print("Placing floor block failed.")
        return false
    end
end

-- Digs and moves into a 1x2x1 (xyz) area.
function basicDigAndMove()
    while not turtle.forward() do
        if not turtle.dig() then
            turtle.attack()
        end
    end
    while turtle.detectUp() do
        turtle.digUp()
        sleep(0.5)
    end
    placeFloorBlock()
end

-- Turn turtle 180 degrees
function turnAround()
    turtle.turnLeft()
    turtle.turnLeft()
end

-- Place torch on floor, in front of the turtle
function placeTorch()
    turtle.select(2)
    if turtle.place() then
        return true
    end
    print("Placing torch failed.")
    return false
end

-- This function mines a 1x2x8 (xyz) tunnel directly infront of the turtle, placing a torch near the end, and returning to start point (but in opposite orientation)
function branch()
    local blocksMovedSideways = 0
    while blocksMovedSideways < 8 do
        fuel()
        basicDigAndMove()
        blocksMovedSideways = blocksMovedSideways + 1

        if blocksMovedSideways == 8 then
            turnAround()
            placeTorch()
        end
    end

    -- Back to start point (goes up to avoid the torch on floor)
    turtle.up()
    for i=1,8 do
        turtle.forward()
        blocksMovedSideways = blocksMovedSideways - 1
    end
    turtle.down()
end

-- Arguments
local tArgs = {...}
if #tArgs ~= 1 or tonumber(tArgs[1]) == nil or math.floor(tonumber(tArgs[1])) ~= tonumber(tArgs[1]) or tonumber(tArgs[1]) < 1 then
    print("Usage: branchMine <length>")
    return
end

local length = tonumber(tArgs[1])

local blocksMovedForward = 0
while blocksMovedForward < length do
    fuel()
    basicDigAndMove()
    blocksMovedForward = blocksMovedForward + 1

    -- Add torch (on floor) every 8 blocks
    if (blocksMovedForward % 8) == 0 then
        turnAround()
        placeTorch()
        turnAround()
    end

    -- n=3n-1
    if ((blocksMovedForward + 1) % 3) == 0 then
        turtle.turnLeft()
        branch()
        branch()
        turtle.turnRight()
    end
end