snakemine

-- Dig the snake-like branch mine four times.
-- Returns frequently to drop off supplies.
-- Places torches reasonably when they are placed in slot 16.

function turnAround()
    for i=1,2 do
       turtle.turnLeft()
    end
end

function smartForward()
    --Dig a 2 high, 1 wide tunnel; gravel and sand friendly.
    while not turtle.forward() do
        turtle.dig()
    end
    while turtle.detectUp() do
        turtle.digUp()
        sleep(0.5)
    end
end

function snakeRight()
    -- Make a right turn in the snake.
    turtle.turnRight()
    for i=1,3 do
        smartForward()
    end
    turtle.select(16)
    turtle.placeUp()
    turtle.turnRight()
end

function snakeLeft()
    -- Make a left turn in the snake.
    turtle.turnLeft()
    for i=1,3 do
        smartForward()
    end
    turtle.select(16)
    turtle.placeUp()
    sleep(0.25)
    turtle.turnLeft()
end

function snakeSegment(l)
    -- Complete one segment of the snake of length l
    -- Turtle starts facing the wall for the first run
    for i=1,l do
        smartForward()
        if i % 10 == 0 then
            torchPlace()
        end
    end
    snakeRight()
    for i=1,l*2 do
        smartForward()
        if i % 10 == 0 then
            torchPlace()
        end
    end
    snakeLeft()
    for i=1,l do
        smartForward()
        if i % 10 == 0 then
            torchPlace()
        end
    end
end

function torchPlace()
    turtle.select(16)
    turtle.turnRight()
    sleep(0.25)
    turtle.placeUp()
    turtle.turnLeft()
end


function goHome(l)
    -- After a segment of length l, return to base
    -- Drop off items
    turtle.turnLeft()
    for i=1,l+2 do
        smartForward()
    end
    for j = 1,15 do
        turtle.select(j)
        turtle.drop()
    end
end

function resume(l)
    for i =1,l+2 do
        turtle.forward()
    end
    turtle.turnLeft()
end

local args = {...}
if table.getn(args) < 1 then
    print("Usage: snakemine maxlength")
    print("maxlength is the length of the largest side branch. Must be multiple of 6")
    print("Make sure torches are in slot 16!")
    return
end
-- first arg is the maximum length of a tunnel off of
local maxLength = tonumber(args[1])
if maxLength % 6 ~= 0 then
    print("maxLength of " .. maxLength .. " is not a multiple of 6! Try again!")
    return
end

for quad = 1,4 do
    for i = 1,3 do smartForward() end
    turtle.turnLeft()
    for seg = 6,maxLength,6 do
        snakeSegment(seg)
        goHome(seg)
        if seg < maxLength then
            turnAround()
            resume(seg)
        else
            for i=1,4 do
                turtle.forward()
            end
            turtle.turnLeft()
        end
    end

end