local coalChest = "minecraft:chest"
local dir = 1
local coalDir = 1
local chestDirs = {["minecraft:iron_block"]=4, ["minecraft:redstone"]=2, ["minecraft:ender_pearl"]=3}


function findCoalChest() 
    for i = 1,4 do
        local block, data = turtle.inspect()
        if block then
            if data.name == coalChest then
                dir = 1
                return
            end
        end
        turtle.turnRight()
    end
end

function right()
    turtle.turnRight()

    dir = dir+1
    if dir > 4 then
        dir = 1
    end
end

function left()
    turtle.turnLeft()

    dir = dir-1
    if dir < 1 then
        dir = 4
    end
end

function setDir(d)
    if dir == 1 and d == 4 then
        left()
    elseif dir == 4 and d == 1 then
        right()
    end

    while d > dir do
        right()
    end

    while d < dir do
        left()
    end
end

function fillInv()
    while turtle.detectUp() == false do
        turtle.up()
    end

    if turtle.getFuelLevel() < 1000 then
        setDir(1)
        turtle.select(16)
        turtle.suck(10)
        turtle.refuel(64)
    end
    local invDef = {[1]="minecraft:iron_block", [2]="minecraft:redstone", [3]="minecraft:ender_pearl"}
    local invLayout =  {1, 1, 2, 2,
                        3, 3, 3, 3,
                        3, 3, 3, 3}

    for i = 1, 12 do
        local item = invDef[invLayout[i]]
        local count = 64
        if item == "minecraft:ender_pearl" then
            count = 16
        end
        if turtle.getItemCount(i) < count then
            setDir(chestDirs[item])
            turtle.select(i)
            turtle.suck(count - turtle.getItemCount())
        end
    end

end

function pick(item)
    for i = 1,12 do
        turtle.select(i)
        local data = turtle.getItemDetail()
        if data then
            if data.name == item then
                return
            end
        end
    end

    --If no items were found then go fill up
    fillInv()
    pick(item)
    turtle.down()
    turtle.down()
end

function makeWall()
    while turtle.detectUp() == false do
        turtle.up()
    end

    turtle.down()
    turtle.down()

    pick("minecraft:iron_block")
    turtle.placeDown()
    
    turtle.up()
    pick("minecraft:redstone")
    turtle.placeDown()

    turtle.up()
    pick("minecraft:ender_pearl")
    turtle.dropDown(1)
end

findCoalChest()


while true do
    makeWall()
    sleep(12)
end