function find_item(name, count)
    for i=1, 16 do
        turtle.select(i)
        item = turtle.getItemDetail()
        if item then
            if item.name == "minecraft:sapling" then
                if count == nil then
                    return true
                end
                if count <= item.count then
                    return true
                end
            end
        end
    end
    return false
end

function forward()
    if not turtle.forward() then
        a, b = turtle.inspect()
        if a then
            if b.name == "minecraft:leaves" then
                turtle.dig()
                turtle.forward()
            end
        end
    end
end

function up()
    if not turtle.up() then
        a, b = turtle.inspectUp()
        if a then
            if b.name == "minecraft:leaves" then
                turtle.digUp()
                turtle.up()
            end
        end
    end
end

function down()
    if not turtle.down() then
        a, b = turtle.inspectDown()
        if a then
            if b.name == "minecraft:leaves" then
                turtle.digDown()
                turtle.down()
            end
        end
    end
end

function harvest_trees()
    print("Harvesting trees")
    refuel()
    down()
    turtle.dig()
    forward()
    turtle.dig()
    turtle.turnLeft()
    local leftSide = false;
    a, b = turtle.inspect()
    print(b.name)
    if a then
        if b.name == "minecraft:log" then
            leftSide = true;
        end
    end
    print("leftSide: " .. tostring(leftSide))
    turtle.turnRight()

    local tree_height = 0
    while turtle.detectUp() do
        tree_height = tree_height + 1
        turtle.digUp()
        up()
        turtle.dig()
        refuel()
    end
    if leftSide then turtle.turnLeft() else turtle.turnRight() end
    turtle.dig()
    forward()
    if leftSide then turtle.turnRight() else turtle.turnLeft() end
    turtle.dig()
    for i=1, tree_height do
        refuel()
        turtle.digDown()
        down()
        turtle.dig()
    end
    if find_item("minecraft:sapling", 4) then
        print("Sapling found in inventory, replanting")
        refuel()
        up()
        turtle.placeDown()
        forward()
        turtle.placeDown()
        if leftSide then turtle.turnRight() else turtle.turnLeft() end
        forward()
        turtle.placeDown()
        if leftSide then turtle.turnRight() else turtle.turnLeft() end
        forward()
        turtle.placeDown()
        forward()
        down()
    else
        refuel()
        if leftSide then turtle.turnRight() else turtle.turnLeft() end
        forward()
        if leftSide then turtle.turnRight() else turtle.turnLeft() end
        forward()
    end
    up()
end

function check_grown()
    for i=1, 4 do
        turtle.turnRight()
        a, b = turtle.inspect()
        if a then
            if b.name == "minecraft:log" then
                return true
            end
        end
    end
    return false
end

function wait_for_grow()
    while not check_grown() do
        sleep(5)
    end
    print("Tree grown!")
end

function collect_saplings()
    print("Collecting saplings")
    local above = false
    refuel()
    above = log_avoidant_forward(above)
    above = log_avoidant_forward(above)
    turtle.turnRight()
    above = log_avoidant_forward(above)
    above = log_avoidant_forward(above)
    turtle.turnRight()

    for j=1, 2 do
        for i=1, 4 do
            above = log_avoidant_forward(above)
        end
        turtle.turnRight()
        above = log_avoidant_forward(above)
        turtle.turnRight()
        for i=1, 4 do
            above = log_avoidant_forward(above)
        end

        turtle.turnLeft()
        above = log_avoidant_forward(above)
        turtle.turnLeft()
    end
    for i=1, 4 do
        above = log_avoidant_forward(above)
    end
    turtle.turnLeft()
    above = log_avoidant_forward(above)
    above = log_avoidant_forward(above)
    turtle.turnLeft()
    above = log_avoidant_forward(above)
    above = log_avoidant_forward(above)
end

function organize_inventory()
    refuel()
    down()
    turtle.select(1)
    item = turtle.getItemDetail()
    if item ~= nil and item.name ~= "minecraft:log" then
        turtle.dropDown()
    end
    turtle.select(2)
    item = turtle.getItemDetail()
    if item ~= nil and item.name ~= "minecraft:sapling" then
        turtle.dropDown()
    end

    for i=3, 16 do
        turtle.select(i)
        item = turtle.getItemDetail()
        if item ~= nil then
            if item.name == "minecraft:log" then
                turtle.transferTo(1)
            elseif item.name == "minecraft:sapling" then
                turtle.transferTo(2)
            end
            turtle.dropDown()
        end
    end

    up()
end

function log_avoidant_forward(above)
    refuel()
    turtle.suckDown()
    a, b = turtle.inspect()
    if a then
        if b.name == "minecraft:log" then
            if not above then
                up()
            end
            turtle.dig()
            forward()
            return true
        else
            turtle.dig()
            forward()
            if above then
                down()
            end
            return false
        end
    else
        forward()
        if above then
            down()
        end
        return false
    end
end

function refuel()
    if turtle.getFuelLevel() > 8 then
        return
    end
    for i=1, 16 do
        turtle.select(i)
        if turtle.refuel(1) then
            break
        end
    end
end

refuel()
if not turtle.detectDown() then
    down()
end

up()

while true do
    wait_for_grow()
    while check_grown() do
        harvest_trees()
    end
    collect_saplings()
    organize_inventory()
end