Tree choppa

-- Mocking the APIs for editor support
-- Remove before running in minecraft
--[[
local turtle = {
    select = function(_) end,
    getFuelLevel = function()
        return 1000
    end,
    refuel = function(_) end,
    dropDown = function() end,
    getItemCount = function(_)
        return 0
    end,
    forward = function()
        return true
    end,
    up = function()
        return true
    end,
    down = function()
        return true
    end,
    dig = function() end,
    digUp = function() end,
    digDown = function() end,
    back = function() end,
}
local redstone = {
    setOutput = function(_, _) end,
    getInput = function(_)
        return false
    end,
}
local os = {
    sleep = function(_) end,
}
local gps = {
    locate = function(_)
        return 0, 0, 0
    end,
}
local fs = {
    exists = function(_)
        return false
    end,
    open = function(_, _)
        return {
            writeLine = function(_) end,
            readLine = function()
                return "0"
            end,
            close = function() end,
        }
    end,
}
local rednet = {
    open = function(_) end,
    close = function(_) end,
}
--]]

-- Sapling goes to slot 1
-- Wood goes to slot 2
-- Fuel goes to slot 3
-- Trees should be on the right side of the turtle

local HOME_FILE_NAME = "tree_choppa_home"
local BLOCKS_BEFORE_TREES = 3
local TREE_BLOCKS = 27
local FUEL_MINIMUM = 1000

local function pulse(side)
    redstone.setOutput(side, true)
    os.sleep(0.05)
    redstone.setOutput(side, false)
    os.sleep(0.05)
end

local function refuel()
    turtle.select(3)
    while turtle.getFuelLevel() < FUEL_MINIMUM do
        print("Refueling...")
        if not turtle.refuel(0) then
            pulse("top")
            print("Waiting for fuel...")
            while not turtle.refuel(0) do
                os.sleep(10)
                pulse("top")
            end
        end
        turtle.refuel()
        print("Refueled!")
    end
    turtle.select(1)
end

local function restock()
    print("Restocking saplings...")
    turtle.dropDown()
    pulse("back")

    if turtle.getItemCount(1) == 0 then
        print("Waiting for saplings...")
        while turtle.getItemCount(1) == 0 do
            os.sleep(10)
            pulse("back")
        end
    end
    print("Restocked!")
end

local function dropAll()
    print("Dropping all collected items...")
    for i = 3, 16 do
        if turtle.getItemCount(i) ~= 0 then
            turtle.select(i)
            turtle.dropDown()
        end
    end
    turtle.select(1)
    print("Dropped all collected items!")
end

local function forward()
    if not turtle.forward() then
        print("Can't go forward, please clear the way manually") --Should happen rarely if ever
        while not turtle.forward() do
            os.sleep(10)
        end
        print("The way is cleared, continuing...")
    end
end

local function back()
    if not turtle.back() then
        print("Can't go back, please clear the way manually") --Should happen rarely if ever
        while not turtle.back() do
            os.sleep(10)
        end
        print("The way is cleared, continuing...")
    end
end

local function down()
    while not turtle.down() do
        turtle.digDown()
    end
end

local function up()
    while not turtle.up() do
        turtle.digUp()
    end
end

local function comeDown(dy)
    print("Coming down for " .. dy .. " blocks")
    for _ = dy, 1, -1 do
        down()
    end
    print("Came down!")
end

local function chopUp()
    print("Chopping up the tree...")
    local dy = 0
    while turtle.detect() do
        turtle.dig()
        up()
        dy = dy + 1
    end
    print("Chopped up the tree of height " .. dy)
    return dy
end

local function locate()
    print("Getting the current location via GPS...")
    rednet.open("right")
    local x, y, z = gps.locate(1)
    if x == nil then
        print("Waiting for GPS signal, probably lost signal due to a storm")
        while x == nil do
            os.sleep(10)
            x, y, z = gps.locate(1)
        end
    end
    rednet.close("right")
    print("Got the current location via GPS!")
    return x, y, z
end

local function comeBack(xz, xz0)
    print("Coming back to the home point...")
    for _ = 1, math.abs(xz0 - xz) do
        back()
    end
    print("At the home point!")
end

local function checkAndChop()
    turtle.turnRight()
    turtle.select(2)
    if turtle.compare() then
        local dy = chopUp()
        comeDown(dy)
        dropAll()
    end
    turtle.select(1)
    turtle.place()
    turtle.turnLeft()
end

local function init()
    local x, y, z = locate()
    turtle.select(1)
    local x0, y0, z0, s0 = nil, nil, nil, nil

    print("Checking if the home point is saved...")
    if not fs.exists(HOME_FILE_NAME) then
        print("Home point is not saved, I am at the very start, creating a file for the home point...")
        x0 = x
        y0 = y
        z0 = z

        print("Home point is at x=" .. x0 .. ", y=" .. y0 .. ", z=" .. z0)

        restock()
        refuel()

        print("Moving to determine the orientation...")
        forward()
        local x1, _, z1 = locate()
        back()
        if x1 > x0 then
            s0 = "x+"
        elseif x1 < x0 then
            s0 = "x-"
        elseif z1 > z0 then
            s0 = "z+"
        else
            s0 = "z-"
        end
        print("Orientation is " .. s0)

        print("Writing the home point and orientation to the file...")
        local f = fs.open(HOME_FILE_NAME, "w")
        f.writeLine(tostring(x0))
        f.writeLine(tostring(y0))
        f.writeLine(tostring(z0))
        f.writeLine(s0)
        f.close()
        print("A home point and an orientation are saved!")
        return
    end

    print("Not at the very start, loading the home point from the file...")
    local f = fs.open(HOME_FILE_NAME, "r")
    x0 = tonumber(f.readLine())
    y0 = tonumber(f.readLine())
    z0 = tonumber(f.readLine())
    s0 = f.readLine()
    f.close()
    print("Home point is at x=" .. x0 .. ", y=" .. y0 .. ", z=" .. z0)
    print("Orientation is " .. s0)

    print("Checking if turtle is in the air...")
    if y > y0 then
        print("Turtle is in the air")
        turtle.dig()
        up()
        local dy = chopUp()
        comeDown(y + 1 + dy - y0)
        turtle.place()
        turtle.turnLeft()
        dropAll()
        if (s0 == "x+") or (s0 == "x-") then
            comeBack(x, x0)
        else
            comeBack(z, z0)
        end
        return
    end

    print("Turtle is on the ground")
    print("Checking if turtle is not in line with the home point...")
    if ((s0 == "x+") or (s0 == "x-")) and (z ~= z0) then
        print("Turtle is not in line with the home point, correcting")
        for _ = 1, math.abs(z - z0) do
            forward()
        end
        turtle.place()
        turtle.turnLeft()
        dropAll()
        comeBack(x, x0)
        return
    end
    if ((s0 == "z+") or (s0 == "z-")) and (x ~= x0) then
        print("Turtle is not in line with the home point, correcting")
        for _ = 1, math.abs(x - x0) do
            forward()
        end
        turtle.place()
        turtle.turnLeft()
        dropAll()
        comeBack(z, z0)
        return
    end

    print("Moving the turtle to tell orientation...")
    if not turtle.back() then
        print("Can't move back, must be at the start") -- Can be false positive, but I doubt this situation will ever happen
        return
    end
    local x1, _, z1 = locate()
    forward()

    if (s0 == "x+") or (s0 == "x-") then
        if z1 ~= z0 then
            turtle.place()
            turtle.turnLeft()
        end
        dropAll()
        comeBack(x, x0)
        return
    else
        if x1 ~= x0 then
            turtle.place()
            turtle.turnLeft()
        end
        dropAll()
        comeBack(z, z0)
        return
    end
end

print("Initializing the turtle...")
init()
restock()
refuel()
print("Initialized!")

local loopCount = 0

-- Main loop
while true do
    loopCount = loopCount + 1
    print("Starting loop " .. loopCount)

    for _ = 1, BLOCKS_BEFORE_TREES do
        forward()
    end
    for _ = 1, TREE_BLOCKS do
        forward()
        checkAndChop()
    end

    for _ = 1, TREE_BLOCKS - 1 do
        back()
        checkAndChop()
    end
    for _ = 1, BLOCKS_BEFORE_TREES + 1 do
        back()
    end

    restock()
    refuel()
end