-- ============================================================
-- Six-tree automatic tree farm
-- For a ComputerCraft / CC:Tweaked Felling Turtle
--
-- Starting position:
--   X = 286
--   Z = 108
--   Y = 63
--
-- IMPORTANT:
-- Turtle must start facing +Z (toward Z=109,110,...)
--
-- Chest must be directly UNDER the turtle's starting position.
-- ============================================================


-- ------------------------------------------------------------
-- CONFIGURATION
-- ------------------------------------------------------------

local HOME_X = 286
local HOME_Z = 108

-- Tree coordinates, expressed as X/Z because all are at Y=63.
local trees = {
    { x = 284, z = 110 },
    { x = 288, z = 110 },

    { x = 284, z = 114 },
    { x = 288, z = 114 },

    { x = 284, z = 118 },
    { x = 288, z = 118 }
}

-- How long to wait between complete farm checks.
local CHECK_INTERVAL = 30

-- Maximum bone-meal attempts before giving up on a sapling.
local MAX_BONEMEAL_ATTEMPTS = 32

-- Refuel if below this amount.
local MIN_FUEL = 250


-- ------------------------------------------------------------
-- POSITION TRACKING
-- ------------------------------------------------------------
--
-- Direction:
--   0 = +Z
--   1 = -X
--   2 = -Z
--   3 = +X
--
-- We start facing +Z.
-- ------------------------------------------------------------

local posX = HOME_X
local posZ = HOME_Z
local direction = 0


local function turnLeft()
    turtle.turnLeft()
    direction = (direction + 1) % 4
end


local function turnRight()
    turtle.turnRight()
    direction = (direction + 3) % 4
end


local function face(target)
    while direction ~= target do
        turnRight()
    end
end


local function forward()
    local attempts = 0

    while not turtle.forward() do
        attempts = attempts + 1

        if attempts > 20 then
            error("Unable to move forward.")
        end

        -- Don't automatically destroy random obstacles.
        sleep(0.25)
    end

    if direction == 0 then
        posZ = posZ + 1
    elseif direction == 1 then
        posX = posX - 1
    elseif direction == 2 then
        posZ = posZ - 1
    elseif direction == 3 then
        posX = posX + 1
    end
end


local function back()
    local attempts = 0

    while not turtle.back() do
        attempts = attempts + 1

        if attempts > 20 then
            error("Unable to move backward.")
        end

        sleep(0.25)
    end

    if direction == 0 then
        posZ = posZ - 1
    elseif direction == 1 then
        posX = posX + 1
    elseif direction == 2 then
        posZ = posZ + 1
    elseif direction == 3 then
        posX = posX - 1
    end
end


-- ------------------------------------------------------------
-- NAVIGATION
-- ------------------------------------------------------------

local function moveTo(x, z)

    -- X movement
    if posX < x then
        face(3) -- +X

        while posX < x do
            forward()
        end

    elseif posX > x then
        face(1) -- -X

        while posX > x do
            forward()
        end
    end


    -- Z movement
    if posZ < z then
        face(0) -- +Z

        while posZ < z do
            forward()
        end

    elseif posZ > z then
        face(2) -- -Z

        while posZ > z do
            forward()
        end
    end
end


local function goHome()
    moveTo(HOME_X, HOME_Z)
    face(0)
end


-- ------------------------------------------------------------
-- ITEM IDENTIFICATION
-- ------------------------------------------------------------

local function endsWith(text, suffix)
    return text:sub(-#suffix) == suffix
end


local function isSaplingName(name)
    if not name then
        return false
    end

    return endsWith(name, "_sapling") or
           name == "minecraft:mangrove_propagule"
end


local function isLogName(name)
    if not name then
        return false
    end

    return endsWith(name, "_log") or
           endsWith(name, "_wood") or
           endsWith(name, "_stem") or
           endsWith(name, "_hyphae")
end


local function isFuelName(name)
    return name == "minecraft:coal" or
           name == "minecraft:charcoal" or
           name == "minecraft:coal_block"
end


local function isBoneMealName(name)
    return name == "minecraft:bone_meal"
end


-- ------------------------------------------------------------
-- INVENTORY SEARCH
-- ------------------------------------------------------------

local function findItem(testFunction)

    for slot = 1, 16 do
        local item = turtle.getItemDetail(slot)

        if item and testFunction(item.name) then
            return slot, item
        end
    end

    return nil
end


local function findBoneMeal()
    return findItem(isBoneMealName)
end


local function findAnySapling()
    return findItem(isSaplingName)
end


local function findExactItem(name)

    for slot = 1, 16 do
        local item = turtle.getItemDetail(slot)

        if item and item.name == name then
            return slot
        end
    end

    return nil
end


-- ------------------------------------------------------------
-- FUEL
-- ------------------------------------------------------------

local function refuel()

    local fuel = turtle.getFuelLevel()

    if fuel == "unlimited" then
        return true
    end

    if fuel >= MIN_FUEL then
        return true
    end

    print("Fuel low: " .. fuel)

    for slot = 1, 16 do

        local item = turtle.getItemDetail(slot)

        if item and isFuelName(item.name) then

            turtle.select(slot)

            while turtle.getItemCount(slot) > 0 and
                  turtle.getFuelLevel() < MIN_FUEL do

                turtle.refuel(1)
            end

            if turtle.getFuelLevel() >= MIN_FUEL then
                print("Refueled: " .. turtle.getFuelLevel())
                return true
            end
        end
    end

    print("WARNING: No fuel available!")
    return false
end


-- ------------------------------------------------------------
-- BLOCK INSPECTION
-- ------------------------------------------------------------

local function blockInFront()

    local success, block = turtle.inspect()

    if success then
        return block
    end

    return nil
end


local function logInFront()

    local block = blockInFront()

    return block and isLogName(block.name)
end


local function logAbove()

    local success, block = turtle.inspectUp()

    return success and isLogName(block.name)
end


local function logBelow()

    local success, block = turtle.inspectDown()

    return success and isLogName(block.name)
end


-- ------------------------------------------------------------
-- RECURSIVE TREE HARVEST
--
-- Turtle should be standing INSIDE the location of a log which
-- it has just removed.
--
-- Every recursive call returns the turtle to exactly the same
-- location and orientation from which that call started.
-- ------------------------------------------------------------

local function harvestConnectedLogs()

    -- ----- LOG ABOVE -----

    if logAbove() then

        turtle.digUp()

        if turtle.up() then

            harvestConnectedLogs()

            turtle.down()
        end
    end


    -- ----- LOG BELOW -----
    --
    -- Normally the parent log has already been removed, so this
    -- will not cause us to walk back through the tree.
    --
    -- It also catches unusual downward-connected branches.
    --

    if logBelow() then

        turtle.digDown()

        if turtle.down() then

            harvestConnectedLogs()

            turtle.up()
        end
    end


    -- ----- FOUR HORIZONTAL DIRECTIONS -----

    for side = 1, 4 do

        if logInFront() then

            turtle.dig()

            if turtle.forward() then

                harvestConnectedLogs()

                turtle.back()
            end
        end

        turtle.turnRight()
    end

end


-- ------------------------------------------------------------
-- DETERMINE REPLACEMENT SAPLING FROM LOG TYPE
-- ------------------------------------------------------------

local function saplingFromLog(logName)

    if not logName then
        return nil
    end

    -- minecraft:oak_log -> minecraft:oak_sapling
    if endsWith(logName, "_log") then

        local prefix = logName:sub(1, #logName - 4)

        return prefix .. "_sapling"
    end


    -- Wood variants
    if endsWith(logName, "_wood") then

        local prefix = logName:sub(1, #logName - 5)

        return prefix .. "_sapling"
    end


    return nil
end


-- ------------------------------------------------------------
-- GROW SAPLING
-- ------------------------------------------------------------

local function growSapling()

    for attempt = 1, MAX_BONEMEAL_ATTEMPTS do

        local block = blockInFront()

        -- It grew.
        if block and isLogName(block.name) then
            print("Tree grew after " .. (attempt - 1) ..
                  " bone meal attempts.")

            return true, block.name
        end


        -- No longer a sapling and not a log.
        if not block or not isSaplingName(block.name) then
            return false, nil
        end


        local slot = findBoneMeal()

        if not slot then
            print("Out of bone meal.")
            return false, nil
        end


        turtle.select(slot)

        turtle.place()

        sleep(0.15)
    end


    local block = blockInFront()

    if block and isLogName(block.name) then
        return true, block.name
    end

    print("Sapling did not grow.")
    return false, nil
end


-- ------------------------------------------------------------
-- PLANT SAPLING
-- ------------------------------------------------------------

local function plantSapling(preferredName)

    local slot = nil


    -- Try to use the same species.
    if preferredName then
        slot = findExactItem(preferredName)
    end


    -- Otherwise use whatever sapling is available.
    if not slot then
        slot = findAnySapling()
    end


    if not slot then
        print("WARNING: No saplings available!")
        return false
    end


    turtle.select(slot)

    if turtle.place() then
        print("Sapling planted.")
        return true
    end


    print("WARNING: Unable to plant sapling.")
    return false
end


-- ------------------------------------------------------------
-- HARVEST A SINGLE TREE
--
-- Turtle is standing one block NORTH (-Z) of the planting spot
-- and facing SOUTH (+Z).
-- ------------------------------------------------------------

local function processTree()

    local block = blockInFront()

    if not block then
        print("Planting spot is empty.")

        plantSapling(nil)

        return
    end


    local preferredSapling = nil


    -- --------------------------------------------------------
    -- SAPLING
    -- --------------------------------------------------------

    if isSaplingName(block.name) then

        print("Sapling detected: " .. block.name)

        preferredSapling = block.name

        local grown, logName = growSapling()

        if not grown then
            print("Leaving sapling for next pass.")
            return
        end

        block = blockInFront()

        if not block then
            return
        end
    end


    -- --------------------------------------------------------
    -- TREE
    -- --------------------------------------------------------

    if isLogName(block.name) then

        print("Tree detected: " .. block.name)

        if not preferredSapling then
            preferredSapling = saplingFromLog(block.name)
        end


        -- Remove base trunk.
        turtle.dig()


        -- Move into the space previously occupied by the trunk.
        if not turtle.forward() then
            print("ERROR: Could not enter trunk location.")
            return
        end


        -- Cut every connected log.
        harvestConnectedLogs()


        -- Return to our approach square.
        turtle.back()


        -- Plant replacement.
        plantSapling(preferredSapling)

        print("Tree harvested.")

        return
    end


    print("Not a tree or sapling: " .. block.name)
end


-- ------------------------------------------------------------
-- DROP HARVEST INTO CHEST
-- ------------------------------------------------------------

local function dumpHarvest()

    goHome()

    print("Dropping harvest into chest...")


    for slot = 1, 16 do

        local item = turtle.getItemDetail(slot)

        if item then

            local keep =
                isBoneMealName(item.name) or
                isSaplingName(item.name) or
                isFuelName(item.name)


            if not keep then
                turtle.select(slot)

                if not turtle.dropDown() then
                    print("Chest may be full!")
                end
            end
        end
    end

end


-- ------------------------------------------------------------
-- VISIT ONE TREE
-- ------------------------------------------------------------

local function visitTree(tree)

    refuel()


    -- Stand one block north of the tree.
    local approachX = tree.x
    local approachZ = tree.z - 1


    moveTo(approachX, approachZ)


    -- Face south, toward the tree.
    face(0)


    print("")
    print("---------------------------")
    print("Tree " .. tree.x .. ", " .. tree.z)
    print("---------------------------")


    processTree()


    -- Deposit after EACH tree.
    dumpHarvest()
end


-- ------------------------------------------------------------
-- MAIN PROGRAM
-- ------------------------------------------------------------

print("")
print("================================")
print(" Six Tree Automatic Tree Farm")
print("================================")
print("")
print("Home: " .. HOME_X .. ", " .. HOME_Z)
print("Trees: " .. #trees)
print("")


refuel()


while true do

    print("")
    print("Beginning farm sweep...")

    for i, tree in ipairs(trees) do

        print("")
        print("Tree " .. i .. " of " .. #trees)

        visitTree(tree)
    end


    goHome()

    dumpHarvest()

    print("")
    print("Sweep complete.")
    print("Sleeping " .. CHECK_INTERVAL .. " seconds.")

    sleep(CHECK_INTERVAL)
end