Collector

local MAX_LEVEL = 2
local price = 16
local WHEREIS_CHANNEL = 420

local LEVEL_DETECTION_BLOCK = "minecraft:planks"
local CHEST_BLOCK = "ironchest:BlockIronChest"
local CHEST_POSITION_BLOCK = "minecraft:sandstone"
local RIGHT_CHEST_TYPE = "smooth_sandstone"

local activities = {
    TRANSIT_DOWN = 1, -- go down until current level == target level. when meeting a plank block increase current level
    TRANSIT_OUT = 2, -- back out of the vertical track until bottom is sandstone
    CHEST_IN = 3, -- turn toward the chest and travel forward until the chest is met
    CHEST_COLLECT = 4, -- fill up the turtle
    CHECK_OUT = 5, -- go backwards from the chest until bottom is sandstone
    TRANSIT_IN = 6, -- turn toward the vertical track until front is not air
    TRANSIT_UP = 7, -- goes up until above is not air
    CHEST_DROP = 8, -- drop entire inventory up. set current level to zero. increase target level by one, wrapping if needed
}

local directions = {
    CROP_TOWARD = 0,
    CHEST_TOWARD = 1,
    CROP_AWAY = 2,
    CHEST_AWAY = 3
}

-- fix the modem bug
if not peripheral.find("modem") then
    -- first find an empty slot
    for i = 1, 16 do
        if turtle.getItemCount(i) == 0 then
            turtle.select(i)
            break
        elseif i == 16 then
            turtle.select(i)
            turtle.drop()
        end
    end
    turtle.equipLeft()
    turtle.equipLeft()
    turtle.equipRight()
    turtle.equipRight()
end

local state
local function loadState()
    local h = fs.open("mover.state", "r")
    if h then
        state = textutils.unserialise(h.readAll())
        h.close()
    else
        state = {
            activity = activities.TRANSIT_DOWN,
            direction = directions.CROP_TOWARD,
            currentLevel = 0,
            targetLevel = 1,
            startFuel = turtle.getFuelLevel(),
            isChestRight = false
        }
    end
end

local function saveState()
    local h = fs.open("mover.state", "w")
    if h then
        h.write(textutils.serialise(state))
        h.close()
    end
end

local function turnTo(direction)
    local difference = direction - state.direction
    if math.abs(difference) >= 3 then
        difference = (difference - 2 * (difference / math.abs(difference))) * -1
    end
    if difference > 0 then
        for i = 1, difference do
            turtle.turnLeft()
            state.direction = (state.direction + 1) % 4
            saveState()
        end
    elseif difference < 0 then
        for i = 1, math.abs(difference) do
            turtle.turnRight()
            state.direction = (state.direction - 1) % 4
            saveState()
        end
    end
end

local function setActivity(activity)
    if not activity then error('act') end
    state.activity = activity
    saveState()
end

local funcs = {}

local function activity(activity)
    setActivity(activity)
    return funcs[activity]()
end

funcs[activities.TRANSIT_DOWN] = function()
    print("Descending to level " .. state.targetLevel)
    turnTo(directions.CROP_TOWARD)
    while true do
        local isBlock, block = turtle.inspect()
        if isBlock and block.name == LEVEL_DETECTION_BLOCK then
            state.currentLevel = state.currentLevel + 1
            print("Level: " .. state.currentLevel)
            if state.currentLevel == state.targetLevel then
                return activity(activities.TRANSIT_OUT)
            end
        end
        turtle.down()
    end
end

funcs[activities.TRANSIT_OUT] = function()
    print("Leaving vertical track")
    turnTo(directions.CROP_TOWARD)
    while true do
        local isBlock, block = turtle.inspectDown()
        if isBlock and block.name == CHEST_POSITION_BLOCK then
            state.isChestRight = block.state.type == RIGHT_CHEST_TYPE
            saveState()
            return activity(activities.CHEST_IN)
        else
            turtle.back()
        end
    end
end

funcs[activities.CHEST_IN] = function()
    print("Heading toward chest")
    turnTo(state.isChestRight and directions.CHEST_AWAY or directions.CHEST_TOWARD)
    while true do
        local isBlock, block = turtle.inspect()
        if isBlock then
            return activity(activities.CHEST_COLLECT)
        else
            turtle.forward()
        end
    end
end

funcs[activities.CHEST_COLLECT] = function()
    print("Collecting items...")
    turnTo(state.isChestRight and directions.CHEST_AWAY or directions.CHEST_TOWARD)
    while turtle.suck() do end
    return activity(activities.CHECK_OUT)
end

funcs[activities.CHECK_OUT] = function()
    print("Leaving chest...")
    turnTo(state.isChestRight and directions.CHEST_AWAY or directions.CHEST_TOWARD)
    while true do
        local isBlock, block = turtle.inspectDown()
        if isBlock and block.name == CHEST_POSITION_BLOCK then
            return activity(activities.TRANSIT_IN)
        else
            turtle.back()
        end
    end
end

funcs[activities.TRANSIT_IN] = function()
    print("Heading toward vertical track...")
    turnTo(directions.CROP_TOWARD)
    while true do
        local isBlock, block = turtle.inspect()
        if isBlock then
            return activity(activities.TRANSIT_UP)
        else
            turtle.forward()
        end
    end
end

funcs[activities.TRANSIT_UP] = function()
    print("Travelling up to the drop chest...")
    turnTo(directions.CROP_TOWARD)
    while true do
        local isBlock, block = turtle.inspectUp()
        if isBlock and block.name == CHEST_BLOCK then
            return activity(activities.CHEST_DROP)
        else
            turtle.up()
        end
    end
end

funcs[activities.CHEST_DROP] = function()
    print("Dropping the items in the chest...")
    local count = 0
    for i = 1, 16 do
        count = count + turtle.getItemCount(i)
        turtle.select(i)
        turtle.dropUp()
    end
    print("Transported " .. count .. " melon.")
    print(string.format("Value: $%.2f", (count / 64) * price))
    print("Fuel consumption: " .. state.startFuel - turtle.getFuelLevel())
    state.currentLevel = 0
    state.targetLevel = state.targetLevel + 1
    if state.targetLevel > MAX_LEVEL then
        state.targetLevel = 1
    end
    print("Now targeting: " .. state.targetLevel)
    return
end

-- depart from the idle chest location
function resume()
    print("Resuming...")
    loadState()
    activity(state.activity)
end

parallel.waitForAll(function()
    resume()
    while true do
        sleep(delay)
        print("Starting fresh...")
        state.startFuel = turtle.getFuelLevel()
        state.isChestRight = false
        saveState()
        activity(activities.TRANSIT_DOWN)
    end
end, function()
    local modem = peripheral.find("modem")
    modem.open(WHEREIS_CHANNEL)
    while true do
        local event, side, channel, replyChannel, message = os.pullEvent("modem_message")
        if channel == WHEREIS_CHANNEL and message == "WHEREIS" then
            modem.transmit(replyChannel, channel, {os.getComputerID(), os.getComputerLabel(), gps.locate()})
        end
    end
end)