-- Created by Jef Roosens
local logger = require('jlib.log').Logger:new{level=3, filename="treefarm.log"}
local fuel   = require('jlib.fuel')
fuel.logger = logger
local move   = require('jlib.move').move


-- Chop a 1x1 tree
--
-- @param max_height height of tallest known tree
--
-- @return height of chopped tree if greater than known highest, otherwise
-- known highest
local function chop(max_height, log_name)
    logger:log(3, "Chopping tree")

    -- Make sure we have enough fuel for the largest known tree
    fuel.check(2 * max_height + 1, { log_name })

    -- Move one forward
    move('f')

    turtle.digDown()

    -- Chop up until we no longer find logs
    local _, data = turtle.inspectUp()

    local height = 0
    while data.name == log_name do
        -- These checks most likely always succeed instantly thanks to the
        -- tallest tree system
        fuel.check(height, { log_name })

        move('u', 1)
        _, data = turtle.inspectUp()

        height = height + 1
    end

    -- Move back down
    move('d', height)

    -- Return the new height if it's greater than the old

    max_height = math.max(max_height, height)
    logger:debug("Max height: " .. max_height)

    return max_height
end


-- Select given item
--
-- @param item_name name of item to select
--
-- @return wether or not the item could be selected
local function select_item(item_name)
    for i = 1, 16 do
        local data = turtle.getItemDetail(i)

        if data and data.name == item_name then
            turtle.select(i)
            return true
        end
    end

    return false
end


-- Do one cycle through the farm
--
-- @param max_height height of tallest known tree
--
-- @return new height of tallest known tree
local function cycle(width, depth, max_height, sapling_name, log_name,
    spacing)
    logger:info("Starting cycle")

    for i = 1, width do
        -- Check for fuel to go through entire row
        fuel.check((spacing + 1) * (depth - 1) + 2, { log_name })

        for j = 1, depth do
            local _, data = turtle.inspect()

            -- Chop down the tree, or move forward
            if data.name == log_name then
                -- Gotta re-do the check from the beginning of this row
                fuel.check(
                    2 * max_height + 1 + (spacing + 1) * (depth - j) + 2,
                    { log_name })

                max_height = chop(max_height, log_name)

            else
                move('f')
            end

            -- Place down a sapling, if possible
            if select_item(sapling_name) then
                turtle.placeDown()
            end

            -- Pick up any dropped saplings
            turtle.suckDown()

            -- Move forward

            if j < depth then
                move('f', spacing)
            else
                move('f')
            end
        end

        -- Turn
        if i < width then
            if i % 2 == 0 then turtle.turnLeft() else turtle.turnRight() end
            fuel.check(spacing + 1, { log_name })
            move('f', spacing + 1)
            if i % 2 == 0 then turtle.turnLeft() else turtle.turnRight() end
        end
    end

    return max_height
end


-- Do maintenance stuff: drop off items, and restock on saplings
local function maintenance(width, depth, sapling_name, log_name)
    logger:info("Doing maintenance")
    fuel.check(6, { log_name })

    -- Move towards sapling chest
    move('f')
    turtle.turnLeft()
    move('f')

    -- Deposite all saplings
    while select_item(sapling_name) do turtle.drop(64) end

    -- Get enough saplings
    turtle.select(1)
    turtle.suck(width * depth)

    -- Move towards log chest
    turtle.turnRight()
    move('f')
    turtle.turnLeft()

    -- Deposite all logs
    -- First, find all spots with logs in them
    local slots, count = {}, 0
    for i = 1, 16 do
        local data = turtle.getItemDetail(i)

        if data and data.name == log_name then
            count = count + data.count
            slots[i] = count

        end
    end

    -- Then, deposit logs as long as we have more than 10 logs left
    for slot, slot_count in pairs(slots) do
        -- Exit the loop if we have 10 or less logs
        if count <= 20 then break end

        -- Refuel with 64 unless count says otherwise
        turtle.select(slot)
        local c = math.min(slot_count, count - 20)
        turtle.drop(c)
        count = count - c
    end

    -- Keep 10 logs for refueling
    turtle.select(2)
    turtle.suck(20 - count)

    -- Get back to start block
    turtle.turnRight()
    turtle.turnRight()
    move('f')
    turtle.turnRight()
    move('f', 2)

    logger:info("Maintenance finished")
end


local function main()
    -- Load the settings, or quit if it fails
    if not settings.load(".treefarm.conf") then
        return logger:critical("Couldn't load configuration file. Please make sure it exists and doesn't contain syntax errors.")
    end

    -- Get all variables (API calls are slow)
    local width, depth, spacing, border_width, log_name, sapling_name, delay =
        settings.get("width"), settings.get("depth"), settings.get("spacing"),
        settings.get("border_width"), settings.get("log_name"),
        settings.get("sapling_name"), settings.get("delay")
    local max_height = 0

    logger:info("Settings loaded")

    -- Start the main loop
    logger:info("Starting main loop")
    while true do
        -- Get into start position for cycle
        fuel.check(2, { log_name })
        move('f', 2)

        -- Run through two cycles
        max_height = cycle(width, depth, max_height, sapling_name, log_name,
            spacing)
        turtle.turnRight()
        turtle.turnRight()
        sleep(delay)
        max_height = cycle(width, depth, max_height, sapling_name, log_name,
            spacing)

        -- Do maintenance and subtract maintenance time from delay
        fuel.check(border_width, { log_name })
        move('f', border_width)

        local seconds = os.clock()
        maintenance(width, depth, sapling_name, log_name)
        sleep(math.max(0, delay - os.clock() + seconds))
    end
end

main()