local T = require("lib")

--[[

States:
- MOVE_TO_TREE
- CHECK_TREE
- ASCEND_TREE 
- FINALIZE_TREE
- OUTPUT
- RESUPPLY_SAPS
- RESUPPLY_FUEL

Persistent Variables:
- current_state
- current_tree [1,14]
- current_row  [1,6]

Inventory:
64 + 20 Saplings in Slots 1 and 2

]]

local MAX_TREE = 14
local MAX_ROW = 6

local OUTPUT_TARGET = { x = 2, z = 0, o = "+z" }
local SAPS_TARGET = { x = 1, z = 0, o = "+z" }
local FUEL_TARGET = { x = 0, z = 0, o = "+z" }

local TREE_MAX_HEIGHT = 7
-- Saplings are at y = -1 (and coordinates are zero-based)
local TREE_MAX_Y = TREE_MAX_HEIGHT - 2
local LOG_NAME = "minecraft:birch_log"

local SAP_SLOT = 1
local BACKUP_SAP_SLOT = 2
local REFUEL_SLOT = 3

local SAP_SLOT_TARGET_COUNT = 64
local BACKUP_SAP_SLOT_TARGET_COUNT = 20

-- Should be enough even if every tree is fully grown
local FUEL_LEVEL_TARGET = 1000

local function calculate_tree_position(row_index, tree_index)

    local x = (row_index - 1) * 5
    local z

    if row_index % 2 == 1 then
        z = -2 * tree_index
    else
        z = -30 + 2 * tree_index
    end

    return x, z
end

local function greedy_move(x, z, o)
    print("Move Target: " .. x .. "," .. z .. " (" .. o .. ")")
    if z ~= T.state.z then
        if z > T.state.z then
            T.rotateTowards("+z")
        else
            T.rotateTowards("-z")
        end
        for _ = 1, math.abs(z - T.state.z) do
            while not T.fwd() do
                sleep(1)
            end
        end
    end

    if x ~= T.state.x then
        if x > T.state.x then
            T.rotateTowards("+x")
        else
            T.rotateTowards("-x")
        end
        for _ = 1, math.abs(x - T.state.x) do
            while not T.fwd() do
                sleep(1)
            end
        end
    end

    T.rotateTowards(o)
end

local function ensure_item_count(count)
    if turtle.getItemCount() >= count then
        return
    end
    turtle.suck(count - turtle.getItemCount())
    -- turtle.suck might not suck enough items if the target container does not have them
    -- but it won't tell us if this happened...
    while turtle.getItemCount() ~= count do
        sleep(1)
        turtle.suck(count - turtle.getItemCount())
    end
end

local state_machine = {

    ["MOVE_TO_TREE"] = function()
        -- get target tree coordinates
        -- and move such that we are facing it
        local x, z = calculate_tree_position(T.state.current_row, T.state.current_tree)
        local o

        if T.state.current_row ~= 1 and T.state.current_tree == 1 then
            -- we just turned towards a new row and are approaching in positive x direction
            x = x - 1
            o = "+x"
        elseif T.state.current_row % 2 == 0 then
            -- we are in an even row and approaching in positive z direction
            z = z - 1
            o = "+z"
        else
            -- we are approaching in negative z direction
            z = z + 1
            o = "-z"
        end

        greedy_move(x, z, o)
        return "CHECK_TREE"
    end,

    ["CHECK_TREE"] = function()
        if not turtle.detect() then
            -- no tree, so skip ascending
            T.fwd()
            return "FINALIZE_TREE"
        else
            -- tree present, chop it down
            turtle.dig()
            T.fwd()
            turtle.digDown()
            return "ASCEND_TREE"
        end
    end,

    ["ASCEND_TREE"] = function()
        local success, data = turtle.inspectUp()
        if not success and T.state.y < TREE_MAX_Y - 1 then
            -- probably reset after chopping a block
            T.up()
        end

        while true do
            local success, data = turtle.inspectUp()
            if not success or data.name ~= LOG_NAME then
                -- chopped all the wood
                break
            end
            turtle.digUp()
            if T.state.y == TREE_MAX_Y - 1 then
                -- we are below the last log, no need to move up
                break
            end
            T.up()
        end
        return "FINALIZE_TREE"
    end,

    ["FINALIZE_TREE"] = function()
        -- make sure we are directly above the sapling target
        while T.state.y > 0 do
            while not T.down() do
                -- another tree might have spawned leaves below us
                turtle.digDown()
            end
        end

        turtle.select(SAP_SLOT)
        -- make sure we have a sapling
        if turtle.getItemCount() == 0 then
            turtle.select(BACKUP_SAP_SLOT)
            turtle.transferTo(SAP_SLOT)
            turtle.select(SAP_SLOT)
        end
        turtle.placeDown()

        if T.state.current_tree < MAX_TREE then
            -- go to the next tree in this row
            T.state.current_tree = T.state.current_tree + 1
            return "MOVE_TO_TREE"
        elseif T.state.current_row < MAX_ROW then
            -- go to the first tree in the next row
            T.state.current_tree = 1
            T.state.current_row = T.state.current_row + 1
            return "MOVE_TO_TREE"
        else
            -- went through the entire farm once
            return "OUTPUT"
        end
    end,

    ["OUTPUT"] = function()

        greedy_move(OUTPUT_TARGET.x, OUTPUT_TARGET.z, OUTPUT_TARGET.o)

        -- Drop all logs
        for slot = 1, 16 do
            turtle.select(slot)
            data = turtle.getItemDetail()
            if data and data.name == LOG_NAME then
                turtle.drop()
            end
        end

        return "RESUPPLY_SAPS"
    end,

    ["RESUPPLY_SAPS"] = function()

        greedy_move(SAPS_TARGET.x, SAPS_TARGET.z, SAPS_TARGET.o)

        turtle.select(SAP_SLOT)
        ensure_item_count(SAP_SLOT_TARGET_COUNT)

        turtle.select(BACKUP_SAP_SLOT)
        ensure_item_count(BACKUP_SAP_SLOT_TARGET_COUNT)

        return "RESUPPLY_FUEL"
    end,

    ["RESUPPLY_FUEL"] = function()

        greedy_move(FUEL_TARGET.x, FUEL_TARGET.z, FUEL_TARGET.o)

        if turtle.getFuelLevel() < FUEL_LEVEL_TARGET then
            local fuel_count = math.ceil((FUEL_LEVEL_TARGET - turtle.getFuelLevel()) / 80)
            turtle.select(REFUEL_SLOT)
            ensure_item_count(fuel_count)
            turtle.refuel()
        end

        T.state.current_row = 1
        T.state.current_tree = 1
        return "MOVE_TO_TREE"
    end,

}

-- initial setup

if not T.state.current_state then
    T.setPosition(0, 0, 0, "+z")
    T.state.current_state = "RESUPPLY_FUEL"
end

-- main loop
while true do
    print("---------------")
    print("State: " .. T.state.current_state)
    print("Pos:   " .. T.state.x .. "," .. T.state.z .. "(" .. T.getOrientation() .. ")")
    T.state.current_state = state_machine[T.state.current_state]()
end