local x,y,z = 0,0,0 -- starting position
-- ^ dont change unless you know what you're doing ^
local dir = "n" -- starting direction, example: n for north
local dirs = {"w","n","e","s"}
local saplingslot = 1
local dirtslot = 2

local trees = {
	-- positions are relative to the starting position.
	-- does not use gps
	-- example:
	-- {x=-2,y=-1,z=-4,dir="n",real={x=-2,y=-1,z=-5}},
	-- x,y,z is where to stand when chopping it
	-- dir is direction the tree is in realtion to the position ^
	-- real x,y,z is the position of the sapling
}

local function checkfuel()
	local fuel = turtle.getFuelLevel()
	if fuel >= 5 then return end
	print("looking for fuel")
	while fuel < 5 do
		for slot = 1,16 do
			if turtle.getItemCount(slot) > 0 then
				turtle.select(slot)
				turtle.refuel(1)
			end
		end
		fuel = turtle.getFuelLevel()
	end
	turtle.select(1)
	print("refueled")
end

local function forcemove(func,dig)
	local state = false
	repeat
		checkfuel()
		if turtle[func] == nil then error("Cant find function \""..func.."\"") end
		state = turtle[func]()
		if dig then
			if func=="up" or func=="down"
			or func=="forward" then
				local face = func
				if face=="forward" then face="" end
				face=func:gsub("^%l", string.upper)
				local tmpfunc=func:gsub("^%l", string.upper)
				if turtle["detect"..face] == true then
					forcemove("dig"..tmpfunc)
				end
			end
		end
	until state
end

local function forward()
	if dir=="n" then
		z=z-1
	elseif dir=="e" then
		x=x+1
	elseif dir=="s" then
		z=z+1
	elseif dir=="w" then
		x=x-1
	end
end

local function back()
	if dir=="n" then
		z=z-1
	elseif dir=="e" then
		x=x-1
	elseif dir=="s" then
		z=z+1
	elseif dir=="w" then
		x=x+1
	end
end

local function turnclockwise()
	local dirid = 0
	for id,face in ipairs(dirs) do
		if face==dir then dirid=id break end
	end
	dirid=dirid+1
	if dirid > #dirs then dirid = 1 end
	dir=dirs[dirid] or error("Unable to calculate direction")
end

local function turncounterclockwise()
	local dirid = 0
	for id,face in ipairs(dirs) do
		if face==dir then dirid=id break end
	end
	dirid = dirid - 1
	if dirid < 1 then dirid = #dirs end
	dir=dirs[dirid] or error("Unable to calculate direction")
end

local go = {}
go.u=function(dig)
	forcemove("up",dig)
	y=y+1
end
go.d=function(dig)
	forcemove("down",dig)
	y=y-1
end
go.f=function(dig)
	forcemove("forward",dig)
	forward()
end
go.b=function()
	forcemove("back")
	back()
end
go.rt=function()
	turtle.turnRight()
	turnclockwise()
end
go.lt=function()
	turtle.turnLeft()
	turncounterclockwise()
end
go.turn=function(face)
	local dirid = 0
	for id,face in ipairs(dirs) do
		if face==dir then dirid=id break end
	end
	local faceid = 0
	for id,vface in ipairs(dirs) do
		if vface==face then faceid=id break end
	end
	
	dirid = dirid - 1
	if dirid < 1 then dirid = #dirs end
	if dirid == faceid then go.lt() end
	
	while face ~= dir do
		go.rt()
	end
end

local function init()
	print("expecting saplings in slot "..saplingslot)
	print("and dirt in slot "..dirtslot)
	print("press any button to continue")
	repeat
		os.pullEvent("key")
	until turtle.getItemCount(saplingslot) >= tset.xcount*tset.zcount
	and turtle.getItemCount(dirtslot) >= tset.xcount*tset.zcount
end

local function chop()
	if not turtle.detect() then
		go.f()
		if turtle.detectDown() then
			repeat until turtle.digDown()
		end
		return
	end
	turtle.select(saplingslot)
	if turtle.compare() then
		forcemove("dig")
		go.f()
		forcemove("digDown")
		return
	elseif turtle.detect() then
		forcemove("dig")
		go.f()
		local height = 0
		while turtle.detectUp() do
			forcemove("digUp")
			go.u()
			height = height + 1
		end
		for count = 1,height do
			go.d()
		end
	end
	if turtle.detectDown() then
		forcemove("digDown")
	end
end

local function goto(xpos,ypos,zpos,newdir)
	while xpos~=x
	or ypos~=y
	or zpos~=z do
		-- vertical
		for count=1,y-ypos do
			if turtle.detectDown() then break end
			go.d(true)
		end
		for count=1,ypos-y do
			if turtle.detectUp() then break end
			go.u(true)
		end
		
		-- x
		for count=1,x-xpos do
			go.turn("w")
			if turtle.detect() then 
				go.rt() go.f() go.lt()
			else
				go.f()
			end
		end
		for count=1,xpos-x do
			go.turn("e")
			if turtle.detect() then
				go.lt() go.f() go.rt()
			else
				go.f()
			end
		end
		
		-- z
		for count=1,z-zpos do
			go.turn("n")
			if turtle.detect() then
				go.rt() go.f() go.lt()
			else
				go.f()
			end
		end
		for count=1,zpos-z do
			go.turn("s")
			if turtle.detect() then 
				go.lt() go.f() go.rt()
			else
				go.f()
			end
		end
	end
	if newdir then
	go.turn(newdir)
	end
end

local function gohome()
	goto(0,0,0,"n")
end

local function collect()
	goto(-4,-5,-3,"e")
	repeat until not turtle.suckDown()
	for count=1,tset.xcount*tset.xspace do
		go.f()
		repeat until not turtle.suckDown()
	end
	gohome()
end

local function replant()
	print("replanting")
	for id,tree in pairs(trees) do
		local real = tree.real
		goto(tree.x,tree.y,tree.z,tree.dir)
		if not turtle.detect() then
			goto(real.x,real.y,real.z)
			if not turtle.detectDown() then
				repeat
					turtle.select(dirtslot)
				until turtle.placeDown()
			end
			go.u()
			repeat
				turtle.select(saplingslot)
			until turtle.placeDown()
		end
	end
end

local function harvest()
	for id,tree in ipairs(trees) do
		print("moving to x"..tree.x.." y"..tree.y.." z"..tree.z)
		goto(tree.x,tree.y,tree.z,tree.dir)
		print("chopping tree")
		chop()
	end
	gohome()
end

local function usage()
	print("Usage: "..shell.getRunningProgram().." <task>")
	print("Tasks avavible: harvest, replant, collect, cycle")
end

local args = {...}
local task = args[1]

if task == nil then
	usage()
elseif task == "harvest" then
	harvest()
	gohome()
	print("all done.")
elseif task == "replant" then
	init()
	replant()
	gohome()
	print("all done.")
elseif task == "collect" then
	collect()
	print("all done.")
elseif task == "cycle" then
	init()
	harvest()
	for i=1,3 do
		collect()
		print("waiting 1min for leaves to despawn")
		sleep(60)
		print("collecting drops")
		collect()
	end
	replant()
	gohome()
	print("all done.")
end