--[[

	Tubelib Addons 3
	================

	Copyright (C) 2018 Joachim Stolberg

	LGPLv2.1+
	See LICENSE.txt for more information

	distributor.lua:
	
	A high performance distributor
]]--

local NUM_FILTER_ELEM = 6
local NUM_FILTER_SLOTS = 4
local TICKS_TO_SLEEP = 5
local CYCLE_TIME = 2
local STOP_STATE = 0
local STANDBY_STATE = -1

-- Get one item-stack from the given ItemList, specified by stack number (1..n).
-- Returns nil if ItemList is empty.
local function get_this_stack(meta, listname, number)
	if meta == nil or meta.get_inventory == nil then return nil end
	local inv = meta:get_inventory()
	if inv:is_empty(listname) then
		return nil
	end
	
	local items = inv:get_stack(listname, number)
	if items:get_count() > 0 then
		return inv:remove_item(listname, items)
	end
	return nil
end

-- Return a key/value table with all items and the corresponding stack numbers
local function invlist_content_as_kvlist(list)
	local res = {}
	for idx,items in ipairs(list) do
		local name = items:get_name()
		if name ~= "" then
			res[name] = idx
		end
	end
	return res
end

-- Return the total number of list entries
local function invlist_num_entries(list)
	local res = 0
	for _,items in ipairs(list) do
		local name = items:get_name()
		if name ~= "" then
			res = res + items:get_count()
		end
	end
	return res
end

-- Return a flat table with all items
local function invlist_entries_as_list(list)
	local res = {}
	for _,items in ipairs(list) do
		local name = items:get_name()
		local count = items:get_count()
		if name ~= "" then
			for i = 1,count do
				res[#res+1] = name
			end
		end
	end
	return res
end


local function AddToTbl(kvTbl, new_items)
	for _, l in ipairs(new_items) do 
		kvTbl[l] = true 
	end
	return kvTbl
end


local function distributor_formspec(state, filter)
	return "size[10,8.5]"..
	default.gui_bg..
	default.gui_bg_img..
	default.gui_slots..
	"list[context;src;0,0;2,4;]"..
	"image[2,1.5;1,1;tubelib_gui_arrow.png]"..
	"image_button[2,3;1,1;".. tubelib.state_button(state) ..";button;]"..
	"checkbox[3,0;filter1;On;"..dump(filter[1]).."]"..
	"checkbox[3,1;filter2;On;"..dump(filter[2]).."]"..
	"checkbox[3,2;filter3;On;"..dump(filter[3]).."]"..
	"checkbox[3,3;filter4;On;"..dump(filter[4]).."]"..
	"image[3.6,0;0.3,1;tubelib_red.png]"..
	"image[3.6,1;0.3,1;tubelib_green.png]"..
	"image[3.6,2;0.3,1;tubelib_blue.png]"..
	"image[3.6,3;0.3,1;tubelib_yellow.png]"..
	"list[context;red;4,0;6,1;]"..
	"list[context;green;4,1;6,1;]"..
	"list[context;blue;4,2;6,1;]"..
	"list[context;yellow;4,3;6,1;]"..
	"list[current_player;main;1,4.5;8,4;]"..
	"listring[context;src]"..
	"listring[current_player;main]"
end

local function allow_metadata_inventory_put(pos, listname, index, stack, player)
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	local list = inv:get_list(listname)
	
	if minetest.is_protected(pos, player:get_player_name()) then
		return 0
	end
	if listname == "src" then
		return stack:get_count()
	elseif invlist_num_entries(list) < NUM_FILTER_ELEM then
		return 1
	end
	return 0
end

local function allow_metadata_inventory_take(pos, listname, index, stack, player)
	if minetest.is_protected(pos, player:get_player_name()) then
		return 0
	end
	return stack:get_count()
end

local function allow_metadata_inventory_move(pos, from_list, from_index, to_list, to_index, count, player)
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	local stack = inv:get_stack(from_list, from_index)
	return allow_metadata_inventory_put(pos, to_list, to_index, stack, player)
end

local SlotColors = {"red", "green", "blue", "yellow"}
local Num2Ascii = {"B", "L", "F", "R"} -- color to side translation
local FilterCache = {} -- local cache for filter settings

local function filter_settings(pos)
	local hash = minetest.hash_node_position(pos)
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	local filter = minetest.deserialize(meta:get_string("filter")) or {false,false,false,false}
	local kvFilterItemNames = {} -- {<item:name> = true,...}
	local kvSide2ItemNames = {} -- {"F" = {<item:name>,...},...}
	
	-- collect all filter settings
	for idx,slot in ipairs(SlotColors) do
		local side = Num2Ascii[idx]
		if filter[idx] == true then
			local list = inv:get_list(slot)
			local filter = invlist_entries_as_list(list)
			AddToTbl(kvFilterItemNames, filter)
			kvSide2ItemNames[side] = filter
		end
	end
	
	FilterCache[hash] = {
		kvFilterItemNames = kvFilterItemNames, 
		kvSide2ItemNames = kvSide2ItemNames
	}
end

local function start_the_machine(pos)
	local node = minetest.get_node(pos)
	local meta = minetest.get_meta(pos)
	local number = meta:get_string("number")
	meta:set_int("running", TICKS_TO_SLEEP)
	node.name = "tubelib_addons3:distributor_active"
	minetest.swap_node(pos, node)
	meta:set_string("infotext", "HighPerf Distributor "..number..": running")
	local filter = minetest.deserialize(meta:get_string("filter"))
	meta:set_string("formspec", distributor_formspec(tubelib.RUNNING, filter))
	minetest.get_node_timer(pos):start(CYCLE_TIME)
	return false
end

local function stop_the_machine(pos)
	local node = minetest.get_node(pos)
	local meta = minetest.get_meta(pos)
	local number = meta:get_string("number")
	meta:set_int("running", STOP_STATE)
	node.name = "tubelib_addons3:distributor"
	minetest.swap_node(pos, node)
	meta:set_string("infotext", "HighPerf Distributor "..number..": stopped")
	local filter = minetest.deserialize(meta:get_string("filter"))
	meta:set_string("formspec", distributor_formspec(tubelib.STOPPED, filter))
	minetest.get_node_timer(pos):stop()
	return false
end

local function goto_sleep(pos)
	local node = minetest.get_node(pos)
	local meta = minetest.get_meta(pos)
	local number = meta:get_string("number")
	meta:set_int("running", STANDBY_STATE)
	node.name = "tubelib_addons3:distributor"
	minetest.swap_node(pos, node)
	meta:set_string("infotext", "HighPerf Distributor "..number..": standby")
	local filter = minetest.deserialize(meta:get_string("filter"))
	meta:set_string("formspec", distributor_formspec(tubelib.STANDBY, filter))
	minetest.get_node_timer(pos):start(CYCLE_TIME * TICKS_TO_SLEEP)
	return false
end	

-- move items to the output slots
local function keep_running(pos, elapsed)
	local meta = minetest.get_meta(pos)
	local running = meta:get_int("running") - 1
	local player_name = meta:get_string("player_name")
	--print("running", running)
	local slot_idx = meta:get_int("slot_idx") or 1
	meta:set_int("slot_idx", (slot_idx + 1) % NUM_FILTER_SLOTS)
	local side = Num2Ascii[slot_idx+1]
	local listname = SlotColors[slot_idx+1]
	local inv = meta:get_inventory()
	local list = inv:get_list("src")
	local kvSrc = invlist_content_as_kvlist(list)
	local counter = minetest.deserialize(meta:get_string("item_counter")) or 
			{red=0, green=0, blue=0, yellow=0}
	
	-- calculate the filter settings only once
	local hash = minetest.hash_node_position(pos)
	if FilterCache[hash] == nil then
		filter_settings(pos)
	end
	
	-- read data from Cache 
	-- all filter items as key/value  {<item:name> = true,...}
	local kvFilterItemNames = FilterCache[hash].kvFilterItemNames
	-- filter items of one slot as list  {<item:name>,...}
	local names = FilterCache[hash].kvSide2ItemNames[side]
	
	if names == nil then
		-- this slot is empty
		return true
	end
	
	local busy = false
	-- move items from configured filters to the output
	if next(names) then
		for _,name in ipairs(names) do
			if kvSrc[name] then
				local item = get_this_stack(meta, "src", kvSrc[name])
				if item then
					if not tubelib.push_items(pos, side, item, player_name) then
						tubelib.put_item(meta, "src", item)
					else
						counter[listname] = counter[listname] + 1
						busy = true
					end
				end
			end
		end
	end
	
	-- move additional items from unconfigured filters to the output
	if next(names) == nil then
		for name,_ in pairs(kvSrc) do
			if kvFilterItemNames[name] == nil then  -- not in the filter so far?
				local item = get_this_stack(meta, "src", kvSrc[name])
				if item then
					if not tubelib.push_items(pos, side, item, player_name) then
						tubelib.put_item(meta, "src", item)
					else
						counter[listname] = counter[listname] + 1
						busy = true
					end
				end
			end
		end
	end
	
	if busy == true then 
		if running <= 0 then
			return start_the_machine(pos)
		else
			running = TICKS_TO_SLEEP
		end
	else
		if running <= 0 then
			return goto_sleep(pos)
		end
	end
	
	meta:set_string("item_counter", minetest.serialize(counter))
	meta:set_int("running", running)
	return true
end

local function on_receive_fields(pos, formname, fields, player)
	if minetest.is_protected(pos, player:get_player_name()) then
		return
	end
	local meta = minetest.get_meta(pos)
	local running = meta:get_int("running")
	local filter = minetest.deserialize(meta:get_string("filter"))
	if fields.filter1 ~= nil then
		filter[1] = fields.filter1 == "true"
	elseif fields.filter2 ~= nil then
		filter[2] = fields.filter2 == "true"
	elseif fields.filter3 ~= nil then
		filter[3] = fields.filter3 == "true"
	elseif fields.filter4 ~= nil then
		filter[4] = fields.filter4 == "true"
	end
	meta:set_string("filter", minetest.serialize(filter))
	
	filter_settings(pos)
	
	if fields.button ~= nil then
		if running > STOP_STATE then
			stop_the_machine(pos)
		else
			start_the_machine(pos)
		end
	else
		meta:set_string("formspec", distributor_formspec(tubelib.state(running), filter))
	end
end

-- tubelib command to turn on/off filter channels
local function change_filter_settings(pos, slot, val)
	local slots = {["red"] = 1, ["green"] = 2, ["blue"] = 3, ["yellow"] = 4}
	local meta = minetest.get_meta(pos)
	local filter = minetest.deserialize(meta:get_string("filter"))
	local num = slots[slot] or 1
	if num >= 1 and num <= 4 then
		filter[num] = val == "on"
	end
	meta:set_string("filter", minetest.serialize(filter))
	
	filter_settings(pos)
	
	local running = meta:get_int("running")
	meta:set_string("formspec", distributor_formspec(tubelib.state(running), filter))
	return true
end

minetest.register_node("tubelib_addons3:distributor", {
	description = "HighPerf Distributor",
	tiles = {
		-- up, down, right, left, back, front
		'tubelib_distributor.png^tubelib_addons3_node_frame.png',
		'tubelib_distributor.png^tubelib_addons3_node_frame.png',
		'tubelib_distributor_yellow.png^tubelib_addons3_node_frame.png',
		'tubelib_distributor_green.png^tubelib_addons3_node_frame.png',
		"tubelib_distributor_red.png^tubelib_addons3_node_frame.png",
		"tubelib_distributor_blue.png^tubelib_addons3_node_frame.png",
	},

	after_place_node = function(pos, placer)
		local number = tubelib.add_node(pos, "tubelib_addons3:distributor")
		local meta = minetest.get_meta(pos)
		meta:set_string("player_name", placer:get_player_name())

		local filter = {false,false,false,false}
		meta:set_string("formspec", distributor_formspec(tubelib.STOPPED, filter))
		meta:set_string("filter", minetest.serialize(filter))
		meta:set_string("number", number)
		meta:set_string("infotext", "HighPerf Distributor "..number..": stopped")
		local inv = meta:get_inventory()
		inv:set_size('src', 8)
		inv:set_size('yellow', 6)
		inv:set_size('green', 6)
		inv:set_size('red', 6)
		inv:set_size('blue', 6)
		meta:set_string("item_counter", minetest.serialize({red=0, green=0, blue=0, yellow=0}))
	end,

	on_receive_fields = on_receive_fields,

	on_dig = function(pos, node, puncher, pointed_thing)
		if minetest.is_protected(pos, puncher:get_player_name()) then
			return
		end
		local meta = minetest.get_meta(pos)
		local inv = meta:get_inventory()
		if inv:is_empty("src") then
			minetest.node_dig(pos, node, puncher, pointed_thing)
			tubelib.remove_node(pos)
		end
	end,

	allow_metadata_inventory_put = allow_metadata_inventory_put,
	allow_metadata_inventory_take = allow_metadata_inventory_take,
	allow_metadata_inventory_move = allow_metadata_inventory_move,

	on_timer = keep_running,
	on_rotate = screwdriver.disallow,
	
	paramtype = "light",
	sunlight_propagates = true,
	paramtype2 = "facedir",
	groups = {choppy=2, cracky=2, crumbly=2},
	is_ground_content = false,
	sounds = default.node_sound_wood_defaults(),
})


minetest.register_node("tubelib_addons3:distributor_active", {
	description = "HighPerf Distributor",
	tiles = {
		-- up, down, right, left, back, front
		{
			image = "tubelib_addons3_distributor_active.png",
			backface_culling = false,
			animation = {
				type = "vertical_frames",
				aspect_w = 32,
				aspect_h = 32,
				length = 2.0,
			},
		},
		'tubelib_distributor.png^tubelib_addons3_node_frame.png',
		'tubelib_distributor_yellow.png^tubelib_addons3_node_frame.png',
		'tubelib_distributor_green.png^tubelib_addons3_node_frame.png',
		"tubelib_distributor_red.png^tubelib_addons3_node_frame.png",
		"tubelib_distributor_blue.png^tubelib_addons3_node_frame.png",
	},

	on_receive_fields = on_receive_fields,
	
	allow_metadata_inventory_put = allow_metadata_inventory_put,
	allow_metadata_inventory_take = allow_metadata_inventory_take,
	allow_metadata_inventory_move = allow_metadata_inventory_move,

	on_timer = keep_running,
	on_rotate = screwdriver.disallow,

	paramtype = "light",
	sunlight_propagates = true,
	paramtype2 = "facedir",
	groups = {crumbly=0, not_in_creative_inventory=1},
	is_ground_content = false,
	sounds = default.node_sound_wood_defaults(),
})

minetest.register_craft({
	output = "tubelib_addons3:distributor",
	recipe = {
		{"default:tin_ingot", "tubelib:distributor", ""},
		{"tubelib:distributor", "default:gold_ingot", ""},
		{"", "", ""},
	},
})


tubelib.register_node("tubelib_addons3:distributor", {"tubelib_addons3:distributor_active"}, {
	on_pull_item = function(pos, side)
		local meta = minetest.get_meta(pos)
		return tubelib.get_item(meta, "src")
	end,
	on_push_item = function(pos, side, item)
		local meta = minetest.get_meta(pos)
		return tubelib.put_item(meta, "src", item)
	end,
	on_unpull_item = function(pos, side, item)
		local meta = minetest.get_meta(pos)
		return tubelib.put_item(meta, "src", item)
	end,
	on_recv_message = function(pos, topic, payload)
		if topic == "on" then
			return start_the_machine(pos)
		elseif topic == "off" then
			return stop_the_machine(pos)
		elseif topic == "state" then
			local meta = minetest.get_meta(pos)
			local running = meta:get_int("running")
			return tubelib.statestring(running)
		elseif topic == "filter" then
			return change_filter_settings(pos, payload.slot, payload.val)
		elseif topic == "counter" then
			local meta = minetest.get_meta(pos)
			return minetest.deserialize(meta:get_string("item_counter")) or 
					{red=0, green=0, blue=0, yellow=0}
		elseif topic == "clear_counter" then
			local meta = minetest.get_meta(pos)
			meta:set_string("item_counter", minetest.serialize({red=0, green=0, blue=0, yellow=0}))
		else
			return "unsupported"
		end
	end,
})