--[[

	Tube Library 2
	==============

	Copyright (C) 2017-2018 Joachim Stolberg

	LGPLv2.1+
	See LICENSE.txt for more information

	tube_api.lua

]]--

-- Version for compatibility checks, see readme.md/history
tubelib2.version = 0.8

-- for lazy programmers
local S = function(pos) if pos then return minetest.pos_to_string(pos) end end
local M = minetest.get_meta

-- Load support for intllib.
local MP = minetest.get_modpath("tubelib2")
local I,IS = dofile(MP.."/intllib.lua")

local Dir2Str = {"north", "east", "south", "west", "down", "up"}

function tubelib2.dir_to_string(dir)
	return Dir2Str[dir]
end

local function Tbl(list)
	local tbl = {}
	for _,item in ipairs(list) do
		tbl[item] = true
	end
	return tbl
end

-- Tubelib2 Class
local Tube = tubelib2.Tube
local Turn180Deg = tubelib2.Turn180Deg
local Dir6dToVector = tubelib2.Dir6dToVector


local function get_pos(pos, dir)
	return vector.add(pos, Dir6dToVector[dir or 0])
end

local function update1(self, pos, dir)
	local fpos,fdir = self:walk_tube_line(pos, dir)
	self:infotext(get_pos(pos, dir), fpos)
	self:infotext(fpos, get_pos(pos, dir))
	-- Translate pos/dir pointing to the secondary node into 
	-- spos/sdir of the secondary node pointing to the tube.
	if fpos and fdir then
		local spos, sdir = get_pos(fpos,fdir), Turn180Deg[fdir]
		self:del_from_cache(spos, sdir)
		self:add_to_cache(pos, dir, spos, sdir)
		self:add_to_cache(spos, sdir, pos, dir)
		self:update_secondary_node(pos, dir, spos, sdir)
		self:update_secondary_node(spos, sdir, pos, dir)
	end
end

local function update2(self, pos1, dir1, pos2, dir2)
	local fpos1,fdir1 = self:walk_tube_line(pos1, dir1)
	local fpos2,fdir2 = self:walk_tube_line(pos2, dir2)
	if not fdir1 or not fdir2 then -- line to long?
		-- reset next tube(s) to head tube(s) again
		local param2 = tubelib2.encode_param2(dir1, dir2, 2)
		self:update_after_dig_tube(pos1, param2)
		M(get_pos(pos1, dir1)):set_string("infotext", I("Maximum length reached!"))
		M(get_pos(pos1, dir2)):set_string("infotext", I("Maximum length reached!"))
		return false 
	end
	self:infotext(fpos1, fpos2)
	self:infotext(fpos2, fpos1)
	-- Translate fpos/fdir pointing to the secondary node into 
	-- spos/sdir of the secondary node pointing to the tube.
	local spos1, sdir1 = get_pos(fpos1,fdir1), Turn180Deg[fdir1]
	local spos2, sdir2 = get_pos(fpos2,fdir2), Turn180Deg[fdir2]
	self:del_from_cache(spos1, sdir1)
	self:del_from_cache(spos2, sdir2)
	self:add_to_cache(spos1, sdir1, spos2, sdir2)
	self:add_to_cache(spos2, sdir2, spos1, sdir1)
	self:update_secondary_node(spos1, sdir1, spos2, sdir2)
	self:update_secondary_node(spos2, sdir2, spos1, sdir1)
	return true
end

local function update3(self, pos, dir1, dir2)
	if pos and dir1 and dir2 then
		local fpos1,fdir1,cnt1 = self:walk_tube_line(pos, dir1)
		local fpos2,fdir2,cnt2 = self:walk_tube_line(pos, dir2)
		self:infotext(fpos1, fpos2)
		self:infotext(fpos2, fpos1)
		-- Translate fpos/fdir pointing to the secondary node into 
		-- spos/sdir of the secondary node pointing to the tube.
		if fpos1 and fpos2 and fdir1 and fdir2 then
			local spos1, sdir1 = get_pos(fpos1,fdir1), Turn180Deg[fdir1]
			local spos2, sdir2 = get_pos(fpos2,fdir2), Turn180Deg[fdir2]
			self:del_from_cache(spos1, sdir1)
			self:del_from_cache(spos2, sdir2)
			self:add_to_cache(spos1, sdir1, spos2, sdir2)
			self:add_to_cache(spos2, sdir2, spos1, sdir1)
			self:update_secondary_node(spos1, sdir1, spos2, sdir2)
			self:update_secondary_node(spos2, sdir2, spos1, sdir1)
			return dir1, dir2, fpos1, fpos2, fdir1, fdir2, cnt1 or 0, cnt2 or 0
		end
		return dir1, dir2, pos, pos, dir1, dir2, cnt1 or 0, cnt2 or 0
	end
end

--
-- API Functions
--

function Tube:new(attr)
	local o = {
		dirs_to_check = attr.dirs_to_check or {1,2,3,4,5,6},
		max_tube_length = attr.max_tube_length or 1000, 
		primary_node_names = Tbl(attr.primary_node_names or {}), 
		secondary_node_names = Tbl(attr.secondary_node_names or {}),
		show_infotext = attr.show_infotext or false,
		clbk_after_place_tube = attr.after_place_tube,
		pairingList = {}, -- teleporting nodes
		connCache = {}, -- connection cache {pos1 = {dir1 = {pos2 = pos2, dir2 = dir2},...}
	}
	o.valid_dirs = Tbl(o.dirs_to_check)
	setmetatable(o, self)
	self.__index = self
	return o
end

-- Register (foreign) tubelib compatible nodes.
function Tube:add_secondary_node_names(names)
	for _,name in ipairs(names) do
		self.secondary_node_names[name] = true
	end
end

-- Called for each connected node when the tube connection has been changed.
-- func(node, pos, out_dir, peer_pos, peer_in_dir)
function Tube:register_on_tube_update(update_secondary_node)
		self.clbk_update_secondary_node = update_secondary_node
end

function Tube:get_pos(pos, dir)
	return vector.add(pos, Dir6dToVector[dir or 0])
end

-- To be called after a secondary node is placed.
-- dirs is a list with valid dirs, like: {1,2,3,4}
function Tube:after_place_node(pos, dirs)
	-- [s][f]----[n] x
	-- s..secondary, f..far, n..near, x..node to be placed
	for _,dir in ipairs(self:update_after_place_node(pos, dirs)) do
		if pos and dir then
			update1(self, pos, dir)
		else
			print("after_place_node", dump(pos), dir)
		end
	end
end

-- To be called after a tube/primary node is placed.
-- Returns false, if placing is not allowed
function Tube:after_place_tube(pos, placer, pointed_thing)
	-- [s1][f1]----[n1] x [n2]-----[f2][s2]
	-- s..secondary, f..far, n..near, x..node to be placed
	local res,dir1,dir2 = self:update_after_place_tube(pos, placer, pointed_thing)
	if res then  -- node placed?
		return update2(self, pos, dir1, pos, dir2)
	end
	return res
end

function Tube:after_dig_node(pos, dirs)
	-- [s][f]----[n] x
	-- s..secondary, f..far, n..near, x..node to be removed
	for _,dir in ipairs(self:update_after_dig_node(pos, dirs)) do
		update1(self, pos, dir)
	end
end

-- To be called after a tube/primary node is removed.
function Tube:after_dig_tube(pos, oldnode)
	-- [s1][f1]----[n1] x [n2]-----[f2][s2]
	-- s..secondary, f..far, n..near, x..node to be removed
	
	-- update tubes
	local dir1, dir2 = self:update_after_dig_tube(pos, oldnode.param2)
	if dir1 then update1(self, pos, dir1) end
	if dir2 then update1(self, pos, dir2) end
	
	-- Update secondary nodes, if right beside
	dir1, dir2 = self:decode_param2(pos, oldnode.param2)
	local npos1,ndir1 = get_pos(pos, dir1),Turn180Deg[dir1]
	local npos2,ndir2 = get_pos(pos, dir2),Turn180Deg[dir2]
	self:del_from_cache(npos1,ndir1)
	self:update_secondary_node(npos1,ndir1)
	self:update_secondary_node(npos2,ndir2)
end


-- From source node to destination node via tubes.
-- pos is the source node position, dir the output dir
-- The returned pos is the destination position, dir
-- is the direction into the destination node.
function Tube:get_connected_node_pos(pos, dir)
	local key = S(pos)
	if self.connCache[key] and self.connCache[key][dir] then
		local item = self.connCache[key][dir]
		return item.pos2, Turn180Deg[item.dir2]
	end	
	local fpos,fdir = self:walk_tube_line(pos, dir)
	local spos = get_pos(fpos,fdir)
	self:add_to_cache(pos, dir, spos, Turn180Deg[fdir])
	self:add_to_cache(spos, Turn180Deg[fdir], pos, dir)
	return spos, fdir
end

-- To be called from a repair tool in the case of a "WorldEdit" or with
-- legacy nodes corrupted tube line.
function Tube:tool_repair_tube(pos)
	local _, node = self:primary_node(pos)
	if node then
		local dir1, dir2 = self:decode_param2(pos, node.param2)
		return update3(self, pos, dir1, dir2)
	end
end

-- To be called from a repair tool in the case, tube nodes are "unbreakable".
function Tube:tool_remove_tube(pos, sound)
	local _,node = self:get_node(pos)
	if self.primary_node_names[node.name] then
		minetest.sound_play({name=sound},{
				pos=pos,
				gain=1,
				max_hear_distance=5,
				loop=false})
		minetest.remove_node(pos)
		self:after_dig_tube(pos, node)
		return true
	end
	return false
end


function Tube:prepare_pairing(pos, tube_dir, sFormspec)
	local meta = M(pos)
	if meta:get_int("tube_dir") ~= 0 then -- already prepared?
		-- update tube_dir only
		meta:set_int("tube_dir", tube_dir)
	elseif tube_dir then
		meta:set_int("tube_dir", tube_dir)
		meta:set_string("channel", nil)
		meta:set_string("infotext", I("Pairing is missing"))
		meta:set_string("formspec", sFormspec)
	else
		meta:set_string("infotext", I("Connection to a tube is missing!"))
	end
end

function Tube:pairing(pos, channel)
	if self.pairingList[channel] and not vector.equals(pos, self.pairingList[channel]) then
		-- store peer position on both nodes
		local peer_pos = self.pairingList[channel]
		local tube_dir1 = self:store_teleport_data(pos, peer_pos)
		local tube_dir2 = self:store_teleport_data(peer_pos, pos)
		update2(self, pos, tube_dir1, peer_pos, tube_dir2)
		self.pairingList[channel] = nil
		return true
	else
		self.pairingList[channel] = pos
		local meta = M(pos)
		meta:set_string("channel", channel)
		meta:set_string("infotext", I("Pairing is missing").." ("..channel..")")
		return false
	end
end

function Tube:stop_pairing(pos, oldmetadata, sFormspec)
	-- unpair peer node
	if oldmetadata and oldmetadata.fields then
		if oldmetadata.fields.tele_pos then
			local tele_pos = minetest.string_to_pos(oldmetadata.fields.tele_pos)
			local peer_meta = M(tele_pos)
			if peer_meta then
				self:after_place_node(tele_pos, {peer_meta:get_int("tube_dir")})
				peer_meta:set_string("channel", nil)
				peer_meta:set_string("tele_pos", nil)
				peer_meta:set_string("formspec", sFormspec)
				peer_meta:set_string("infotext", I("Pairing is missing"))
			end
		elseif oldmetadata.fields.channel then
			self.pairingList[oldmetadata.fields.channel] = nil
		end
	end
end


-- Used by chat commands, when tubes are placed e.g. via WorldEdit
function Tube:replace_tube_line(pos1, pos2)
	if pos1 and pos2 and not vector.equals(pos1, pos2) then
		local check = (((pos1.x == pos2.x) and 1) or 0) + 
				(((pos1.y == pos2.y) and 1) or 0) + 
				(((pos1.z == pos2.z) and 1) or 0)
		if check == 2 then
			local v = vector.direction(pos1, pos2)
			local dir1 = minetest.dir_to_facedir(v, true) + 1
			local dir2 = Turn180Deg[dir1]
		
			self:replace_nodes(pos1, pos2, dir1, dir2)
			update3(self, pos1, dir1, dir2)
		end
	end
end