-- Boilerplate to support localized strings if intllib mod is installed.
if minetest.get_modpath("intllib") then
    attrans = intllib.Getter()
else
    attrans = function(s,a,...)a={a,...}return s:gsub("@(%d+)",function(n)return a[tonumber(n)]end)end
end

--advtrains

--Constant for maximum connection value/division of the circle
AT_CMAX = 16

advtrains = {trains={}, wagon_save={}, player_to_train_mapping={}}

--pcall
local no_action=false

local function reload_saves()
	atwarn("Restoring saved state in 1 second...")
	no_action=true
	--read last save state and continue, as if server was restarted
	for aoi, le in pairs(minetest.luaentities) do
		if le.is_wagon then
			le.object:remove()
		end
	end
	minetest.after(1, function()
		advtrains.load()
		atwarn("Reload successful!")
		advtrains.ndb.restore_all()
	end)
end

function advtrains.pcall(fun)
	if no_action then return end
	
	local succ, return1, return2, return3, return4=xpcall(fun, function(err)
			if advtrains.atprint_context_tid then
				local train=advtrains.trains[advtrains.atprint_context_tid_full]
				advtrains.dumppath(train.path)
				atwarn("Dumping last debug outputs: ", err)
				atprint("Train state: index",train.index,"end_index", train.end_index,"| max_iot", train.max_index_on_track, "min_iot", train.min_index_on_track, "<> pe_min", train.path_extent_min,"pe_max", train.path_extent_max)
				if minetest.settings:get_bool("advtrains_enable_debugging") then
					advtrains.drb_dump(advtrains.atprint_context_tid)
				end
			end
			atwarn("Lua Error occured: ", err)
			atwarn(debug.traceback())
		end)
	if not succ then
		reload_saves()
	else
		return return1, return2, return3, return4
	end
end


advtrains.modpath = minetest.get_modpath("advtrains")

function advtrains.print_concat_table(a)
	local str=""
	local stra=""
	local t
	for i=1,20 do
		t=a[i]
		if t==nil then
			stra=stra.."nil "
		else
			str=str..stra
			stra=""
			if type(t)=="table" then
				if t.x and t.y and t.z then
					str=str..minetest.pos_to_string(t)
				else
					str=str..dump(t)
				end
			elseif type(t)=="boolean" then
				if t then
					str=str.."true"
				else
					str=str.."false"
				end
			elseif type(t)=="function" then
				str=str.."<function>"
			elseif type(t)=="userdata" then
				str=str.."<userdata>"
			else
				str=str..t
			end
			str=str.." "
		end
	end
	return str
end

atprint=function() end
atlog=function(t, ...)
	local text=advtrains.print_concat_table({t, ...})
	minetest.log("action", "[advtrains]"..text)
end
atwarn=function(t, ...)
	local text=advtrains.print_concat_table({t, ...})
	minetest.log("warning", "[advtrains]"..text)
	minetest.chat_send_all("[advtrains] -!- "..text)
end
sid=function(id) if id then return string.sub(id, -6) end end

--ONLY use this function for temporary debugging. for consistent debug prints use atprint
atdebug=function(t, ...)
	local text=advtrains.print_concat_table({t, ...})
	minetest.log("action", "[advtrains]"..text)
	minetest.chat_send_all("[advtrains]"..text)
end

if minetest.settings:get_bool("advtrains_enable_debugging") then
	atprint=function(t, ...)
		local context=advtrains.atprint_context_tid or ""
		if not context then return end
		local text=advtrains.print_concat_table({t, ...})
		advtrains.drb_record(context, text)
		
		--atlog("@@",advtrains.atprint_context_tid,t,...)
	end
	dofile(advtrains.modpath.."/debugringbuffer.lua")
end

dofile(advtrains.modpath.."/helpers.lua");
--dofile(advtrains.modpath.."/debugitems.lua");

advtrains.meseconrules = 
{{x=0,  y=0,  z=-1},
 {x=1,  y=0,  z=0},
 {x=-1, y=0,  z=0},
 {x=0,  y=0,  z=1},
 {x=1,  y=1,  z=0},
 {x=1,  y=-1, z=0},
 {x=-1, y=1,  z=0},
 {x=-1, y=-1, z=0},
 {x=0,  y=1,  z=1},
 {x=0,  y=-1, z=1},
 {x=0,  y=1,  z=-1},
 {x=0,  y=-1, z=-1},
 {x=0, y=-2, z=0}}

advtrains.fpath=minetest.get_worldpath().."/advtrains"

dofile(advtrains.modpath.."/path.lua")
dofile(advtrains.modpath.."/trainlogic.lua")
dofile(advtrains.modpath.."/trainhud.lua")
dofile(advtrains.modpath.."/trackplacer.lua")
dofile(advtrains.modpath.."/tracks.lua")
dofile(advtrains.modpath.."/atc.lua")
dofile(advtrains.modpath.."/wagons.lua")

dofile(advtrains.modpath.."/trackdb_legacy.lua")
dofile(advtrains.modpath.."/nodedb.lua")
dofile(advtrains.modpath.."/couple.lua")

dofile(advtrains.modpath.."/signals.lua")
dofile(advtrains.modpath.."/misc_nodes.lua")
dofile(advtrains.modpath.."/crafting.lua")
dofile(advtrains.modpath.."/craft_items.lua")

dofile(advtrains.modpath.."/log.lua")


--load/save


advtrains.fpath=minetest.get_worldpath().."/advtrains"
dofile(advtrains.modpath.."/log.lua")

local saving_disabled

function advtrains.avt_load()
	local file, err = io.open(advtrains.fpath, "r")
	if not file then
		minetest.log("error", " Failed to read advtrains save data from file "..advtrains.fpath..": "..(err or "Unknown Error"))
	else
		local tbl = minetest.deserialize(file:read("*a"))
		if type(tbl) == "table" then
			if tbl.version then
				--congrats, we have the new save format.
				if tbl.version > 1 then
					-- we are going to downgrade! that's not good!
					atwarn("The save file of this world has been saved from a newer version of advtrains.")
					atwarn("Opening it in this version could cause significant data loss once it's saved again.")
					atwarn("Advtrains data is therefore not saved in this session.")
					atwarn("To downgrade permanently, locate the 'version' entry in the save file and set it to 1")
					saving_disabled = true
				end
				
				advtrains.trains = tbl.trains
				advtrains.wagon_save = tbl.wagon_save
				advtrains.player_to_train_mapping = tbl.ptmap or {}
				advtrains.ndb.load_data(tbl.ndb)
				advtrains.atc.load_data(tbl.atc)
				--remove wagon_save entries that are not part of a train
				local todel=advtrains.merge_tables(advtrains.wagon_save)
				for tid, train in pairs(advtrains.trains) do
					for _, wid in ipairs(train.trainparts) do
						todel[wid]=nil
					end
				end
				for wid, _ in pairs(todel) do
					atwarn("Removing unused wagon", wid, "from wagon_save table.")
					advtrains.wagon_save[wid]=nil
				end
			else
				--oh no, its the old one...
				advtrains.trains=tbl
				--load ATC
				advtrains.fpath_atc=minetest.get_worldpath().."/advtrains_atc"
				local file, err = io.open(advtrains.fpath_atc, "r")
				if not file then
					local er=err or "Unknown Error"
					atprint("Failed loading advtrains atc save file "..er)
				else
					local tbl = minetest.deserialize(file:read("*a"))
					if type(tbl) == "table" then
						advtrains.atc.controllers=tbl.controllers
					end
					file:close()
				end
				--load wagon saves
				advtrains.fpath_ws=minetest.get_worldpath().."/advtrains_wagon_save"
				local file, err = io.open(advtrains.fpath_ws, "r")
				if not file then
					local er=err or "Unknown Error"
					atprint("Failed loading advtrains save file "..er)
				else
					local tbl = minetest.deserialize(file:read("*a"))
					if type(tbl) == "table" then
						advtrains.wagon_save=tbl
					end
					file:close()
				end
			end
		else
			minetest.log("error", " Failed to deserialize advtrains save data: Not a table!")
		end
		file:close()
	end
end

advtrains.avt_save = function(remove_players_from_wagons)
	--atprint("saving")
	--No more invalidating.
	--Instead, remove path a.s.o from the saved table manually
	
	-- update wagon saves
	for _,wagon in pairs(minetest.luaentities) do
		if wagon.is_wagon and wagon.initialized then
			wagon:get_staticdata()
		end
	end
	--cross out userdata
	for w_id, data in pairs(advtrains.wagon_save) do
		data.name=nil
		data.object=nil
		if data.driver then
			data.driver_name=data.driver:get_player_name()
			data.driver=nil
		else
			data.driver_name=nil
		end
		if data.discouple then
			data.discouple.object:remove()
			data.discouple=nil
		end
		if remove_players_from_wagons then
			data.seatp={}
		end
	end
	if remove_players_from_wagons then
		advtrains.player_to_train_mapping={}
	end
	
	local tmp_trains={}
	for id, train in pairs(advtrains.trains) do
		--first, deep_copy the train
		local v=advtrains.save_keys(train, {
			"last_pos", "last_pos_prev", "movedir", "velocity", "tarvelocity",
			"trainparts", "savedpos_off_track_index_offset", "recently_collided_with_env",
			"atc_brake_target", "atc_wait_finish", "atc_command", "atc_delay", "door_open",
			"text_outside", "text_inside", "couple_lck_front", "couple_lck_back"
		})
		--then invalidate
		if train.index then
			v.restore_add_index=train.index-math.floor(train.index+1)
		end
		--then save it
		tmp_trains[id]=v
	end
	
	--versions:
	-- 1 - Initial new save format.
	local save_tbl={
		trains = tmp_trains,
		wagon_save = advtrains.wagon_save,
		ptmap = advtrains.player_to_train_mapping,
		atc = advtrains.atc.save_data(),
		ndb = advtrains.ndb.save_data(),
		version = 1,
	}
	local datastr = minetest.serialize(save_tbl)
	if not datastr then
		minetest.log("error", " Failed to serialize advtrains save data!")
		return
	end
	local file, err = io.open(advtrains.fpath, "w")
	if err then
		minetest.log("error", " Failed to write advtrains save data to file "..advtrains.fpath..": "..(err or "Unknown Error"))
		return
	end
	file:write(datastr)
	file:close()
end

--## MAIN LOOP ##--
--Calls all subsequent main tasks of both advtrains and atlatc
local init_load=false
local save_interval=20
local save_timer=save_interval
advtrains.mainloop_runcnt=0

minetest.register_globalstep(function(dtime_mt)
	return advtrains.pcall(function()
		advtrains.mainloop_runcnt=advtrains.mainloop_runcnt+1
		--atprint("Running the main loop, runcnt",advtrains.mainloop_runcnt)
		--call load once. see advtrains.load() comment
		if not init_load then
			advtrains.load()
		end
		--limit dtime: if trains move too far in one step, automation may cause stuck and wrongly braking trains
		local dtime=dtime_mt
		if dtime>0.2 then
			atprint("Limiting dtime to 0.2!")
			dtime=0.2
		end
		
		advtrains.mainloop_trainlogic(dtime)
		if advtrains_itm_mainloop then
			advtrains_itm_mainloop(dtime)
		end
		if atlatc then
			atlatc.mainloop_stepcode(dtime)
			atlatc.interrupt.mainloop(dtime)
		end
		
		
		--trigger a save when necessary
		save_timer=save_timer-dtime
		if save_timer<=0 then
			local t=os.clock()
			--save
			advtrains.save()
			save_timer=save_interval
			atprintbm("saving", t)
		end
	end)
end)

--if something goes wrong in these functions, there is no help. no pcall here.

--## MAIN LOAD ROUTINE ##
-- Causes the loading of everything
-- first time called in main loop (after the init phase) because luaautomation has to initialize first.
function advtrains.load()
	advtrains.avt_load() --loading advtrains. includes ndb at advtrains.ndb.load_data()
	if atlatc then
		atlatc.load() --includes interrupts
	end
	if advtrains_itm_init then
		advtrains_itm_init()
	end
	init_load=true
	no_action=false
	atlog("[load_all]Loaded advtrains save files")
end

--## MAIN SAVE ROUTINE ##
-- Causes the saving of everything
function advtrains.save(remove_players_from_wagons)
	if not init_load then
		--wait... we haven't loaded yet?!
		atwarn("Instructed to save() but load() was never called!")
		return
	end
	if saving_disabled then
		return
	end
	advtrains.avt_save(remove_players_from_wagons) --saving advtrains. includes ndb at advtrains.ndb.save_data()
	if atlatc then
		atlatc.save()
	end
	atprint("[save_all]Saved advtrains save files")
end
minetest.register_on_shutdown(advtrains.save)

-- This chat command provides a solution to the problem known on the LinuxWorks server
-- There are many players that joined a single time, got on a train and then left forever
-- These players still occupy seats in the trains.
minetest.register_chatcommand("at_empty_seats",
	{
        params = "", -- Short parameter description
        description = "Detach all players, especially the offline ones, from all trains. Use only when no one serious is on a train.", -- Full description
        privs = {train_operator=true, server=true}, -- Require the "privs" privilege to run
        func = function(name, param)
			return advtrains.pcall(function()
				atwarn("Data is being saved. While saving, advtrains will remove the players from trains. Save files will be reloaded afterwards!")
				advtrains.save(true)
				reload_saves()
			end)
        end,
})
-- This chat command solves another problem: Trains getting randomly stuck.
minetest.register_chatcommand("at_reroute",
	{
        params = "", 
        description = "Delete all train routes, force them to recalculate", 
        privs = {train_operator=true}, -- Only train operator is required, since this is relatively safe.
        func = function(name, param)
			return advtrains.pcall(function()
				advtrains.invalidate_all_paths()
				return true, "Successfully invalidated train routes"
			end)
        end,
})