local enet = require"enet"
local json = require"common.dkjson"
local chunk = require"common.chunk"
local noise = require"noise"
local coords = require"common.coords"
local Pos = coords.Pos
local worldgen = require"worldgen"
local MapS = require"map".MapS
local posix_time = require"posix.time"
local posix_signal = require"posix.signal"

math.randomseed(os.time())

local host = enet.host_create("*:8473",nil,2)
print(host:get_socket_address())

-- sequential list of all players
local playerlist = {}
local nextid = 1

-- this is maybe suboptimal
-- but it is simplest for now
local function player_by_id(id)
	for i,pl in ipairs(playerlist) do
		if pl.id == id then return pl, i end
	end
	return nil
end
local function player_by_peer(peer)
	for i,pl in ipairs(playerlist) do
		if pl.peer == peer then return pl, i end
	end
	return nil
end

local function random_color()
	return {math.random(),math.random(),math.random()}
end
local function make_player(peer)
	local p = {pos=Pos:make(0,0),color=random_color(),peer=peer,id=nextid}
	nextid = nextid + 1
	return p
end

local function player_info_part(player)
	return {
		id=player.id,
		x=player.pos.x,
		y=player.pos.y,
		color=player.color,
	}
end
local function player_join_packet(player)
	return json.encode{t="join",pl=player_info_part(player)}
end
local function player_you_packet(player)
	return json.encode{t="you",pl=player_info_part(player)}
end
local function player_leave_packet(player)
	return json.encode{t="leave",id=player.id}
end
local function player_move_packet(player,x,y)
	return json.encode{t="move",id=player.id,x=x,y=y}
end
local function chat_packet(fromplayer,msg)
	return json.encode{t="chat",from=fromplayer.id,msg=msg}
end

local map = MapS:make()

local function handle_ev(ev)
	-- handle network event
	if ev.type == "connect" then
		local player = make_player(ev.peer)
		table.insert(playerlist,player)
		print("connect",player.peer,player.id)
		player.peer:send(player_you_packet(player))
		local central_chunk = map:obtain(coords.ChunkPos:make(0,0))
		player.peer:send(central_chunk:data_packet())

		for i,otherplayer in ipairs(playerlist) do
			if otherplayer ~= player then
				-- tell new player about each other player
				player.peer:send(player_join_packet(otherplayer))
				-- tell each other player about new player
				otherplayer.peer:send(player_join_packet(player))
			end
		end
	elseif ev.type == "disconnect" then
		local player, idx = player_by_peer(ev.peer)
		if not player then error("sneeze "..ev.peer) end
		print("disconnect",player.peer,player.id)
		table.remove(playerlist,idx)
		for i,otherplayer in ipairs(playerlist) do
			otherplayer.peer:send(player_leave_packet(player))
		end
	elseif ev.type == "receive" then
		local player = player_by_peer(ev.peer)
		if not player then error("sneezey "..ev.peer) end
		local j = json.decode(ev.data)
		-- print(ev.channel,ev.data)
		local op = j.t
		if op == "ppos" then
			local x,y = j.x,j.y
			player.pos = coords.Pos:make(x,y)
			-- print(player.id,"-->",player.pos[1],player.pos[2])
			for i,otherplayer in ipairs(playerlist) do
				if otherplayer ~= player then
					otherplayer.peer:send(player_move_packet(player,x,y),1)
				end
			end
		elseif op == "settile" then
			local h = coords.Hex:make(j.q,j.r)
			map:set_at(h,j.tile)
			-- print(player.id,"settile",h,j.tile)
			for i,otherplayer in ipairs(playerlist) do
				if otherplayer ~= player then
					-- same packet structure s2c as c2s
					-- when multiple chunks exist and players only get info
					-- about stuff near to them, that won't be the case any more
					otherplayer.peer:send(ev.data)
				end
			end
		elseif op == "reqchunk" then
			-- i am not certain this is the best way for this to work
			-- i might change it later
			local cp = coords.ChunkPos:make(j.u,j.v)
			local ch = map:obtain(cp)
			player.peer:send(ch:data_packet())
		elseif op == "chat" then
			print("chat ["..player.id.."] "..j.msg)
			for i,otherplayer in ipairs(playerlist) do
				otherplayer.peer:send(chat_packet(player,j.msg))
			end
		end
	end
end

local function timenow()
	-- monotonic clock, guaranteed to never go backwards
	local tv = posix_time.clock_gettime(posix_time.CLOCK_MONOTONIC)
	-- this discards some precision but i don't care
	return tv.tv_sec + (tv.tv_nsec/1000000000)
end
-- do something only every x seconds
-- returns function(dt) -> bool
-- which returns true if you should, and false otherwise
local function every(interval)
	local time_since = interval+100
	return function(dt)
		time_since = time_since + dt
		if time_since > interval then
			time_since = 0
			return true
		else
			return false
		end
	end
end

local tick_interval = 1 -- seconds
local last_tick_time = timenow()

-- average tps calculation
local dts = {}
local ndt = 1
local ndts = 100
local ntick = 0


local function player_near_chunk(cp)
	-- true: chunk at cp should stay loaded (because of a nearby player),
	-- false: no players nearby, can be unloaded
	-- this is maybe not as efficient as it possibly could be
	for _,player in ipairs(playerlist) do
		local pcp = player.pos:to_hex():containing_chunk()
		for _,neighb in ipairs(pcp:neighborhood()) do
			if neighb == cp then
				return true
			end
		end
	end
	return false
end

local function save_things()
	for cp,ch in map:iter_chunks() do
		map:save_chunk(cp)
		if not player_near_chunk(cp) then
			-- print("unloading chunk",cp)
			map:remove_chunk(cp)
		end
	end
end

local function tick(ntick)
	if ntick % 30 == 0 then
		-- print("saving things")
		save_things()
	end
end

local stopping=false

posix_signal.signal(posix_signal.SIGINT, function() stopping=true end)

while true do
	if stopping then
		print("stopping...")
		save_things()
		break
	end

	local now = timenow()
	local dt = now - last_tick_time
	local time_till_next_tick = (last_tick_time+tick_interval)-now
	if time_till_next_tick > 0.001 then
		local ev = host:service(time_till_next_tick*1000)
		if ev then handle_ev(ev) end
	else
		last_tick_time = now
		ntick = ntick + 1
		tick(ntick)
	end
end