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 Player=require'player'.Player
local posix_time = require"posix.time"
local posix_signal = require"posix.signal"
local db = require'db'

math.randomseed(os.time())

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

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

-- 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 player_join_packet(player)
	return json.encode{t="join",pl=player:info_part()}
end
local function player_you_packet(player)
	return json.encode{t="you",pl=player:info_part()}
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()





-- set of peers currently within handshake procedure
local connecting_peers = {}

local function create_player(...)
	-- advances connecting peer to player
	local player = Player:make(...)
	table.insert(playerlist, player)

	connecting_peers[player.peer] = nil

	player.peer:send(player_you_packet(player))

	for i,otherplayer in ipairs(playerlist) do
		if otherplayer ~= player then
			player.peer:send(player_join_packet(otherplayer))
			otherplayer.peer:send(player_join_packet(player))
		end
	end

	print("connect",player.id,player.peer)
end

local function connecting_peer_ev()
	local ev = coroutine.yield()
	print("hello")
	local j = json.decode(ev.data)
	local op = j.t
	if op == "handshake" then
		print(ev,'handshake; username',j.username)
		create_player(ev.peer,j.username)
	else
		error("weird handshake: "..op)
	end
end


local function on_peer_connect(peer)
	print("peer connect: ",peer)
	local co = coroutine.create(connecting_peer_ev)
	assert(coroutine.resume(co))
	connecting_peers[peer] = co
end


local function on_peer_disconnect(peer)
	print("peer disconnect: ",peer)
	connecting_peers[peer] = nil
	local player,idx = player_by_peer(peer)
	if player then
		table.remove(playerlist, idx)
		for i,otherplayer in ipairs(playerlist) do
			otherplayer.peer:send(player_leave_packet(player))
		end
		print("disconnect", player.id, player.peer)
	end
end

local function handle_player_packet(player,ev)
	print('player packet ',player,ev.data)
	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

local function handle_ev(ev)
	if ev.type == 'connect' then
		on_peer_connect(ev.peer)
	elseif ev.type == 'disconnect' then
		on_peer_disconnect(ev.peer)
	elseif ev.type == 'receive' then
		print("recv:",ev.peer,ev.data)
		if connecting_peers[ev.peer] then
			local co = connecting_peers[ev.peer]
			print("\t-> hshake",co,coroutine.status(co))
			local ok,err = coroutine.resume(co, ev)
			if not ok then
				print("hshake error: ",ev.peer,err)
				connecting_peers[ev.peer] = nil
				ev.peer:disconnect_now()
			end
		else
			local player = player_by_peer(ev.peer)
			if not player then error("packet from unknown peer ",ev.peer) end
			print("\t-> player",player)
			handle_player_packet(player, ev)
		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

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


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()
	local txn = db.txn(true)
	for cp,ch in map:iter_chunks() do
		map:save_chunk(cp,txn)
		if not player_near_chunk(cp) then
			-- print("unloading chunk",cp)
			map:remove_chunk(cp)
		end
	end
	txn:commit()
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)

local ntick = 0

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