xban = { }

local MP = minetest.get_modpath(minetest.get_current_modname())

dofile(MP.."/serialize.lua")
dofile(MP.."/shutil.lua")

local db = { }
local tempbans = { }

local DEF_SAVE_INTERVAL = 300 -- 5 minutes
local DEF_DB_FILENAME = minetest.get_worldpath().."/xban.db"

local DB_FILENAME = minetest.setting_get("xban.db_filename")
local SAVE_INTERVAL = tonumber(
  minetest.setting_get("xban.db_save_interval")) or DEF_SAVE_INTERVAL

if (not DB_FILENAME) or (DB_FILENAME == "") then
	DB_FILENAME = DEF_DB_FILENAME
end

local function make_logger(level)
	return function(text, ...)
		minetest.log(level, "[xban] "..text:format(...))
	end
end

local ACTION = make_logger("action")
local INFO = make_logger("info")
local WARNING = make_logger("warning")
local ERROR = make_logger("error")

local unit_to_secs = {
	s = 1, m = 60, h = 3600,
	D = 86400, W = 604800, M = 2592000, Y = 31104000,
	[""] = 1,
}

local function parse_time(t) --> secs
	local secs = 0
	for num, unit in t:gmatch("(%d+)([smhDWMY]?)") do
		secs = secs + (tonumber(num) * (unit_to_secs[unit] or 1))
	end
	return secs
end

function xban.find_entry(player, create) --> entry, index
	for index, e in ipairs(db) do
		for name in pairs(e.names) do
			if name == player then
				return e, index
			end
		end
	end
	if create then
		local e = {
			names = { [player]=true },
			banned = false,
			record = { },
		}
		table.insert(db, e)
		return e, #db
	end
	return nil
end

function xban.get_info(player) --> ip_name_list, banned, last_record
	local e = xban.find_entry(player)
	if not e then
		return nil, "No such entry"
	end
	return e.names, e.banned, e.record[#e.record]
end

function xban.ban_player(player, source, expires, reason) --> bool, err
	local e = xban.find_entry(player, true)
	local rec = {
		source = source,
		time = os.time(),
		expires = expires,
		reason = reason,
	}
	table.insert(e.record, rec)
	e.names[player] = true
	local pl = minetest.get_player_by_name(player)
	if pl then
		local ip = minetest.get_player_ip(player)
		if ip then
			e.names[ip] = true
		end
	end
	e.reason = reason
	e.time = rec.time
	e.expires = expires
	e.banned = true
	local msg
	local date = (expires and os.date("%c", expires)
	  or "the end of time")
	if expires then
		table.insert(tempbans, e)
		msg = ("Banned: Expires: %s, Reason: %s"):format(date, reason)
	else
		msg = ("Banned: Reason: %s"):format(reason)
	end
	for nm in pairs(e.names) do
		minetest.kick_player(nm, msg)
	end
	ACTION("%s bans %s until %s for reason: %s", source, player,
	  date, reason)
	ACTION("Banned Names/IPs: %s", table.concat(e.names, ", "))
	return true
end

function xban.unban_player(player, source) --> bool, err
	local e = xban.find_entry(player)
	if not e then
		return nil, "No such entry"
	end
	local rec = {
		source = source,
		time = os.time(),
		reason = "Unbanned",
	}
	table.insert(e.record, rec)
	e.banned = false
	e.reason = nil
	e.expires = nil
	e.time = nil
	ACTION("%s unbans %s", source, player)
	ACTION("Unbanned Names/IPs: %s", table.concat(e.names, ", "))
	return true
end

minetest.register_on_prejoinplayer(function(name, ip)
	local e = xban.find_entry(name) or xban.find_entry(ip, true)
	e.names[name] = true
	e.names[ip] = true
	if e.banned then
		local date = (e.expires and os.date("%c", e.expires)
		  or "the end of time")
		return ("Banned: Expires: %s, Reason: %s"):format(
		  date, e.reason)
	end
end)

minetest.register_chatcommand("xban", {
	description = "XBan a player",
	params = "<player> <reason>",
	privs = { ban=true },
	func = function(name, params)
		local plname, reason = params:match("(%S+)%s+(.+)")
		if not (plname and reason) then
			minetest.chat_send_player(name,
			  "Usage: /xban <player> <reason>")
			return
		end
		xban.ban_player(plname, name, nil, reason)
		minetest.chat_send_player(name,
		  ("Banned %s."):format(plname))
	end,
})

minetest.register_chatcommand("xtempban", {
	description = "XBan a player temporarily",
	params = "<player> <time> <reason>",
	privs = { ban=true },
	func = function(name, params)
		local plname, time, reason = params:match("(%S+)%s+(%S+)%s+(.+)")
		if not (plname and time and reason) then
			minetest.chat_send_player(name,
			  "Usage: /xtempban <player> <time> <reason>")
			return
		end
		time = parse_time(time)
		if time < 60 then
			minetest.chat_send_player(name,
			  "You must ban for at least 60 seconds.")
			return
		end
		local expires = os.time() + time
		xban.ban_player(plname, name, expires, reason)
		minetest.chat_send_player(name,
		  ("Banned %s until %s."):format(
		  plname, os.date("%c", expires)))
	end,
})

minetest.register_chatcommand("xunban", {
	description = "XUnBan a player",
	params = "<player_or_ip>",
	privs = { ban=true },
	func = function(name, params)
		local plname = params:match("%S+")
		if not plname then
			minetest.chat_send_player(name,
			  "Usage: /xunban <player_or_ip>")
			return
		end
		local ok, e = xban.unban_player(plname, name)
		minetest.chat_send_player(name,
		  ("Unbanned %s."):format(plname))
	end,
})

local function check_temp_bans()
	minetest.after(60, check_temp_bans)
	local to_rm = { }
	local now = os.time()
	for i, e in ipairs(tempbans) do
		if e.expires and (e.expires <= now) then
			table.insert(to_rm, i)
			e.banned = false
			e.expires = nil
			e.reason = nil
			e.time = nil
		end
	end
	for _, i in ipairs(to_rm) do
		table.remove(tempbans, i)
	end
end

local function save_db()
	minetest.after(SAVE_INTERVAL, save_db)
	local ok
	local f, e = io.open(DB_FILENAME, "wt")
	db.timestamp = os.time()
	if f then
		ok, e = f:write(xban.serialize(db))
		WARNING("Unable to save database: %s", e)
	end
	if f then f:close() end
	return
end

local function load_db()
	local f, e = io.open(DB_FILENAME, "rt")
	if not f then
		WARNING("Unable to load database: %s", e)
		return
	end
	local cont
	cont, e = f:read("*a")
	if not cont then
		WARNING("Unable to load database: %s", e)
		return
	end
	local t = minetest.deserialize(cont)
	if not t then
		WARNING("Unable to load database: %s",
		  "Deserialization failed")
		return
	end
	db = t
	tempbans = { }
	for _, entry in ipairs(db) do
		if entry.banned and entry.expires then
			table.insert(tempbans, entry)
		end
	end
end

-- Backup database
shutil.copy_file(DB_FILENAME,
  DB_FILENAME.."."..os.date("%Y%m%d%H%M%S"))

minetest.register_on_shutdown(save_db)
minetest.after(SAVE_INTERVAL, save_db)
load_db()
xban.db = db