--
--  rhnop
--
--  Copyright (C) 2011-2016 Christian Pointner <equinox@helsinki.at>
--
--  This file is part of rhnop.
--
--  rhnop is free software: you can redistribute it and/or modify
--  it under the terms of the GNU General Public License as published by
--  the Free Software Foundation, either version 3 of the License, or
--  any later version.
--
--  rhnop is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--  GNU General Public License for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with rhnop. If not, see <http://www.gnu.org/licenses/>.
--

socket = require "socket"

package.path = package.path .. ";" .. rhnoplibdir .. "/?.lua"
conf = require "conf"

function init_server()
   local server = assert(socket.tcp())

   cnf = conf.load(rhnopescdir .. "/nopfetchd.conf")
   assert(server:setoption('reuseaddr', true))
   assert(server:bind(cnf.tcp_host, cnf.tcp_port))
   assert(server:listen(5))

   print("TCPServer: listening on " .. cnf.tcp_host .. ":" .. cnf.tcp_port)

   return server
end

local clients = {}

function add_client(hdl)
   -- print("new client(" .. hdl:getfd() .. ") from " .. hdl:getpeername())
   local client = {}
   client.buffer = ""
   client.hdl = hdl
   client.getfd = function() return hdl:getfd() end
   client.dirty = function() return hdl:dirty() end
   table.insert(clients, client)
end

function remove_client(c)
   local idx = -1
   for n, client in ipairs(clients) do
      if client.getfd() == c.getfd() then
         idx = n
         break
      end
   end

   if idx > 0 then
--      print("removing client(" .. c.getfd() .. ")")
      c.hdl:close()
      table.remove(clients, idx)
   end
end

function cleanup_clients()
   for _, client in ipairs(clients) do
      client:close()
   end
end

function clients_get_writeables()
   local fds = {}

   for _, client in ipairs(clients) do
      if client.buffer ~= "" then
         table.insert(fds, client)
      end
   end

   return fds
end

function clients_senddata(timestamp)
   for _, client in ipairs(clients) do
      client.buffer  = client.buffer .. timestamp .. "\n"
   end
end

function main_loop()
   local pipefd = pipe.getreadfd()

   server = init_server()
   while true do
      local readables, writeables, err = socket.select({ pipefd , server , unpack(clients) } , clients_get_writeables())
      if err then
         print("select returned with error: " .. err)
         return -1
      else
         for _, input in ipairs(readables) do
            if input == pipefd then
               local timestamp = pipe.consume()
               if timestamp == nil then
                  return 2
               end
               -- print("pipe was signaled with timestamp: " .. timestamp)
               clients_senddata(timestamp)
            elseif input == server then
               local client = assert(server:accept())
               add_client(client)
            else
               if input.hdl then
                  -- receive is insanely stupid, therefore we must always read one byte only
                  local _, err = input.hdl:receive(1)
                  if err then
                     remove_client(input)
                  end
               end
            end
         end

         for _, output in ipairs(writeables) do
            local ret = output.hdl:send(output.buffer)
            if(ret == nil) then
               remove_client(output)
            else
               output.buffer = string.sub(output.buffer, ret+1)
            end
         end
      end
   end

   server:close()
   cleanup_clients()

   return 0
end