--[[ $%BEGINLICENSE%$
 Copyright (C) 2009 MySQL AB, 2009 Sun Microsystems, Inc

 This program 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; version 2 of the License.

 This program 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 this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 $%ENDLICENSE%$ --]]


-- To make query parsing easier
local tokenizer = require("proxy.tokenizer")
-- To avoid messing with the protocol
local proto = assert(require("mysql.proto"))
-- To overwrite print() and print to logs
require("chassis")
-- We assign the value of the same table to itself
-- or initialize it if not existent
proxy.global.db = proxy.global.db or {}
proxy.global.last_node = proxy.global.last_node or 0




-- connection pool
if not proxy.global.config.rwsplit then
  proxy.global.config.rwsplit = {
    min_idle_connections = 1,
    max_idle_connections = 1,
  }
end
proxy.global.config.rwsplit.is_debug = false

--[[ ====================================================================== ]]--

--[[

function connect_server()
    -- emulate a server
    proxy.response = {
        type = proxy.MYSQLD_PACKET_RAW,
        packets = {
            proto.to_challenge_packet({
            server_status       = 2
            , server_version    = 50132
            , thread_id         = 12345678922222
            })
        }
    }
    -- You need to specify a nil backend when you start the proxy
    -- like this:
    -- proxy-backend-addresses=
    -- otherwise you get the default 127.0.0.1:3306
    if proxy.global.backends[1] == nil  then
        proxy.global.last_node = 1
        return proxy.PROXY_SEND_RESULT
    end
    -----------------------

  local is_debug = proxy.global.config.rwsplit.is_debug
    
  -- make sure that we connect to each backend at least ones to 
  -- keep the connections to the servers alive
  --
  -- on read_query we can switch the backends again to another backend

  if is_debug then
    print("[connect_server] " .. proxy.connection.client.src.name)
        print("[connect_server] " .. proxy.connection.client.dst.name)
  end

  local rw_ndx = 0

  -- init all backends 
  for i = 1, #proxy.global.backends do
    local s        = proxy.global.backends[i]
    local pool     = s.pool -- we don't have a username yet, try to find a connections which is idling
    local cur_idle = pool.users[""].cur_idle_connections

    pool.min_idle_connections = proxy.global.config.rwsplit.min_idle_connections
    pool.max_idle_connections = proxy.global.config.rwsplit.max_idle_connections
    
    if is_debug then
      print("  [".. i .."].connected_clients = " .. s.connected_clients)
      print("  [".. i .."].pool.cur_idle     = " .. cur_idle)
      print("  [".. i .."].pool.max_idle     = " .. pool.max_idle_connections)
      print("  [".. i .."].pool.min_idle     = " .. pool.min_idle_connections)
      print("  [".. i .."].type = " .. s.type)
      print("  [".. i .."].state = " .. s.state)
    end

    -- prefer connections to the master 
    if s.type == proxy.BACKEND_TYPE_RW and
       s.state ~= proxy.BACKEND_STATE_DOWN and
       cur_idle < pool.min_idle_connections then
      proxy.connection.backend_ndx = i
      break
    elseif s.type == proxy.BACKEND_TYPE_RO and
           s.state ~= proxy.BACKEND_STATE_DOWN and
           cur_idle < pool.min_idle_connections then
      proxy.connection.backend_ndx = i
      break
    elseif s.type == proxy.BACKEND_TYPE_RW and
           s.state ~= proxy.BACKEND_STATE_DOWN and
           rw_ndx == 0 then
            rw_ndx = i
    end
  end

  if proxy.connection.backend_ndx == 0 then
    if is_debug then
      print("  [" .. rw_ndx .. "] taking master as default")
    end
    proxy.connection.backend_ndx = rw_ndx
  end

  -- pick a random backend
  --
  -- we someone have to skip DOWN backends

  -- ok, did we got a backend ?

  if proxy.connection.server then 
    if is_debug then
      print("  using pooled connection from: " .. proxy.connection.backend_ndx)
    end

    -- stay with it
    return proxy.PROXY_IGNORE_RESULT
  end

  if is_debug then
    print("  [" .. proxy.connection.backend_ndx .. "] idle-conns below min-idle")
  end

  -- open a new connection 


end

--]]


--[[ ====================================================================== ]]--
function read_query( packet )
    -- we use this to send it to the other
    -- backends
    query = packet:sub(2)
    
    if (string.byte(packet) == proxy.COM_QUIT) 
        or (string.byte(packet) == proxy.COM_INIT_DB)
    then
        -- This gets called when you disconnect from the server
        proxy.response.type = proxy.MYSQLD_PACKET_OK
        return proxy.PROXY_SEND_RESULT
    elseif string.byte(packet) ~= proxy.COM_QUERY then
        proxy.response.type = proxy.MYSQLD_PACKET_OK
        return proxy.PROXY_SEND_RESULT 

    end
end -- End of read_query()
--[[ ====================================================================== ]]--

function disconnect_client()
  local is_debug = proxy.global.config.rwsplit.is_debug
  if is_debug then
    print("[disconnect_client] " .. proxy.connection.client.src.name)
  end

  -- make sure we are disconnection from the connection
  -- to move the connection into the pool
  proxy.connection.backend_ndx = 0
end
--[[ ====================================================================== ]]--

--[[

How to use:
It supports 5 types of queries

mysql> INSERT "key" = "value";
mysql> SELECT "key";
mysql> DELETE "key";
mysql> SELECT *;
mysql> DROP;

If using in replication, you need to start some connection to create
the pool of connections. Yo ucan use something like:

$ for i in `seq 1 100` ; do mysql -h127.0.0.1 -P4040 -e "exit"; done ; 



--]]