--[[ $%BEGINLICENSE%$
 Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved.

 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., 51 Franklin St, Fifth Floor, Boston, MA
 02110-1301  USA

 $%ENDLICENSE%$ --]]
--[[

   

--]]

-- init the query-counter if it isn't done yet
if not proxy.global.query_counter then
    proxy.global.query_counter = 0
end

local query_counter = 0

---
-- read_query() can return a resultset
--
-- You can use read_query() to return a result-set. 
--
-- @param packet the mysql-packet sent by the client
--
-- @return 
--   * nothing to pass on the packet as is, 
--   * proxy.PROXY_SEND_QUERY to send the queries from the proxy.queries queue
--   * proxy.PROXY_SEND_RESULT to send your own result-set
--
function read_query( packet )
    -- a new query came in in this connection
    proxy.global.query_counter = proxy.global.query_counter + 1
    query_counter = query_counter + 1

    if string.byte(packet) == proxy.COM_QUERY then
        --[[

        we use a simple string-match to split commands are word-boundaries
        
        mysql> show querycounter

        is split into 
        command = "show"
        option  = "querycounter"
        
        spaces are ignored, the case has to be as is.

        mysql> show myerror

        returns a error-packet

        --]]
        
        -- try to match the string up to the first non-alphanum
        local f_s, f_e, command = string.find(packet, "^%s*(%w+)", 2)
        local option

        if f_e then
            -- if that match, take the next sub-string as option
            f_s, f_e, option = string.find(packet, "^%s+(%w+)", f_e + 1)
        end
    
        -- we got our commands, execute it
        if string.lower(command) == "show" and string.lower(option) == "querycounter" then
            ---
            -- proxy.PROXY_SEND_RESULT requires 
            --
            -- proxy.response.type to be either 
            -- * proxy.MYSQLD_PACKET_OK or
            -- * proxy.MYSQLD_PACKET_ERR
            --
            -- for proxy.MYSQLD_PACKET_OK you need a resultset
            -- * fields
            -- * rows
            --
            -- for proxy.MYSQLD_PACKET_ERR
            -- * errmsg
            proxy.response.type = proxy.MYSQLD_PACKET_OK
            proxy.response.resultset = {
                fields = { 
                    { type = proxy.MYSQL_TYPE_LONG, name = "global_query_counter", },
                    { type = proxy.MYSQL_TYPE_LONG, name = "query_counter", },
                }, 
                rows = { 
                    { proxy.global.query_counter, query_counter }
                }
            }

            -- we have our result, send it back
            return proxy.PROXY_SEND_RESULT
        elseif string.lower(command) == "show" and string.lower(option) == "myerror" then
            proxy.response.type = proxy.MYSQLD_PACKET_ERR
            proxy.response.errmsg = "my first error"
            
            return proxy.PROXY_SEND_RESULT
        end
    end
end


