asterisk voip automatic dialing improvement

I have a automatic dialer today This is a custom made automatic dialer based on asterisk realtime_queues. When the agent is logged into the queue, the dialer will call a number from the table and put it to the first available agent I addition the dialer will diale x number of call set by the parameter "call_ahead" in a table. If there is no free agent, it will get a queue status "abandon" I would like this process to be automated, so the call ahead is adding up, when more agents are logging in or the waittime is increasing. Likewise I would like the call_ahead to decrease if the percent of abandon calls is rising above a setting. So: Long waiting time = more call ahead. to many abandon = less call ahead.. I need 2 settings: 1)how many agent will sign in before increasing the call_ahead with one. for example if the setting is 4 then 4 agent need to sign in before increasing the callahead with 1 2) abandon rate: a percent of abandon calls allowed before decreasing the Call_ahead with 1 There is a lot of other things going on in this program. The number is loaded from a webservice and so on, but that is other people taking care of. your only job will be to tune the speed of the dialing