linux bash - Parse date in custom format

Question

I have a date in a the %c format (could be any other) and I need to use it in the date command. %c is NOT the American format. It is the G

Answer 1

Why don't you store the time as unixtime (ie milliseconds since 1st of january 1970) Like 1388198714?

The requested exercise in trying to parse all date formats from all around the world as a one shot bash script without reasonable dependecies is slightly ridiculous.