Bulk search/extract from my WordPress site

I need to be able to extract information from my WordPress posts, as follows: 1. I choose a particular word or phrase and date range. 2. The program reads through all the WordPress postings within the specified date range, looking for the occurrence of the keyword. 3. Each time the keyword is found, the program extracts the five lines of the posting before the line on which the keyword was found, the keyword line, and the five lines after. It doesn't have to be exactly five lines -- I just need to be able to see the text surrounding the keyword without having to read the entire post. 4. The text lines are written to a text file or Web page, along with the post's date, title, and URL. This can run either from the Web or desktop, but it needs to be simple to launch and run. The use of this script or program is to see how and when I've mentioned particular products in my posts over a given period, i.e. "How many times did I mention Twinkies, what did I say about them, and how do I find those particular posts?"