I have a Dallas client who has given me a tough process to work out. I'm seeking your advice. I use PHP, but the language doesn't matter. We can work this out in pseudocode.

In a nutshell, this involves showing products on a page based on matching keyword phrases, and using a preferred product provider, but varying this up so that I try to show products from each provider as much as possible when I can.

He has 3 product companies: Amazon, eBay, and Overstock. I already have worked out with the API to get products back in an array via a function. He wants to give the user the preference of which one to use primarily -- so a priority number on each. He wants to display anywhere from 1 to 6 products on a page from them. Let's go with 6 for now in this example to start with. Let's assume Amazon first, then eBay, then Overstock as far as priority. He wants me to attempt to take a keyword phrase and find relevant products (all the keywords found in product title) from Amazon, eBay, and Overstock. If we find > 1 product from each provider, he wants me to only display one product from each. But if we run out of a particular provider with a matching product, I start over again and grab another product from another provider until we reach 6 products. If there just aren't 6 relevant products, then I do the best I can -- even if I only display one product. If no relevant products, then I don't display anything.