Recipes table : it tooks some months to fill it with our choices (prefered recipes) and add attributes to that : cold/warm meal, difficulty, time taken, kind of meal (junk, bistrot, classical, exotic...), does it scale (x0.5, x2, x4...).

ingredient_table : each receipe got ingredients. Every kind of ingredrients are on a separate table.

product_table : it is there i display what you can buy from stores : 6/12/24 eggs bundle, 250/500g butter

Then it starts to be ugly, cause there is constraints : loose and hard. Timetable is a hard constraint (i don't want to cook monday evening), so it will be double ration one of the day before, Season is a hard constraint (you buy vegetables when they are in season) Tastes are a hard constraint : you decides what kind of meal you want to eat during the weak

With that you get available recipes and a timetable for cooking and quantity to cook.

Price is a lose constraint, leftovers are a lose constraint, time spent cooking is a lose constraint (could be a hard, if you have enough recipes, but as i like cooking, it's no matter for me)

After, i enumerate all possibilities and each one get a score based on lose constraints : you can use a simple weighted average, exponentially weighted average... You tweak coefs to prefer a nice price or a little time spent and then it's done. Usually a chose randomly between the ten best solutions.

I got enough recipes to cover all hard constraints. I avoid lot of problems doing a big enumeration for all possibilities (it takes a couple of minutes at my scale for 200 recipes), also, hard constraints are pretty easy to deal with, it could be a lot more complicated if user become picky on meals. I'm no coder so i don't know any design pattern or anything that could help me to design a better algo. But, as far as i know, when you can't evaluate all possibilities you have to go the optimization road.

Answers to questions : - Yeah, there is this website : https://fr-en.openfoodfacts.org/ (broken TLS it seems) that could be used to pull data on ingredients, - I don't have plan to open-source it : it's pretty hacky, ugly and probably defy any coding rule (except 4 space ident PEP8). it's not even packeged (i've never done that before...)