I am working on a web functionality that allows an user to request an appointment with another user. However, users may have not met nor known about each others schedule. Therefore, options must be flexible enough so that it is not too intrusive.
For example, A proposes to B that they can meet any time next week between 1 and 5 PM. C can propose to D that they can meet any time between now and next month.
How should I design an UI to fit such a diverse options? One way is to let them write their own text, but it might be too chaostic for data handling (search, sort etc.). What are common solutions for this problem?