What is the purpose of setting a Price Floor?

Two real life Price Floor examples are:
Price Floor in Agricultural Products
Minimum Wage Level.
Price Floor in Agricultural Products: In case of Agricultural products, there are many farmers growing a particular product. They all harvest their product at the same time and since their holding capacity is less, they all sell their products at the same time due to which, the supply of the commodity goes very high in the market. As a result, price goes down extremely. Thus, the farmer becomes poor because his productivity was high, which is very unfair. As result, they will be willing to produce lesser quantity of the product in the next season.