Could you tell me what are correct English?

1. If you come to my birthday party, I would be very glad!
2. If you come to my birthday party, I will be very glad!
3. If you came to my birthday party, I would be very glad!
4. If you came to my birthday party, I will be very glad!

Could you tell me what are correct English?

I think 1, 2, 3 are all correct, although 1 sounds a little natural, I seem to have seen and heard native speakers use "would" when the tense of verb is present.