To wish and present simple

[Simone]

I every one, I'm Simone, I'm learning English and this is my first message in this forum :)
So, I'm a little bit confusing whit the right use of "to wish" and the present simple.
The fact is that I'm learning that the I should use the present simple when I'm talking about an routine, or if I'm using a non-progressive verb (to wish isn't it).
Now, I don't understand for example the expression "I wish you a goodnight" because the fact is that I'm wishing you a goodnight now, in this right moment, I'm not wish you a goodnight usually, same think for "I wish you a merry Christmas".
So, why in this case, I have to use the present simple?
I really don't understand this fact :/

[Alan]

'Wish' when used with a NOUN as object ("I wish you every success", etc.) refers to a possible (and hoped-for) event, while 'wish' followed by a VERBAL construction ("I wish I were a bird", etc.) refers to things considered by the speaker to be either unlikely or impossible.

I hope that resolves your confusion!