I've been trying to work out what scale a song with chords Em A C D is in.

The major chords A, C, D are never together in any scale. If C and D are there it would suggest the key is G but then the A would be minor. How is it possible the song can have these chords and it what scale would it be?

Edit: Later in the song the A major sounds more like Asus2.

Edit: As an example this is a song that has this chord progression