I don't understand the following sentence (song lyric):
聖夜【せいや】だなんだと繰【く】り返【かえ】す歌【うた】と
(then it goes like: わざとらしくきらめく街【まち】のせいかな )
More specifically, I cannot decide which character belongs to where in "だなんだと". Is it the expression なんだ or is it a form of "なのです" (even though I didn't know this was possible after a だ).
Could someone help me with this?
Thanks