We have three people one of whom is a knight, one a knave, and one a spy. The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth.

There are three persons A, B, and C which say the following:
A says: "C is a knave."
B says: "A is a knight."
C says: "I am the spy."

Who is the knight, who the knave, who the spy?