import ctypes
from test.base import ChessLibTestBase
from test.chess_ffi import gen_white_pawn_quiet_pushes
from test.chess_ffi import gen_white_pawn_push_promotions
from test.chess_ffi import gen_white_pawn_capture_promotions
from test.chess_ffi import gen_white_pawn_captures
from test.chess_ffi import Move
from test.chess_ffi import Board


MAX_MOVES = 256


class TestMoveGeneration(ChessLibTestBase):


    def test_quiet_pawn_pushes_white(self):
        cases = [
            ("8/pppppppp/8/8/8/8/PPPPPPPP/8 w - - 0 1", 16, "open ranks"),
            ("8/8/8/8/8/8/P7/8 w - - 0 1", 2, "single pawn open"),
            ("8/8/8/8/8/p7/P7/8 w - - 0 1", 0, "blocked single enemy"),
            ("8/8/8/8/8/n7/P7/8 w - - 0 1", 0, "blocked single friendly"),
            # Although legal move, we have a separate function that calculates this move type.
            ("8/9P/8/8/8/8/8/8 w - - 0 1", 0, "no promotion push"),
        ]

        for fen, expected, msg in cases:
            with self.subTest(msg=msg, fen=fen):
                cnt = ctypes.c_int(0)
                moves = (Move * MAX_MOVES)()
                b = Board()

                self.load_fen(fen, board=b)
                gen_white_pawn_quiet_pushes(b, moves, ctypes.byref(cnt))

                self.assertEqual(expected, cnt.value)


    def test_quiet_pawn_promotions_white(self):
        cases = [
            ("8/PPPPPPPP/8/8/8/8/8/8 w - - 0 1", 8, "all open on 7th rank"),
            ("8/8/7P/8/8/8/8/8 w - - 0 1", 0, "no promotions"),
            ("7n/7P/8/8/8/8/8/8 w - - 0 1", 0, "blocked by enemy"),
            ("7N/7P/8/8/8/8/8/8 w - - 0 1", 0, "blocked by friendly"),
        ]

        for fen, expected, msg in cases:
            with self.subTest(msg=msg, fen=fen):
                cnt = ctypes.c_int(0)
                moves = (Move * MAX_MOVES)()
                b = Board()

                self.load_fen(fen, board=b)
                gen_white_pawn_push_promotions(b, moves, ctypes.byref(cnt))

                self.assertEqual(expected, cnt.value)


    def test_capture_pawn_promotions_white(self):
        cases = [
            ("6n1/7P/8/8/8/8/8/8 w - - 0 1", 1, "one capture"),
            ("5n1n/6P1/8/8/8/8/8/8 w - - 0 1", 2, "two captures"),
            ("8/7P/8/8/8/8/8/8 w - - 0 1", 0, "no capture"),
        ]

        for fen, expected, msg in cases:
            with self.subTest(msg=msg, fen=fen):
                cnt = ctypes.c_int(0)
                moves = (Move * MAX_MOVES)()
                b = Board()

                self.load_fen(fen, board=b)
                gen_white_pawn_capture_promotions(b, moves, ctypes.byref(cnt))

                self.assertEqual(expected, cnt.value)


    def test_capture_pawn_white(self):
        cases = [
            # normal diagonal captures
            ("8/8/8/3n4/4P3/8/8/8 w - - 0 1", 1, "e4xd5"),
            ("8/8/8/3n1n2/4P3/8/8/8 w - - 0 1", 2, "e4xd5 and e4xf5"),
            ("8/8/8/1p6/P7/8/8/8 w - - 0 1", 1, "edge file: a4xb5"),
            ("8/7P/8/8/8/8/8/8 w - - 0 1", 0, "no capture"),

            # en passant
            ("8/8/8/3pP3/8/8/8/8 w - d6 0 1", 1, "EP available: e5xd6 e.p. (black pawn on d5)"),
            ("8/8/5n2/3pP3/8/8/8/8 w - d6 0 1", 2, "EP e5xd6 and normal e5xf6"),
            ("8/8/8/3p4/8/4P3/8/8 w - d6 0 1", 0, "EP square present but no white pawn can take"),
        ]

        for fen, expected, msg in cases:
            with self.subTest(msg=msg, fen=fen):
                cnt = ctypes.c_int(0)
                moves = (Move * MAX_MOVES)()
                b = Board()

                self.load_fen(fen, board=b)
                gen_white_pawn_captures(b, moves, ctypes.byref(cnt))

                self.assertEqual(expected, cnt.value)