/**
 * Check whether growing on a half-tile coast tile ends up blocking a water connection
 *
 * @param tile The target tile
 * @return true if building here blocks a water connection
 */
static bool GrowingBlocksWaterConnection(TileIndex tile)
{
	if (!IsValidTile(tile) || !IsCoastTile(tile)) return false;

	Slope slope = GetTileSlope(tile);

	/* Is this a coast tile with one corner raised ? */
	if (IsSlopeWithOneCornerRaised(slope)) {
		Corner corner = GetHighestSlopeCorner(slope);
		static const Direction corner_to_direction[] = { DIR_W, DIR_S, DIR_E, DIR_N };
		TileIndex opposite_tile = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDir(corner_to_direction[OppositeCorner(corner)]));

		if (IsValidTile(opposite_tile)) {
			Track main_track_mask = TrackBitsToTrack(TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0)));
			Trackdir main_trackdir = TrackToTrackdir(main_track_mask);

			DiagDirection main_dir_1 = TrackdirToExitdir(main_trackdir);
			DiagDirection main_dir_2 = TrackdirToExitdir(ReverseTrackdir(main_trackdir));

			TileIndex tile_1 = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_1));
			TileIndex tile_2 = AddTileIndexDiffCWrap(tile, TileIndexDiffCByDiagDir(main_dir_2));

			TrackBits track_1 = TrackStatusToTrackBits(GetTileTrackStatus(tile_1, TRANSPORT_WATER, 0));
			TrackBits track_2 = TrackStatusToTrackBits(GetTileTrackStatus(tile_2, TRANSPORT_WATER, 0));

			TrackBits main_trackbits_mask_1 = DiagdirReachesTracks(main_dir_1);
			TrackBits main_trackbits_mask_2 = DiagdirReachesTracks(main_dir_2);

			TrackBits main_track_1 = main_trackbits_mask_1 & track_1;
			TrackBits main_track_2 = main_trackbits_mask_2 & track_2;

			/* Is there a connection between tile_1 and tile_2 via tile? */
			if (main_track_1 && main_track_2) {
				TrackBits oppo_trackbits = TrackStatusToTrackBits(GetTileTrackStatus(opposite_tile, TRANSPORT_WATER, 0));
				Track oppo_track_mask = TrackToOppositeTrack(main_track_mask);

				/* Is there a track in the opposite_tile that can be used to try an alternative connection? */
				if (HasTrack(oppo_trackbits, oppo_track_mask)) {
					TrackBits mirror = TRACK_BIT_CROSS | (corner & 1 ? TRACK_BIT_HORZ : TRACK_BIT_VERT);

					Trackdir oppo_trackdir = TrackToTrackdir(oppo_track_mask);

					DiagDirection oppo_dir_1 = TrackdirToExitdir(oppo_trackdir);
					DiagDirection oppo_dir_2 = TrackdirToExitdir(ReverseTrackdir(oppo_trackdir));

					TrackBits oppo_trackbits_mask_1 = DiagdirReachesTracks(oppo_dir_1);
					TrackBits oppo_trackbits_mask_2 = DiagdirReachesTracks(oppo_dir_2);

					TrackBits oppo_track_1 = oppo_trackbits_mask_1 & track_1;
					TrackBits oppo_track_2 = oppo_trackbits_mask_2 & track_2;

					/* Is there a connection between tile_1 and tile_2 via opposite_tile? */
					if (oppo_track_1 & (main_track_1 ^ mirror) && oppo_track_2 & (main_track_2 ^ mirror)) {
						/* There is an alternative connection. Town can grow on tile. */
						return false;
					}
				}
				/* There is either no track or an incomplete connection via opposite_tile. */
				return true;
			}
		}
	}
	/* There was no connection via tile, or it was incomplete, or the opposite_tile is outside the map. */
	return false;
}