namespace CheckersSpielBot
{
    public static class BoardEvaluator
    {
        private const int PieceValue = 100;
        private const int KingValue = 160;

        //Weights (Musst be Balanced To have a good Ai)
        private const int AdvancementWeight = 5;
        private const int BackRowWeight = 15;
        private const int CenterWeight = 10;
        private const int MobilityWeight = 8;

        public static int Evaluate(int[,] board, int aiPlayer)
        {
            int score = 0;
            int humanPlayer = aiPlayer == 1 ? 2 : 1;

            MoveGeneratorService moveGen = new MoveGeneratorService(board);

            int aiMobility = 0;
            int humanMobility = 0;

            for (int row = 0; row < 8; row++)
            {
                for (int col = 0; col < 8; col++)
                {
                    int piece = board[row, col];
                    if (piece == 0) continue;

                    //Reward For who will play first
                    bool isAi = BoardHelper.BelongsToPlayer(piece, aiPlayer);
                    bool isKing = BoardHelper.IsKing(piece);

                    int sign = isAi ? 1 : -1;

                    // Material
                    score += sign * (isKing ? KingValue : PieceValue);

                    // Advancement — how far the piece has advanced toward promotion
                    int advancement = isAi ? (aiPlayer == 1 ? 7 - row : row) : (aiPlayer == 1 ? row : 7 - row); // Red moves up, Blue moves down

                    score += sign * advancement * AdvancementWeight;

                    // Back row protection — pieces on starting back row
                    bool onBackRow = isAi ? (aiPlayer == 1 && row == 7) || (aiPlayer == 2 && row == 0) : (aiPlayer == 1 && row == 0) || (aiPlayer == 2 && row == 7);
                    if (onBackRow && !isKing) { score += sign * BackRowWeight; }

                    // Center control — [columns:2,3,4,5 && rows:2,3,4,5]
                    if (col >= 2 && col <= 5 && row >= 2 && row <= 5) { score += sign * CenterWeight; }

                    // Mobility
                    int moves = moveGen.GetLegalMoves(row, col, capturesOnly: false).Count;

                    if (isAi) { aiMobility += moves; }
                    else { humanMobility += moves; }
                }
            }

            // Mobility difference
            score += (aiMobility - humanMobility) * MobilityWeight;

            return score;
        }
    }
}