import game.Board;
import java.util.Stack;
import game.algorithm.Swarm;

public class AlfaBeta {
	
	private Board board;
	private Swarm swarm;
	private int init_depth;
	
	public AlfaBeta(Board x, Swarm myswarm, int depth) {
		init_depth = depth;
		board = x;
		swarm = myswarm;
	}
	
	private int alphabeta(Board table, int depth, int alfa, int beta) {
		
		// Terminal Node
		if (depth==0 || table.terminal==true) {
			// Evaluation
			swarm.init(table);
			return swarm.process();
		}
		
		table.alfa = Integer.MIN_VALUE+1;
		table.beta = Integer.MAX_VALUE-1;
			
		// MIN
		if(!table.type) {
			Stack <Board> pos1 = table.generate();
			for(int i=0; i<pos1.size(); i++) {
				Board child = pos1.elementAt(i);
				int newb = Math.min(beta, table.beta);
				int val = alphabeta(child, depth-1, alfa, newb);
				table.beta = Math.min(table.beta, val);
				if(alfa>=table.beta) break;
			}
			return table.beta;
		}
		// MAX
		else {
			Stack <Board> pos2 = table.generate();
			for(int j=0; j<pos2.size(); j++) {
				Board child = pos2.elementAt(j);
				int newa = Math.max(alfa, table.alfa);
				int val = alphabeta(child, depth-1, newa, beta);
				table.alfa = Math.max(table.alfa, val);
				if(table.alfa>=beta) break;
			}
			return table.alfa;
		}
	}
	
	public int minimax(int alfa, int beta) {
		return alphabeta(board, init_depth, alfa, beta);
	}
}