package ch.rfin.ai.search.problems;

import ch.rfin.ai.search.AbstractSearchProblem;

import java.util.*;

public class EightQueens extends AbstractSearchProblem<EightQueens.State, EightQueens.Action> {

    private static final int SIZE = 8;

    public EightQueens() {
        super(new State(0), new State(SIZE));
    }

    private State result(State state, Action move){

        int[] board = state.board;

        for(int x = 0; x < SIZE; x++){
            if(board[x + move.y * SIZE] == 1){
                return null;
            }
        }

        for(int y = 0; y < SIZE; y++){
            if(board[move.x + y * SIZE] == 1){
                return null;
            }
        }

        for(int y = 0; y < SIZE; y++){
           for(int x = 0; x < SIZE; x++){
               if(board[x + y * SIZE] == 1){

                   int deltaRow = Math.abs(x - move.x);
                   int deltaCol = Math.abs(y - move.y);
                   if(deltaCol == deltaRow){
                       return null;
                   }
               }
           }
        }

        return new State(state, move);
    }

    @Override
    public Collection<Action> possibleActionsIn(State state) {

        List<Action> actions = new ArrayList<>();

        for(int y = 0; y < SIZE; y++){
            for(int x = 0; x < SIZE; x++){
                Action action = new Action(x, y);
                State after = result(state, action);
                if(after != null){
                    actions.add(action);
                }
            }
        }

        return actions;
    }

    @Override
    public State transition(State state, Action action) {

        State result = result(state, action);

        if(result == null){
            throw new IllegalArgumentException("No transition for " + action + " in " + state + ".");
        }
        return result;
    }

    public static class State{
        public int queens = 0;

        public int board[] =    {0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
                                0, 0, 0, 0, 0, 0, 0, 0,
        };


        public State(int queens){
            this.queens = queens;
        };

        public State(State oldState, Action action){
            board = oldState.board.clone();

            this.board[action.x + action.y * SIZE] = 1;
            this.queens = oldState.queens + 1;

        }

        @Override
        public boolean equals(Object obj) {
            return queens == ((State) obj).queens;
        }

        @Override
        public String toString() {
            String string = "State: \n queens: " + queens + "\n board:  \n";
            for(int y = 0; y < SIZE; y++){
                for(int x = 0; x < SIZE; x++){
                    string += board[x + y * SIZE] + " ";
                }
                string += "\n";
            }
            return string;
        }


    }

    public static class Action{
        public int x;
        public int y;

        public Action(int x, int y){
            this.x = x;
            this.y = y;
        }

        @Override
        public String toString() {
            return "Action{" +
                    "x=" + x +
                    ", y=" + y +
                    '}';
        }
    }
}