package tsp.pacman;

import java.util.HashMap;
import java.util.List;


public class GhostDirectional implements Ghost{

    private HashMap<Position, Character> prevDirections;

    private char getRandomDirection(PacmanState state, Position position){
        List<Position> moves = state.findPossibleMoves(position);
        char resDirection = 'S';
        if (moves.isEmpty()) return 'S';
        char direction = 'S';
        if (prevDirections.containsKey(position))
            direction = prevDirections.get(position);
        int index = (int)(Math.random() * moves.size());
        Position target = moves.get(index);
        if (target.getRow() == position.getRow() + 1) resDirection =  'D';
        else if (target.getRow() == position.getRow() - 1) resDirection =  'U';
        else if (target.getCol() == position.getCol() + 1) resDirection =  'R';
        else if (target.getCol() == position.getCol() - 1) resDirection =  'L';
        // To avoid up turns
        if (moves.size() > 1){
            if ((direction == 'D' && resDirection == 'U') ||
                    (direction == 'U' && resDirection == 'D') ||
                    (direction == 'R' && resDirection == 'L') ||
                    (direction == 'L' && resDirection == 'R')
            ){
                return getRandomDirection(state, position);
            }
        }
        return resDirection;
    }

    public GhostDirectional(){
        prevDirections = new HashMap<>();
    }

    private Position getNextPosition(PacmanState state, Position position){
        Position resPos = position;
        char direction = prevDirections.get(position);
        if (direction == 'U'){
            Position posUp = new Position(position.getRow() - 1, position.getCol());
            if (state.isLegalMove(posUp)){
                resPos = posUp;
            } else {
                prevDirections.put(position, getRandomDirection(state, position));
                return getNextPosition(state, position);
            }
        } else if (direction == 'D') {
            Position posDown = new Position(position.getRow() + 1, position.getCol());
            if (state.isLegalMove(posDown)){
                resPos = posDown;
            } else {
                prevDirections.put(position, getRandomDirection(state, position));
                return getNextPosition(state, position);
            }
        } else if (direction == 'R') {
            Position posRight = new Position(position.getRow(), position.getCol() + 1);
            if (state.isLegalMove(posRight)){
                resPos = posRight;
            } else {
                prevDirections.put(position, getRandomDirection(state, position));
                return getNextPosition(state, position);
            }
        } else if (direction == 'L') {
            Position posLeft = new Position(position.getRow(), position.getCol() - 1);
            if (state.isLegalMove(posLeft)){
                resPos = posLeft;
            } else {
                prevDirections.put(position, getRandomDirection(state, position));
                return getNextPosition(state, position);
            }
        }
        return resPos;
    }

    @Override
    public Position chooseAction(PacmanState state, Position position) {
        if (!prevDirections.containsKey(position)){
            prevDirections.put(position, getRandomDirection(state, position));
        }
        char direction = prevDirections.get(position);
        if (direction == 'S' || state.findPossibleMoves(position).size() > 2)
            prevDirections.put(position, getRandomDirection(state, position));
        Position resPos = getNextPosition(state, position);
        prevDirections.put(resPos, prevDirections.get(position));
        return resPos;
    }
}