package labs.course15_16.lab5dynamic.roadsInCity;

/**
 * The complexity of the algorithm is quadratic because we have to iterate
 * through all the rows and columns of the map in order to fill it.
 * @author UO244826
 *
 */

public class RoadsInCity {

	//First i initialize the "map" and variables for the rows and columns
    long road [][];
    int x;
    int y;

    //just the constructor
    public RoadsInCity(int x, int y) {
        this.road = new long [x][y];
        this.x = x;
        this.y = y;
    }

    //we add the barrier wherever we want as a -1
    public void addBarrier(int x, int y) {
        road[x][y] = -1;

    }

    public void interchange(int beginX,int beginY,int endX,int endY){

    	int auxbeginX= beginX;
    	int auxendX = endX;
    	int auxbeginY = beginY;
    	int auxendY = endY;
    	if (beginX < endX || beginY > endY )
    		beginX = auxbeginY;
    		beginY = auxbeginX;
    		endX = auxendY;
    		endY = auxendX;


    }

    public long calculate(int beginX, int beginY, int endX, int endY) {

    	interchange(beginX,beginY,endX,endY);
    	//first, we check some logical conditions that must be fulfilled
    	//in the map in order to make sense. If one of them it's true
    	//it means something is wrong and we have to return -1

    	//a) if we begin and end in the same place
    	if (beginX == endX && beginY == endY ||
    	//b) if they have incorrect positions
    		beginX < endX || beginY > endY||
    	//c) more incorrect positions, it cannot be outside the limits
    		endX >= x || beginY >= y ||
    	    beginX >= x || endY>= y) {
            return -1;
        } else {
        //we call to other to methods which i will explain later in order to
        //simplify the code
        initialize(beginX,beginY,endX,endY);
        fill(beginX,beginY,endX,endY);
        // i return the beginning because i decided to do it backwards
        // because it was easier for me to understand the axis
        showRoads(beginX, beginY, endX, endY);
        return road[beginX][beginY];
        }

    }

    //method for filling the road
    //if we find a barrier we have to make it a 0 in order not to sum the -1
    // if not, we just sum the diagonals

	private void fill(int beginX, int beginY, int endX, int endY) {
		interchange(beginX,beginY,endX,endY);
		for (int row = endX+1; row <= beginX; row++)
            for (int col = endY-1; col >= beginY; col--){
            	if (road[row][col]==-1){
            		road[row][col]=0;
            	}
            	else {
                road [row][col] = road[row][col+1] + road[row-1][col];
            	}
        }
	}

	private void initialize(int beginX, int beginY, int endX, int endY) {
		interchange(beginX,beginY,endX,endY);

		//initialize: we first fill with ones the column which
		// has the same Y coordinate as the end position
		// (always if there is no barrier. If there is a barrier
		// we should put zeros in all the positions next to the barrier)
		for (int i = endX; i<=beginX; i++){
            if (road[i][endY]!=-1){
                road[i][endY]=1;
            }
            else{
                for (int k = i; k<beginX; k++){
                    road[k][endY]=0;
                }
                break;
            }
        }

		//and then the row which has the same X coordinate as the end position
		//(same thing as before with the barriers)
		for (int j = endY-1;j>=beginY; j--){
            if (road[endX][j]!=-1){
                road[endX][j]=1;
            }
            else{
                for (int k = j; k>=beginY; k--){
                    road[endX][k]=0;
                }
                break;
            }
        }
	}

	//method for printing the roads, i adjunt the screencaptures
	// i didn't print the ones who gave me errors (last three)
	public void showRoads(int beginX, int beginY, int endX, int endY){
        System.out.println();
		for(int i = 0; i < road.length; i++){
			for(int j = 0; j < road[0].length; j++){
				if (i == beginX && j == beginY)
                    System.out.print("START\t");
				else if (i == endX && j == endY)
                    System.out.print("END\t\t");
				else
                    System.out.print(road[i][j] + "\t\t");
			}
			System.out.println();
		}
	}



}