import java.util.ArrayList;

/**
 * Adjacency matrix implementation of a graph
 * @author gtowell
 * Created: Dec 1, 2021
 */
public class AdjMatrix<M> {
    //The adjacency matrix
    double[][] aMatrix;
    ArrayList<M> nodes;

    /**
     * Constructor, taking a list of the node payloads.
     * Once this list of set, it cannot be changed. 
     * @param nds the list of node payloads
     */
    public AdjMatrix(ArrayList<M> nds) {
        nodes = new ArrayList<>();
        for (M nm : nds) {
            nodes.add(nm);
        }
        aMatrix = new double[nodes.size()][nodes.size()];
        for (int i=0; i<nodes.size(); i++)
            for (int j = 0; j < nodes.size(); j++) {
                aMatrix[i][j] = -99;
            }
    }

    /**
     * Add an edge with weight 1.0 between two nodes
     * @param fr from
     * @param t2 to
     */
    public void addEdge(M fr, M t2) {
        addEdge(fr, t2, 1.0);
    }

    /**
     * Add an edge with a given weight
     * @param fr from
     * @param t2 to
     * @param w the weight
     */
    public void addEdge(M fr, M t2, double w) {
        int fri = nodes.indexOf(fr);
        int t2i = nodes.indexOf(t2);
        if (fri < 0 || t2i < 0)
            return;
        aMatrix[fri][t2i] = w;
    }

    public String toString() {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < aMatrix.length; i++) {
            for (int j = 0; j < aMatrix[i].length; j++) {
                if (aMatrix[i][j]>=0) {
                    sb.append(String.format("[%s->%s:%.2f]", nodes.get(i), nodes.get(j), aMatrix[i][j]));
                }
            }
        }
        return sb.toString();
    }
    public static void main(String[] args) {
        ArrayList<String> al = new ArrayList<>();
        al.add("A");
        al.add("B");
        al.add("C");
        al.add("D");
        AdjMatrix<String> amat = new AdjMatrix<>(al);
        amat.addEdge("A", "B");
        amat.addEdge("A", "D");
        amat.addEdge("B", "D");
        amat.addEdge("C", "D");
        amat.addEdge("C", "B");
        amat.addEdge("C", "A");
        amat.addEdge("D", "B");
        System.out.println(amat);
    }

}