/******************************************************************************
 * Compilation:  javac SymbolGraph.java
 * Execution:    java SymbolGraph filename.txt delimiter
 * Dependencies: ST.java Graph.java In.java StdIn.java StdOut.java
 * Data files:   http://algs4.cs.princeton.edu/41graph/routes.txt
 * http://algs4.cs.princeton.edu/41graph/movies.txt
 * http://algs4.cs.princeton.edu/41graph/moviestiny.txt
 * http://algs4.cs.princeton.edu/41graph/moviesG.txt
 * http://algs4.cs.princeton.edu/41graph/moviestopGrossing.txt
 *
 * %  java SymbolGraph routes.txt " "
 * JFK
 * MCO
 * ATL
 * ORD
 * LAX
 * PHX
 * LAS
 *
 * % java SymbolGraph movies.txt "/"
 * Tin Men (1987)
 * Hershey, Barbara
 * Geppi, Cindy
 * Jones, Kathy (II)
 * Herr, Marcia
 * ...
 * Blumenfeld, Alan
 * DeBoy, David
 * Bacon, Kevin
 * Woodsman, The (2004)
 * Wild Things (1998)
 * Where the Truth Lies (2005)
 * Tremors (1990)
 * ...
 * Apollo 13 (1995)
 * Animal House (1978)
 *
 *
 * Assumes that input file is encoded using UTF-8.
 * % iconv -f ISO-8859-1 -t UTF-8 movies-iso8859.txt > movies.txt
 ******************************************************************************/

package com.brianway.learning.algorithms.algs4utils;

/**
 * The <tt>SymbolGraph</tt> class represents an undirected graph, where the
 * vertex names are arbitrary strings.
 * By providing mappings between string vertex names and integers,
 * it serves as a wrapper around the
 * {@link Graph} data type, which assumes the vertex names are integers
 * between 0 and <em>V</em> - 1.
 * It also supports initializing a symbol graph from a file.
 * <p>
 * This implementation uses an {@link ST} to map from strings to integers,
 * an array to map from integers to strings, and a {@link Graph} to store
 * the underlying graph.
 * The <em>index</em> and <em>contains</em> operations take time
 * proportional to log <em>V</em>, where <em>V</em> is the number of vertices.
 * The <em>name</em> operation takes constant time.
 * <p>
 * For additional documentation, see <a href="http://algs4.cs.princeton.edu/41graph">Section 4.1</a> of
 * <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
 *
 * @author Robert Sedgewick
 * @author Kevin Wayne
 */
public class SymbolGraph {
    private ST<String, Integer> st;  // string -> index
    private String[] keys;           // index  -> string
    private Graph G;

    /**
     * Initializes a graph from a file using the specified delimiter.
     * Each line in the file contains
     * the name of a vertex, followed by a list of the names
     * of the vertices adjacent to that vertex, separated by the delimiter.
     *
     * @param filename the name of the file
     * @param delimiter the delimiter between fields
     */
    public SymbolGraph(String filename, String delimiter) {
        st = new ST<String, Integer>();

        // First pass builds the index by reading strings to associate
        // distinct strings with an index
        In in = new In(filename);
        // while (in.hasNextLine()) {
        while (!in.isEmpty()) {
            String[] a = in.readLine().split(delimiter);
            for (int i = 0; i < a.length; i++) {
                if (!st.contains(a[i])) {
                    st.put(a[i], st.size());
                }
            }
        }
        StdOut.println("Done reading " + filename);

        // inverted index to get string keys in an aray
        keys = new String[st.size()];
        for (String name : st.keys()) {
            keys[st.get(name)] = name;
        }

        // second pass builds the graph by connecting first vertex on each
        // line to all others
        G = new Graph(st.size());
        in = new In(filename);
        while (in.hasNextLine()) {
            String[] a = in.readLine().split(delimiter);
            int v = st.get(a[0]);
            for (int i = 1; i < a.length; i++) {
                int w = st.get(a[i]);
                G.addEdge(v, w);
            }
        }
    }

    /**
     * Does the graph contain the vertex named <tt>s</tt>?
     *
     * @param s the name of a vertex
     * @return <tt>true</tt> if <tt>s</tt> is the name of a vertex, and <tt>false</tt> otherwise
     */
    public boolean contains(String s) {
        return st.contains(s);
    }

    /**
     * Returns the integer associated with the vertex named <tt>s</tt>.
     *
     * @param s the name of a vertex
     * @return the integer (between 0 and <em>V</em> - 1) associated with the vertex named <tt>s</tt>
     */
    public int index(String s) {
        return st.get(s);
    }

    /**
     * Returns the name of the vertex associated with the integer <tt>v</tt>.
     *
     * @param v the integer corresponding to a vertex (between 0 and <em>V</em> - 1)
     * @return the name of the vertex associated with the integer <tt>v</tt>
     */
    public String name(int v) {
        return keys[v];
    }

    /**
     * Returns the graph assoicated with the symbol graph. It is the client's responsibility
     * not to mutate the graph.
     *
     * @return the graph associated with the symbol graph
     */
    public Graph G() {
        return G;
    }

    /**
     * Unit tests the <tt>SymbolGraph</tt> data type.
     */
    public static void main(String[] args) {
        String filename = args[0];
        String delimiter = args[1];
        SymbolGraph sg = new SymbolGraph(filename, delimiter);
        Graph G = sg.G();
        while (StdIn.hasNextLine()) {
            String source = StdIn.readLine();
            if (sg.contains(source)) {
                int s = sg.index(source);
                for (int v : G.adj(s)) {
                    StdOut.println("   " + sg.name(v));
                }
            } else {
                StdOut.println("input not contain '" + source + "'");
            }
        }
    }
}

/******************************************************************************
 * Copyright 2002-2015, Robert Sedgewick and Kevin Wayne.
 *
 * This file is part of algs4.jar, which accompanies the textbook
 *
 * Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
 * Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
 * http://algs4.cs.princeton.edu
 *
 *
 * algs4.jar is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * algs4.jar is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with algs4.jar.  If not, see http://www.gnu.org/licenses.
 ******************************************************************************/
