// Exercise 3.1.5 (Solution published at http://algs4.cs.princeton.edu/)
package algs31;
import stdlib.*;
import algs13.Queue;
/* ***********************************************************************
 *  Compilation:  javac SequentialSearchST.java
 *  Execution:    java SequentialSearchST
 *  Dependencies: StdIn.java StdOut.java
 *  Data files:   http://algs4.cs.princeton.edu/31elementary/tinyST.txt
 *
 *  Symbol table implementation with sequential search in an
 *  unordered linked list of key-value pairs.
 *
 *  % more tinyST.txt
 *  S E A R C H E X A M P L E
 *
 *  % java SequentialSearchST < tiny.txt
 *  L 11
 *  P 10
 *  M 9
 *  X 7
 *  H 5
 *  C 4
 *  R 3
 *  A 8
 *  E 12
 *  S 0
 *
 *************************************************************************/

public class SequentialSearchST<K, V> {
  private int N;           // number of key-value pairs
  private Node<K,V> first;      // the linked list of key-value pairs

  // a helper linked list data type
  private static class Node<K,V> {
    public final K key;
    public V val;
    public Node<K,V> next;

    public Node(K key, V val, Node<K,V> next)  {
      this.key  = key;
      this.val  = val;
      this.next = next;
    }
  }

  // return number of key-value pairs
  public int size() { return N; }

  // is the symbol table empty?
  public boolean isEmpty() { return size() == 0; }

  // does this symbol table contain the given key?
  public boolean contains(K key) {
    return get(key) != null;
  }

  // return the value associated with the key, or null if the key is not present
  public V get(K key) {
    for (Node<K,V> x = first; x != null; x = x.next) {
      if (key.equals(x.key)) return x.val;
    }
    return null;
  }
  public V getR(K key) {
    return getR(key, first);
  }
  private V getR(K key, Node<K,V> x) {
    if (x == null) return null;
    if (key.equals (x.key)) return x.val;
    return getR(key, x.next);
  }

  // add a key-value pair, replacing old key-value pair if key is already present
  public void put(K key, V val) {
    if (val == null) { delete(key); return; }
    for (Node<K,V> x = first; x != null; x = x.next)
      if (key.equals(x.key)) { x.val = val; return; }
    first = new Node<>(key, val, first);
    N++;
  }

  // remove key-value pair with given key (if it's in the table)
  public void delete(K key) {
    first = delete(first, key);
  }

  // delete key in linked list beginning at Node<K,V> x
  // warning: function call stack too large if table is large
  private Node<K,V> delete(Node<K,V> x, K key) {
    if (x == null) return null;
    if (key.equals(x.key)) { N--; return x.next; }
    x.next = delete(x.next, key);
    return x;
  }


  // return all keys as an Iterable
  public Iterable<K> keys()  {
    Queue<K> queue = new Queue<>();
    for (Node<K,V> x = first; x != null; x = x.next)
      queue.enqueue(x.key);
    return queue;
  }




  /* *********************************************************************
   * Test client
   **********************************************************************/
  public static void main(String[] args) {
    StdIn.fromString ("S E A R C H E X A M P L E");
    SequentialSearchST<String, Integer> st = new SequentialSearchST<>();
    for (int i = 0; !StdIn.isEmpty(); i++) {
      String key = StdIn.readString();
      st.put(key, i);
    }
    for (String s : st.keys())
      StdOut.println(s + " " + st.get(s));
  }
}