package resourceCode.map;

import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

public abstract class MyAbstractMap<K, V> implements MyMap<K, V> {

	/**
	 * Sole constructor. (For invocation by subclass constructors, typically
	 * implicit.)
	 */
	protected MyAbstractMap() {
	}

	// Query Operations

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation returns <tt>entrySet().size()</tt>.
	 */
	public int size() {
		return entrySet().size();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation returns <tt>size() == 0</tt>.
	 */
	public boolean isEmpty() {
		return size() == 0;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation iterates over <tt>entrySet()</tt> searching for an entry
	 * with the specified value. If such an entry is found, <tt>true</tt> is
	 * returned. If the iteration terminates without finding such an entry,
	 * <tt>false</tt> is returned. Note that this implementation requires linear
	 * time in the size of the map.
	 * 
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public boolean containsValue(Object value) {
		Iterator<Entry<K, V>> i = entrySet().iterator();
		if (value == null) {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (e.getValue() == null)
					return true;
			}
		} else {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (value.equals(e.getValue()))
					return true;
			}
		}
		return false;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation iterates over <tt>entrySet()</tt> searching for an entry
	 * with the specified key. If such an entry is found, <tt>true</tt> is returned.
	 * If the iteration terminates without finding such an entry, <tt>false</tt> is
	 * returned. Note that this implementation requires linear time in the size of
	 * the map; many implementations will override this method.
	 * 
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public boolean containsKey(Object key) {
		Iterator<MyMap.Entry<K, V>> i = entrySet().iterator();
		if (key == null) {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (e.getKey() == null)
					return true;
			}
		} else {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (key.equals(e.getKey()))
					return true;
			}
		}
		return false;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation iterates over <tt>entrySet()</tt> searching for an entry
	 * with the specified key. If such an entry is found, the entry's value is
	 * returned. If the iteration terminates without finding such an entry,
	 * <tt>null</tt> is returned. Note that this implementation requires linear time
	 * in the size of the map; many implementations will override this method.
	 * 
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public V get(Object key) {
		Iterator<Entry<K, V>> i = entrySet().iterator();
		if (key == null) {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (e.getKey() == null)
					return e.getValue();
			}
		} else {
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				if (key.equals(e.getKey()))
					return e.getValue();
			}
		}
		return null;
	}

	// Modification Operations

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation always throws an <tt>UnsupportedOperationException</tt>.
	 * 
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 * @throws IllegalArgumentException
	 *             {@inheritDoc}
	 */
	public V put(K key, V value) {
		throw new UnsupportedOperationException();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation iterates over <tt>entrySet()</tt> searching for an entry
	 * with the specified key. If such an entry is found, its value is obtained with
	 * its <tt>getValue</tt> operation, the entry is removed from the collection
	 * (and the backing map) with the iterator's <tt>remove</tt> operation, and the
	 * saved value is returned. If the iteration terminates without finding such an
	 * entry, <tt>null</tt> is returned. Note that this implementation requires
	 * linear time in the size of the map; many implementations will override this
	 * method.
	 * 
	 * <p>
	 * Note that this implementation throws an
	 * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> iterator does
	 * not support the <tt>remove</tt> method and this map contains a mapping for
	 * the specified key.
	 * 
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public V remove(Object key) {
		Iterator<Entry<K, V>> i = entrySet().iterator();
		Entry<K, V> correctEntry = null;
		if (key == null) {
			while (correctEntry == null && i.hasNext()) {
				Entry<K, V> e = i.next();
				if (e.getKey() == null)
					correctEntry = e;
			}
		} else {
			while (correctEntry == null && i.hasNext()) {
				Entry<K, V> e = i.next();
				if (key.equals(e.getKey()))
					correctEntry = e;
			}
		}

		V oldValue = null;
		if (correctEntry != null) {
			oldValue = correctEntry.getValue();
			i.remove();
		}
		return oldValue;
	}

	// Bulk Operations

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation iterates over the specified map's <tt>entrySet()</tt>
	 * collection, and calls this map's <tt>put</tt> operation once for each entry
	 * returned by the iteration.
	 * 
	 * <p>
	 * Note that this implementation throws an
	 * <tt>UnsupportedOperationException</tt> if this map does not support the
	 * <tt>put</tt> operation and the specified map is nonempty.
	 * 
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 * @throws IllegalArgumentException
	 *             {@inheritDoc}
	 */
	public void putAll(MyMap<? extends K, ? extends V> m) {
		for (MyMap.Entry<? extends K, ? extends V> e : m.entrySet())
			put(e.getKey(), e.getValue());
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation calls <tt>entrySet().clear()</tt>.
	 * 
	 * <p>
	 * Note that this implementation throws an
	 * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> does not
	 * support the <tt>clear</tt> operation.
	 * 
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 */
	public void clear() {
		entrySet().clear();
	}

	// Views

	/**
	 * Each of these fields are initialized to contain an instance of the
	 * appropriate view the first time this view is requested. The views are
	 * stateless, so there's no reason to create more than one of each.
	 */
	transient volatile Set<K> keySet = null;
	transient volatile Collection<V> values = null;

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation returns a set that subclasses {@link AbstractSet}. The
	 * subclass's iterator method returns a "wrapper object" over this map's
	 * <tt>entrySet()</tt> iterator. The <tt>size</tt> method delegates to this
	 * map's <tt>size</tt> method and the <tt>contains</tt> method delegates to this
	 * map's <tt>containsKey</tt> method.
	 * 
	 * <p>
	 * The set is created the first time this method is called, and returned in
	 * response to all subsequent calls. No synchronization is performed, so there
	 * is a slight chance that multiple calls to this method will not all return the
	 * same set.
	 */
	public Set<K> keySet() {
		if (keySet == null) {
			keySet = new AbstractSet<K>() {
				public Iterator<K> iterator() {
					return new Iterator<K>() {
						private Iterator<Entry<K, V>> i = entrySet().iterator();

						public boolean hasNext() {
							return i.hasNext();
						}

						public K next() {
							return i.next().getKey();
						}

						public void remove() {
							i.remove();
						}
					};
				}

				public int size() {
					return MyAbstractMap.this.size();
				}

				public boolean contains(Object k) {
					return MyAbstractMap.this.containsKey(k);
				}
			};
		}
		return keySet;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * <p>
	 * This implementation returns a collection that subclasses
	 * {@link AbstractCollection}. The subclass's iterator method returns a "wrapper
	 * object" over this map's <tt>entrySet()</tt> iterator. The <tt>size</tt>
	 * method delegates to this map's <tt>size</tt> method and the <tt>contains</tt>
	 * method delegates to this map's <tt>containsValue</tt> method.
	 * 
	 * <p>
	 * The collection is created the first time this method is called, and returned
	 * in response to all subsequent calls. No synchronization is performed, so
	 * there is a slight chance that multiple calls to this method will not all
	 * return the same collection.
	 */
	public Collection<V> values() {
		if (values == null) {
			values = new AbstractCollection<V>() {
				public Iterator<V> iterator() {
					return new Iterator<V>() {
						private Iterator<Entry<K, V>> i = entrySet().iterator();

						public boolean hasNext() {
							return i.hasNext();
						}

						public V next() {
							return i.next().getValue();
						}

						public void remove() {
							i.remove();
						}
					};
				}

				public int size() {
					return MyAbstractMap.this.size();
				}

				public boolean contains(Object v) {
					return MyAbstractMap.this.containsValue(v);
				}
			};
		}
		return values;
	}

	public abstract Set<Entry<K, V>> entrySet();

	// Comparison and hashing

	/**
	 * Compares the specified object with this map for equality. Returns
	 * <tt>true</tt> if the given object is also a map and the two maps represent
	 * the same mappings. More formally, two maps <tt>m1</tt> and <tt>m2</tt>
	 * represent the same mappings if <tt>m1.entrySet().equals(m2.entrySet())</tt>.
	 * This ensures that the <tt>equals</tt> method works properly across different
	 * implementations of the <tt>MyMap</tt> interface.
	 * 
	 * <p>
	 * This implementation first checks if the specified object is this map; if so
	 * it returns <tt>true</tt>. Then, it checks if the specified object is a map
	 * whose size is identical to the size of this map; if not, it returns
	 * <tt>false</tt>. If so, it iterates over this map's <tt>entrySet</tt>
	 * collection, and checks that the specified map contains each mapping that this
	 * map contains. If the specified map fails to contain such a mapping,
	 * <tt>false</tt> is returned. If the iteration completes, <tt>true</tt> is
	 * returned.
	 * 
	 * @param o
	 *            object to be compared for equality with this map
	 * @return <tt>true</tt> if the specified object is equal to this map
	 */
	public boolean equals(Object o) {
		if (o == this)
			return true;

		if (!(o instanceof MyMap))
			return false;
		MyMap<K, V> m = (MyMap<K, V>) o;
		if (m.size() != size())
			return false;

		try {
			Iterator<Entry<K, V>> i = entrySet().iterator();
			while (i.hasNext()) {
				Entry<K, V> e = i.next();
				K key = e.getKey();
				V value = e.getValue();
				if (value == null) {
					if (!(m.get(key) == null && m.containsKey(key)))
						return false;
				} else {
					if (!value.equals(m.get(key)))
						return false;
				}
			}
		} catch (ClassCastException unused) {
			return false;
		} catch (NullPointerException unused) {
			return false;
		}

		return true;
	}

	/**
	 * Returns the hash code value for this map. The hash code of a map is defined
	 * to be the sum of the hash codes of each entry in the map's
	 * <tt>entrySet()</tt> view. This ensures that <tt>m1.equals(m2)</tt> implies
	 * that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps <tt>m1</tt> and
	 * <tt>m2</tt>, as required by the general contract of {@link Object#hashCode}.
	 * 
	 * <p>
	 * This implementation iterates over <tt>entrySet()</tt>, calling
	 * {@link MyMap.Entry#hashCode hashCode()} on each element (entry) in the set,
	 * and adding up the results.
	 * 
	 * @return the hash code value for this map
	 * @see MyMap.Entry#hashCode()
	 * @see Object#equals(Object)
	 * @see Set#equals(Object)
	 */
	public int hashCode() {
		int h = 0;
		Iterator<Entry<K, V>> i = entrySet().iterator();
		while (i.hasNext())
			h += i.next().hashCode();
		return h;
	}

	/**
	 * Returns a string representation of this map. The string representation
	 * consists of a list of key-value mappings in the order returned by the map's
	 * <tt>entrySet</tt> view's iterator, enclosed in braces ( <tt>"{}"</tt>).
	 * Adjacent mappings are separated by the characters <tt>", "</tt> (comma and
	 * space). Each key-value mapping is rendered as the key followed by an equals
	 * sign (<tt>"="</tt>) followed by the associated value. Keys and values are
	 * converted to strings as by {@link String#valueOf(Object)}.
	 * 
	 * @return a string representation of this map
	 */
	public String toString() {
		Iterator<Entry<K, V>> i = entrySet().iterator();
		if (!i.hasNext())
			return "{}";

		StringBuilder sb = new StringBuilder();
		sb.append('{');
		for (;;) {
			Entry<K, V> e = i.next();
			K key = e.getKey();
			V value = e.getValue();
			sb.append(key == this ? "(this MyMap)" : key);
			sb.append('=');
			sb.append(value == this ? "(this MyMap)" : value);
			if (!i.hasNext())
				return sb.append('}').toString();
			sb.append(", ");
		}
	}

	/**
	 * Returns a shallow copy of this <tt>MyAbstractMyMap</tt> instance: the keys
	 * and values themselves are not cloned.
	 * 
	 * @return a shallow copy of this map
	 */
	protected Object clone() throws CloneNotSupportedException {
		MyAbstractMap<K, V> result = (MyAbstractMap<K, V>) super.clone();
		result.keySet = null;
		result.values = null;
		return result;
	}

	/**
	 * Utility method for SimpleEntry and SimpleImmutableEntry. Test for equality,
	 * checking for nulls.
	 */
	private static boolean eq(Object o1, Object o2) {
		return o1 == null ? o2 == null : o1.equals(o2);
	}

	// Implementation Note: SimpleEntry and SimpleImmutableEntry
	// are distinct unrelated classes, even though they share
	// some code. Since you can't add or subtract final-ness
	// of a field in a subclass, they can't share representations,
	// and the amount of duplicated code is too small to warrant
	// exposing a common abstract class.

	/**
	 * An Entry maintaining a key and a value. The value may be changed using the
	 * <tt>setValue</tt> method. This class facilitates the process of building
	 * custom map implementations. For example, it may be convenient to return
	 * arrays of <tt>SimpleEntry</tt> instances in method
	 * <tt>MyMap.entrySet().toArray</tt>.
	 * 
	 * @since 1.6
	 */
	public static class SimpleEntry<K, V> implements Entry<K, V>, java.io.Serializable {
		private static final long serialVersionUID = -8499721149061103585L;

		private final K key;
		private V value;

		/**
		 * Creates an entry representing a mapping from the specified key to the
		 * specified value.
		 * 
		 * @param key
		 *            the key represented by this entry
		 * @param value
		 *            the value represented by this entry
		 */
		public SimpleEntry(K key, V value) {
			this.key = key;
			this.value = value;
		}

		/**
		 * Creates an entry representing the same mapping as the specified entry.
		 * 
		 * @param entry
		 *            the entry to copy
		 */
		public SimpleEntry(Entry<? extends K, ? extends V> entry) {
			this.key = entry.getKey();
			this.value = entry.getValue();
		}

		/**
		 * Returns the key corresponding to this entry.
		 * 
		 * @return the key corresponding to this entry
		 */
		public K getKey() {
			return key;
		}

		/**
		 * Returns the value corresponding to this entry.
		 * 
		 * @return the value corresponding to this entry
		 */
		public V getValue() {
			return value;
		}

		/**
		 * Replaces the value corresponding to this entry with the specified value.
		 * 
		 * @param value
		 *            new value to be stored in this entry
		 * @return the old value corresponding to the entry
		 */
		public V setValue(V value) {
			V oldValue = this.value;
			this.value = value;
			return oldValue;
		}

		/**
		 * Compares the specified object with this entry for equality. Returns
		 * {@code true} if the given object is also a map entry and the two entries
		 * represent the same mapping. More formally, two entries {@code e1} and
		 * {@code e2} represent the same mapping if
		 * 
		 * <pre>
		 * (e1.getKey() == null ? e2.getKey() == null : e1.getKey().equals(e2.getKey()))
		 * 		&amp;&amp; (e1.getValue() == null ? e2.getValue() == null : e1.getValue().equals(e2.getValue()))
		 * </pre>
		 * 
		 * This ensures that the {@code equals} method works properly across different
		 * implementations of the {@code MyMap.Entry} interface.
		 * 
		 * @param o
		 *            object to be compared for equality with this map entry
		 * @return {@code true} if the specified object is equal to this map entry
		 * @see #hashCode
		 */
		public boolean equals(Object o) {
			if (!(o instanceof MyMap.Entry))
				return false;
			MyMap.Entry e = (MyMap.Entry) o;
			return eq(key, e.getKey()) && eq(value, e.getValue());
		}

		/**
		 * Returns the hash code value for this map entry. The hash code of a map entry
		 * {@code e} is defined to be:
		 * 
		 * <pre>
		 * (e.getKey() == null ? 0 : e.getKey().hashCode()) &circ; (e.getValue() == null ? 0 : e.getValue().hashCode())
		 * </pre>
		 * 
		 * This ensures that {@code e1.equals(e2)} implies that {@code
		 * e1.hashCode()==e2.hashCode()} for any two Entries {@code e1} and {@code e2},
		 * as required by the general contract of {@link Object#hashCode}.
		 * 
		 * @return the hash code value for this map entry
		 * @see #equals
		 */
		public int hashCode() {
			return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode());
		}

		/**
		 * Returns a String representation of this map entry. This implementation
		 * returns the string representation of this entry's key followed by the equals
		 * character ("<tt>=</tt>") followed by the string representation of this
		 * entry's value.
		 * 
		 * @return a String representation of this map entry
		 */
		public String toString() {
			return key + "=" + value;
		}

	}

	/**
	 * An Entry maintaining an immutable key and value. This class does not support
	 * method <tt>setValue</tt>. This class may be convenient in methods that return
	 * thread-safe snapshots of key-value mappings.
	 * 
	 * @since 1.6
	 */
	public static class SimpleImmutableEntry<K, V> implements Entry<K, V>, java.io.Serializable {
		private static final long serialVersionUID = 7138329143949025153L;

		private final K key;
		private final V value;

		/**
		 * Creates an entry representing a mapping from the specified key to the
		 * specified value.
		 * 
		 * @param key
		 *            the key represented by this entry
		 * @param value
		 *            the value represented by this entry
		 */
		public SimpleImmutableEntry(K key, V value) {
			this.key = key;
			this.value = value;
		}

		/**
		 * Creates an entry representing the same mapping as the specified entry.
		 * 
		 * @param entry
		 *            the entry to copy
		 */
		public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) {
			this.key = entry.getKey();
			this.value = entry.getValue();
		}

		/**
		 * Returns the key corresponding to this entry.
		 * 
		 * @return the key corresponding to this entry
		 */
		public K getKey() {
			return key;
		}

		/**
		 * Returns the value corresponding to this entry.
		 * 
		 * @return the value corresponding to this entry
		 */
		public V getValue() {
			return value;
		}

		/**
		 * Replaces the value corresponding to this entry with the specified value
		 * (optional operation). This implementation simply throws
		 * <tt>UnsupportedOperationException</tt>, as this class implements an
		 * <i>immutable</i> map entry.
		 * 
		 * @param value
		 *            new value to be stored in this entry
		 * @return (Does not return)
		 * @throws UnsupportedOperationException
		 *             always
		 */
		public V setValue(V value) {
			throw new UnsupportedOperationException();
		}

		/**
		 * Compares the specified object with this entry for equality. Returns
		 * {@code true} if the given object is also a map entry and the two entries
		 * represent the same mapping. More formally, two entries {@code e1} and
		 * {@code e2} represent the same mapping if
		 * 
		 * <pre>
		 * (e1.getKey() == null ? e2.getKey() == null : e1.getKey().equals(e2.getKey()))
		 * 		&amp;&amp; (e1.getValue() == null ? e2.getValue() == null : e1.getValue().equals(e2.getValue()))
		 * </pre>
		 * 
		 * This ensures that the {@code equals} method works properly across different
		 * implementations of the {@code MyMap.Entry} interface.
		 * 
		 * @param o
		 *            object to be compared for equality with this map entry
		 * @return {@code true} if the specified object is equal to this map entry
		 * @see #hashCode
		 */
		public boolean equals(Object o) {
			if (!(o instanceof MyMap.Entry))
				return false;
			MyMap.Entry e = (MyMap.Entry) o;
			return eq(key, e.getKey()) && eq(value, e.getValue());
		}

		/**
		 * Returns the hash code value for this map entry. The hash code of a map entry
		 * {@code e} is defined to be:
		 * 
		 * <pre>
		 * (e.getKey() == null ? 0 : e.getKey().hashCode()) &circ; (e.getValue() == null ? 0 : e.getValue().hashCode())
		 * </pre>
		 * 
		 * This ensures that {@code e1.equals(e2)} implies that {@code
		 * e1.hashCode()==e2.hashCode()} for any two Entries {@code e1} and {@code e2},
		 * as required by the general contract of {@link Object#hashCode}.
		 * 
		 * @return the hash code value for this map entry
		 * @see #equals
		 */
		public int hashCode() {
			return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode());
		}

		/**
		 * Returns a String representation of this map entry. This implementation
		 * returns the string representation of this entry's key followed by the equals
		 * character ("<tt>=</tt>") followed by the string representation of this
		 * entry's value.
		 * 
		 * @return a String representation of this map entry
		 */
		public String toString() {
			return key + "=" + value;
		}

	}
}