/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2000-2004
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: StoredMap.java,v 1.4 2004/09/22 18:01:03 bostic Exp $
 */

package com.sleepycat.collections;

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import com.sleepycat.bind.EntityBinding;
import com.sleepycat.bind.EntryBinding;
import com.sleepycat.db.Database;

/**
 * A Map view of a {@link Database}.
 *
 * <p><em>Note that this class does not conform to the standard Java
 * collections interface in the following ways:</em></p>
 * <ul>
 * <li>The {@link #size} method always throws
 * <code>UnsupportedOperationException</code> because, for performance reasons,
 * databases do not maintain their total record count.</li>
 * <li>All iterators must be explicitly closed using {@link
 * StoredIterator#close()} or {@link StoredIterator#close(java.util.Iterator)}
 * to release the underlying database cursor resources.</li>
 * </ul>
 *
 * <p>In addition to the standard Map methods, this class provides the
 * following methods for stored maps only.  Note that the use of these methods
 * is not compatible with the standard Java collections interface.</p>
 * <ul>
 * <li>{@link #duplicates(Object)}</li>
 * <li>{@link #append(Object)}</li>
 * </ul>
 *
 * @author Mark Hayes
 */
public class StoredMap extends StoredContainer implements Map {

    private StoredKeySet keySet;
    private boolean keySetInitialized = false;
    private StoredEntrySet entrySet;
    private boolean entrySetInitialized = false;
    private StoredValueSet valueSet;
    private boolean valueSetInitialized = false;

    /**
     * Creates a map view of a {@link Database}.
     *
     * @param database is the Database underlying the new collection.
     *
     * @param keyBinding is the binding used to translate between key buffers
     * and key objects.
     *
     * @param valueBinding is the binding used to translate between value
     * buffers and value objects.
     *
     * @param writeAllowed is true to create a read-write collection or false
     * to create a read-only collection.
     *
     * @throws IllegalArgumentException if formats are not consistently
     * defined or a parameter is invalid.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public StoredMap(Database database, EntryBinding keyBinding,
                     EntryBinding valueBinding, boolean writeAllowed) {

        super(new DataView(database, keyBinding, valueBinding, null,
                           writeAllowed, null));
    }

    /**
     * Creates a map view of a {@link Database} with a {@link
     * PrimaryKeyAssigner}.  Writing is allowed for the created map.
     *
     * @param database is the Database underlying the new collection.
     *
     * @param keyBinding is the binding used to translate between key buffers
     * and key objects.
     *
     * @param valueBinding is the binding used to translate between value
     * buffers and value objects.
     *
     * @param keyAssigner is used by the {@link #append} method to assign
     * primary keys.
     *
     * @throws IllegalArgumentException if formats are not consistently
     * defined or a parameter is invalid.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public StoredMap(Database database, EntryBinding keyBinding,
                     EntryBinding valueBinding,
                     PrimaryKeyAssigner keyAssigner) {

        super(new DataView(database, keyBinding, valueBinding, null,
                           true, keyAssigner));
    }

    protected Object clone()
        throws CloneNotSupportedException {

        // cached collections must be cleared and recreated with the new view
        // of the map to inherit the new view's properties
        StoredMap other = (StoredMap) super.clone();
        other.keySet = null;
	other.keySetInitialized = false;
        other.entrySet = null;
	other.entrySetInitialized = false;
        other.valueSet = null;
	other.valueSetInitialized = false;
        return other;
    }

    /**
     * Creates a map entity view of a {@link Database}.
     *
     * @param database is the Database underlying the new collection.
     *
     * @param keyBinding is the binding used to translate between key buffers
     * and key objects.
     *
     * @param valueEntityBinding is the binding used to translate between
     * key/value buffers and entity value objects.
     *
     * @param writeAllowed is true to create a read-write collection or false
     * to create a read-only collection.
     *
     * @throws IllegalArgumentException if formats are not consistently
     * defined or a parameter is invalid.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public StoredMap(Database database, EntryBinding keyBinding,
                     EntityBinding valueEntityBinding, boolean writeAllowed) {

        super(new DataView(database, keyBinding, null, valueEntityBinding,
                           writeAllowed, null));
    }

    /**
     * Creates a map entity view of a {@link Database} with a {@link
     * PrimaryKeyAssigner}.  Writing is allowed for the created map.
     *
     * @param database is the Database underlying the new collection.
     *
     * @param keyBinding is the binding used to translate between key buffers
     * and key objects.
     *
     * @param valueEntityBinding is the binding used to translate between
     * key/value buffers and entity value objects.
     *
     * @param keyAssigner is used by the {@link #append} method to assign
     * primary keys.
     *
     * @throws IllegalArgumentException if formats are not consistently
     * defined or a parameter is invalid.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public StoredMap(Database database, EntryBinding keyBinding,
                     EntityBinding valueEntityBinding,
                     PrimaryKeyAssigner keyAssigner) {

        super(new DataView(database, keyBinding, null, valueEntityBinding,
                           true, keyAssigner));
    }

    StoredMap(DataView view) {

        super(view);
    }

    /**
     * Returns the value to which this map maps the specified key.  If
     * duplicates are allowed, this method returns the first duplicate, in the
     * order in which duplicates are configured, that maps to the specified
     * key.
     *
     * This method conforms to the {@link Map#get} interface.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public Object get(Object key) {

        return super.get(key);
    }

    /**
     * Associates the specified value with the specified key in this map
     * (optional operation).  If duplicates are allowed and the specified key
     * is already mapped to a value, this method appends the new duplicate
     * after the existing duplicates.  This method conforms to the {@link
     * Map#put} interface.
     *
     * <p>The key parameter may be null if an entity binding is used and the
     * key will be derived from the value (entity) parameter.  If an entity
     * binding is used and the key parameter is non-null, then the key
     * parameter must be equal to the key derived from the value parameter.</p>
     *
     * @return the previous value associated with specified key, or null if
     * there was no mapping for the key or if duplicates are allowed.
     *
     * @throws UnsupportedOperationException if the collection is indexed, or
     * if the collection is read-only.
     *
     * @throws IllegalArgumentException if an entity value binding is used and
     * the primary key of the value given is different than the existing stored
     * primary key.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public Object put(Object key, Object value) {

        return super.put(key, value);
    }

    /**
     * Appends a given value returning the newly assigned key.  If a {@link
     * PrimaryKeyAssigner} is associated with Store for this map, it will be
     * used to assigned the returned key.  Otherwise the Store must be a QUEUE
     * or RECNO database and the next available record number is assigned as
     * the key.  This method does not exist in the standard {@link Map}
     * interface.
     *
     * @param value the value to be appended.
     *
     * @return the assigned key.
     *
     * @throws UnsupportedOperationException if the collection is indexed, or
     * if the collection is read-only, or if the Store has no {@link
     * PrimaryKeyAssigner} and is not a QUEUE or RECNO database.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public Object append(Object value) {

        boolean doAutoCommit = beginAutoCommit();
        try {
            Object[] key = new Object[1];
            view.append(value, key, null);
            commitAutoCommit(doAutoCommit);
            return key[0];
        } catch (Exception e) {
            throw handleException(e, doAutoCommit);
        }
    }

    /**
     * Removes the mapping for this key from this map if present (optional
     * operation).  If duplicates are allowed, this method removes all
     * duplicates for the given key.  This method conforms to the {@link
     * Map#remove} interface.
     *
     * @throws UnsupportedOperationException if the collection is read-only.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public Object remove(Object key) {

        Object[] oldVal = new Object[1];
        removeKey(key, oldVal);
        return oldVal[0];
    }

    /**
     * Returns true if this map contains the specified key.  This method
     * conforms to the {@link Map#containsKey} interface.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public boolean containsKey(Object key) {

        return super.containsKey(key);
    }

    /**
     * Returns true if this map contains the specified value.  When an entity
     * binding is used, this method returns whether the map contains the
     * primary key and value mapping of the entity.  This method conforms to
     * the {@link Map#containsValue} interface.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public boolean containsValue(Object value) {

        return super.containsValue(value);
    }

    /**
     * Copies all of the mappings from the specified map to this map (optional
     * operation).  When duplicates are allowed, the mappings in the specified
     * map are effectively appended to the existing mappings in this map, that
     * is no previously existing mappings in this map are replaced.  This
     * method conforms to the {@link Map#putAll} interface.
     *
     * @throws UnsupportedOperationException if the collection is read-only, or
     * if the collection is indexed.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public void putAll(Map map) {

        boolean doAutoCommit = beginAutoCommit();
        Iterator entries = null;
        try {
            entries = map.entrySet().iterator();
            while (entries.hasNext()) {
                Map.Entry entry = (Map.Entry) entries.next();
                put(entry.getKey(), entry.getValue());
            }
            StoredIterator.close(entries);
            commitAutoCommit(doAutoCommit);
        } catch (Exception e) {
            StoredIterator.close(entries);
            throw handleException(e, doAutoCommit);
        }
    }

    /**
     * Returns a set view of the keys contained in this map.  A {@link
     * java.util.SortedSet} is returned if the map is ordered.  The returned
     * collection will be read-only if the map is read-only.  This method
     * conforms to the {@link Map#keySet()} interface.
     *
     * @return a {@link StoredKeySet} or a {@link StoredSortedKeySet} for this
     * map.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     *
     * @see #isOrdered
     * @see #isWriteAllowed
     */
    public Set keySet() {

        if (!keySetInitialized) {
            synchronized (this) {
                if (!keySetInitialized) {
                    DataView newView = view.keySetView();
                    if (isOrdered()) {
                        keySet = new StoredSortedKeySet(newView);
                    } else {
                        keySet = new StoredKeySet(newView);
                    }
		    keySetInitialized = true;
                }
            }
        }
        return keySet;
    }

    /**
     * Returns a set view of the mappings contained in this map.  A {@link
     * java.util.SortedSet} is returned if the map is ordered.  The returned
     * collection will be read-only if the map is read-only.  This method
     * conforms to the {@link Map#entrySet()} interface.
     *
     * @return a {@link StoredEntrySet} or a {@link StoredSortedEntrySet} for
     * this map.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     *
     * @see #isOrdered
     * @see #isWriteAllowed
     */
    public Set entrySet() {

        if (!entrySetInitialized) {
            synchronized (this) {
                if (!entrySetInitialized) {
                    if (isOrdered()) {
                        entrySet = new StoredSortedEntrySet(view);
                    } else {
                        entrySet = new StoredEntrySet(view);
                    }
		    entrySetInitialized = true;
                }
            }
        }
        return entrySet;
    }

    /**
     * Returns a collection view of the values contained in this map.  A {@link
     * java.util.SortedSet} is returned if the map is ordered and the
     * value/entity binding can be used to derive the map's key from its
     * value/entity object.  The returned collection will be read-only if the
     * map is read-only.  This method conforms to the {@link Map#entrySet()}
     * interface.
     *
     * @return a {@link StoredValueSet} or a {@link StoredSortedValueSet} for
     * this map.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     *
     * @see #isOrdered
     * @see #isWriteAllowed
     */
    public Collection values() {

	if (!valueSetInitialized) {
            synchronized (this) {
                if (!valueSetInitialized) {
                    DataView newView = view.valueSetView();
                    if (isOrdered() && newView.canDeriveKeyFromValue()) {
                        valueSet = new StoredSortedValueSet(newView);
                    } else {
                        valueSet = new StoredValueSet(newView);
                    }
		    valueSetInitialized = true;
                }
            }
        }
        return valueSet;
    }

    /**
     * Returns a new collection containing the values mapped to the given key
     * in this map.  This collection's iterator() method is particularly useful
     * for iterating over the duplicates for a given key, since this is not
     * supported by the standard Map interface.  This method does not exist in
     * the standard {@link Map} interface.
     *
     * <p>If no mapping for the given key is present, an empty collection is
     * returned.  If duplicates are not allowed, at most a single value will be
     * in the collection returned.  If duplicates are allowed, the returned
     * collection's add() method may be used to add values for the given
     * key.</p>
     *
     * @param key is the key for which values are to be returned.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public Collection duplicates(Object key) {

        try {
            DataView newView = view.valueSetView(key);
            return new StoredValueSet(newView, true);
        } catch (KeyRangeException e) {
            return Collections.EMPTY_SET;
        } catch (Exception e) {
            throw StoredContainer.convertException(e);
        }
    }

    /**
     * Compares the specified object with this map for equality.  A value
     * comparison is performed by this method and the stored values are
     * compared rather than calling the equals() method of each element.  This
     * method conforms to the {@link Map#equals} interface.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public boolean equals(Object other) {

        if (other instanceof Map) {
            return entrySet().equals(((Map) other).entrySet());
        } else {
            return false;
        }
    }

    /*
     * Add this in to keep FindBugs from whining at us about implementing
     * equals(), but not hashCode().
     */
    public int hashCode() {
	return super.hashCode();
    }

    /**
     * Converts the map to a string representation for debugging.  WARNING: All
     * mappings will be converted to strings and returned and therefore the
     * returned string may be very large.
     *
     * @return the string representation.
     *
     * @throws RuntimeExceptionWrapper if a {@link
     * com.sleepycat.db.DatabaseException} is thrown.
     */
    public String toString() {

        return entrySet().toString();
    }
}