/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.glassfish.jersey.internal.guava;

import java.util.Map;
import java.util.Set;

/**
 * A collection that associates an ordered pair of keys, called a row key and a
 * column key, with a single value. A table may be sparse, with only a small
 * fraction of row key / column key pairs possessing a corresponding value.
 * <p>
 * <p>The mappings corresponding to a given row key may be viewed as a {@link
 * Map} whose keys are the columns. The reverse is also available, associating a
 * column with a row key / value map. Note that, in some implementations, data
 * access by column key may have fewer supported operations or worse performance
 * than data access by row key.
 * <p>
 * <p>The methods returning collections or maps always return views of the
 * underlying table. Updating the table can change the contents of those
 * collections, and updating the collections will change the table.
 * <p>
 * <p>All methods that modify the table are optional, and the views returned by
 * the table may or may not be modifiable. When modification isn't supported,
 * those methods will throw an {@link UnsupportedOperationException}.
 * <p>
 * <p>See the Guava User Guide article on <a href=
 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Table">
 * {@code Table}</a>.
 *
 * @param <R> the type of the table row keys
 * @param <C> the type of the table column keys
 * @param <V> the type of the mapped values
 * @author Jared Levy
 * @since 7.0
 */
public interface Table<R, C, V> {
    // TODO(jlevy): Consider adding methods similar to ConcurrentMap methods.

    // Accessors

    /**
     * Returns {@code true} if the table contains a mapping with the specified
     * row and column keys.
     *
     * @param rowKey    key of row to search for
     * @param columnKey key of column to search for
     */
    boolean contains(Object rowKey, Object columnKey);

    /**
     * Returns {@code true} if the table contains a mapping with the specified
     * row key.
     *
     * @param rowKey key of row to search for
     */
    boolean containsRow(Object rowKey);

    /**
     * Returns {@code true} if the table contains a mapping with the specified
     * column.
     *
     * @param columnKey key of column to search for
     */
    boolean containsColumn(Object columnKey);

    /**
     * Returns {@code true} if the table contains a mapping with the specified
     * value.
     *
     * @param value value to search for
     */
    boolean containsValue(Object value);

    /**
     * Returns the value corresponding to the given row and column keys, or
     * {@code null} if no such mapping exists.
     *
     * @param rowKey    key of row to search for
     * @param columnKey key of column to search for
     */
    V get(Object rowKey, Object columnKey);

    /**
     * Returns the number of row key / column key / value mappings in the table.
     */
    int size();

    /**
     * Compares the specified object with this table for equality. Two tables are
     * equal when their cell views, as returned by {@link #cellSet}, are equal.
     */
    @Override
    boolean equals(Object obj);

    /**
     * Returns the hash code for this table. The hash code of a table is defined
     * as the hash code of its cell view, as returned by {@link #cellSet}.
     */
    @Override
    int hashCode();

    // Mutators

    /**
     * Removes all mappings from the table.
     */
    void clear();

    /**
     * Associates the specified value with the specified keys. If the table
     * already contained a mapping for those keys, the old value is replaced with
     * the specified value.
     *
     * @param rowKey    row key that the value should be associated with
     * @param columnKey column key that the value should be associated with
     * @param value     value to be associated with the specified keys
     * @return the value previously associated with the keys, or {@code null} if
     * no mapping existed for the keys
     */
    V put(R rowKey, C columnKey, V value);

    /**
     * Copies all mappings from the specified table to this table. The effect is
     * equivalent to calling {@link #put} with each row key / column key / value
     * mapping in {@code table}.
     *
     * @param table the table to add to this table
     */
    void putAll(Table<? extends R, ? extends C, ? extends V> table);

    /**
     * Removes the mapping, if any, associated with the given keys.
     *
     * @param rowKey    row key of mapping to be removed
     * @param columnKey column key of mapping to be removed
     * @return the value previously associated with the keys, or {@code null} if
     * no such value existed
     */
    V remove(Object rowKey, Object columnKey);

    // Views

    /**
     * Returns a view of all mappings that have the given row key. For each row
     * key / column key / value mapping in the table with that row key, the
     * returned map associates the column key with the value. If no mappings in
     * the table have the provided row key, an empty map is returned.
     * <p>
     * <p>Changes to the returned map will update the underlying table, and vice
     * versa.
     *
     * @param rowKey key of row to search for in the table
     * @return the corresponding map from column keys to values
     */
    Map<C, V> row(R rowKey);

    /**
     * Returns a view of all mappings that have the given column key. For each row
     * key / column key / value mapping in the table with that column key, the
     * returned map associates the row key with the value. If no mappings in the
     * table have the provided column key, an empty map is returned.
     * <p>
     * <p>Changes to the returned map will update the underlying table, and vice
     * versa.
     *
     * @param columnKey key of column to search for in the table
     * @return the corresponding map from row keys to values
     */
    Map<R, V> column(C columnKey);

    /**
     * Returns a set of all row key / column key / value triplets. Changes to the
     * returned set will update the underlying table, and vice versa. The cell set
     * does not support the {@code add} or {@code addAll} methods.
     *
     * @return set of table cells consisting of row key / column key / value
     * triplets
     */
    Set<Cell<R, C, V>> cellSet();

    /**
     * Returns a set of row keys that have one or more values in the table.
     * Changes to the set will update the underlying table, and vice versa.
     *
     * @return set of row keys
     */
    Set<R> rowKeySet();

    /**
     * Returns a set of column keys that have one or more values in the table.
     * Changes to the set will update the underlying table, and vice versa.
     *
     * @return set of column keys
     */
    Set<C> columnKeySet();

    /**
     * Returns a view that associates each row key with the corresponding map from
     * column keys to values. Changes to the returned map will update this table.
     * The returned map does not support {@code put()} or {@code putAll()}, or
     * {@code setValue()} on its entries.
     * <p>
     * <p>In contrast, the maps returned by {@code rowMap().get()} have the same
     * behavior as those returned by {@link #row}. Those maps may support {@code
     * setValue()}, {@code put()}, and {@code putAll()}.
     *
     * @return a map view from each row key to a secondary map from column keys to
     * values
     */
    Map<R, Map<C, V>> rowMap();

    /**
     * Returns a view that associates each column key with the corresponding map
     * from row keys to values. Changes to the returned map will update this
     * table. The returned map does not support {@code put()} or {@code putAll()},
     * or {@code setValue()} on its entries.
     * <p>
     * <p>In contrast, the maps returned by {@code columnMap().get()} have the
     * same behavior as those returned by {@link #column}. Those maps may support
     * {@code setValue()}, {@code put()}, and {@code putAll()}.
     *
     * @return a map view from each column key to a secondary map from row keys to
     * values
     */
    Map<C, Map<R, V>> columnMap();

    /**
     * Row key / column key / value triplet corresponding to a mapping in a table.
     *
     * @since 7.0
     */
    interface Cell<R, C, V> {
        /**
         * Returns the row key of this cell.
         */
        R getRowKey();

        /**
         * Returns the column key of this cell.
         */
        C getColumnKey();

        /**
         * Returns the value of this cell.
         */
        V getValue();

        /**
         * Compares the specified object with this cell for equality. Two cells are
         * equal when they have equal row keys, column keys, and values.
         */
        @Override
        boolean equals(Object obj);

        /**
         * Returns the hash code of this cell.
         * <p>
         * <p>The hash code of a table cell is equal to {@link
         * Objects#hashCode}{@code (e.getRowKey(), e.getColumnKey(), e.getValue())}.
         */
        @Override
        int hashCode();
    }
}
