/*
 * Copyright (c) 2006-2015 DMDirc Developers
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.dmdirc.util.collections;

import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

import javax.annotation.Nonnull;

/**
 * An object that maps keys to values, and values back to keys. Currently
 * does no checking for duplicates. Does not allow null values.
 * <p>Note that this implementation is NOT thread safe.
 *
 * @param <A> The first type of data to be mapped
 * @param <B> The second type of data to be mapped
 */
public class DoubleMap<A,B> implements Map<A, B> {

    /** The keys in this map. */
    private final List<A> keys = new ArrayList<>();
    /** The values in this map. */
    private final List<B> values = new ArrayList<>();

    /**
     * Retrieves the value associated with the specified key.
     *
     * @param key The key to search for
     * @return The value of the specified key
     */
    public B getValue(final A key) {
        if (keys.indexOf(key) == -1) {
            return null;
        }
        return values.get(keys.indexOf(key));
    }

    /**
     * Retrieves the key associated with the specified value.
     *
     * @param value The value to search for
     * @return The key of the specified value
     */
    public A getKey(final B value) {
        if (values.indexOf(value) == -1) {
            return null;
        }
        return keys.get(values.indexOf(value));
    }

    @Override
    public B put(final A key, final B value) {
        if (key == null || value == null) {
            throw new NullPointerException();
        }

        keys.add(key);
        values.add(value);

        return value;
    }

    @Nonnull
    @Override
    public Set<A> keySet() {
        return new HashSet<>(keys);
    }

    @Override
    public int size() {
        return keys.size();
    }

    @Override
    public boolean isEmpty() {
        return keys.isEmpty();
    }

    @Override
    public boolean containsKey(final Object key) {
        return keys.contains(key);
    }

    @Override
    public boolean containsValue(final Object value) {
        return values.contains(value);
    }

    @Override
    @SuppressWarnings("unchecked")
    public B get(final Object key) {
        return getValue((A) key);
    }

    @Override
    public B remove(final Object key) {
        if (keys.indexOf(key) == -1) {
            return null;
        }
        final B value = values.remove(keys.indexOf(key));
        keys.remove(keys.indexOf(key));
        return value;
    }

    @Override
    public void putAll(@Nonnull final Map<? extends A, ? extends B> m) {
        for (Entry<? extends A, ? extends B> entry : m.entrySet()) {
            put(entry.getKey(), entry.getValue());
        }
    }

    @Override
    public void clear() {
        keys.clear();
        values.clear();
    }

    @Nonnull
    @Override
    public Collection<B> values() {
        return new ArrayList<>(values);
    }

    @Nonnull
    @Override
    public Set<Entry<A, B>> entrySet() {
        return keys.stream()
                .map(key -> new SimpleEntry<>(key, getValue(key)))
                .collect(Collectors.toSet());
    }
}