/*******************************************************************************
 * Copyright (c) 2007- VTT Technical Research Centre of Finland.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
/*
 * Created on Jan 21, 2005
 *
 * Copyright Toni Kalajainen
 *
 * 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.simantics.databoard.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

/**
 * Bijection map is a Map that has no values or keys, only 1:1 mappings
 * of values. These value/keys will be called with left and right side
 * values.
 *
 * Each value can exist only once on a side
 *
 * @author Toni Kalajainen
 */
public class BijectionMap<L, R> {

    /** The keys of tableLeft are left-side-values and
     * values are right-side-values */
    private final Map<L, R> tableLeft = new HashMap<L, R>();
    /** The keys of tableRight are right-side-values and
     * values on it are left-side-values */
    private final Map<R, L> tableRight = new HashMap<R, L>();

    /** The keys of tableLeft are left-side-values and
     * values are right-side-values */
    private final Map<L, R> imTableLeft = Collections.unmodifiableMap(tableLeft);
    /** The keys of tableRight are right-side-values and
     * values on it are left-side-values */
    private final Map<R, L> imTableRight = Collections.unmodifiableMap(tableRight);

    private final Set<L> imLeftSet = Collections.unmodifiableSet(tableLeft.keySet());
    private final Set<R> imRightSet = Collections.unmodifiableSet(tableRight.keySet());

	public BijectionMap() {

	}

	public BijectionMap(BijectionMap<L, R> copyFrom) {
		this.tableLeft.putAll(copyFrom.tableLeft);
		this.tableRight.putAll(copyFrom.tableRight);
	}

	public void addAll(BijectionMap<L, R> map)
	{
		for (Entry<L, R> e : map.getEntries())
			map(e.getKey(), e.getValue());
	}

    public boolean retainAllLeft(Collection<L> values)
    {
        boolean result = false;
        Collection<L> remove = new ArrayList<L>(size());
        for (L lValue : imLeftSet) {
            if (!values.contains(lValue)) {
                remove.add(lValue);
                result = true;
            }
        }
        if (!remove.isEmpty()) {
            for (L lValue : remove)
                removeWithLeft(lValue);
        }
        return result;
    }

    public boolean retainAllRight(Collection<R> values)
    {
        boolean result = false;
        Collection<R> remove = new ArrayList<R>(size());
        for (R rValue : imRightSet) {
            if (!values.contains(rValue)) {
                remove.add(rValue);
                result = true;
            }
        }
        if (!remove.isEmpty()) {
            for (R rValue : remove)
                removeWithRight(rValue);
        }
        return result;
    }

	public Set<Entry<L, R>> getEntries()
	{
		return tableLeft.entrySet();
	}

	public boolean containsLeft(L leftValue)
	{
		return tableLeft.containsKey(leftValue);
	}

	public boolean containsRight(R rightValue)
	{
		return tableRight.containsKey(rightValue);
	}

	public boolean contains(L leftValue, R rightValue)
	{
		if (leftValue==null || rightValue==null) return false;
		return rightValue.equals(tableLeft.get(leftValue));
	}

	public void map(L leftValue, R rightValue)
	{
        if (leftValue == null || rightValue == null)
            throw new NullPointerException();
        // Remove possible old mapping
        R oldRight = tableLeft.remove(leftValue);
        if (oldRight != null) {
            tableRight.remove(oldRight);
        } else {
            L oldLeft = tableRight.remove(rightValue);
            if (oldLeft != null) {
                tableLeft.remove(oldLeft);
            }
        }

		tableLeft.put(leftValue, rightValue);
		tableRight.put(rightValue, leftValue);
	}

	public boolean isEmpty() {
	    return tableLeft.isEmpty();
	}

    public int size()
    {
        return tableLeft.size();
    }

	public L getLeft(R rightValue) {
		return tableRight.get(rightValue);
	}

	public R getRight(L leftValue) {
		return tableLeft.get(leftValue);
	}

	public R removeWithLeft(L leftValue) {
		R rightValue = tableLeft.remove(leftValue);
		if (rightValue!=null)
			tableRight.remove(rightValue);
		return rightValue;
	}

	public L removeWithRight(R rightValue) {
		L leftValue = tableRight.remove(rightValue);
		if (leftValue!=null)
			tableLeft.remove(leftValue);
		return leftValue;
	}

	/**
	 * Get set of left values
	 *
	 * @return read-only set
	 */
    public Set<L> getLeftSet() {
        return imLeftSet;
    }

    /**
     * Get set of right values
     *
     * @return read-only set
     */
    public Set<R> getRightSet() {
        return imRightSet;
    }

    /**
     * Get left-to-right map
     *
     * @return read only map
     */
    public Map<L, R> getLeftToRightMap() {
        return imTableLeft;
    }

    /**
     * Get right-to-left map
     *
     * @return read only map
     */
    public Map<R, L> getRightToLeftMap() {
        return imTableRight;
    }

    public void clear() {
        tableLeft.clear();
        tableRight.clear();
    }

    @Override
    public String toString() {
    	int count = 0;
    	StringBuilder sb = new StringBuilder();
    	sb.append("[");
    	for (Entry<L, R> e : tableLeft.entrySet())
    	{
    		if (count++>0) sb.append(", ");
    		sb.append(e.getKey().toString());
    		sb.append("=");
    		sb.append(e.getValue().toString());
    	}
    	sb.append("]");
    	return sb.toString();
    }

    @Override
    public BijectionMap<L, R> clone() {
        return new BijectionMap<L, R>(this);
    }

}