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A library for Java that provides re-usable components commonly used by Flow libraries.
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/*
 * This file is part of Flow Commons, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2013 Flow Powered 
 *
 * 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.flowpowered.commons;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReferenceArray;

import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;

import com.flowpowered.commons.store.MemoryStore;
import com.flowpowered.commons.store.SimpleStore;
import com.flowpowered.commons.store.SimpleStoredMap;

/**
 * Represents a map for mapping Strings to unique ids.
 *
 * The class supports conversion of ids between maps and allocation of new unique ids for unknown Strings
 *
 * Conversions to and from parent/child maps are cached
 */
public class StringToUniqueIntegerMap extends SimpleStoredMap {
    private final StringToUniqueIntegerMap parent;
    private final AtomicReferenceArray thisToParentMap;
    private final AtomicReferenceArray parentToThisMap;
    private final int minId;
    private final int maxId;
    private AtomicInteger nextId;

    public StringToUniqueIntegerMap(String name) {
        this(null, new MemoryStore(), 0, Integer.MAX_VALUE, name);
    }

    public StringToUniqueIntegerMap(String name, int maxId) {
        this(null, new MemoryStore(), 0, maxId, name);
    }

    /**
     * @param parent the parent of this map
     * @param store the store to store ids
     * @param minId the lowest valid id for dynamic allocation (ids below this are assumed to be reserved)
     * @param maxId the highest valid id + 1
     * @param name The name of this StringToUniqueIntegerMap
     */
    public StringToUniqueIntegerMap(StringToUniqueIntegerMap parent, SimpleStore store, int minId, int maxId, String name) {
        super(store, name);
        this.parent = parent;
        if (this.parent != null) {
            thisToParentMap = new AtomicReferenceArray<>(maxId);
            parentToThisMap = new AtomicReferenceArray<>(maxId);
        } else {
            thisToParentMap = null;
            parentToThisMap = null;
        }
        this.minId = minId;
        this.maxId = maxId;
        nextId = new AtomicInteger(minId);
    }

    /**
     * Converts an id local to this map to the id local to the parent map
     *
     * @param localId to convert
     * @return the foreign id, or 0 on failure
     */
    public int convertToParent(int localId) {
        if (parent == null) {
            throw new IllegalStateException("Parent map is null!");
        }
        return convertTo(parent, localId);
    }

    /**
     * Converts an id local to this map to a foreign id, local to another map.
     *
     * @param other the other map
     * @param localId to convert
     * @return returns the foreign id, or 0 on failure
     */
    public int convertTo(StringToUniqueIntegerMap other, int localId) {
        if (other == null) {
            throw new IllegalStateException("Other map is null");
        }
        String localKey = store.reverseGet(localId);
        if (localKey == null) {
            throw new IllegalArgumentException("Cannot convert an id that is not registered locally.");
        }

        Integer foreignId = null;

        if (other == this) {
            return localId;
        } else if (other == parent) {
            foreignId = thisToParentMap.get(localId);
        } else if (other.parent == this) {
            foreignId = other.parentToThisMap.get(localId);
        }

        // Cache hit
        if (foreignId != null) {
            return foreignId;
        }

        Integer integerForeignId = other.store.get(localKey);

        // The other map doesn't have an entry for this key
        if (integerForeignId == null) {
            integerForeignId = other.register(localKey);
        }

        // Add the key/value pair to the cache
        if (other == parent) {
            thisToParentMap.set(localId, integerForeignId);
            parentToThisMap.set(integerForeignId, localId);
        } else if (other.parent == this) {
            other.thisToParentMap.set(integerForeignId, localId);
            other.parentToThisMap.set(localId, integerForeignId);
        }

        return integerForeignId;
    }

    /**
     * Converts a foreign id, local to a foreign map to an id local to this map.
     *
     * @param other the other map
     * @return returns the local id, or 0 on failure
     */
    public int convertFrom(StringToUniqueIntegerMap other, int foreignId) {
        return other.convertTo(this, foreignId);
    }

    /**
     * Registers a key with the map and returns the matching id.
     *
     * The id corresponding to a key will be consistent if registered more than once, including over restarts, subject to the persistence of the store.
     *
     * @param key the key to be added
     * @return returns the local id, or 0 on failure
     */
    public int register(String key) {
        Integer id = store.get(key);
        if (id != null) {
            return id;
        }

        int localId = nextId.getAndIncrement();

        while (localId < maxId) {
            if (store.setIfAbsent(key, localId)) {
                return localId;
            }

            Integer storeId = store.get(key);
            if (storeId != null) {
                return storeId;
            }

            localId = nextId.getAndIncrement();
        }

        throw new IllegalStateException("StringMap id space exhausted");
    }

    /**
     * Registers a key/id pair with the map.  If the id is already in use the method will fail.
 
 The id must be lower than the min id for the map to prevent clashing with the dynamically
     * allocated ids
     *
     * @param key the key to be added
     * @param id the desired id to be matched to the key
     * @return true if the key/id pair was successfully registered
     * @throws IllegalArgumentException if the id >= minId
     */
    public boolean register(String key, int id) {
        if (id >= this.minId) {
            throw new IllegalArgumentException("Hardcoded ids must be below the minimum id value");
        }

        return store.setIfAbsent(key, id);
    }

    /**
     * Gets the String corresponding to a given int.
     *
     * @return the String or null if no match
     */
    @Override
    public String getString(Integer value) {
        return store.reverseGet(value);
    }

    /**
     * Gets the int corresponding to a given String
     *
     * @param key The key
     * @return The int or null if no match
     */
    @Override
    public Integer getValue(String key) {
        return store.get(key);
    }

    /**
     * Saves the map to the persistence system
     *
     * @return returns true if the map saves correctly
     */
    @Override
    public boolean save() {
        return store.save();
    }

    /**
     * Returns a collection of all keys for all (key, value) pairs within the Store
     *
     * @return returns a Collection containing all the keys
     */
    @Override
    public Collection getKeys() {
        return store.getKeys();
    }

    @Override
    public List> getItems() {
        List> items = new ArrayList<>();
        for (Map.Entry entry : store.getEntrySet()) {
            items.add(new ImmutablePair<>(entry.getValue(), entry.getKey()));
        }
        return items;
    }

    @Override
    public void clear() {
        while (this.nextId.getAndSet(minId) != minId) {
            if (this.parent != null) {
                for (int i = 0; i < maxId; i++) {
                    thisToParentMap.set(i, null);
                    parentToThisMap.set(i, null);
                }
            }
            store.clear();
        }
    }
}