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/*
 * Copyright 2013 Samppa Saarela
 *
 * 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.javersion.util;

import java.util.*;

import javax.annotation.concurrent.NotThreadSafe;

import org.javersion.util.AbstractTreeMap.Node;

@NotThreadSafe
public class MutableTreeMap extends AbstractMap implements MutableSortedMap {

    private MMap map;

    private V previousValue;

    private final Merger> defaultMerger = new Merger>() {

        @Override
        public boolean insert(java.util.Map.Entry newEntry) {
            previousValue = null;
            return true;
        }

        @Override
        public boolean merge(java.util.Map.Entry oldEntry, java.util.Map.Entry newEntry) {
            previousValue = oldEntry.getValue();
            return true;
        }

        @Override
        public boolean delete(java.util.Map.Entry oldEntry) {
            previousValue = oldEntry.getValue();
            return true;
        }
    };

    public MutableTreeMap() {
        this.map = new MMap();
    }

    public MutableTreeMap(Comparator comparator) {
        this.map = new MMap(comparator);
    }

    MutableTreeMap(Comparator comparator, Node root, int size) {
        this.map = new MMap(comparator, root, size);
    }

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

    @Override
    public boolean containsKey(Object key) {
        return map.containsKey(key);
    }

    @Override
    public V get(Object key) {
        return map.get(key);
    }

    Node root() {
        // For tests
        return map.root;
    }

    @Override
    public Set> entrySet() {
        return new AbstractSet>() {

            @Override
            public Iterator> iterator() {
                return map.iterator();
            }

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

            @Override
            public Spliterator> spliterator() {
                return new AbstractTreeMap.EntrySpliterator<>(map.root, map.size(), map.comparator, false);
            }

            // TODO: clear, contains etc

        };
    }

    // TODO: values(), keySet() with spliterator()

    @Override
    public V put(final K key, final V value) {
        map.merge(key, value, defaultMerger);
        return previousValue;
    }

    @Override
    public V remove(final Object key) {
        map.dissoc(key, defaultMerger);
        return previousValue;
    }

    @Override
    public void putAll(final Map m) {
        map.assocAll(m);
    }

    @Override
    public void clear() {
        map = new MMap(map.comparator);
    }


    @Override
    public Iterator> iterator() {
        return map.iterator();
    }


    @Override
    public void merge(K key, V value, Merger> merger) {
        map.merge(key, value, merger);
    }

    @Override
    public void mergeAll(Map m, Merger> merger) {
        map.mergeAll(m, merger);
    }

    @Override
    public void mergeAll(Iterable> entries, Merger> merger) {
        map.mergeAll(entries, merger);
    }

    @Override
    public PersistentTreeMap toPersistentMap() {
        return map.toPersistentMap();
    }


    private static class MMap extends AbstractTreeMap> {

        private final Thread owner = Thread.currentThread();

        private UpdateContext>  updateContext;

        private Node root;

        private int size;

        private MMap() {
            super();
            this.root = null;
            this.size = 0;
            updateContext = new UpdateContext<>();
        }

        private MMap(Comparator comparator) {
            this(comparator, null, 0);
        }

        private MMap(Comparator comparator, Node root, int size) {
            super(comparator);
            this.updateContext = new UpdateContext<>();
            this.root = root;
            this.size = size;
        }

        @Override
        protected Node root() {
            verifyThread();
            return root;
        }

        @Override
        protected MMap self() {
            return this;
        }

        public PersistentTreeMap toPersistentMap() {
            verifyThread();
            updateContext.commit();
            return new PersistentTreeMap(comparator, root, size);
        }

        private void verifyThread() {
            if (owner != Thread.currentThread()) {
                throw new IllegalStateException("MutableMap should only be accessed form the thread it was created in.");
            }
        }

        @Override
        public int size() {
            verifyThread();
            return size;
        }

        @Override
        protected MMap doReturn(Comparator comparator, Node newRoot, int newSize) {
            this.root = newRoot;
            this.size = newSize;
            return this;
        }

        @Override
        protected UpdateContext> updateContext(Merger> merger) {
            verifyThread();
            if (updateContext.isCommitted()) {
                updateContext = new UpdateContext<>(32, merger);
            } else {
                updateContext.merger(merger);
            }
            return updateContext;
        }

        @Override
        protected void commit(UpdateContext updateContext) {
            // Nothing to do here
        }
    }
}