package com.romix.scala.collection.concurrent;

import java.util.Iterator;
import java.util.Map.Entry;

import org.junit.Before;
import org.junit.Test;

/***
 * 
 * Test that read-only iterators do not allow for any updates.
 * Test that non read-only iterators allow for updates. 
 *
 */
public class TestReadOnlyAndUpdatableIterators {
    TrieMap<Integer, Integer> bt;
    private static final int MAP_SIZE = 200;
    
    @Before
    public void setUp() {
        bt = new TrieMap <Integer, Integer> ();
        for (int j = 0; j < MAP_SIZE; j++) {
            TestHelper.assertEquals (null, bt.put (Integer.valueOf (j), Integer.valueOf (j)));
        }                
    }
    
    @Test
    public void testReadOnlyIterator () {
        Iterator<Entry<Integer, Integer>> it = bt.readOnlyIterator ();
        try {
            it.next().setValue (0);
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
        try {
            it.remove ();
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
    }

    @Test
    public void testReadOnlySnapshotReadOnlyIterator () {
        TrieMap<Integer, Integer> roSnapshot = bt.readOnlySnapshot ();
        Iterator<Entry<Integer, Integer>> it = roSnapshot.readOnlyIterator ();
        try {
            it.next().setValue (0);
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
        try {
            it.remove ();
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
    }

    @Test
    public void testReadOnlySnapshotIterator () {
        TrieMap<Integer, Integer> roSnapshot = bt.readOnlySnapshot ();
        Iterator<Entry<Integer, Integer>> it = roSnapshot.iterator ();
        try {
            it.next().setValue (0);
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
        try {
            it.remove ();
            // It should have generated an exception, because it is a read-only iterator
            TestHelper.assertFalse (true);
        } catch (Exception e) {
            
        }
    }

    @Test
    public void testIterator () {
        Iterator<Entry<Integer, Integer>> it = bt.iterator ();
        try {
            it.next().setValue (0);
        } catch (Exception e) {
            // It should not have generated an exception, because it is a non read-only iterator
            TestHelper.assertFalse (true);            
        }
        
        try {
            it.remove ();
        } catch (Exception e) {
            // It should not have generated an exception, because it is a non read-only iterator
            TestHelper.assertFalse (true);            
        }
        
        // All changes are done on the original map
        TestHelper.assertEquals (MAP_SIZE - 1, bt.size ());            
    }

    @Test
    public void testSnapshotIterator () {
        TrieMap<Integer, Integer> snapshot = bt.snapshot ();
        Iterator<Entry<Integer, Integer>> it = snapshot.iterator ();
        try {
            it.next().setValue (0);
        } catch (Exception e) {
            // It should not have generated an exception, because it is a non read-only iterator
            TestHelper.assertFalse (true);            
        }
        try {
            it.remove ();
        } catch (Exception e) {
            // It should not have generated an exception, because it is a non read-only iterator
            TestHelper.assertFalse (true);            
        }

        // All changes are done on the snapshot, not on the original map
        // Map size should remain unchanged
        TestHelper.assertEquals (MAP_SIZE, bt.size ());
        // snapshot size was changed
        TestHelper.assertEquals (MAP_SIZE-1, snapshot.size ());            
    }
}