package it.unimi.dsi.fastutil.ints;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import it.unimi.dsi.fastutil.Hash;

import java.io.IOException;
import java.io.Serializable;
import java.util.HashSet;

import org.junit.Ignore;
import org.junit.Test;

@SuppressWarnings("rawtypes")
/** Not a particularly good test, but it will check that we use everywhere the same hashing strategy. */
public class IntOpenCustomHashSetTest {

	@Test
	public void testGetNullKey() {
		final IntOpenCustomHashSet s = new IntOpenCustomHashSet( new IntHash.Strategy() {

			@Override
			public int hashCode( int o ) {
				return o % 10;
			}

			@Override
			public boolean equals( int a, int b ) {
				return ( a - b ) % 10 == 0;
			}
		} );

		s.add( 10 );
		assertTrue( s.contains( 0 ) );
		assertEquals( 10, s.iterator().nextInt() );
	}


	@Test
	public void testCustomUsed() {
		IntOpenCustomHashSet set = new IntOpenCustomHashSet( new IntHash.Strategy() {
			@Override
			public int hashCode( int e ) {
				return Integer.hashCode( e & 0xFFFF );
			}

			@Override
			public boolean equals( int a, int b ) {
				return ( a & 0xFFFF ) == ( b & 0xFFFF );
			}
		} );

		set.add( 1 << 16 | 1 );
		set.add( 1 );
		assertEquals( 1, set.size() );
		assertTrue( set.contains( 1 ) );
		assertTrue( set.contains( 1 << 16 | 1 ) );
	}

	private static final class Strategy implements IntHash.Strategy, Serializable {
		private static final long serialVersionUID = 1L;

		@Override
		public int hashCode( int e ) {
			return Integer.reverse( e );
		}

		@Override
		public boolean equals( int a, int b ) {
			return a == b;
		}
	}

	private final static Strategy strategy = new Strategy();

	private static java.util.Random r = new java.util.Random( 0 );

	private static int genKey() {
		return r.nextInt( 10 );
	}

	@SuppressWarnings("boxing")
	private static void checkTable( IntOpenCustomHashSet s ) {
		final int[] key = s.key;
		assert ( s.n & -s.n ) == s.n : "Table length is not a power of two: " + s.n;
		assert s.n == s.key.length - 1;
		int n = s.n;
		while ( n-- != 0 )
			if ( key[ n ] != 0 && !s.contains( key[ n ] ) ) throw new AssertionError( "Hash table has key " + key[ n ]
					+ " marked as occupied, but the key does not belong to the table" );

		if ( s.containsNull && !s.contains( 0 ) ) throw new AssertionError( "Hash table should contain zero by internal state, but it doesn't when queried" );
		if ( !s.containsNull && s.contains( 0 ) ) throw new AssertionError( "Hash table should not contain zero by internal state, but it does when queried" );

		java.util.HashSet<Integer> t = new java.util.HashSet<Integer>();
		for ( int i = s.size(); i-- != 0; )
			if ( key[ i ] != 0 && !t.add( key[ i ] ) ) throw new AssertionError( "Key " + key[ i ] + " appears twice" );

	}

	private static void printProbes( IntOpenCustomHashSet m ) {
		long totProbes = 0;
		double totSquareProbes = 0;
		int maxProbes = 0;
		final int[] key = m.key;
		final double f = (double)m.size / m.n;
		for ( int i = 0, c = 0; i < m.n; i++ ) {
			if ( key[ i ] != 0 ) c++;
			else {
				if ( c != 0 ) {
					final long p = ( c + 1 ) * ( c + 2 ) / 2;
					totProbes += p;
					totSquareProbes += (double)p * p;
				}
				maxProbes = Math.max( c, maxProbes );
				c = 0;
				totProbes++;
				totSquareProbes++;
			}
		}

		final double expected = (double)totProbes / m.n;
		System.err.println( "Expected probes: " + (
				3 * Math.sqrt( 3 ) * ( f / ( ( 1 - f ) * ( 1 - f ) ) ) + 4 / ( 9 * f ) - 1
				) + "; actual: " + expected + "; stddev: " + Math.sqrt( totSquareProbes / m.n - expected * expected ) + "; max probes: " + maxProbes );
	}

	@SuppressWarnings({ "boxing" })
	private static void test( int n, float f ) throws IOException, ClassNotFoundException {
		int c;
		final Integer key[] = new Integer[ (int)Math.ceil( n * f ) ];
		HashSet<Integer> t = new HashSet<Integer>();
		/* First of all, we fill t with random data. */

		for ( int i = 0; i < key.length; i++ )
			t.add( ( key[ i ] = new Integer( genKey() ) ) );

		IntOpenCustomHashSet m = new IntOpenCustomHashSet( Hash.DEFAULT_INITIAL_SIZE, f, strategy );


		/* Now we add to m the same data */

		m.addAll( t );
		checkTable( m );

		assertTrue( "Error: !m.equals(t) after insertion", m.equals( t ) );
		assertTrue( "Error: !t.equals(m) after insertion", t.equals( m ) );
		printProbes( m );

		/* Now we check that m actually holds that data. */

		for ( java.util.Iterator i = t.iterator(); i.hasNext(); ) {
			Object e = i.next();
			assertTrue( "Error: m and t differ on a key (" + e + ") after insertion (iterating on t)", m.contains( e ) );
		}

		/* Now we check that m actually holds that data, but iterating on m. */

		c = 0;
		for ( java.util.Iterator i = m.iterator(); i.hasNext(); ) {
			Object e = i.next();
			c++;
			assertTrue( "Error: m and t differ on a key (" + e + ") after insertion (iterating on m)", t.contains( e ) );
		}

		assertEquals( "Error: m has only " + c + " keys instead of " + t.size() + " after insertion (iterating on m)", c, t.size() );
		/* Now we check that inquiries about random data give the same answer in m and t. For m we use the polymorphic method. */

		for ( int i = 0; i < n; i++ ) {
			int T = genKey();
			assertEquals( "Error: divergence in keys between t and m (polymorphic method)", m.contains( T ), t.contains( ( Integer.valueOf( T ) ) ) );
		}

		/* Again, we check that inquiries about random data give the same answer in m and t, but for m we use the standard method. */

		for ( int i = 0; i < n; i++ ) {
			int T = genKey();
			assertFalse( "Error: divergence between t and m (standard method)", m.contains( ( Integer.valueOf( T ) ) ) != t.contains( ( Integer.valueOf( T ) ) ) );
		}


		/* Now we put and remove random data in m and t, checking that the result is the same. */

		for ( int i = 0; i < 20 * n; i++ ) {
			int T = genKey();
			assertFalse( "Error: divergence in add() between t and m", m.add( ( Integer.valueOf( T ) ) ) != t.add( ( Integer.valueOf( T ) ) ) );
			T = genKey();
			assertFalse( "Error: divergence in remove() between t and m", m.remove( ( Integer.valueOf( T ) ) ) != t.remove( ( Integer.valueOf( T ) ) ) );
		}

		checkTable( m );
		assertTrue( "Error: !m.equals(t) after removal", m.equals( t ) );
		assertTrue( "Error: !t.equals(m) after removal", t.equals( m ) );
		/* Now we check that m actually holds that data. */

		for ( java.util.Iterator i = t.iterator(); i.hasNext(); ) {
			Object e = i.next();
			assertFalse( "Error: m and t differ on a key (" + e + ") after removal (iterating on t)", !m.contains( e ) );
		}

		/* Now we check that m actually holds that data, but iterating on m. */

		for ( java.util.Iterator i = m.iterator(); i.hasNext(); ) {
			Object e = i.next();
			assertFalse( "Error: m and t differ on a key (" + e + ") after removal (iterating on m)", !t.contains( e ) );
		}

		/* Now we make m into an array, make it again a set and check it is OK. */
		int a[] = m.toIntArray();

		assertTrue( "Error: toArray() output (or array-based constructor) is not OK", new IntOpenHashSet( a ).equals( m ) );

		/* Now we check cloning. */

		assertTrue( "Error: m does not equal m.clone()", m.equals( m.clone() ) );
		assertTrue( "Error: m.clone() does not equal m", m.clone().equals( m ) );

		int h = m.hashCode();

		/* Now we save and read m. */

		java.io.File ff = new java.io.File( "it.unimi.dsi.fastutil.test" );
		java.io.OutputStream os = new java.io.FileOutputStream( ff );
		java.io.ObjectOutputStream oos = new java.io.ObjectOutputStream( os );

		oos.writeObject( m );
		oos.close();

		java.io.InputStream is = new java.io.FileInputStream( ff );
		java.io.ObjectInputStream ois = new java.io.ObjectInputStream( is );

		m = (IntOpenCustomHashSet)ois.readObject();
		ois.close();
		ff.delete();

		assertEquals( "Error: hashCode() changed after save/read", h, m.hashCode() );

		printProbes( m );
		checkTable( m );

		/* Now we check that m actually holds that data, but iterating on m. */

		for ( java.util.Iterator i = m.iterator(); i.hasNext(); ) {
			Object e = i.next();
			assertFalse( "Error: m and t differ on a key (" + e + ") after save/read", !t.contains( e ) );
		}


		/* Now we put and remove random data in m and t, checking that the result is the same. */

		for ( int i = 0; i < 20 * n; i++ ) {
			int T = genKey();
			assertFalse( "Error: divergence in add() between t and m after save/read", m.add( ( Integer.valueOf( T ) ) ) != t.add( ( Integer.valueOf( T ) ) ) );
			T = genKey();
			assertFalse( "Error: divergence in remove() between t and m after save/read", m.remove( ( Integer.valueOf( T ) ) ) != t.remove( ( Integer.valueOf( T ) ) ) );
		}

		assertTrue( "Error: !m.equals(t) after post-save/read removal", m.equals( t ) );
		assertTrue( "Error: !t.equals(m) after post-save/read removal", t.equals( m ) );

		/* Now we take out of m everything, and check that it is empty. */

		for ( java.util.Iterator i = m.iterator(); i.hasNext(); ) {
			i.next();
			i.remove();
		}

		assertFalse( "Error: m is not empty (as it should be)", !m.isEmpty() );


		m = new IntOpenCustomHashSet( n, f, strategy );
		t.clear();

		/* Now we torture-test the hash table. This part is implemented only for integers and longs. */

		for ( int i = n; i-- != 0; )
			m.add( i );
		t.addAll( m );
		printProbes( m );
		checkTable( m );

		for ( int i = n; i-- != 0; )
			assertEquals( "Error: m and t differ on a key during torture-test insertion.", m.add( i ), t.add( ( Integer.valueOf( i ) ) ) );

		assertTrue( "Error: !m.equals(t) after torture-test insertion", m.equals( t ) );
		assertTrue( "Error: !t.equals(m) after torture-test insertion", t.equals( m ) );

		for ( int i = n; i-- != 0; )
			assertEquals( "Error: m and t differ on a key during torture-test insertion.", m.remove( i ), t.remove( ( Integer.valueOf( i ) ) ) );

		assertTrue( "Error: !m.equals(t) after torture-test removal", m.equals( t ) );
		assertTrue( "Error: !t.equals(m) after torture-test removal", t.equals( m ) );
		assertTrue( "Error: !m.equals(m.clone()) after torture-test removal", m.equals( m.clone() ) );
		assertTrue( "Error: !m.clone().equals(m) after torture-test removal", m.clone().equals( m ) );

		return;
	}


	@Test
	public void test1() throws IOException, ClassNotFoundException {
		test( 1, Hash.DEFAULT_LOAD_FACTOR );
		test( 1, Hash.FAST_LOAD_FACTOR );
		test( 1, Hash.VERY_FAST_LOAD_FACTOR );
	}

	@Test
	public void test10() throws IOException, ClassNotFoundException {
		test( 10, Hash.DEFAULT_LOAD_FACTOR );
		test( 10, Hash.FAST_LOAD_FACTOR );
		test( 10, Hash.VERY_FAST_LOAD_FACTOR );
	}

	@Test
	public void test100() throws IOException, ClassNotFoundException {
		test( 100, Hash.DEFAULT_LOAD_FACTOR );
		test( 100, Hash.FAST_LOAD_FACTOR );
		test( 100, Hash.VERY_FAST_LOAD_FACTOR );
	}

	@Ignore("Too long")
	@Test
	public void test1000() throws IOException, ClassNotFoundException {
		test( 1000, Hash.DEFAULT_LOAD_FACTOR );
		test( 1000, Hash.FAST_LOAD_FACTOR );
		test( 1000, Hash.VERY_FAST_LOAD_FACTOR );
	}
}
