/*
 * This file is part of Nuts Framework.
 * Copyright(C) 2009-2012 Nuts Develop Team.
 *
 * Nuts Framework is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License any later version.
 * 
 * Nuts Framework is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Nuts Framework. If not, see <http://www.gnu.org/licenses/>.
 */
package nuts.core.lang.builder;


/**
 * <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
 *
 * <p> This class provides methods to build a good equals method for any
 * class. It follows rules laid out in
 * <a href="http://java.sun.com/docs/books/effective/index.html">Effective Java</a>
 * , by Joshua Bloch. In particular the rule for comparing <code>doubles</code>,
 * <code>floats</code>, and arrays can be tricky. Also, making sure that
 * <code>equals()</code> and <code>hashCode()</code> are consistent can be
 * difficult.</p>
 *
 * <p>Two Objects that compare as equals must generate the same hash code,
 * but two Objects with the same hash code do not have to be equal.</p>
 *
 * <p>All relevant fields should be included in the calculation of equals.
 * Derived fields may be ignored. In particular, any field used in
 * generating a hash code must be used in the equals method, and vice
 * versa.</p>
 *
 * <p>Typical use for the code is as follows:</p>
 * <pre>
 * public boolean equals(Object obj) {
 *   if (obj == null) { return false; }
 *   if (obj == this) { return true; }
 *   if (obj.getClass() != getClass()) {
 *     return false;
 *   }
 *   MyClass rhs = (MyClass) obj;
 *   return new EqualsBuilder()
 *                 .appendSuper(super.equals(obj))
 *                 .append(field1, rhs.field1)
 *                 .append(field2, rhs.field2)
 *                 .append(field3, rhs.field3)
 *                 .isEquals();
 *  }
 * </pre>
 */
public class EqualsBuilder implements Builder<Boolean> {
	/**
	 * If the fields tested are equals. The default value is <code>true</code>.
	 */
	private boolean isEquals = true;

	/**
	 * <p>
	 * Constructor for EqualsBuilder.
	 * </p>
	 * <p>
	 * Starts off assuming that equals is <code>true</code>.
	 * </p>
	 * 
	 * @see Object#equals(Object)
	 */
	public EqualsBuilder() {
		// do nothing for now.
	}

	// -------------------------------------------------------------------------

	/**
	 * <p>
	 * Adds the result of <code>super.equals()</code> to this builder.
	 * </p>
	 * 
	 * @param superEquals the result of calling <code>super.equals()</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder appendSuper(boolean superEquals) {
		if (isEquals == false) {
			return this;
		}
		isEquals = superEquals;
		return this;
	}

	// -------------------------------------------------------------------------

	/**
	 * <p>
	 * Test if two <code>Object</code>s are equal using their <code>equals</code> method.
	 * </p>
	 * 
	 * @param lhs the left hand object
	 * @param rhs the right hand object
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(Object lhs, Object rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		Class<?> lhsClass = lhs.getClass();
		if (!lhsClass.isArray()) {
			// The simple case, not an array, just test the element
			isEquals = lhs.equals(rhs);
		}
		else if (lhs.getClass() != rhs.getClass()) {
			// Here when we compare different dimensions, for example: a boolean[][] to a boolean[]
			this.setEquals(false);
		}
		// 'Switch' on type of array, to dispatch to the correct handler
		// This handles multi dimensional arrays of the same depth
		else if (lhs instanceof long[]) {
			append((long[])lhs, (long[])rhs);
		}
		else if (lhs instanceof int[]) {
			append((int[])lhs, (int[])rhs);
		}
		else if (lhs instanceof short[]) {
			append((short[])lhs, (short[])rhs);
		}
		else if (lhs instanceof char[]) {
			append((char[])lhs, (char[])rhs);
		}
		else if (lhs instanceof byte[]) {
			append((byte[])lhs, (byte[])rhs);
		}
		else if (lhs instanceof double[]) {
			append((double[])lhs, (double[])rhs);
		}
		else if (lhs instanceof float[]) {
			append((float[])lhs, (float[])rhs);
		}
		else if (lhs instanceof boolean[]) {
			append((boolean[])lhs, (boolean[])rhs);
		}
		else {
			// Not an array of primitives
			append((Object[])lhs, (Object[])rhs);
		}
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>long</code> s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>long</code>
	 * @param rhs the right hand <code>long</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(long lhs, long rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>int</code>s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>int</code>
	 * @param rhs the right hand <code>int</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(int lhs, int rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>short</code>s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>short</code>
	 * @param rhs the right hand <code>short</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(short lhs, short rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>char</code>s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>char</code>
	 * @param rhs the right hand <code>char</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(char lhs, char rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>byte</code>s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>byte</code>
	 * @param rhs the right hand <code>byte</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(byte lhs, byte rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Test if two <code>double</code>s are equal by testing that the pattern of bits returned by
	 * <code>doubleToLong</code> are equal.
	 * </p>
	 * <p>
	 * This handles NaNs, Infinities, and <code>-0.0</code>.
	 * </p>
	 * <p>
	 * It is compatible with the hash code generated by <code>HashCodeBuilder</code>.
	 * </p>
	 * 
	 * @param lhs the left hand <code>double</code>
	 * @param rhs the right hand <code>double</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(double lhs, double rhs) {
		if (isEquals == false) {
			return this;
		}
		return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
	}

	/**
	 * <p>
	 * Test if two <code>float</code>s are equal byt testing that the pattern of bits returned by
	 * doubleToLong are equal.
	 * </p>
	 * <p>
	 * This handles NaNs, Infinities, and <code>-0.0</code>.
	 * </p>
	 * <p>
	 * It is compatible with the hash code generated by <code>HashCodeBuilder</code>.
	 * </p>
	 * 
	 * @param lhs the left hand <code>float</code>
	 * @param rhs the right hand <code>float</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(float lhs, float rhs) {
		if (isEquals == false) {
			return this;
		}
		return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
	}

	/**
	 * <p>
	 * Test if two <code>booleans</code>s are equal.
	 * </p>
	 * 
	 * @param lhs the left hand <code>boolean</code>
	 * @param rhs the right hand <code>boolean</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(boolean lhs, boolean rhs) {
		if (isEquals == false) {
			return this;
		}
		isEquals = (lhs == rhs);
		return this;
	}

	/**
	 * <p>
	 * Performs a deep comparison of two <code>Object</code> arrays.
	 * </p>
	 * <p>
	 * This also will be called for the top level of multi-dimensional, ragged, and multi-typed
	 * arrays.
	 * </p>
	 * 
	 * @param lhs the left hand <code>Object[]</code>
	 * @param rhs the right hand <code>Object[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(Object[] lhs, Object[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>long</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(long, long)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>long[]</code>
	 * @param rhs the right hand <code>long[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(long[] lhs, long[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>int</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(int, int)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>int[]</code>
	 * @param rhs the right hand <code>int[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(int[] lhs, int[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>short</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(short, short)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>short[]</code>
	 * @param rhs the right hand <code>short[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(short[] lhs, short[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>char</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(char, char)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>char[]</code>
	 * @param rhs the right hand <code>char[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(char[] lhs, char[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>byte</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(byte, byte)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>byte[]</code>
	 * @param rhs the right hand <code>byte[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(byte[] lhs, byte[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>double</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(double, double)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>double[]</code>
	 * @param rhs the right hand <code>double[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(double[] lhs, double[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>float</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(float, float)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>float[]</code>
	 * @param rhs the right hand <code>float[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(float[] lhs, float[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Deep comparison of array of <code>boolean</code>. Length and all values are compared.
	 * </p>
	 * <p>
	 * The method {@link #append(boolean, boolean)} is used.
	 * </p>
	 * 
	 * @param lhs the left hand <code>boolean[]</code>
	 * @param rhs the right hand <code>boolean[]</code>
	 * @return EqualsBuilder - used to chain calls.
	 */
	public EqualsBuilder append(boolean[] lhs, boolean[] rhs) {
		if (isEquals == false) {
			return this;
		}
		if (lhs == rhs) {
			return this;
		}
		if (lhs == null || rhs == null) {
			this.setEquals(false);
			return this;
		}
		if (lhs.length != rhs.length) {
			this.setEquals(false);
			return this;
		}
		for (int i = 0; i < lhs.length && isEquals; ++i) {
			append(lhs[i], rhs[i]);
		}
		return this;
	}

	/**
	 * <p>
	 * Returns <code>true</code> if the fields that have been checked are all equal.
	 * </p>
	 * 
	 * @return boolean
	 */
	public boolean isEquals() {
		return this.isEquals;
	}

	/**
	 * <p>
	 * Returns <code>true</code> if the fields that have been checked are all equal.
	 * </p>
	 * 
	 * @return <code>true</code> if all of the fields that have been checked are equal,
	 *         <code>false</code> otherwise.
	 */
	public Boolean build() {
		return Boolean.valueOf(isEquals());
	}

	/**
	 * Sets the <code>isEquals</code> value.
	 * 
	 * @param isEquals The value to set.
	 */
	protected void setEquals(boolean isEquals) {
		this.isEquals = isEquals;
	}

	/**
	 * Reset the EqualsBuilder so you can use the same object again
	 */
	public void reset() {
		this.isEquals = true;
	}
}
