/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 bingo.lang.builder;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import bingo.lang.Classes;

/**
 * <p>
 * Assists in implementing {@link Object#toString()} methods using reflection.
 * </p>
 * <p>
 * This class uses reflection to determine the fields to append. Because these fields are usually private, the class
 * uses {@link java.lang.reflect.AccessibleObject#setAccessible(java.lang.reflect.AccessibleObject[], boolean)} to
 * change the visibility of the fields. This will fail under a security manager, unless the appropriate permissions are
 * set up correctly.
 * </p>
 * <p>
 * Using reflection to access (private) fields circumvents any synchronization protection guarding access to these
 * fields. If a toString method cannot safely read a field, you should exclude it from the toString method, or use
 * synchronization consistent with the class' lock management around the invocation of the method. Take special care to
 * exclude non-thread-safe collection classes, because these classes may throw ConcurrentModificationException if
 * modified while the toString method is executing.
 * </p>
 * <p>
 * A typical invocation for this method would look like:
 * </p>
 * 
 * <pre>
 * public String toString() {
 * 	return ReflectionToStringBuilder.toString(this);
 * }
 * </pre>
 * <p>
 * You can also use the builder to debug 3rd party objects:
 * </p>
 * 
 * <pre>
 * System.out.println(&quot;An object: &quot; + ReflectionToStringBuilder.toString(anObject));
 * </pre>
 * <p>
 * A subclass can control field output by overriding the methods:
 * <ul>
 * <li>{@link #accept(java.lang.reflect.Field)}</li>
 * <li>{@link #getValue(java.lang.reflect.Field)}</li>
 * </ul>
 * </p>
 * <p>
 * For example, this method does <i>not</i> include the <code>password</code> field in the returned <code>String</code>:
 * </p>
 * 
 * <pre>
 * public String toString() {
 * 	return (new ReflectionToStringBuilder(this) {
 * 		protected boolean accept(Field f) {
 * 			return super.accept(f) &amp;&amp; !f.getName().equals(&quot;password&quot;);
 * 		}
 * 	}).toString();
 * }
 * </pre>
 * <p>
 * The exact format of the <code>toString</code> is determined by the {@link ToStringStyle} passed into the constructor.
 * </p>
 * 
 * @since 2.0
 * @version $Id: ReflectionToStringBuilder.java 1200177 2011-11-10 06:14:33Z ggregory $
 */
public class ReflectionToStringBuilder extends ToStringBuilder {

	/**
	 * <p>
	 * Builds a <code>toString</code> value using the default <code>ToStringStyle</code> through reflection.
	 * </p>
	 * 
	 * <p>
	 * It uses <code>AccessibleObject.setAccessible</code> to gain access to private fields. This means that it will
	 * throw a security exception if run under a security manager, if the permissions are not set up correctly. It is
	 * also not as efficient as testing explicitly.
	 * </p>
	 * 
	 * <p>
	 * Transient members will be not be included, as they are likely derived. Static fields will not be included.
	 * Superclass fields will be appended.
	 * </p>
	 * 
	 * @param object the Object to be output
	 * @return the String result
	 * @throws IllegalArgumentException if the Object is <code>null</code>
	 */
	public static String toString(Object object) {
		return toString(object, null, false, false, null);
	}

	/**
	 * <p>
	 * Builds a <code>toString</code> value through reflection.
	 * </p>
	 * 
	 * <p>
	 * It uses <code>AccessibleObject.setAccessible</code> to gain access to private fields. This means that it will
	 * throw a security exception if run under a security manager, if the permissions are not set up correctly. It is
	 * also not as efficient as testing explicitly.
	 * </p>
	 * 
	 * <p>
	 * Transient members will be not be included, as they are likely derived. Static fields will not be included.
	 * Superclass fields will be appended.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default <code>ToStringStyle</code> is used.
	 * </p>
	 * 
	 * @param object the Object to be output
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @return the String result
	 * @throws IllegalArgumentException if the Object or <code>ToStringStyle</code> is <code>null</code>
	 */
	public static String toString(Object object, ToStringStyle style) {
		return toString(object, style, false, false, null);
	}

	/**
	 * <p>
	 * Builds a <code>toString</code> value through reflection.
	 * </p>
	 * 
	 * <p>
	 * It uses <code>AccessibleObject.setAccessible</code> to gain access to private fields. This means that it will
	 * throw a security exception if run under a security manager, if the permissions are not set up correctly. It is
	 * also not as efficient as testing explicitly.
	 * </p>
	 * 
	 * <p>
	 * If the <code>outputTransients</code> is <code>true</code>, transient members will be output, otherwise they are
	 * ignored, as they are likely derived fields, and not part of the value of the Object.
	 * </p>
	 * 
	 * <p>
	 * Static fields will not be included. Superclass fields will be appended.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default <code>ToStringStyle</code> is used.
	 * </p>
	 * 
	 * @param object the Object to be output
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @param outputTransients whether to include transient fields
	 * @return the String result
	 * @throws IllegalArgumentException if the Object is <code>null</code>
	 */
	public static String toString(Object object, ToStringStyle style, boolean outputTransients) {
		return toString(object, style, outputTransients, false, null);
	}

	/**
	 * <p>
	 * Builds a <code>toString</code> value through reflection.
	 * </p>
	 * 
	 * <p>
	 * It uses <code>AccessibleObject.setAccessible</code> to gain access to private fields. This means that it will
	 * throw a security exception if run under a security manager, if the permissions are not set up correctly. It is
	 * also not as efficient as testing explicitly.
	 * </p>
	 * 
	 * <p>
	 * If the <code>outputTransients</code> is <code>true</code>, transient fields will be output, otherwise they are
	 * ignored, as they are likely derived fields, and not part of the value of the Object.
	 * </p>
	 * 
	 * <p>
	 * If the <code>outputStatics</code> is <code>true</code>, static fields will be output, otherwise they are ignored.
	 * </p>
	 * 
	 * <p>
	 * Static fields will not be included. Superclass fields will be appended.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default <code>ToStringStyle</code> is used.
	 * </p>
	 * 
	 * @param object the Object to be output
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @param outputTransients whether to include transient fields
	 * @param outputStatics whether to include transient fields
	 * @return the String result
	 * @throws IllegalArgumentException if the Object is <code>null</code>
	 * @since 2.1
	 */
	public static String toString(Object object, ToStringStyle style, boolean outputTransients, boolean outputStatics) {
		return toString(object, style, outputTransients, outputStatics, null);
	}

	/**
	 * <p>
	 * Builds a <code>toString</code> value through reflection.
	 * </p>
	 * 
	 * <p>
	 * It uses <code>AccessibleObject.setAccessible</code> to gain access to private fields. This means that it will
	 * throw a security exception if run under a security manager, if the permissions are not set up correctly. It is
	 * also not as efficient as testing explicitly.
	 * </p>
	 * 
	 * <p>
	 * If the <code>outputTransients</code> is <code>true</code>, transient fields will be output, otherwise they are
	 * ignored, as they are likely derived fields, and not part of the value of the Object.
	 * </p>
	 * 
	 * <p>
	 * If the <code>outputStatics</code> is <code>true</code>, static fields will be output, otherwise they are ignored.
	 * </p>
	 * 
	 * <p>
	 * Superclass fields will be appended up to and including the specified superclass. A null superclass is treated as
	 * <code>java.lang.Object</code>.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default <code>ToStringStyle</code> is used.
	 * </p>
	 * 
	 * @param <T> the type of the object
	 * @param object the Object to be output
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @param outputTransients whether to include transient fields
	 * @param outputStatics whether to include static fields
	 * @param reflectUpToClass the superclass to reflect up to (inclusive), may be <code>null</code>
	 * @return the String result
	 * @throws IllegalArgumentException if the Object is <code>null</code>
	 * @since 2.1
	 */
	public static <T> String toString(T object, ToStringStyle style, boolean outputTransients, boolean outputStatics,
	        Class<? super T> reflectUpToClass) {
		return new ReflectionToStringBuilder(object, style, null, reflectUpToClass, outputTransients, outputStatics).toString();
	}

	/**
	 * Builds a String for a toString method excluding the given field names.
	 * 
	 * @param object The object to "toString".
	 * @param excludeFieldNames The field names to exclude. Null excludes nothing.
	 * @return The toString value.
	 */
	public static String toStringExclude(Object object, Collection<String> excludeFieldNames) {
		return toStringExclude(object, toNoNullStringArray(excludeFieldNames));
	}

	/**
	 * Converts the given Collection into an array of Strings. The returned array does not contain <code>null</code>
	 * entries. Note that {@link Arrays#sort(Object[])} will throw an {@link NullPointerException} if an array element
	 * is <code>null</code>.
	 * 
	 * @param collection The collection to convert
	 * @return A new array of Strings.
	 */
	static String[] toNoNullStringArray(Collection<String> collection) {
		if (collection == null) {
			return bingo.lang.Arrays.EMPTY_STRING_ARRAY;
		}
		return toNoNullStringArray(collection.toArray());
	}

	/**
	 * Returns a new array of Strings without null elements. Internal method used to normalize exclude lists (arrays and
	 * collections). Note that {@link Arrays#sort(Object[])} will throw an {@link NullPointerException} if an array
	 * element is <code>null</code>.
	 * 
	 * @param array The array to check
	 * @return The given array or a new array without null.
	 */
	static String[] toNoNullStringArray(Object[] array) {
		List<String> list = new ArrayList<String>(array.length);
		for (Object e : array) {
			if (e != null) {
				list.add(e.toString());
			}
		}
		return list.toArray(bingo.lang.Arrays.EMPTY_STRING_ARRAY);
	}

	/**
	 * Builds a String for a toString method excluding the given field names.
	 * 
	 * @param object The object to "toString".
	 * @param excludeFieldNames The field names to exclude
	 * @return The toString value.
	 */
	public static String toStringExclude(Object object, String... excludeFieldNames) {
		return new ReflectionToStringBuilder(object).setExcludeFieldNames(excludeFieldNames).toString();
	}

	/**
	 * Whether or not to append static fields.
	 */
	private boolean	   appendStatics	= false;

	/**
	 * Whether or not to append transient fields.
	 */
	private boolean	   appendTransients	= false;

	/**
	 * Which field names to exclude from output. Intended for fields like <code>"password"</code>.
	 * 
	 * @since 3.0 this is protected instead of private
	 */
	protected String[]	excludeFieldNames;

	/**
	 * The last super class to stop appending fields for.
	 */
	private Class<?>	upToClass	    = null;

	/**
	 * <p>
	 * Constructor.
	 * </p>
	 * 
	 * <p>
	 * This constructor outputs using the default style set with <code>setDefaultStyle</code>.
	 * </p>
	 * 
	 * @param object the Object to build a <code>toString</code> for, must not be <code>null</code>
	 * @throws IllegalArgumentException if the Object passed in is <code>null</code>
	 */
	public ReflectionToStringBuilder(Object object) {
		super(object);
	}

	/**
	 * <p>
	 * Constructor.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default style is used.
	 * </p>
	 * 
	 * @param object the Object to build a <code>toString</code> for, must not be <code>null</code>
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @throws IllegalArgumentException if the Object passed in is <code>null</code>
	 */
	public ReflectionToStringBuilder(Object object, ToStringStyle style) {
		super(object, style);
	}

	/**
	 * <p>
	 * Constructor.
	 * </p>
	 * 
	 * <p>
	 * If the style is <code>null</code>, the default style is used.
	 * </p>
	 * 
	 * <p>
	 * If the buffer is <code>null</code>, a new one is created.
	 * </p>
	 * 
	 * @param object the Object to build a <code>toString</code> for
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @param buffer the <code>StringBuffer</code> to populate, may be <code>null</code>
	 * @throws IllegalArgumentException if the Object passed in is <code>null</code>
	 */
	public ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer) {
		super(object, style, buffer);
	}

	/**
	 * Constructor.
	 * 
	 * @param <T> the type of the object
	 * @param object the Object to build a <code>toString</code> for
	 * @param style the style of the <code>toString</code> to create, may be <code>null</code>
	 * @param buffer the <code>StringBuffer</code> to populate, may be <code>null</code>
	 * @param reflectUpToClass the superclass to reflect up to (inclusive), may be <code>null</code>
	 * @param outputTransients whether to include transient fields
	 * @param outputStatics whether to include static fields
	 * @since 2.1
	 */
	public <T> ReflectionToStringBuilder(T object, ToStringStyle style, StringBuffer buffer, Class<? super T> reflectUpToClass,
	        boolean outputTransients, boolean outputStatics) {
		super(object, style, buffer);
		this.setUpToClass(reflectUpToClass);
		this.setAppendTransients(outputTransients);
		this.setAppendStatics(outputStatics);
	}

	/**
	 * Returns whether or not to append the given <code>Field</code>.
	 * <ul>
	 * <li>Transient fields are appended only if {@link #isAppendTransients()} returns <code>true</code>.
	 * <li>Static fields are appended only if {@link #isAppendStatics()} returns <code>true</code>.
	 * <li>Inner class fields are not appened.</li>
	 * </ul>
	 * 
	 * @param field The Field to test.
	 * @return Whether or not to append the given <code>Field</code>.
	 */
	protected boolean accept(Field field) {
		if (field.getName().indexOf(Classes.INNER_CLASS_SEPARATOR_CHAR) != -1) {
			// Reject field from inner class.
			return false;
		}
		if (Modifier.isTransient(field.getModifiers()) && !this.isAppendTransients()) {
			// Reject transient fields.
			return false;
		}
		if (Modifier.isStatic(field.getModifiers()) && !this.isAppendStatics()) {
			// Reject static fields.
			return false;
		}
		if (this.excludeFieldNames != null && Arrays.binarySearch(this.excludeFieldNames, field.getName()) >= 0) {
			// Reject fields from the getExcludeFieldNames list.
			return false;
		}
		return true;
	}

	/**
	 * <p>
	 * Appends the fields and values defined by the given object of the given Class.
	 * </p>
	 * 
	 * <p>
	 * If a cycle is detected as an object is &quot;toString()'ed&quot;, such an object is rendered as if
	 * <code>Object.toString()</code> had been called and not implemented by the object.
	 * </p>
	 * 
	 * @param clazz The class of object parameter
	 */
	protected void appendFieldsIn(Class<?> clazz) {
		if (clazz.isArray()) {
			this.reflectionAppendArray(this.getObject());
			return;
		}
		Field[] fields = clazz.getDeclaredFields();
		AccessibleObject.setAccessible(fields, true);
		for (Field field : fields) {
			String fieldName = field.getName();
			if (this.accept(field)) {
				try {
					// Warning: Field.get(Object) creates wrappers objects
					// for primitive types.
					Object fieldValue = this.getValue(field);
					this.append(fieldName, fieldValue);
				} catch (IllegalAccessException ex) {
					//this can't happen. Would get a Security exception
					// instead
					//throw a runtime exception in case the impossible
					// happens.
					throw new InternalError("Unexpected IllegalAccessException: " + ex.getMessage());
				}
			}
		}
	}

	/**
	 * @return Returns the excludeFieldNames.
	 */
	public String[] getExcludeFieldNames() {
		return this.excludeFieldNames.clone();
	}

	/**
	 * <p>
	 * Gets the last super class to stop appending fields for.
	 * </p>
	 * 
	 * @return The last super class to stop appending fields for.
	 */
	public Class<?> getUpToClass() {
		return this.upToClass;
	}

	/**
	 * <p>
	 * Calls <code>java.lang.reflect.Field.get(Object)</code>.
	 * </p>
	 * 
	 * @param field The Field to query.
	 * @return The Object from the given Field.
	 * 
	 * @throws IllegalArgumentException see {@link java.lang.reflect.Field#get(Object)}
	 * @throws IllegalAccessException see {@link java.lang.reflect.Field#get(Object)}
	 * 
	 * @see java.lang.reflect.Field#get(Object)
	 */
	protected Object getValue(Field field) throws IllegalArgumentException, IllegalAccessException {
		return field.get(this.getObject());
	}

	/**
	 * <p>
	 * Gets whether or not to append static fields.
	 * </p>
	 * 
	 * @return Whether or not to append static fields.
	 * @since 2.1
	 */
	public boolean isAppendStatics() {
		return this.appendStatics;
	}

	/**
	 * <p>
	 * Gets whether or not to append transient fields.
	 * </p>
	 * 
	 * @return Whether or not to append transient fields.
	 */
	public boolean isAppendTransients() {
		return this.appendTransients;
	}

	/**
	 * <p>
	 * Append to the <code>toString</code> an <code>Object</code> array.
	 * </p>
	 * 
	 * @param array the array to add to the <code>toString</code>
	 * @return this
	 */
	public ReflectionToStringBuilder reflectionAppendArray(Object array) {
		this.getStyle().reflectionAppendArrayDetail(this.getStringBuffer(), null, array);
		return this;
	}

	/**
	 * <p>
	 * Sets whether or not to append static fields.
	 * </p>
	 * 
	 * @param appendStatics Whether or not to append static fields.
	 * @since 2.1
	 */
	public void setAppendStatics(boolean appendStatics) {
		this.appendStatics = appendStatics;
	}

	/**
	 * <p>
	 * Sets whether or not to append transient fields.
	 * </p>
	 * 
	 * @param appendTransients Whether or not to append transient fields.
	 */
	public void setAppendTransients(boolean appendTransients) {
		this.appendTransients = appendTransients;
	}

	/**
	 * Sets the field names to exclude.
	 * 
	 * @param excludeFieldNamesParam The excludeFieldNames to excluding from toString or <code>null</code>.
	 * @return <code>this</code>
	 */
	public ReflectionToStringBuilder setExcludeFieldNames(String... excludeFieldNamesParam) {
		if (excludeFieldNamesParam == null) {
			this.excludeFieldNames = null;
		} else {
			//clone and remove nulls
			this.excludeFieldNames = toNoNullStringArray(excludeFieldNamesParam);
			Arrays.sort(this.excludeFieldNames);
		}
		return this;
	}

	/**
	 * <p>
	 * Sets the last super class to stop appending fields for.
	 * </p>
	 * 
	 * @param clazz The last super class to stop appending fields for.
	 */
	public void setUpToClass(Class<?> clazz) {
		if (clazz != null) {
			Object object = getObject();
			if (object != null && clazz.isInstance(object) == false) {
				throw new IllegalArgumentException("Specified class is not a superclass of the object");
			}
		}
		this.upToClass = clazz;
	}

	/**
	 * <p>
	 * Gets the String built by this builder.
	 * </p>
	 * 
	 * @return the built string
	 */
	@Override
	public String toString() {
		if (this.getObject() == null) {
			return this.getStyle().getNullText();
		}
		Class<?> clazz = this.getObject().getClass();
		this.appendFieldsIn(clazz);
		while (clazz.getSuperclass() != null && clazz != this.getUpToClass()) {
			clazz = clazz.getSuperclass();
			this.appendFieldsIn(clazz);
		}
		return super.toString();
	}

}
