/*
    * 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 org.apache.shiro.util;
  
  import java.util.Collection;
  import java.util.Map;
  
  /**
   * Assertion utility class that assists in validating arguments.
   * Useful for identifying programmer errors early and clearly at runtime.
   * Usage also reduces a program's
   * <a href="http://en.wikipedia.org/wiki/Cyclomatic_complexity">cyclomatic complexity</a>.
   *
   * <p>For example, if the contract of a public method states it does not
   * allow <code>null</code> arguments, Assert can be used to validate that
   * contract. Doing this clearly indicates a contract violation when it
   * occurs and protects the class's invariants.
   *
   * <p>Typically used to validate method arguments rather than configuration
   * properties, to check for cases that are usually programmer errors rather than
   * configuration errors. In contrast to config initialization code, there is
   * usally no point in falling back to defaults in such methods.
   *
   * <p>This class is similar to JUnit's assertion library. If an argument value is
   * deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
   * For example:
   *
   * <pre class="code">
   * Assert.notNull(clazz, "The class must not be null");
   * Assert.isTrue(i > 0, "The value must be greater than zero");</pre>
   *
   * Mainly for internal use within the framework; consider Jakarta's Commons Lang
   * >= 2.0 for a more comprehensive suite of assertion utilities.
   * <p/>
   * <em>Gratefully borrowed from the Spring Framework, also Apache 2.0 licensed</em>
   *
   * @author Keith Donald
   * @author Juergen Hoeller
   * @author Colin Sampaleanu
   * @author Rob Harrop
   * @since 1.3
   */
  public abstract class Assert {
  
      /**
       * Assert a boolean expression, throwing <code>IllegalArgumentException</code>
       * if the test result is <code>false</code>.
       * <pre class="code">Assert.isTrue(i &gt; 0, "The value must be greater than zero");</pre>
       * @param expression a boolean expression
       * @param message the exception message to use if the assertion fails
       * @throws IllegalArgumentException if expression is <code>false</code>
       */
      public static void isTrue(boolean expression, String message) {
          if (!expression) {
              throw new IllegalArgumentException(message);
          }
      }
  
      /**
       * Assert a boolean expression, throwing <code>IllegalArgumentException</code>
       * if the test result is <code>false</code>.
       * <pre class="code">Assert.isTrue(i &gt; 0);</pre>
       * @param expression a boolean expression
       * @throws IllegalArgumentException if expression is <code>false</code>
       */
      public static void isTrue(boolean expression) {
          isTrue(expression, "[Assertion failed] - this expression must be true");
      }
  
      /**
       * Assert that an object is <code>null</code> .
       * <pre class="code">Assert.isNull(value, "The value must be null");</pre>
       * @param object the object to check
       * @param message the exception message to use if the assertion fails
       * @throws IllegalArgumentException if the object is not <code>null</code>
       */
      public static void isNull(Object object, String message) {
          if (object != null) {
              throw new IllegalArgumentException(message);
          }
      }
  
      /**
      * Assert that an object is <code>null</code> .
      * <pre class="code">Assert.isNull(value);</pre>
      * @param object the object to check
      * @throws IllegalArgumentException if the object is not <code>null</code>
      */
     public static void isNull(Object object) {
         isNull(object, "[Assertion failed] - the object argument must be null");
     }
 
     /**
      * Assert that an object is not <code>null</code> .
      * <pre class="code">Assert.notNull(clazz, "The class must not be null");</pre>
      * @param object the object to check
      * @param message the exception message to use if the assertion fails
      * @throws IllegalArgumentException if the object is <code>null</code>
      */
     public static void notNull(Object object, String message) {
         if (object == null) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that an object is not <code>null</code> .
      * <pre class="code">Assert.notNull(clazz);</pre>
      * @param object the object to check
      * @throws IllegalArgumentException if the object is <code>null</code>
      */
     public static void notNull(Object object) {
         notNull(object, "[Assertion failed] - this argument is required; it must not be null");
     }
 
     /**
      * Assert that the given String is not empty; that is,
      * it must not be <code>null</code> and not the empty String.
      * <pre class="code">Assert.hasLength(name, "Name must not be empty");</pre>
      * @param text the String to check
      * @param message the exception message to use if the assertion fails
      * @see StringUtils#hasLength
      */
     public static void hasLength(String text, String message) {
         if (!StringUtils.hasLength(text)) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that the given String is not empty; that is,
      * it must not be <code>null</code> and not the empty String.
      * <pre class="code">Assert.hasLength(name);</pre>
      * @param text the String to check
      * @see StringUtils#hasLength
      */
     public static void hasLength(String text) {
         hasLength(text,
                 "[Assertion failed] - this String argument must have length; it must not be null or empty");
     }
 
     /**
      * Assert that the given String has valid text content; that is, it must not
      * be <code>null</code> and must contain at least one non-whitespace character.
      * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
      * @param text the String to check
      * @param message the exception message to use if the assertion fails
      * @see StringUtils#hasText
      */
     public static void hasText(String text, String message) {
         if (!StringUtils.hasText(text)) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that the given String has valid text content; that is, it must not
      * be <code>null</code> and must contain at least one non-whitespace character.
      * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
      * @param text the String to check
      * @see StringUtils#hasText
      */
     public static void hasText(String text) {
         hasText(text,
                 "[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
     }
 
     /**
      * Assert that the given text does not contain the given substring.
      * <pre class="code">Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");</pre>
      * @param textToSearch the text to search
      * @param substring the substring to find within the text
      * @param message the exception message to use if the assertion fails
      */
     public static void doesNotContain(String textToSearch, String substring, String message) {
         if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
                 textToSearch.indexOf(substring) != -1) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that the given text does not contain the given substring.
      * <pre class="code">Assert.doesNotContain(name, "rod");</pre>
      * @param textToSearch the text to search
      * @param substring the substring to find within the text
      */
     public static void doesNotContain(String textToSearch, String substring) {
         doesNotContain(textToSearch, substring,
                 "[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
     }
 
 
     /**
      * Assert that an array has elements; that is, it must not be
      * <code>null</code> and must have at least one element.
      * <pre class="code">Assert.notEmpty(array, "The array must have elements");</pre>
      * @param array the array to check
      * @param message the exception message to use if the assertion fails
      * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements
      */
     public static void notEmpty(Object[] array, String message) {
         if (array == null || array.length == 0) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that an array has elements; that is, it must not be
      * <code>null</code> and must have at least one element.
      * <pre class="code">Assert.notEmpty(array);</pre>
      * @param array the array to check
      * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements
      */
     public static void notEmpty(Object[] array) {
         notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
     }
 
     /**
      * Assert that an array has no null elements.
      * Note: Does not complain if the array is empty!
      * <pre class="code">Assert.noNullElements(array, "The array must have non-null elements");</pre>
      * @param array the array to check
      * @param message the exception message to use if the assertion fails
      * @throws IllegalArgumentException if the object array contains a <code>null</code> element
      */
     public static void noNullElements(Object[] array, String message) {
         if (array != null) {
             for (int i = 0; i < array.length; i++) {
                 if (array[i] == null) {
                     throw new IllegalArgumentException(message);
                 }
             }
         }
     }
 
     /**
      * Assert that an array has no null elements.
      * Note: Does not complain if the array is empty!
      * <pre class="code">Assert.noNullElements(array);</pre>
      * @param array the array to check
      * @throws IllegalArgumentException if the object array contains a <code>null</code> element
      */
     public static void noNullElements(Object[] array) {
         noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
     }
 
     /**
      * Assert that a collection has elements; that is, it must not be
      * <code>null</code> and must have at least one element.
      * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
      * @param collection the collection to check
      * @param message the exception message to use if the assertion fails
      * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements
      */
     public static void notEmpty(Collection collection, String message) {
         if (isEmpty(collection)) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that a collection has elements; that is, it must not be
      * <code>null</code> and must have at least one element.
      * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
      * @param collection the collection to check
      * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements
      */
     public static void notEmpty(Collection collection) {
         notEmpty(collection,
                 "[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
     }
 
     /**
      * Assert that a Map has entries; that is, it must not be <code>null</code>
      * and must have at least one entry.
      * <pre class="code">Assert.notEmpty(map, "Map must have entries");</pre>
      * @param map the map to check
      * @param message the exception message to use if the assertion fails
      * @throws IllegalArgumentException if the map is <code>null</code> or has no entries
      */
     public static void notEmpty(Map map, String message) {
         if (isEmpty(map)) {
             throw new IllegalArgumentException(message);
         }
     }
 
     /**
      * Assert that a Map has entries; that is, it must not be <code>null</code>
      * and must have at least one entry.
      * <pre class="code">Assert.notEmpty(map);</pre>
      * @param map the map to check
      * @throws IllegalArgumentException if the map is <code>null</code> or has no entries
      */
     public static void notEmpty(Map map) {
         notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
     }
 
 
     /**
      * Assert that the provided object is an instance of the provided class.
      * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
      * @param clazz the required class
      * @param obj the object to check
      * @throws IllegalArgumentException if the object is not an instance of clazz
      * @see Class#isInstance
      */
     public static void isInstanceOf(Class clazz, Object obj) {
         isInstanceOf(clazz, obj, "");
     }
 
     /**
      * Assert that the provided object is an instance of the provided class.
      * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
      * @param type the type to check against
      * @param obj the object to check
      * @param message a message which will be prepended to the message produced by
      * the function itself, and which may be used to provide context. It should
      * normally end in a ": " or ". " so that the function generate message looks
      * ok when prepended to it.
      * @throws IllegalArgumentException if the object is not an instance of clazz
      * @see Class#isInstance
      */
     public static void isInstanceOf(Class type, Object obj, String message) {
         notNull(type, "Type to check against must not be null");
         if (!type.isInstance(obj)) {
             throw new IllegalArgumentException(message +
                     "Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
                     "] must be an instance of " + type);
         }
     }
 
     /**
      * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>.
      * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
      * @param superType the super type to check
      * @param subType the sub type to check
      * @throws IllegalArgumentException if the classes are not assignable
      */
     public static void isAssignable(Class superType, Class subType) {
         isAssignable(superType, subType, "");
     }
 
     /**
      * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>.
      * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
      * @param superType the super type to check against
      * @param subType the sub type to check
      * @param message a message which will be prepended to the message produced by
      * the function itself, and which may be used to provide context. It should
      * normally end in a ": " or ". " so that the function generate message looks
      * ok when prepended to it.
      * @throws IllegalArgumentException if the classes are not assignable
      */
     public static void isAssignable(Class superType, Class subType, String message) {
         notNull(superType, "Type to check against must not be null");
         if (subType == null || !superType.isAssignableFrom(subType)) {
             throw new IllegalArgumentException(message + subType + " is not assignable to " + superType);
         }
     }
 
 
     /**
      * Assert a boolean expression, throwing <code>IllegalStateException</code>
      * if the test result is <code>false</code>. Call isTrue if you wish to
      * throw IllegalArgumentException on an assertion failure.
      * <pre class="code">Assert.state(id == null, "The id property must not already be initialized");</pre>
      * @param expression a boolean expression
      * @param message the exception message to use if the assertion fails
      * @throws IllegalStateException if expression is <code>false</code>
      */
     public static void state(boolean expression, String message) {
         if (!expression) {
             throw new IllegalStateException(message);
         }
     }
 
     /**
      * Assert a boolean expression, throwing {@link IllegalStateException}
      * if the test result is <code>false</code>.
      * <p>Call {@link #isTrue(boolean)} if you wish to
      * throw {@link IllegalArgumentException} on an assertion failure.
      * <pre class="code">Assert.state(id == null);</pre>
      * @param expression a boolean expression
      * @throws IllegalStateException if the supplied expression is <code>false</code>
      */
     public static void state(boolean expression) {
         state(expression, "[Assertion failed] - this state invariant must be true");
     }
 
 
     //////////////////////////
     // From CollectionUtils //
     //////////////////////////
     // CollectionUtils cannot be removed from shiro-core until 2.0 as it has a dependency on PrincipalCollection
 
     private static boolean isEmpty(Map m) {
         return m == null || m.isEmpty();
     }
 
     private static boolean isEmpty(Collection c) {
         return c == null || c.isEmpty();
     }
 
 }