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// * 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                                                                             *
// *                                                                                                                         *
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package org.apache.juneau.utils;

import java.io.*;
import java.lang.reflect.*;

import org.apache.juneau.internal.*;
import org.apache.juneau.json.*;
import org.apache.juneau.parser.*;

/**
 * Used to invoke methods on {@code Objects} using arguments in serialized form.
 * 
 * <h5 class='section'>Example:</h5>
 * <p class='bcode'>
 *    String s = <js>"foobar"</js>;
 *    String s2 = (String)<jk>new</jk> PojoIntrospector(s)
 *       .invoke(<js>"substring(int,int)"</js>, <js>"[3,6]"</js>);  <jc>// "bar"</jc>
 * </p>
 */
public final class PojoIntrospector {

   private final Object o;
   private final ReaderParser p;

   /**
    * Constructor.
    * 
    * @param o The object on which Java methods will be invoked.
    * @param p The parser to use to parse the method arguments.
    * If <jk>null</jk>, {@link JsonParser#DEFAULT} is used.
    */
   public PojoIntrospector(Object o, ReaderParser p) {
      if (p == null)
         p = JsonParser.DEFAULT;
      this.o = o;
      this.p = p;
   }

   /**
    * Shortcut for calling <code><jk>new</jk> PojoIntrospector(o, <jk>null</jk>);</code>
    * 
    * @param o The object on which Java methods will be invoked.
    */
   public PojoIntrospector(Object o) {
      this(o, null);
   }

   /**
    * Primary method.  Invokes the specified method on this bean.
    * 
    * @param method The method being invoked.
    * @param args
    *    The arguments to pass as parameters to the method.
    *    These will automatically be converted to the appropriate object type if possible.
    *    Can be <jk>null</jk> if method has no arguments.
    * @return The object returned by the call to the method, or <jk>null</jk> if target object is <jk>null</jk>.
    * @throws IllegalAccessException
    *    If the <code>Constructor</code> object enforces Java language access control and the underlying constructor is
    *    inaccessible.
    * @throws IllegalArgumentException
    *    If one of the following occurs:
    *    <ul class='spaced-list'>
    *       <li>
    *          The number of actual and formal parameters differ.
    *       <li>
    *          An unwrapping conversion for primitive arguments fails.
    *       <li>
    *          A parameter value cannot be converted to the corresponding formal parameter type by a method invocation
    *          conversion.
    *       <li>
    *          The constructor pertains to an enum type.
    *    </ul>
    * @throws InvocationTargetException If the underlying constructor throws an exception.
    * @throws ParseException If the input contains a syntax error or is malformed.
    * @throws IOException
    */
   public Object invokeMethod(Method method, Reader args) throws InvocationTargetException, IllegalArgumentException,
         IllegalAccessException, ParseException, IOException {
      if (o == null)
         return null;
      Object[] params = args == null ? null : p.parseArgs(args, method.getGenericParameterTypes());
      return method.invoke(o, params);
   }

   /**
    * Convenience method for invoking argument from method signature (@see {@link ClassUtils#getMethodSignature(Method)}.
    * 
    * @param method The method being invoked.
    * @param args
    *    The arguments to pass as parameters to the method.
    *    These will automatically be converted to the appropriate object type if possible.
    *    Can be <jk>null</jk> if method has no arguments.
    * @return The object returned by the call to the method, or <jk>null</jk> if target object is <jk>null</jk>.
    * @throws NoSuchMethodException If method does not exist.
    * @throws IllegalAccessException
    *    If the <code>Constructor</code> object enforces Java language access control and
    *    the underlying constructor is inaccessible.
    * @throws IllegalArgumentException
    *    If one of the following occurs:
    *    <ul class='spaced-list'>
    *       <li>
    *          The number of actual and formal parameters differ.
    *       <li>
    *          An unwrapping conversion for primitive arguments fails.
    *       <li>
    *          A parameter value cannot be converted to the corresponding formal parameter type by a method invocation
    *          conversion.
    *       <li>
    *          The constructor pertains to an enum type.
    *    </ul>
    * @throws InvocationTargetException If the underlying constructor throws an exception.
    * @throws ParseException If the input contains a syntax error or is malformed.
    * @throws IOException
    */
   public Object invokeMethod(String method, String args) throws NoSuchMethodException, IllegalArgumentException,
         InvocationTargetException, IllegalAccessException, ParseException, IOException {
      if (o == null)
         return null;
      Method m = p.getClassMeta(o.getClass()).getPublicMethods().get(method);
      if (m == null)
         throw new NoSuchMethodException(method);
      return invokeMethod(m, args == null ? null : new StringReader(args));
   }
}