/*
    * 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.bcel.verifier;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.bcel.classfile.JavaClass;
  import org.apache.bcel.classfile.Utility;
  import org.apache.bcel.verifier.statics.Pass1Verifier;
  import org.apache.bcel.verifier.statics.Pass2Verifier;
  import org.apache.bcel.verifier.statics.Pass3aVerifier;
  import org.apache.bcel.verifier.structurals.Pass3bVerifier;
  import org.apache.commons.lang3.ArrayUtils;
  
  /**
   * A Verifier instance is there to verify a class file according to The Java Virtual Machine Specification, 2nd Edition.
   *
   * Pass-3b-verification includes pass-3a-verification; pass-3a-verification includes pass-2-verification;
   * pass-2-verification includes pass-1-verification.
   *
   * A Verifier creates PassVerifier instances to perform the actual verification. Verifier instances are usually
   * generated by the VerifierFactory.
   *
   * @see VerifierFactory
   * @see PassVerifier
   */
  public class Verifier {
  
      static final String NAME = "Apache Commons BCEL";
      static final String BANNER = NAME + "\nhttps://commons.apache.org/bcel\n";
  
      static final Verifier[] EMPTY_ARRAY = {};
  
      /**
       * Verifies class files. This is a simple demonstration of how the API of BCEL's class file verifier "JustIce" may be
       * used. You should supply command-line arguments which are fully qualified namea of the classes to verify. These class
       * files must be somewhere in your CLASSPATH (refer to Sun's documentation for questions about this) or you must have
       * put the classes into the BCEL Repository yourself (via 'addClass(JavaClass)').
       */
      public static void main(final String[] args) {
          System.out.println(BANNER);
          for (int index = 0; index < args.length; index++) {
              try {
                  if (args[index].endsWith(JavaClass.EXTENSION)) {
                      final int dotclasspos = args[index].lastIndexOf(JavaClass.EXTENSION);
                      if (dotclasspos != -1) {
                          args[index] = args[index].substring(0, dotclasspos);
                      }
                  }
                  args[index] = Utility.pathToPackage(args[index]);
                  System.out.println("Now verifying: " + args[index] + "\n");
                  verifyType(args[index]);
                  org.apache.bcel.Repository.clearCache();
                  System.gc();
              } catch (final ClassNotFoundException e) {
                  e.printStackTrace();
              }
          }
      }
  
      static void verifyType(final String fullyQualifiedClassName) throws ClassNotFoundException {
          final Verifier verifier = VerifierFactory.getVerifier(fullyQualifiedClassName);
          VerificationResult verificationResult;
          verificationResult = verifier.doPass1();
          System.out.println("Pass 1:\n" + verificationResult);
          verificationResult = verifier.doPass2();
          System.out.println("Pass 2:\n" + verificationResult);
          if (verificationResult == VerificationResult.VR_OK) {
              final JavaClass jc = org.apache.bcel.Repository.lookupClass(fullyQualifiedClassName);
              for (int i = 0; i < jc.getMethods().length; i++) {
                  verificationResult = verifier.doPass3a(i);
                  System.out.println("Pass 3a, method number " + i + " ['" + jc.getMethods()[i] + "']:\n" + verificationResult);
                  verificationResult = verifier.doPass3b(i);
                  System.out.println("Pass 3b, method number " + i + " ['" + jc.getMethods()[i] + "']:\n" + verificationResult);
              }
          }
          System.out.println("Warnings:");
          final String[] warnings = verifier.getMessages();
          if (warnings.length == 0) {
              System.out.println("<none>");
          }
          for (final String warning : warnings) {
             System.out.println(warning);
         }
         System.out.println("\n");
         // avoid swapping.
         verifier.flush();
     }
 
     /**
      * The name of the class this verifier operates on.
      */
     private final String className;
 
     /** A Pass1Verifier for this Verifier instance. */
     private Pass1Verifier p1v;
 
     /** A Pass2Verifier for this Verifier instance. */
     private Pass2Verifier p2v;
 
     /** The Pass3aVerifiers for this Verifier instance. Key: Interned string specifying the method number. */
     private final Map<String, Pass3aVerifier> p3avs = new HashMap<>();
 
     /** The Pass3bVerifiers for this Verifier instance. Key: Interned string specifying the method number. */
     private final Map<String, Pass3bVerifier> p3bvs = new HashMap<>();
 
     /**
      * Instantiation is done by the VerifierFactory.
      *
      * @see VerifierFactory
      */
     Verifier(final String fullyQualifiedClassName) {
         className = fullyQualifiedClassName;
     }
 
     /** Returns the VerificationResult for the given pass. */
     public VerificationResult doPass1() {
         if (p1v == null) {
             p1v = new Pass1Verifier(this);
         }
         return p1v.verify();
     }
 
     /** Returns the VerificationResult for the given pass. */
     public VerificationResult doPass2() {
         if (p2v == null) {
             p2v = new Pass2Verifier(this);
         }
         return p2v.verify();
     }
 
     /**
      * Returns the VerificationResult for the given pass.
      *
      * @param methodNo The method to verify
      * @return the VerificationResult
      */
     public VerificationResult doPass3a(final int methodNo) {
         return p3avs.computeIfAbsent(Integer.toString(methodNo), k -> new Pass3aVerifier(this, methodNo)).verify();
     }
 
     /**
      * Returns the VerificationResult for the given pass.
      *
      * @param methodNo The method to verify
      * @return the VerificationResult
      */
     public VerificationResult doPass3b(final int methodNo) {
         return p3bvs.computeIfAbsent(Integer.toString(methodNo), k -> new Pass3bVerifier(this, methodNo)).verify();
     }
 
     /**
      * Forget everything known about the class file; that means, really start a new verification of a possibly different
      * class file from BCEL's repository.
      */
     public void flush() {
         p1v = null;
         p2v = null;
         p3avs.clear();
         p3bvs.clear();
     }
 
     /**
      * Returns the name of the class this verifier operates on. This is particularly interesting when this verifier was
      * created recursively by another Verifier and you got a reference to this Verifier by the getVerifiers() method of the
      * VerifierFactory.
      *
      * @see VerifierFactory
      */
     public final String getClassName() {
         return className;
     }
 
     /**
      * This returns all the (warning) messages collected during verification. A prefix shows from which verifying pass a
      * message originates.
      *
      * @throws ClassNotFoundException if this class can't be found.
      */
     public String[] getMessages() throws ClassNotFoundException {
         final List<String> messages = new ArrayList<>();
         if (p1v != null) {
             p1v.getMessagesList().forEach(element -> messages.add("Pass 1: " + element));
         }
         if (p2v != null) {
             p2v.getMessagesList().forEach(element -> messages.add("Pass 2: " + element));
         }
         for (final Pass3aVerifier pv : p3avs.values()) {
             final int meth = pv.getMethodNo();
             for (final String element : pv.getMessages()) {
                 messages.add("Pass 3a, method " + meth + " ('" + org.apache.bcel.Repository.lookupClass(className).getMethods()[meth] + "'): " + element);
             }
         }
         for (final Pass3bVerifier pv : p3bvs.values()) {
             final int meth = pv.getMethodNo();
             for (final String element : pv.getMessages()) {
                 messages.add("Pass 3b, method " + meth + " ('" + org.apache.bcel.Repository.lookupClass(className).getMethods()[meth] + "'): " + element);
             }
         }
 
         return messages.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
     }
 }