# JavaRestService.java

    /*
    ** Module   : JavaRestService.java
    ** Abstract : Details of a REST service specification, which is implemented as a Java API call.
    **
    ** Copyright (c) 2022, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
    ** 001 CA  20220323 Created initial version.
    **     CA  20220405 Added authentication and authorization for web requests.  When this is enabled, the target
    **                  API call will be executed under the authenticated FWD context, and not the agent's context.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.rest;

    import java.lang.reflect.*;
    import java.util.*;

    import com.goldencode.p2j.util.*;

    /**
     * Invocation implementation for REST service which are mapped to APIs written directly in Java.
     */
    public class JavaRestService
    extends RestService
    {
       /** The Java class defining this REST service. */
       private final Class<?> cls;

       /**
        * The Java method (in the target {@link #cls class}) which implements this service.  Must be a public
        * instance or static method; for an instance method, the Java class must have a no-argument constructor
        * and must not be abstract.
        */
       private final Method method;

       /**
        * Create a new REST service implemented in a Java method.
        *
        * @param    cls
        *           The target class.
        * @param    m
        *           The target method.
        * @param    ls
        *           The service signature, as it appears at the method annotation.
        * @param    key
        *           The service key.
        * @param    timeout
        *           The invocation timeout.
        */
       public JavaRestService(Class<?>               cls,
                              Method                 m,
                              LegacyService          ls,
                              ServiceKey             key,
                              int                    timeout)
       {
          super(ls, null, key, timeout);

          this.cls = cls;
          this.method = m;

          try
          {
             if (!Modifier.isPublic(cls.getModifiers()))
             {
                // public class
                throw new IllegalStateException("Class " + cls.getName() + " must be public!");
             }
             if (!Modifier.isPublic(m.getModifiers()))
             {
                // public method
                throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() +
                                                " must be public!");
             }
             if (Modifier.isAbstract(m.getModifiers()))
             {
                // non-abstract method
                throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() +
                                                " must not be abstract!");
             }
             if (Modifier.isAbstract(cls.getModifiers()) && !Modifier.isStatic(m.getModifiers()))
             {
                // static method for abstract classes
                throw new IllegalStateException("Method " + m.getName() + " in class " + cls.getName() +
                                                " must be static!");
             }
             if (!Modifier.isStatic(m.getModifiers()) && cls.getConstructor() == null)
             {
                // instance method must have a default constructor at the class
                throw new IllegalStateException("To register method " + m.getName() + " in class " + cls.getName() +
                                                " as a service, the class must have a default constructor!");
             }
          }
          catch (NoSuchMethodException |
                 SecurityException e)
          {
             throw new RuntimeException("Could not register method " + m.getName() + " in class " + cls.getName(),
                                        e);
          }

          buildDefinitionParameters();
       }

       /**
        * Invoke this service.
        *
        * @param    helper
        *           The appserver helper used to execute the requests.
        * @param    token
        *           When not null, it represents the token of a FWD context created for an authenticated and
        *           authorized web service call.  The API call will be performed in that context.
        * @param    args
        *           The arguments.  Any change to a mutable argument will be reflected back at the caller.
        *
        * @return   The returned value.
        */
       @Override
       public Object invoke(AppServerHelper helper, String token, Object[] args)
       {
          JavaInvokeConfig cfg = new JavaInvokeConfig(cls, method);
          cfg.setWebServiceToken(token);
          cfg.setArguments(args);

          return helper.invoke(timeout, cfg);
       }

       /**
        * Get the parser to be used for parsing the arguments, to be attached to the service's parser.
        *
        * @param    argumentsParser
        *           The service's parser.
        *
        * @return   Always a new {@link LegacyArgumentsParser} instance.
        */
       @Override
       protected ArgumentsParser getParser(ServiceArgumentsParser argumentsParser)
       {
          return new JavaArgumentsParser(argumentsParser);
       }

       /**
        * Get the serialized to be used for writing the response arguments.
        *
        * @param    argumentsSerializer
        *           The service's serializer.
        *
        * @return   Always a {@link LegacyArgumentsSerializer} instance.
        */
       @Override
       protected ArgumentsSerializer getSerializer(ResponseArguments argumentsSerializer)
       {
          return new JavaArgumentsSerializer(argumentsSerializer);
       }

       /**
        * Build the parameter definitions, from the {@link LegacyServiceParameter} annotations at the method
        * definition.  This will set the {@link RestService#definitionParameters}.
        */
       @Override
       protected void buildDefinitionParameters()
       {
          List<LegacyServiceParameter> params = new ArrayList<>();
          for (LegacyServiceParameter param : ls.parameters())
          {
             if (!param.returnValue())
             {
                params.add(param);
             }
          }

          definitionParameters = params.toArray(new LegacyServiceParameter[0]);
       }
    }