/*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.handler.codec.smtp;
  
  import io.netty.util.AsciiString;
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.UnstableApi;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * Provides utility methods to create {@link SmtpRequest}s.
   */
  @UnstableApi
  public final class SmtpRequests {
  
      private static final SmtpRequest DATA = new DefaultSmtpRequest(SmtpCommand.DATA);
      private static final SmtpRequest NOOP = new DefaultSmtpRequest(SmtpCommand.NOOP);
      private static final SmtpRequest RSET = new DefaultSmtpRequest(SmtpCommand.RSET);
      private static final SmtpRequest HELP_NO_ARG = new DefaultSmtpRequest(SmtpCommand.HELP);
      private static final SmtpRequest QUIT = new DefaultSmtpRequest(SmtpCommand.QUIT);
      private static final AsciiString FROM_NULL_SENDER = AsciiString.cached("FROM:<>");
  
      /**
       * Creates a {@code HELO} request.
       */
      public static SmtpRequest helo(CharSequence hostname) {
          return new DefaultSmtpRequest(SmtpCommand.HELO, hostname);
      }
  
      /**
       * Creates a {@code EHLO} request.
       */
      public static SmtpRequest ehlo(CharSequence hostname) {
          return new DefaultSmtpRequest(SmtpCommand.EHLO, hostname);
      }
  
      /**
       * Creates a {@code EMPTY} request.
       */
      public static SmtpRequest empty(CharSequence... parameter) {
          return new DefaultSmtpRequest(SmtpCommand.EMPTY, parameter);
      }
  
      /**
       * Creates a {@code AUTH} request.
       */
      public static SmtpRequest auth(CharSequence... parameter) {
          return new DefaultSmtpRequest(SmtpCommand.AUTH, parameter);
      }
  
      /**
       * Creates a {@code NOOP} request.
       */
      public static SmtpRequest noop() {
          return NOOP;
      }
  
      /**
       * Creates a {@code DATA} request.
       */
      public static SmtpRequest data() {
          return DATA;
      }
  
      /**
       * Creates a {@code RSET} request.
       */
      public static SmtpRequest rset() {
          return RSET;
      }
  
      /**
       * Creates a {@code HELP} request.
       */
      public static SmtpRequest help(String cmd) {
          return cmd == null ? HELP_NO_ARG : new DefaultSmtpRequest(SmtpCommand.HELP, cmd);
      }
  
      /**
       * Creates a {@code QUIT} request.
       */
      public static SmtpRequest quit() {
          return QUIT;
     }
 
     /**
      * Creates a {@code MAIL} request.
      */
     public static SmtpRequest mail(CharSequence sender, CharSequence... mailParameters) {
         if (mailParameters == null || mailParameters.length == 0) {
             return new DefaultSmtpRequest(SmtpCommand.MAIL,
                                           sender != null ? "FROM:<" + sender + '>' : FROM_NULL_SENDER);
         } else {
             List<CharSequence> params = new ArrayList<CharSequence>(mailParameters.length + 1);
             params.add(sender != null? "FROM:<" + sender + '>' : FROM_NULL_SENDER);
             Collections.addAll(params, mailParameters);
             return new DefaultSmtpRequest(SmtpCommand.MAIL, params);
         }
     }
 
     /**
      * Creates a {@code RCPT} request.
      */
     public static SmtpRequest rcpt(CharSequence recipient, CharSequence... rcptParameters) {
         ObjectUtil.checkNotNull(recipient, "recipient");
         if (rcptParameters == null || rcptParameters.length == 0) {
             return new DefaultSmtpRequest(SmtpCommand.RCPT, "TO:<" + recipient + '>');
         } else {
             List<CharSequence> params = new ArrayList<CharSequence>(rcptParameters.length + 1);
             params.add("TO:<" + recipient + '>');
             Collections.addAll(params, rcptParameters);
             return new DefaultSmtpRequest(SmtpCommand.RCPT, params);
         }
     }
 
     /**
      * Creates a {@code EXPN} request.
      */
     public static SmtpRequest expn(CharSequence mailingList) {
         return new DefaultSmtpRequest(SmtpCommand.EXPN, ObjectUtil.checkNotNull(mailingList, "mailingList"));
     }
 
     /**
      * Creates a {@code VRFY} request.
      */
     public static SmtpRequest vrfy(CharSequence user) {
         return new DefaultSmtpRequest(SmtpCommand.VRFY, ObjectUtil.checkNotNull(user, "user"));
     }
 
     private SmtpRequests() { }
 }