/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.client5.http.entity.mime;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.charset.Charset;
  import java.nio.charset.CharsetEncoder;
  import java.nio.charset.StandardCharsets;
  import java.util.BitSet;
  import java.util.List;
  
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.util.ByteArrayBuffer;
  
  class HttpRFC7578Multipart extends AbstractMultipartFormat {
  
      private static final PercentCodec PERCENT_CODEC = new PercentCodec();
  
      private final List<MultipartPart> parts;
  
      public HttpRFC7578Multipart(
          final Charset charset,
          final String boundary,
          final List<MultipartPart> parts) {
          super(charset, boundary);
          this.parts = parts;
      }
  
      @Override
      public List<MultipartPart> getParts() {
          return parts;
      }
  
      @Override
      protected void formatMultipartHeader(final MultipartPart part, final OutputStream out) throws IOException {
          for (final MimeField field: part.getHeader()) {
              if (MimeConsts.CONTENT_DISPOSITION.equalsIgnoreCase(field.getName())) {
                  writeBytes(field.getName(), charset, out);
                  writeBytes(FIELD_SEP, out);
                  writeBytes(field.getValue(), out);
                  final List<NameValuePair> parameters = field.getParameters();
                  for (int i = 0; i < parameters.size(); i++) {
                      final NameValuePair parameter = parameters.get(i);
                      final String name = parameter.getName();
                      final String value = parameter.getValue();
                      writeBytes("; ", out);
                      writeBytes(name, out);
                      writeBytes("=\"", out);
                      if (value != null) {
                          if (name.equalsIgnoreCase(MimeConsts.FIELD_PARAM_FILENAME)) {
                              out.write(PERCENT_CODEC.encode(value.getBytes(charset)));
                          } else {
                              writeBytes(value, out);
                          }
                      }
                      writeBytes("\"", out);
                  }
                  writeBytes(CR_LF, out);
              } else {
                  writeField(field, charset, out);
              }
          }
      }
  
      static class PercentCodec {
  
          private static final byte ESCAPE_CHAR = '%';
  
          private static final BitSet ALWAYSENCODECHARS = new BitSet();
  
          static {
              ALWAYSENCODECHARS.set(' ');
             ALWAYSENCODECHARS.set('%');
         }
 
         /**
          * Percent-Encoding implementation based on RFC 3986
          */
         public byte[] encode(final byte[] bytes) {
             if (bytes == null) {
                 return null;
             }
 
             final CharsetEncoder characterSetEncoder = StandardCharsets.US_ASCII.newEncoder();
             final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
             for (final byte c : bytes) {
                 int b = c;
                 if (b < 0) {
                     b = 256 + b;
                 }
                 if (characterSetEncoder.canEncode((char) b) && !ALWAYSENCODECHARS.get(c)) {
                     buffer.write(b);
                 } else {
                     buffer.write(ESCAPE_CHAR);
                     final char hex1 = hexDigit(b >> 4);
                     final char hex2 = hexDigit(b);
                     buffer.write(hex1);
                     buffer.write(hex2);
                 }
             }
             return buffer.toByteArray();
         }
 
         public byte[] decode(final byte[] bytes) {
             if (bytes == null) {
                 return null;
             }
             final ByteArrayBuffer buffer = new ByteArrayBuffer(bytes.length);
             for (int i = 0; i < bytes.length; i++) {
                 final int b = bytes[i];
                 if (b == ESCAPE_CHAR) {
                     if (i >= bytes.length - 2) {
                         throw new IllegalArgumentException("Invalid encoding: too short");
                     }
                     final int u = digit16(bytes[++i]);
                     final int l = digit16(bytes[++i]);
                     buffer.append((char) ((u << 4) + l));
                 } else {
                     buffer.append(b);
                 }
             }
             return buffer.toByteArray();
         }
     }
 
     /**
      * Radix used in encoding and decoding.
      */
     private static final int RADIX = 16;
 
     /**
      * Returns the numeric value of the character {@code b} in radix 16.
      *
      * @param b
      *            The byte to be converted.
      * @return The numeric value represented by the character in radix 16.
      *
      * @throws IllegalArgumentException
      *             Thrown when the byte is not valid per {@link Character#digit(char,int)}
      */
     static int digit16(final byte b) {
         final int i = Character.digit((char) b, RADIX);
         if (i == -1) {
             throw new IllegalArgumentException("Invalid encoding: not a valid digit (radix " + RADIX + "): " + b);
         }
         return i;
     }
 
     /**
      * Returns the upper case hex digit of the lower 4 bits of the int.
      *
      * @param b the input int
      * @return the upper case hex digit of the lower 4 bits of the int.
      */
     static char hexDigit(final int b) {
         return Character.toUpperCase(Character.forDigit(b & 0xF, RADIX));
     }
 
 }