/*
    * Copyright 2012 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.http.multipart;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  import io.netty.handler.codec.http.HttpConstants;
  import io.netty.handler.codec.http.HttpContent;
  import io.netty.handler.codec.http.HttpRequest;
  import io.netty.handler.codec.http.LastHttpContent;
  import io.netty.handler.codec.http.QueryStringDecoder;
  import io.netty.handler.codec.http.HttpHeaderValues;
  import io.netty.handler.codec.http.HttpHeaderNames;
  import io.netty.handler.codec.http.multipart.HttpPostBodyUtil.SeekAheadOptimize;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.EndOfDataDecoderException;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.ErrorDataDecoderException;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.MultiPartStatus;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.NotEnoughDataDecoderException;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.TooManyFormFieldsException;
  import io.netty.handler.codec.http.multipart.HttpPostRequestDecoder.TooLongFormFieldException;
  import io.netty.util.ByteProcessor;
  import io.netty.util.internal.PlatformDependent;
  import io.netty.util.internal.StringUtil;
  
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  
  import static io.netty.util.internal.ObjectUtil.*;
  
  /**
   * This decoder will decode Body and can handle POST BODY.
   *
   * You <strong>MUST</strong> call {@link #destroy()} after completion to release all resources.
   *
   */
  public class HttpPostStandardRequestDecoder implements InterfaceHttpPostRequestDecoder {
  
      /**
       * Factory used to create InterfaceHttpData
       */
      private final HttpDataFactory factory;
  
      /**
       * Request to decode
       */
      private final HttpRequest request;
  
      /**
       * Default charset to use
       */
      private final Charset charset;
  
      /**
       * The maximum number of fields allows by the form
       */
      private final int maxFields;
  
      /**
       * The maximum number of accumulated bytes when decoding a field
       */
      private final int maxBufferedBytes;
  
      /**
       * Does the last chunk already received
       */
      private boolean isLastChunk;
  
      /**
       * HttpDatas from Body
       */
      private final List<InterfaceHttpData> bodyListHttpData = new ArrayList<InterfaceHttpData>();
  
      /**
       * HttpDatas as Map from Body
       */
      private final Map<String, List<InterfaceHttpData>> bodyMapHttpData = new TreeMap<String, List<InterfaceHttpData>>(
              CaseIgnoringComparator.INSTANCE);
  
      /**
       * The current channelBuffer
       */
      private ByteBuf undecodedChunk;
 
     /**
      * Body HttpDatas current position
      */
     private int bodyListHttpDataRank;
 
     /**
      * Current getStatus
      */
     private MultiPartStatus currentStatus = MultiPartStatus.NOTSTARTED;
 
     /**
      * The current Attribute that is currently in decode process
      */
     private Attribute currentAttribute;
 
     private boolean destroyed;
 
     private int discardThreshold = HttpPostRequestDecoder.DEFAULT_DISCARD_THRESHOLD;
 
     /**
      *
      * @param request
      *            the request to decode
      * @throws NullPointerException
      *             for request
      * @throws ErrorDataDecoderException
      *             if the default charset was wrong when decoding or other
      *             errors
      */
     public HttpPostStandardRequestDecoder(HttpRequest request) {
         this(new DefaultHttpDataFactory(DefaultHttpDataFactory.MINSIZE), request, HttpConstants.DEFAULT_CHARSET);
     }
 
     /**
      *
      * @param factory
      *            the factory used to create InterfaceHttpData
      * @param request
      *            the request to decode
      * @throws NullPointerException
      *             for request or factory
      * @throws ErrorDataDecoderException
      *             if the default charset was wrong when decoding or other
      *             errors
      */
     public HttpPostStandardRequestDecoder(HttpDataFactory factory, HttpRequest request) {
         this(factory, request, HttpConstants.DEFAULT_CHARSET);
     }
 
     /**
      *
      * @param factory
      *            the factory used to create InterfaceHttpData
      * @param request
      *            the request to decode
      * @param charset
      *            the charset to use as default
      * @throws NullPointerException
      *             for request or charset or factory
      * @throws ErrorDataDecoderException
      *             if the default charset was wrong when decoding or other
      *             errors
      */
     public HttpPostStandardRequestDecoder(HttpDataFactory factory, HttpRequest request, Charset charset) {
         this(factory, request, charset, HttpPostRequestDecoder.DEFAULT_MAX_FIELDS,
                 HttpPostRequestDecoder.DEFAULT_MAX_BUFFERED_BYTES);
     }
 
     /**
      *
      * @param factory
      *            the factory used to create InterfaceHttpData
      * @param request
      *            the request to decode
      * @param charset
      *            the charset to use as default
      * @param maxFields
      *            the maximum number of fields the form can have, {@code -1} to disable
      * @param maxBufferedBytes
      *            the maximum number of bytes the decoder can buffer when decoding a field, {@code -1} to disable
      * @throws NullPointerException
      *             for request or charset or factory
      * @throws ErrorDataDecoderException
      *             if the default charset was wrong when decoding or other
      *             errors
      */
     public HttpPostStandardRequestDecoder(HttpDataFactory factory, HttpRequest request, Charset charset,
                                           int maxFields, int maxBufferedBytes) {
         this.request = checkNotNull(request, "request");
         this.charset = checkNotNull(charset, "charset");
         this.factory = checkNotNull(factory, "factory");
         this.maxFields = maxFields;
         this.maxBufferedBytes = maxBufferedBytes;
         try {
             if (request instanceof HttpContent) {
                 // Offer automatically if the given request is as type of HttpContent
                 // See #1089
                 offer((HttpContent) request);
             } else {
                 parseBody();
             }
         } catch (Throwable e) {
             destroy();
             PlatformDependent.throwException(e);
         }
     }
 
     private void checkDestroyed() {
         if (destroyed) {
             throw new IllegalStateException(HttpPostStandardRequestDecoder.class.getSimpleName()
                     + " was destroyed already");
         }
     }
 
     /**
      * True if this request is a Multipart request
      *
      * @return True if this request is a Multipart request
      */
     @Override
     public boolean isMultipart() {
         checkDestroyed();
         return false;
     }
 
     /**
      * Set the amount of bytes after which read bytes in the buffer should be discarded.
      * Setting this lower gives lower memory usage but with the overhead of more memory copies.
      * Use {@code 0} to disable it.
      */
     @Override
     public void setDiscardThreshold(int discardThreshold) {
         this.discardThreshold = checkPositiveOrZero(discardThreshold, "discardThreshold");
     }
 
     /**
      * Return the threshold in bytes after which read data in the buffer should be discarded.
      */
     @Override
     public int getDiscardThreshold() {
         return discardThreshold;
     }
 
     /**
      * This getMethod returns a List of all HttpDatas from body.<br>
      *
      * If chunked, all chunks must have been offered using offer() getMethod. If
      * not, NotEnoughDataDecoderException will be raised.
      *
      * @return the list of HttpDatas from Body part for POST getMethod
      * @throws NotEnoughDataDecoderException
      *             Need more chunks
      */
     @Override
     public List<InterfaceHttpData> getBodyHttpDatas() {
         checkDestroyed();
 
         if (!isLastChunk) {
             throw new NotEnoughDataDecoderException();
         }
         return bodyListHttpData;
     }
 
     /**
      * This getMethod returns a List of all HttpDatas with the given name from
      * body.<br>
      *
      * If chunked, all chunks must have been offered using offer() getMethod. If
      * not, NotEnoughDataDecoderException will be raised.
      *
      * @return All Body HttpDatas with the given name (ignore case)
      * @throws NotEnoughDataDecoderException
      *             need more chunks
      */
     @Override
     public List<InterfaceHttpData> getBodyHttpDatas(String name) {
         checkDestroyed();
 
         if (!isLastChunk) {
             throw new NotEnoughDataDecoderException();
         }
         return bodyMapHttpData.get(name);
     }
 
     /**
      * This getMethod returns the first InterfaceHttpData with the given name from
      * body.<br>
      *
      * If chunked, all chunks must have been offered using offer() getMethod. If
      * not, NotEnoughDataDecoderException will be raised.
      *
      * @return The first Body InterfaceHttpData with the given name (ignore
      *         case)
      * @throws NotEnoughDataDecoderException
      *             need more chunks
      */
     @Override
     public InterfaceHttpData getBodyHttpData(String name) {
         checkDestroyed();
 
         if (!isLastChunk) {
             throw new NotEnoughDataDecoderException();
         }
         List<InterfaceHttpData> list = bodyMapHttpData.get(name);
         if (list != null) {
             return list.get(0);
         }
         return null;
     }
 
     /**
      * Initialized the internals from a new chunk
      *
      * @param content
      *            the new received chunk
      * @throws ErrorDataDecoderException
      *             if there is a problem with the charset decoding or other
      *             errors
      */
     @Override
     public HttpPostStandardRequestDecoder offer(HttpContent content) {
         checkDestroyed();
 
         if (content instanceof LastHttpContent) {
             isLastChunk = true;
         }
 
         ByteBuf buf = content.content();
         if (undecodedChunk == null) {
             undecodedChunk =
                     // Since the Handler will release the incoming later on, we need to copy it
                     //
                     // We are explicit allocate a buffer and NOT calling copy() as otherwise it may set a maxCapacity
                     // which is not really usable for us as we may exceed it once we add more bytes.
                     buf.alloc().buffer(buf.readableBytes()).writeBytes(buf);
         } else {
             undecodedChunk.writeBytes(buf);
         }
         parseBody();
         if (maxBufferedBytes > 0 && undecodedChunk != null && undecodedChunk.readableBytes() > maxBufferedBytes) {
             throw new TooLongFormFieldException();
         }
         if (undecodedChunk != null && undecodedChunk.writerIndex() > discardThreshold) {
             if (undecodedChunk.refCnt() == 1) {
                 // It's safe to call discardBytes() as we are the only owner of the buffer.
                 undecodedChunk.discardReadBytes();
             } else {
                 // There seems to be multiple references of the buffer. Let's copy the data and release the buffer to
                 // ensure we can give back memory to the system.
                 ByteBuf buffer = undecodedChunk.alloc().buffer(undecodedChunk.readableBytes());
                 buffer.writeBytes(undecodedChunk);
                 undecodedChunk.release();
                 undecodedChunk = buffer;
             }
         }
         return this;
     }
 
     /**
      * True if at current getStatus, there is an available decoded
      * InterfaceHttpData from the Body.
      *
      * This getMethod works for chunked and not chunked request.
      *
      * @return True if at current getStatus, there is a decoded InterfaceHttpData
      * @throws EndOfDataDecoderException
      *             No more data will be available
      */
     @Override
     public boolean hasNext() {
         checkDestroyed();
 
         if (currentStatus == MultiPartStatus.EPILOGUE) {
             // OK except if end of list
             if (bodyListHttpDataRank >= bodyListHttpData.size()) {
                 throw new EndOfDataDecoderException();
             }
         }
         return !bodyListHttpData.isEmpty() && bodyListHttpDataRank < bodyListHttpData.size();
     }
 
     /**
      * Returns the next available InterfaceHttpData or null if, at the time it
      * is called, there is no more available InterfaceHttpData. A subsequent
      * call to offer(httpChunk) could enable more data.
      *
      * Be sure to call {@link InterfaceHttpData#release()} after you are done
      * with processing to make sure to not leak any resources
      *
      * @return the next available InterfaceHttpData or null if none
      * @throws EndOfDataDecoderException
      *             No more data will be available
      */
     @Override
     public InterfaceHttpData next() {
         checkDestroyed();
 
         if (hasNext()) {
             return bodyListHttpData.get(bodyListHttpDataRank++);
         }
         return null;
     }
 
     @Override
     public InterfaceHttpData currentPartialHttpData() {
         return currentAttribute;
     }
 
     /**
      * This getMethod will parse as much as possible data and fill the list and map
      *
      * @throws ErrorDataDecoderException
      *             if there is a problem with the charset decoding or other
      *             errors
      */
     private void parseBody() {
         if (currentStatus == MultiPartStatus.PREEPILOGUE || currentStatus == MultiPartStatus.EPILOGUE) {
             if (isLastChunk) {
                 currentStatus = MultiPartStatus.EPILOGUE;
             }
             return;
         }
         parseBodyAttributes();
     }
 
     /**
      * Utility function to add a new decoded data
      */
     protected void addHttpData(InterfaceHttpData data) {
         if (data == null) {
             return;
         }
         if (maxFields > 0 && bodyListHttpData.size() >= maxFields) {
             throw new TooManyFormFieldsException();
         }
         List<InterfaceHttpData> datas = bodyMapHttpData.get(data.getName());
         if (datas == null) {
             datas = new ArrayList<InterfaceHttpData>(1);
             bodyMapHttpData.put(data.getName(), datas);
         }
         datas.add(data);
         bodyListHttpData.add(data);
     }
 
     /**
      * This getMethod fill the map and list with as much Attribute as possible from
      * Body in not Multipart mode.
      *
      * @throws ErrorDataDecoderException
      *             if there is a problem with the charset decoding or other
      *             errors
      */
     private void parseBodyAttributesStandard() {
         int firstpos = undecodedChunk.readerIndex();
         int currentpos = firstpos;
         int equalpos;
         int ampersandpos;
         if (currentStatus == MultiPartStatus.NOTSTARTED) {
             currentStatus = MultiPartStatus.DISPOSITION;
         }
         boolean contRead = true;
         try {
             while (undecodedChunk.isReadable() && contRead) {
                 char read = (char) undecodedChunk.readUnsignedByte();
                 currentpos++;
                 switch (currentStatus) {
                 case DISPOSITION:// search '='
                     if (read == '=') {
                         currentStatus = MultiPartStatus.FIELD;
                         equalpos = currentpos - 1;
                         String key = decodeAttribute(undecodedChunk.toString(firstpos, equalpos - firstpos, charset),
                                 charset);
                         currentAttribute = factory.createAttribute(request, key);
                         firstpos = currentpos;
                     } else if (read == '&' ||
                             (isLastChunk && !undecodedChunk.isReadable() && hasFormBody())) { // special empty FIELD
                         currentStatus = MultiPartStatus.DISPOSITION;
                         ampersandpos = read == '&' ? currentpos - 1 : currentpos;
                         String key = decodeAttribute(
                                 undecodedChunk.toString(firstpos, ampersandpos - firstpos, charset), charset);
                         // Some weird request bodies start with an '&' character, eg: &name=J&age=17.
                         // In that case, key would be "", will get exception:
                         // java.lang.IllegalArgumentException: Param 'name' must not be empty;
                         // Just check and skip empty key.
                         if (!key.isEmpty()) {
                             currentAttribute = factory.createAttribute(request, key);
                             currentAttribute.setValue(""); // empty
                             addHttpData(currentAttribute);
                         }
                         currentAttribute = null;
                         firstpos = currentpos;
                         contRead = true;
                     }
                     break;
                 case FIELD:// search '&' or end of line
                     if (read == '&') {
                         currentStatus = MultiPartStatus.DISPOSITION;
                         ampersandpos = currentpos - 1;
                         setFinalBuffer(undecodedChunk.retainedSlice(firstpos, ampersandpos - firstpos));
                         firstpos = currentpos;
                         contRead = true;
                     } else if (read == HttpConstants.CR) {
                         if (undecodedChunk.isReadable()) {
                             read = (char) undecodedChunk.readUnsignedByte();
                             currentpos++;
                             if (read == HttpConstants.LF) {
                                 currentStatus = MultiPartStatus.PREEPILOGUE;
                                 ampersandpos = currentpos - 2;
                                 setFinalBuffer(undecodedChunk.retainedSlice(firstpos, ampersandpos - firstpos));
                                 firstpos = currentpos;
                                 contRead = false;
                             } else {
                                 // Error
                                 throw new ErrorDataDecoderException("Bad end of line");
                             }
                         } else {
                             currentpos--;
                         }
                     } else if (read == HttpConstants.LF) {
                         currentStatus = MultiPartStatus.PREEPILOGUE;
                         ampersandpos = currentpos - 1;
                         setFinalBuffer(undecodedChunk.retainedSlice(firstpos, ampersandpos - firstpos));
                         firstpos = currentpos;
                         contRead = false;
                     }
                     break;
                 default:
                     // just stop
                     contRead = false;
                 }
             }
             if (isLastChunk && currentAttribute != null) {
                 // special case
                 ampersandpos = currentpos;
                 if (ampersandpos > firstpos) {
                     setFinalBuffer(undecodedChunk.retainedSlice(firstpos, ampersandpos - firstpos));
                 } else if (!currentAttribute.isCompleted()) {
                     setFinalBuffer(Unpooled.EMPTY_BUFFER);
                 }
                 firstpos = currentpos;
                 currentStatus = MultiPartStatus.EPILOGUE;
             } else if (contRead && currentAttribute != null && currentStatus == MultiPartStatus.FIELD) {
                 // reset index except if to continue in case of FIELD getStatus
                 currentAttribute.addContent(undecodedChunk.retainedSlice(firstpos, currentpos - firstpos),
                                             false);
                 firstpos = currentpos;
             }
             undecodedChunk.readerIndex(firstpos);
         } catch (ErrorDataDecoderException e) {
             // error while decoding
             undecodedChunk.readerIndex(firstpos);
             throw e;
         } catch (IOException | IllegalArgumentException e) {
             // error while decoding
             undecodedChunk.readerIndex(firstpos);
             throw new ErrorDataDecoderException(e);
         }
     }
 
     /**
      * This getMethod fill the map and list with as much Attribute as possible from
      * Body in not Multipart mode.
      *
      * @throws ErrorDataDecoderException
      *             if there is a problem with the charset decoding or other
      *             errors
      */
     private void parseBodyAttributes() {
         if (undecodedChunk == null) {
             return;
         }
         parseBodyAttributesStandard();
     }
 
     private void setFinalBuffer(ByteBuf buffer) throws IOException {
         currentAttribute.addContent(buffer, true);
         ByteBuf decodedBuf = decodeAttribute(currentAttribute.getByteBuf(), charset);
         if (decodedBuf != null) { // override content only when ByteBuf needed decoding
             currentAttribute.setContent(decodedBuf);
         }
         addHttpData(currentAttribute);
         currentAttribute = null;
     }
 
     /**
      * Decode component
      *
      * @return the decoded component
      */
     private static String decodeAttribute(String s, Charset charset) {
         try {
             return QueryStringDecoder.decodeComponent(s, charset);
         } catch (IllegalArgumentException e) {
             throw new ErrorDataDecoderException("Bad string: '" + s + '\'', e);
         }
     }
 
     private static ByteBuf decodeAttribute(ByteBuf b, Charset charset) {
         int firstEscaped = b.forEachByte(new UrlEncodedDetector());
         if (firstEscaped == -1) {
             return null; // nothing to decode
         }
 
         ByteBuf buf = b.alloc().buffer(b.readableBytes());
         UrlDecoder urlDecode = new UrlDecoder(buf);
         int idx = b.forEachByte(urlDecode);
         if (urlDecode.nextEscapedIdx != 0) { // incomplete hex byte
             if (idx == -1) {
                 idx = b.readableBytes() - 1;
             }
             idx -= urlDecode.nextEscapedIdx - 1;
             buf.release();
             throw new ErrorDataDecoderException(
                 String.format("Invalid hex byte at index '%d' in string: '%s'", idx, b.toString(charset)));
         }
 
         return buf;
     }
 
     /**
      * Destroy the {@link HttpPostStandardRequestDecoder} and release all it resources. After this method
      * was called it is not possible to operate on it anymore.
      */
     @Override
     public void destroy() {
         // Release all data items, including those not yet pulled, only file based items
         cleanFiles();
         // Clean Memory based data
         for (InterfaceHttpData httpData : bodyListHttpData) {
             // Might have been already released by the user
             if (httpData.refCnt() > 0) {
                 httpData.release();
             }
         }
 
         destroyed = true;
 
         if (undecodedChunk != null && undecodedChunk.refCnt() > 0) {
             undecodedChunk.release();
             undecodedChunk = null;
         }
     }
 
     /**
      * Clean all {@link HttpData}s for the current request.
      */
     @Override
     public void cleanFiles() {
         checkDestroyed();
 
         factory.cleanRequestHttpData(request);
     }
 
     /**
      * Remove the given FileUpload from the list of FileUploads to clean
      */
     @Override
     public void removeHttpDataFromClean(InterfaceHttpData data) {
         checkDestroyed();
 
         factory.removeHttpDataFromClean(request, data);
     }
 
     /**
      * Check if request has headers indicating that it contains form body
      */
     private boolean hasFormBody() {
         String contentHeaderValue = request.headers().get(HttpHeaderNames.CONTENT_TYPE);
         if (contentHeaderValue == null) {
             return false;
         }
         return HttpHeaderValues.APPLICATION_X_WWW_FORM_URLENCODED.contentEquals(contentHeaderValue)
                 || HttpHeaderValues.MULTIPART_FORM_DATA.contentEquals(contentHeaderValue);
     }
 
     private static final class UrlEncodedDetector implements ByteProcessor {
         @Override
         public boolean process(byte value) throws Exception {
             return value != '%' && value != '+';
         }
     }
 
     private static final class UrlDecoder implements ByteProcessor {
 
         private final ByteBuf output;
         private int nextEscapedIdx;
         private byte hiByte;
 
         UrlDecoder(ByteBuf output) {
             this.output = output;
         }
 
         @Override
         public boolean process(byte value) {
             if (nextEscapedIdx != 0) {
                 if (nextEscapedIdx == 1) {
                     hiByte = value;
                     ++nextEscapedIdx;
                 } else {
                     int hi = StringUtil.decodeHexNibble((char) hiByte);
                     int lo = StringUtil.decodeHexNibble((char) value);
                     if (hi == -1 || lo == -1) {
                         ++nextEscapedIdx;
                         return false;
                     }
                     output.writeByte((hi << 4) + lo);
                     nextEscapedIdx = 0;
                 }
             } else if (value == '%') {
                 nextEscapedIdx = 1;
             } else if (value == '+') {
                 output.writeByte(' ');
             } else {
                 output.writeByte(value);
             }
             return true;
         }
     }
 }