/*
 * 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.juneau.rest;

import static org.apache.juneau.common.utils.StringUtils.*;
import static org.apache.juneau.http.HttpHeaders.*;
import static org.apache.juneau.httppart.HttpPartType.*;

import java.io.*;
import java.nio.charset.*;
import java.util.*;

import org.apache.http.*;
import org.apache.juneau.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.common.utils.*;
import org.apache.juneau.encoders.*;
import org.apache.juneau.http.header.*;
import org.apache.juneau.http.response.*;
import org.apache.juneau.httppart.*;
import org.apache.juneau.httppart.bean.*;
import org.apache.juneau.marshaller.*;
import org.apache.juneau.oapi.*;
import org.apache.juneau.rest.httppart.*;
import org.apache.juneau.rest.logger.*;
import org.apache.juneau.rest.util.*;
import org.apache.juneau.serializer.*;

import jakarta.servlet.*;
import jakarta.servlet.http.*;

/**
 * Represents an HTTP response for a REST resource.
 *
 * <p>
 *    The {@link RestResponse} object is an extension of the <l>HttpServletResponse</l> class
 *    with various built-in convenience methods for use in building REST interfaces.
 *    It can be accessed by passing it as a parameter on your REST Java method:
 * </p>
 *
 * <p class='bjava'>
 *    <ja>@RestPost</ja>(...)
 *    <jk>public</jk> Object myMethod(RestResponse <jv>res</jv>) {...}
 * </p>
 *
 * <p>
 *    The primary methods on this class are:
 * </p>
 * <ul class='javatree'>
 *    <li class='jc'>{@link RestResponse}
 *    <ul class='spaced-list'>
 *       <li>Methods for setting response headers:
 *       <ul class='javatreec'>
 *          <li class='jm'>{@link RestResponse#addHeader(Header) addHeader(Header)}
 *          <li class='jm'>{@link RestResponse#addHeader(String,String) addHeader(String,String)}
 *          <li class='jm'>{@link RestResponse#containsHeader(String) containsHeader(String)}
 *          <li class='jm'>{@link RestResponse#getHeader(String) getHeader(String)}
 *          <li class='jm'>{@link RestResponse#setCharacterEncoding(String) setCharacterEncoding(String)}
 *          <li class='jm'>{@link RestResponse#setContentType(String) setContentType(String)}
 *          <li class='jm'>{@link RestResponse#setHeader(Header) setHeader(Header)}
 *          <li class='jm'>{@link RestResponse#setHeader(HttpPartSchema,String,Object) setHeader(HttpPartSchema,String,Object)}
 *          <li class='jm'>{@link RestResponse#setHeader(String,Object) setHeader(String,Object)}
 *          <li class='jm'>{@link RestResponse#setHeader(String,String) setHeader(String,String)}
 *          <li class='jm'>{@link RestResponse#setMaxHeaderLength(int) setMaxHeaderLength(int)}
 *          <li class='jm'>{@link RestResponse#setSafeHeaders() setSafeHeaders()}
 *       </ul>
 *       <li>Methods for setting response bodies:
 *       <ul class='javatreec'>
 *          <li class='jm'>{@link RestResponse#flushBuffer() flushBuffer()}
 *          <li class='jm'>{@link RestResponse#getDirectWriter(String) getDirectWriter(String)}
 *          <li class='jm'>{@link RestResponse#getNegotiatedOutputStream() getNegotiatedOutputStream()}
 *          <li class='jm'>{@link RestResponse#getNegotiatedWriter() getNegotiatedWriter()}
 *          <li class='jm'>{@link RestResponse#getSerializerMatch() getSerializerMatch()}
 *          <li class='jm'>{@link RestResponse#getWriter() getWriter()}
 *          <li class='jm'>{@link RestResponse#sendPlainText(String) sendPlainText(String)}
 *          <li class='jm'>{@link RestResponse#sendRedirect(String) sendRedirect(String)}
 *          <li class='jm'>{@link RestResponse#setContentSchema(HttpPartSchema) setContentSchema(HttpPartSchema)}
 *          <li class='jm'>{@link RestResponse#setContent(Object) setOutput(Object)}
 *          <li class='jm'>{@link RestResponse#setResponseBeanMeta(ResponseBeanMeta) setResponseBeanMeta(ResponseBeanMeta)}
 *          <li class='jm'>{@link RestResponse#setException(Throwable) setException(Throwable)}
 *       </ul>
 *       <li>Other:
 *       <ul class='javatreec'>
 *          <li class='jm'>{@link RestResponse#getAttributes() getAttributes()}
 *          <li class='jm'>{@link RestResponse#getContext() getContext()}
 *          <li class='jm'>{@link RestResponse#getOpContext() getOpContext()}
 *          <li class='jm'>{@link RestResponse#setAttribute(String,Object) setAttribute(String,Object)}
 *          <li class='jm'>{@link RestResponse#setDebug() setDebug()}
 *          <li class='jm'>{@link RestResponse#setNoTrace() setNoTrace()}
 *          <li class='jm'>{@link RestResponse#setStatus(int) setStatus(int)}
 *       </ul>
 *    </ul>
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>

 * </ul>
 */
public class RestResponse extends HttpServletResponseWrapper {

   private HttpServletResponse inner;
   private final RestRequest request;

   private Optional<Object> content;  // The POJO being sent to the output.
   private ServletOutputStream sos;
   private FinishableServletOutputStream os;
   private FinishablePrintWriter w;
   private ResponseBeanMeta responseBeanMeta;
   private RestOpContext opContext;
   private Optional<HttpPartSchema> contentSchema;
   private Serializer serializer;
   private Optional<SerializerMatch> serializerMatch;
   private boolean safeHeaders;
   private int maxHeaderLength = 8096;

   /**
    * Constructor.
    */
   RestResponse(RestOpContext opContext, RestSession session, RestRequest req) throws Exception {
      super(session.getResponse());

      inner = session.getResponse();
      request = req;

      this.opContext = opContext;
      responseBeanMeta = opContext.getResponseMeta();

      RestContext context = session.getContext();

      try {
         String passThroughHeaders = request.getHeaderParam("x-response-headers").orElse(null);
         if (passThroughHeaders != null) {
            JsonMap m = context.getPartParser().getPartSession().parse(HEADER, null, passThroughHeaders, BeanContext.DEFAULT.getClassMeta(JsonMap.class));
            for (Map.Entry<String,Object> e : m.entrySet())
               addHeader(e.getKey(), resolveUris(e.getValue()));
         }
      } catch (Exception e1) {
         throw new BadRequest(e1, "Invalid format for header 'x-response-headers'.  Must be in URL-encoded format.");
      }

      // Find acceptable charset
      String h = request.getHeaderParam("accept-charset").orElse(null);
      Charset charset = null;
      if (h == null)
         charset = opContext.getDefaultCharset();
      else for (StringRange r : StringRanges.of(h).toList()) {
         if (r.getQValue() > 0) {
            if (r.getName().equals("*"))
               charset = opContext.getDefaultCharset();
            else if (Charset.isSupported(r.getName()))
               charset = Charset.forName(r.getName());
            if (charset != null)
               break;
         }
      }

      request.getContext().getDefaultResponseHeaders().forEach(x->addHeader(x.getValue(), resolveUris(x.getValue())));  // Done this way to avoid list/array copy.

      opContext.getDefaultResponseHeaders().forEach(x->addHeader(x.getName(), resolveUris(x.getValue())));

      if (charset == null)
         throw new NotAcceptable("No supported charsets in header ''Accept-Charset'': ''{0}''", request.getHeaderParam("Accept-Charset").orElse(null));
      inner.setCharacterEncoding(charset.name());

   }

   /**
    * Returns access to the inner {@link RestContext} of the class of this method.
    *
    * @return The {@link RestContext} of this class.  Never <jk>null</jk>.
    */
   public RestContext getContext() {
      return request.getContext();
   }

   /**
    * Returns access to the inner {@link RestOpContext} of this method.
    *
    * @return The {@link RestOpContext} of this method.  Never <jk>null</jk>.
    */
   public RestOpContext getOpContext() {
      return request.getOpContext();
   }

   /**
    * Sets the HTTP output on the response.
    *
    * <p>
    * The object type can be anything allowed by the registered response handlers.
    *
    * <p>
    * Calling this method is functionally equivalent to returning the object in the REST Java method.
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    <ja>@RestGet</ja>(<js>"/example2/{personId}"</js>)
    *    <jk>public void</jk> doGet(RestResponse <jv>res</jv>, <ja>@Path</ja> UUID <jv>personId</jv>) {
    *       Person <jv>person</jv> = getPersonById(<jv>personId</jv>);
    *       <jv>res</jv>.setOutput(<jv>person</jv>);
    *    }
    * </p>
    *
    * <h5 class='section'>Notes:</h5><ul>
    *    <li class='note'>
    *       Calling this method with a <jk>null</jk> value is NOT the same as not calling this method at all.
    *       <br>A <jk>null</jk> output value means we want to serialize <jk>null</jk> as a response (e.g. as a JSON <c>null</c>).
    *       <br>Not calling this method or returning a value means you're handing the response yourself via the underlying stream or writer.
    * </ul>
    *
    * <h5 class='section'>See Also:</h5><ul>
    *    <li class='jm'>{@link RestContext.Builder#responseProcessors()}
    *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/RestOpAnnotatedMethodBasics">@RestOp-Annotated Method Basics</a>
    * </ul>
    *
    * @param output The output to serialize to the connection.
    * @return This object.
    */
   public RestResponse setContent(Object output) {
      this.content = Utils.opt(output);
      return this;
   }

   /**
    * Shortcut for calling <c>getRequest().getAttributes()</c>.
    *
    * @return The request attributes object.
    */
   public RequestAttributes getAttributes() {
      return request.getAttributes();
   }

   /**
    * Shortcut for calling <c>getRequest().setAttribute(String,Object)</c>.
    *
    * @param name The property name.
    * @param value The property value.
    * @return This object.
    */
   public RestResponse setAttribute(String name, Object value) {
      request.setAttribute(name, value);
      return this;
   }

   /**
    * Returns the output that was set by calling {@link #setContent(Object)}.
    *
    * <p>
    * If it's null, then {@link #setContent(Object)} wasn't called.
    * <br>If it contains an empty, then <c>setObject(<jk>null</jk>)</c> was called.
    * <br>Otherwise, {@link #setContent(Object)} was called with a non-null value.
    *
    * @return The output object, or <jk>null</jk> if {@link #setContent(Object)} was never called.
    */
   public Optional<Object> getContent() {
      return content;
   }

   /**
    * Returns <jk>true</jk> if the response contains output.
    *
    * <p>
    * This implies {@link #setContent(Object)} has been called on this object.
    *
    * <p>
    * Note that this also returns <jk>true</jk> even if {@link #setContent(Object)} was called with a <jk>null</jk>
    * value as this means the response contains an output value of <jk>null</jk> as opposed to no value at all.
    *
    * @return <jk>true</jk> if the response contains output.
    */
   public boolean hasContent() {
      return content != null;
   }

   /**
    * Sets the output to a plain-text message regardless of the content type.
    *
    * @param text The output text to send.
    * @return This object.
    * @throws IOException If a problem occurred trying to write to the writer.
    */
   public RestResponse sendPlainText(String text) throws IOException {
      setContentType("text/plain");
      getNegotiatedWriter().write(text);
      return this;
   }

   /**
    * Equivalent to {@link HttpServletResponse#getOutputStream()}, except wraps the output stream if an {@link Encoder}
    * was found that matched the <c>Accept-Encoding</c> header.
    *
    * @return A negotiated output stream.
    * @throws NotAcceptable If unsupported Accept-Encoding value specified.
    * @throws IOException Thrown by underlying stream.
    */
   public FinishableServletOutputStream getNegotiatedOutputStream() throws NotAcceptable, IOException {
      if (os == null) {
         Encoder encoder = null;
         EncoderSet encoders = request.getOpContext().getEncoders();

         String ae = request.getHeaderParam("Accept-Encoding").orElse(null);
         if (! (ae == null || ae.isEmpty())) {
            EncoderMatch match = encoders.getEncoderMatch(ae);
            if (match == null) {
               // Identity should always match unless "identity;q=0" or "*;q=0" is specified.
               if (ae.matches(".*(identity|\\*)\\s*;\\s*q\\s*=\\s*(0(?!\\.)|0\\.0).*")) {
                  throw new NotAcceptable(
                     "Unsupported encoding in request header ''Accept-Encoding'': ''{0}''\n\tSupported codings: {1}",
                     ae, Json5.of(encoders.getSupportedEncodings())
                  );
               }
            } else {
               encoder = match.getEncoder();
               String encoding = match.getEncoding().toString();

               // Some clients don't recognize identity as an encoding, so don't set it.
               if (! encoding.equals("identity"))
                  setHeader("content-encoding", encoding);
            }
         }
         @SuppressWarnings("resource")
         ServletOutputStream sos = getOutputStream();
         os = new FinishableServletOutputStream(encoder == null ? sos : encoder.getOutputStream(sos));
      }
      return os;
   }

   /**
    * Returns a ServletOutputStream suitable for writing binary data in the response.
    *
    * <p>
    * The servlet container does not encode the binary data.
    *
    * <p>
    * Calling <c>flush()</c> on the ServletOutputStream commits the response.
    * Either this method or <c>getWriter</c> may be called to write the content, not both, except when reset has been called.
    *
    * @return The stream.
    * @throws IOException If stream could not be accessed.
    */
   @Override
   public ServletOutputStream getOutputStream() throws IOException {
      if (sos == null)
         sos = inner.getOutputStream();
      return sos;
   }

   /**
    * Returns <jk>true</jk> if {@link #getOutputStream()} has been called.
    *
    * @return <jk>true</jk> if {@link #getOutputStream()} has been called.
    */
   public boolean getOutputStreamCalled() {
      return sos != null;
   }

   /**
    * Returns the writer to the response content.
    *
    * <p>
    * This methods bypasses any specified encoders and returns a regular unbuffered writer.
    * Use the {@link #getNegotiatedWriter()} method if you want to use the matched encoder (if any).
    *
    * @return The writer.
    * @throws IOException If writer could not be accessed.
    */
   @Override
   public PrintWriter getWriter() throws IOException {
      return getWriter(true, false);
   }

   /**
    * Convenience method meant to be used when rendering directly to a browser with no buffering.
    *
    * <p>
    * Sets the header <js>"x-content-type-options=nosniff"</js> so that output is rendered immediately on IE and Chrome
    * without any buffering for content-type sniffing.
    *
    * <p>
    * This can be useful if you want to render a streaming 'console' on a web page.
    *
    * @param contentType The value to set as the <c>Content-Type</c> on the response.
    * @return The raw writer.
    * @throws IOException Thrown by underlying stream.
    */
   public PrintWriter getDirectWriter(String contentType) throws IOException {
      setContentType(contentType);
      setHeader("X-Content-Type-Options", "nosniff");
      setHeader("Content-Encoding", "identity");
      return getWriter(true, true);
   }

   /**
    * Equivalent to {@link HttpServletResponse#getWriter()}, except wraps the output stream if an {@link Encoder} was
    * found that matched the <c>Accept-Encoding</c> header and sets the <c>Content-Encoding</c>
    * header to the appropriate value.
    *
    * @return The negotiated writer.
    * @throws NotAcceptable If unsupported charset in request header Accept-Charset.
    * @throws IOException Thrown by underlying stream.
    */
   public FinishablePrintWriter getNegotiatedWriter() throws NotAcceptable, IOException {
      return getWriter(false, false);
   }

   @SuppressWarnings("resource")
   private FinishablePrintWriter getWriter(boolean raw, boolean autoflush) throws NotAcceptable, IOException {
      if (w != null)
         return w;

      // If plain text requested, override it now.
      if (request.isPlainText())
         setHeader("Content-Type", "text/plain");

      try {
         OutputStream out = (raw ? getOutputStream() : getNegotiatedOutputStream());
         w = new FinishablePrintWriter(out, getCharacterEncoding(), autoflush);
         return w;
      } catch (UnsupportedEncodingException e) {
         String ce = getCharacterEncoding();
         setCharacterEncoding("UTF-8");
         throw new NotAcceptable("Unsupported charset in request header ''Accept-Charset'': ''{0}''", ce);
      }
   }

   /**
    * Returns the <c>Content-Type</c> header stripped of the charset attribute if present.
    *
    * @return The <c>media-type</c> portion of the <c>Content-Type</c> header.
    */
   public MediaType getMediaType() {
      return MediaType.of(getContentType());
   }

   /**
    * Wrapper around {@link #getCharacterEncoding()} that converts the value to a {@link Charset}.
    *
    * @return The request character encoding converted to a {@link Charset}.
    */
   public Charset getCharset() {
      String s = getCharacterEncoding();
      return s == null ? null : Charset.forName(s);
   }

   /**
    * Redirects to the specified URI.
    *
    * <p>
    * Relative URIs are always interpreted as relative to the context root.
    * This is similar to how WAS handles redirect requests, and is different from how Tomcat handles redirect requests.
    *
    * @param uri The redirection URL.
    * @throws IOException If an input or output exception occurs
    */
   @Override
   public void sendRedirect(String uri) throws IOException {
      char c = (uri.length() > 0 ? uri.charAt(0) : 0);
      if (c != '/' && uri.indexOf("://") == -1)
         uri = request.getContextPath() + '/' + uri;
      inner.sendRedirect(uri);
   }

   /**
    * Sets a response header with the given name and value.
    *
    * <p>
    * If the header had already been set, the new value overwrites the previous one.
    *
    * <p>
    * The {@link #containsHeader(String)} method can be used to test for the presence of a header before setting its value.
    *
    * @param name The header name.
    * @param value The header value.
    */
   @Override
   public void setHeader(String name, String value) {

      // Jetty doesn't set the content type correctly if set through this method.
      // Tomcat/WAS does.
      if (name.equalsIgnoreCase("Content-Type")) {
         inner.setContentType(value);
         ContentType ct = contentType(value);
         if (ct != null && ct.getParameter("charset") != null)
            inner.setCharacterEncoding(ct.getParameter("charset"));
      } else {
         if (safeHeaders)
            value = stripInvalidHttpHeaderChars(value);
         value = abbreviate(value, maxHeaderLength);
         inner.setHeader(name, value);
      }
   }

   /**
    * Sets a header on the request.
    *
    * @param name The header name.
    * @param value The header value.
    *    <ul>
    *       <li>Can be any POJO.
    *       <li>Converted to a string using the specified part serializer.
    *    </ul>
    * @return This object.
    * @throws SchemaValidationException Header failed schema validation.
    * @throws SerializeException Header could not be serialized.
    */
   public RestResponse setHeader(String name, Object value) throws SchemaValidationException, SerializeException {
      setHeader(name, request.getPartSerializerSession().serialize(HEADER, null, value));
      return this;
   }

   /**
    * Sets a header on the request.
    *
    * @param schema
    *    The schema to use to serialize the header, or <jk>null</jk> to use the default schema.
    * @param name The header name.
    * @param value The header value.
    *    <ul>
    *       <li>Can be any POJO.
    *       <li>Converted to a string using the specified part serializer.
    *    </ul>
    * @return This object.
    * @throws SchemaValidationException Header failed schema validation.
    * @throws SerializeException Header could not be serialized.
    */
   public RestResponse setHeader(HttpPartSchema schema, String name, Object value) throws SchemaValidationException, SerializeException {
      setHeader(name, request.getPartSerializerSession().serialize(HEADER, schema, value));
      return this;
   }

   /**
    * Specifies the schema for the response content.
    *
    * <p>
    * Used by schema-aware serializers such as {@link OpenApiSerializer}.  Ignored by other serializers.
    *
    * @param schema The content schema
    * @return This object.
    */
   public RestResponse setContentSchema(HttpPartSchema schema) {
      this.contentSchema = Utils.opt(schema);
      return this;
   }

   /**
    * Sets the <js>"Exception"</js> attribute to the specified throwable.
    *
    * <p>
    * This exception is used by {@link CallLogger} for logging purposes.
    *
    * @param t The attribute value.
    * @return This object.
    */
   public RestResponse setException(Throwable t) {
      request.setException(t);
      return this;
   }

   /**
    * Sets the <js>"NoTrace"</js> attribute to the specified boolean.
    *
    * <p>
    * This flag is used by {@link CallLogger} and tells it not to log the current request.
    *
    * @param b The attribute value.
    * @return This object.
    */
   public RestResponse setNoTrace(Boolean b) {
      request.setNoTrace(b);
      return this;
   }

   /**
    * Shortcut for calling <c>setNoTrace(<jk>true</jk>)</c>.
    *
    * @return This object.
    */
   public RestResponse setNoTrace() {
      return setNoTrace(true);
   }

   /**
    * Sets the <js>"Debug"</js> attribute to the specified boolean.
    *
    * <p>
    * This flag is used by {@link CallLogger} to help determine how a request should be logged.
    *
    * @param b The attribute value.
    * @return This object.
    * @throws IOException If bodies could not be cached.
    */
   public RestResponse setDebug(Boolean b) throws IOException {
      request.setDebug(b);
      if (b)
         inner = CachingHttpServletResponse.wrap(inner);
      return this;
   }

   /**
    * Shortcut for calling <c>setDebug(<jk>true</jk>)</c>.
    *
    * @return This object.
    * @throws IOException If bodies could not be cached.
    */
   public RestResponse setDebug() throws IOException {
      return setDebug(true);
   }

   /**
    * Returns the metadata about this response.
    *
    * @return
    *    The metadata about this response.
    *    <br>Never <jk>null</jk>.
    */
   public ResponseBeanMeta getResponseBeanMeta() {
      return responseBeanMeta;
   }

   /**
    * Sets metadata about this response.
    *
    * @param rbm The metadata about this response.
    * @return This object.
    */
   public RestResponse setResponseBeanMeta(ResponseBeanMeta rbm) {
      this.responseBeanMeta = rbm;
      return this;
   }

   /**
    * Returns <jk>true</jk> if this response object is of the specified type.
    *
    * @param c The type to check against.
    * @return <jk>true</jk> if this response object is of the specified type.
    */
   public boolean isContentOfType(Class<?> c) {
      return c.isInstance(getRawOutput());
   }

   /**
    * Returns this value cast to the specified class.
    *
    * @param <T> The class to cast to.
    * @param c The class to cast to.
    * @return This value cast to the specified class, or <jk>null</jk> if the object doesn't exist or isn't the specified type.
    */
   @SuppressWarnings("unchecked")
   public <T> T getContent(Class<T> c) {
      if (isContentOfType(c))
         return (T)getRawOutput();
      return null;
   }

   /**
    * Returns the wrapped servlet request.
    *
    * @return The wrapped servlet request.
    */
   public HttpServletResponse getHttpServletResponse() {
      return inner;
   }

   /**
    * Forces any content in the buffer to be written to the client.
    *
    * <p>
    * A call to this method automatically commits the response, meaning the status code and headers will be written.
    *
    * @throws IOException If an I/O error occurred.
    */
   @Override
   public void flushBuffer() throws IOException {
      if (w != null)
         w.flush();
      if (os != null)
         os.flush();
      inner.flushBuffer();
   }

   private Object getRawOutput() {
      return content == null ? null : content.orElse(null);
   }

   /**
    * Enabled safe-header mode.
    *
    * <p>
    * When enabled, invalid characters such as CTRL characters will be stripped from header values
    * before they get set.
    *
    * @return This object.
    */
   public RestResponse setSafeHeaders() {
      this.safeHeaders = true;
      return this;
   }

   /**
    * Specifies the maximum length for header values.
    *
    * <p>
    * Header values that exceed this length will get truncated.
    *
    * @param value The new value for this setting.  The default is <c>8096</c>.
    * @return This object.
    */
   public RestResponse setMaxHeaderLength(int value) {
      this.maxHeaderLength = value;
      return this;
   }

   /**
    * Adds a response header with the given name and value.
    *
    * <p>
    * This method allows response headers to have multiple values.
    *
    * <p>
    * A no-op of either the name or value is <jk>null</jk>.
    *
    * <p>
    * Note that per <a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2'>RFC2616</a>,
    * only headers defined as comma-delimited lists [i.e., #(values)] should be defined as multiple message header fields.
    *
    * @param name The header name.
    * @param value The header value.
    */
   @Override
   public void addHeader(String name, String value) {
      if (name != null && value != null) {
         if (name.equalsIgnoreCase("Content-Type"))
            setHeader(name, value);
         else {
            if (safeHeaders)
               value = stripInvalidHttpHeaderChars(value);
            value = abbreviate(value, maxHeaderLength);
            inner.addHeader(name, value);
         }
      }
   }

   /**
    * Sets a response header.
    *
    * <p>
    * Any previous header values are removed.
    *
    * <p>
    * Value is added at the end of the headers.
    *
    * @param header The header.
    * @return This object.
    */
   public RestResponse setHeader(Header header) {
      if (header == null) {
         // Do nothing.
      } else if (header instanceof BasicUriHeader) {
         BasicUriHeader x = (BasicUriHeader)header;
         setHeader(x.getName(), resolveUris(x.getValue()));
      } else if (header instanceof SerializedHeader) {
         SerializedHeader x = ((SerializedHeader)header).copyWith(request.getPartSerializerSession(), null);
         String v = x.getValue();
         if (v != null && v.indexOf("://") != -1)
            v = resolveUris(v);
         setHeader(x.getName(), v);
      } else {
         setHeader(header.getName(), header.getValue());
      }
      return this;
   }

   /**
    * Adds a response header.
    *
    * <p>
    * Any previous header values are preserved.
    *
    * <p>
    * Value is added at the end of the headers.
    *
    * <p>
    * If the header is a {@link BasicUriHeader}, the URI will be resolved using the {@link RestRequest#getUriResolver()} object.
    *
    * <p>
    * If the header is a {@link SerializedHeader} and the serializer session is not set, it will be set to the one returned by {@link RestRequest#getPartSerializerSession()} before serialization.
    *
    * <p>
    * Note that per <a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2'>RFC2616</a>,
    * only headers defined as comma-delimited lists [i.e., #(values)] should be defined as multiple message header fields.
    *
    * @param header The header.
    * @return This object.
    */
   public RestResponse addHeader(Header header) {
      if (header == null) {
         // Do nothing.
      } else if (header instanceof BasicUriHeader) {
         BasicUriHeader x = (BasicUriHeader)header;
         addHeader(x.getName(), resolveUris(x.getValue()));
      } else if (header instanceof SerializedHeader) {
         SerializedHeader x = ((SerializedHeader)header).copyWith(request.getPartSerializerSession(), null);
         addHeader(x.getName(), resolveUris(x.getValue()));
      } else {
         addHeader(header.getName(), header.getValue());
      }
      return this;
   }

   private String resolveUris(Object value) {
      String s = Utils.s(value);
      return request.getUriResolver().resolve(s);
   }

   /**
    * Returns the matching serializer and media type for this response.
    *
    * @return The matching serializer, never <jk>null</jk>.
    */
   public Optional<SerializerMatch> getSerializerMatch() {
      if (serializerMatch != null)
         return serializerMatch;
      if (serializer != null) {
         serializerMatch = Utils.opt(new SerializerMatch(getMediaType(), serializer));
      } else {
         serializerMatch = Utils.opt(opContext.getSerializers().getSerializerMatch(request.getHeaderParam("Accept").orElse("*/*")));
      }
      return serializerMatch;
   }

   /**
    * Returns the schema of the response content.
    *
    * @return The schema of the response content, never <jk>null</jk>.
    */
   public Optional<HttpPartSchema> getContentSchema() {
      if (contentSchema != null)
         return contentSchema;
      if (responseBeanMeta != null)
         contentSchema = Utils.opt(responseBeanMeta.getSchema());
      else {
         ResponseBeanMeta rbm = opContext.getResponseBeanMeta(getContent(Object.class));
         if (rbm != null)
            contentSchema = Utils.opt(rbm.getSchema());
         else
            contentSchema = Utils.opte();
      }
      return contentSchema;
   }
}