/*
    * ====================================================================
    * 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.impl.cache;
  
  import java.io.InputStream;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Random;
  
  import org.apache.hc.client5.http.cache.HttpCacheEntry;
  import org.apache.hc.client5.http.utils.DateUtils;
  import org.apache.hc.core5.http.ClassicHttpRequest;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HeaderElement;
  import org.apache.hc.core5.http.HttpEntity;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpMessage;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.HttpStatus;
  import org.apache.hc.core5.http.HttpVersion;
  import org.apache.hc.core5.http.ProtocolVersion;
  import org.apache.hc.core5.http.io.entity.ByteArrayEntity;
  import org.apache.hc.core5.http.message.BasicClassicHttpRequest;
  import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
  import org.apache.hc.core5.http.message.BasicHeader;
  import org.apache.hc.core5.http.message.MessageSupport;
  import org.apache.hc.core5.util.ByteArrayBuffer;
  import org.apache.hc.core5.util.LangUtils;
  import org.junit.Assert;
  
  public class HttpTestUtils {
  
      /*
       * "The following HTTP/1.1 headers are hop-by-hop headers..."
       *
       * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.5.1
       */
      private static final String[] HOP_BY_HOP_HEADERS = { "Connection", "Keep-Alive", "Proxy-Authenticate",
          "Proxy-Authorization", "TE", "Trailers", "Transfer-Encoding", "Upgrade" };
  
      /*
       * "Multiple message-header fields with the same field-name MAY be present
       * in a message if and only if the entire field-value for that header field
       * is defined as a comma-separated list [i.e., #(values)]."
       *
       * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
       */
      private static final String[] MULTI_HEADERS = { "Accept", "Accept-Charset", "Accept-Encoding",
          "Accept-Language", "Allow", "Cache-Control", "Connection", "Content-Encoding",
          "Content-Language", "Expect", "Pragma", "Proxy-Authenticate", "TE", "Trailer",
          "Transfer-Encoding", "Upgrade", "Via", HttpHeaders.WARNING, "WWW-Authenticate" };
      private static final String[] SINGLE_HEADERS = { "Accept-Ranges", "Age", "Authorization",
          "Content-Length", "Content-Location", "Content-MD5", "Content-Range", "Content-Type",
          "Date", "ETag", "Expires", "From", "Host", "If-Match", "If-Modified-Since",
          "If-None-Match", "If-Range", "If-Unmodified-Since", "Last-Modified", "Location",
          "Max-Forwards", "Proxy-Authorization", "Range", "Referer", "Retry-After", "Server",
          "User-Agent", "Vary" };
  
      /*
       * Determines whether the given header name is considered a hop-by-hop
       * header.
       *
       * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.5.1
       */
      public static boolean isHopByHopHeader(final String name) {
          for (final String s : HOP_BY_HOP_HEADERS) {
              if (s.equalsIgnoreCase(name)) {
                  return true;
              }
          }
          return false;
     }
 
     /*
      * Determines whether a given header name may only appear once in a message.
      */
     public static boolean isSingleHeader(final String name) {
         for (final String s : SINGLE_HEADERS) {
             if (s.equalsIgnoreCase(name)) {
                 return true;
             }
         }
         return false;
     }
     /*
      * Assert.asserts that two request or response bodies are byte-equivalent.
      */
     public static boolean equivalent(final HttpEntity e1, final HttpEntity e2) throws Exception {
         final InputStream i1 = e1.getContent();
         final InputStream i2 = e2.getContent();
         if (i1 == null && i2 == null) {
             return true;
         }
         if (i1 == null || i2 == null) {
             return false; // avoid possible NPEs below
         }
         int b1 = -1;
         while ((b1 = i1.read()) != -1) {
             if (b1 != i2.read()) {
                 return false;
             }
         }
         return (-1 == i2.read());
     }
 
     /*
      * Retrieves the full header value by combining multiple headers and
      * separating with commas, canonicalizing whitespace along the way.
      *
      * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
      */
     public static String getCanonicalHeaderValue(final HttpMessage r, final String name) {
         if (isSingleHeader(name)) {
             final Header h = r.getFirstHeader(name);
             return (h != null) ? h.getValue() : null;
         }
         final StringBuilder buf = new StringBuilder();
         boolean first = true;
         for (final Header h : r.getHeaders(name)) {
             if (!first) {
                 buf.append(", ");
             }
             buf.append(h.getValue().trim());
             first = false;
         }
         return buf.toString();
     }
 
     /*
      * Assert.asserts that all the headers appearing in r1 also appear in r2
      * with the same canonical header values.
      */
     public static boolean isEndToEndHeaderSubset(final HttpMessage r1, final HttpMessage r2) {
         for (final Header h : r1.getHeaders()) {
             if (!isHopByHopHeader(h.getName())) {
                 final String r1val = getCanonicalHeaderValue(r1, h.getName());
                 final String r2val = getCanonicalHeaderValue(r2, h.getName());
                 if (!r1val.equals(r2val)) {
                     return false;
                 }
             }
         }
         return true;
     }
 
     /*
      * Assert.asserts that message {@code r2} represents exactly the same
      * message as {@code r1}, except for hop-by-hop headers. "When a cache
      * is semantically transparent, the client receives exactly the same
      * response (except for hop-by-hop headers) that it would have received had
      * its request been handled directly by the origin server."
      *
      * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec1.html#sec1.3
      */
     public static boolean semanticallyTransparent(
             final ClassicHttpResponse r1, final ClassicHttpResponse r2) throws Exception {
         final boolean entitiesEquivalent = equivalent(r1.getEntity(), r2.getEntity());
         if (!entitiesEquivalent) {
             return false;
         }
         final boolean statusLinesEquivalent = LangUtils.equals(r1.getReasonPhrase(), r2.getReasonPhrase())
                 && r1.getCode() == r2.getCode();
         if (!statusLinesEquivalent) {
             return false;
         }
         return isEndToEndHeaderSubset(r1, r2);
     }
 
     /* Assert.asserts that protocol versions equivalent. */
     public static boolean equivalent(final ProtocolVersion v1, final ProtocolVersion v2) {
         return LangUtils.equals(v1 != null ? v1 : HttpVersion.DEFAULT, v2 != null ? v2 : HttpVersion.DEFAULT );
     }
 
     /* Assert.asserts that two requests are morally equivalent. */
     public static boolean equivalent(final HttpRequest r1, final HttpRequest r2) {
         return equivalent(r1.getVersion(), r2.getVersion()) &&
                 LangUtils.equals(r1.getMethod(), r2.getMethod()) &&
                 LangUtils.equals(r1.getRequestUri(), r2.getRequestUri()) &&
                 isEndToEndHeaderSubset(r1, r2);
     }
 
     /* Assert.asserts that two requests are morally equivalent. */
     public static boolean equivalent(final HttpResponse r1, final HttpResponse r2) {
         return equivalent(r1.getVersion(), r2.getVersion()) &&
                 r1.getCode() == r2.getCode() &&
                 LangUtils.equals(r1.getReasonPhrase(), r2.getReasonPhrase()) &&
                 isEndToEndHeaderSubset(r1, r2);
     }
 
     public static byte[] getRandomBytes(final int nbytes) {
         final byte[] bytes = new byte[nbytes];
         new Random().nextBytes(bytes);
         return bytes;
     }
 
     public static ByteArrayBuffer getRandomBuffer(final int nbytes) {
         final ByteArrayBuffer buf = new ByteArrayBuffer(nbytes);
         buf.setLength(nbytes);
         new Random().nextBytes(buf.array());
         return buf;
     }
 
     /** Generates a response body with random content.
      *  @param nbytes length of the desired response body
      *  @return an {@link HttpEntity}
      */
     public static HttpEntity makeBody(final int nbytes) {
         return new ByteArrayEntity(getRandomBytes(nbytes), null);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Date requestDate, final Date responseDate) {
         final Date when = new Date((responseDate.getTime() + requestDate.getTime()) / 2);
         return makeCacheEntry(requestDate, responseDate, getStockHeaders(when));
     }
 
     public static Header[] getStockHeaders(final Date when) {
         final Header[] headers = {
                 new BasicHeader("Date", DateUtils.formatDate(when)),
                 new BasicHeader("Server", "MockServer/1.0")
         };
         return headers;
     }
 
     public static HttpCacheEntry makeCacheEntry(final Date requestDate,
             final Date responseDate, final Header[] headers) {
         final byte[] bytes = getRandomBytes(128);
         return makeCacheEntry(requestDate, responseDate, headers, bytes);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Date requestDate,
             final Date responseDate, final Header[] headers, final byte[] bytes) {
         final Map<String,String> variantMap = null;
         return makeCacheEntry(requestDate, responseDate, headers, bytes,
                 variantMap);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Map<String,String> variantMap) {
         final Date now = new Date();
         return makeCacheEntry(now, now, getStockHeaders(now),
                 getRandomBytes(128), variantMap);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Date requestDate,
             final Date responseDate, final Header[] headers, final byte[] bytes,
             final Map<String,String> variantMap) {
         return new HttpCacheEntry(requestDate, responseDate, HttpStatus.SC_OK, headers, new HeapResource(bytes), variantMap);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Header[] headers, final byte[] bytes) {
         final Date now = new Date();
         return makeCacheEntry(now, now, headers, bytes);
     }
 
     public static HttpCacheEntry makeCacheEntry(final byte[] bytes) {
         return makeCacheEntry(getStockHeaders(new Date()), bytes);
     }
 
     public static HttpCacheEntry makeCacheEntry(final Header[] headers) {
         return makeCacheEntry(headers, getRandomBytes(128));
     }
 
     public static HttpCacheEntry makeCacheEntry() {
         final Date now = new Date();
         return makeCacheEntry(now, now);
     }
 
     public static HttpCacheEntry makeCacheEntryWithNoRequestMethodOrEntity(final Header[] headers) {
         final Date now = new Date();
         return new HttpCacheEntry(now, now, HttpStatus.SC_OK, headers, null, null);
     }
 
     public static HttpCacheEntry makeCacheEntryWithNoRequestMethod(final Header[] headers) {
         final Date now = new Date();
         return new HttpCacheEntry(now, now, HttpStatus.SC_OK, headers, new HeapResource(getRandomBytes(128)), null);
     }
 
     public static HttpCacheEntry make204CacheEntryWithNoRequestMethod(final Header[] headers) {
         final Date now = new Date();
         return new HttpCacheEntry(now, now, HttpStatus.SC_NO_CONTENT, headers, null, null);
     }
 
     public static HttpCacheEntry makeHeadCacheEntry(final Header[] headers) {
         final Date now = new Date();
         return new HttpCacheEntry(now, now, HttpStatus.SC_OK, headers, null, null);
     }
 
     public static HttpCacheEntry makeHeadCacheEntryWithNoRequestMethod(final Header[] headers) {
         final Date now = new Date();
         return new HttpCacheEntry(now, now, HttpStatus.SC_OK, headers, null, null);
     }
 
     public static ClassicHttpResponse make200Response() {
         final ClassicHttpResponse out = new BasicClassicHttpResponse(HttpStatus.SC_OK, "OK");
         out.setHeader("Date", DateUtils.formatDate(new Date()));
         out.setHeader("Server", "MockOrigin/1.0");
         out.setHeader("Content-Length", "128");
         out.setEntity(makeBody(128));
         return out;
     }
 
     public static final ClassicHttpResponse make200Response(final Date date, final String cacheControl) {
         final ClassicHttpResponse response = HttpTestUtils.make200Response();
         response.setHeader("Date", DateUtils.formatDate(date));
         response.setHeader("Cache-Control",cacheControl);
         response.setHeader("Etag","\"etag\"");
         return response;
     }
 
     public static ClassicHttpResponse make304Response() {
         return new BasicClassicHttpResponse(HttpStatus.SC_NOT_MODIFIED, "Not modified");
     }
 
     public static final void assert110WarningFound(final HttpResponse response) {
         boolean found110Warning = false;
         final Iterator<HeaderElement> it = MessageSupport.iterate(response, HttpHeaders.WARNING);
         while (it.hasNext()) {
             final HeaderElement elt = it.next();
             final String[] parts = elt.getName().split("\\s");
             if ("110".equals(parts[0])) {
                 found110Warning = true;
                 break;
             }
         }
         Assert.assertTrue(found110Warning);
     }
 
     public static ClassicHttpRequest makeDefaultRequest() {
         return new BasicClassicHttpRequest("GET", "/");
     }
 
     public static ClassicHttpRequest makeDefaultHEADRequest() {
         return new BasicClassicHttpRequest("HEAD", "/");
     }
 
     public static ClassicHttpResponse make500Response() {
         return new BasicClassicHttpResponse(HttpStatus.SC_INTERNAL_SERVER_ERROR, "Internal Server Error");
     }
 
     public static Map<String, String> makeDefaultVariantMap(final String key, final String value) {
         final Map<String, String> variants = new HashMap<>();
         variants.put(key, value);
 
         return variants;
     }
 }