/*
    * Copyright (C) 2023 B3Partners B.V.
    *
    * SPDX-License-Identifier: MIT
    */
   package org.tailormap.api.geotools;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
  import java.io.InputStream;
  import java.net.URL;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  import java.util.function.BiConsumer;
  import org.geotools.http.HTTPClient;
  import org.geotools.http.HTTPResponse;
  
  /**
   * Wrapper for a GeoTools HTTPClient that allows access to the response headers and body after the original response has
   * been consumed and disposed of by other code. The response body for the latest request is kept in memory, a consumer
   * can be specified to get responses of earlier requests. Response headers of an unwrapped HTTPClient can only be
   * retrieved when the response isn't disposed, this wrapper allows response headers to be cached for retrieval even
   * after disposal.
   */
  public class ResponseTeeingHTTPClient implements HTTPClient {
  
    public class TeeHTTPResponseWrapper implements HTTPResponse {
      private final HTTPResponse wrapped;
  
      private boolean disposed = false;
      private final ByteArrayOutputStream copy = new ByteArrayOutputStream();
  
      private String contentType;
      private final Map<String, String> cachedResponseHeaders = new HashMap<>();
  
      public TeeHTTPResponseWrapper(HTTPResponse wrapped) {
        this.wrapped = wrapped;
      }
  
      public byte[] getCopy() {
        return copy.toByteArray();
      }
  
      // <editor-fold desc="methods directly delegated to wrapped object">
      @Override
      public void dispose() {
        disposed = true;
        wrapped.dispose();
      }
  
      public boolean isDisposed() {
        return disposed;
      }
  
      @Override
      public String getContentType() {
        if (contentType == null) {
          contentType = wrapped.getContentType();
        }
        return contentType;
      }
  
      @Override
      public String getResponseHeader(String header) {
        if (cachedResponseHeaders.containsKey(header)) {
          return cachedResponseHeaders.get(header);
        }
        // When disposed, the wrapped client will probably throw a NPE when trying to get a response
        // header
        if (isDisposed()) {
          return null;
        }
        return wrapped.getResponseHeader(header);
      }
  
      @Override
      public InputStream getResponseStream() throws IOException {
        // Cache response headers now, when the internal connection is still available
        for (String header : responseHeadersToCache) {
          cachedResponseHeaders.put(header, wrapped.getResponseHeader(header));
        }
        return new org.apache.commons.io.input.TeeInputStream(wrapped.getResponseStream(), copy);
      }
  
      @Override
      public String getResponseCharset() {
        return wrapped.getResponseCharset();
      }
      // </editor-fold>
    }
  
    private TeeHTTPResponseWrapper responseWrapper;
  
    private final HTTPClient wrapped;
  
    private final BiConsumer<URL, TeeHTTPResponseWrapper> requestConsumer;
  
    private final Set<String> responseHeadersToCache;
 
   /**
    * Wrap a GeoTools HTTPClient allowing access to the latest response body after it has been consumed by handing the
    * client to a GeoTools module. Note that getting the response headers after the original response has been consumed
    * will return null without explicitly calling the other constructor with the responseHeadersToCache parameter.
    *
    * @param wrapped The GeoTools HTTPClient to wrap
    */
   public ResponseTeeingHTTPClient(HTTPClient wrapped) {
     this(wrapped, null, null);
   }
 
   /**
    * Wrap a GeoTools HTTPClient allowing access to the all responses after they have been consumed by handing the
    * client to a GeoTools module by passing a consumer for each request URL and wrapped response. The
    * responseHeadersToCache parameter allows access to response headers after the original wrapped response has been
    * disposed (only cached when getResponseStream() is requested).
    *
    * @param wrapped The GeoTools HTTPClient to wrap
    * @param requestConsumer Consumer for each request so not only the latest response can be accessed, may be null
    * @param responseHeadersToCache Which response headers to cache, may be null
    */
   public ResponseTeeingHTTPClient(
       HTTPClient wrapped,
       BiConsumer<URL, TeeHTTPResponseWrapper> requestConsumer,
       Set<String> responseHeadersToCache) {
     this.wrapped = wrapped;
     this.requestConsumer = requestConsumer == null ? (url, response) -> {} : requestConsumer;
     this.responseHeadersToCache = responseHeadersToCache == null ? Set.of() : responseHeadersToCache;
   }
 
   @Override
   public HTTPResponse get(URL url, Map<String, String> headers) throws IOException {
     this.responseWrapper = new TeeHTTPResponseWrapper(wrapped.get(url, headers));
     requestConsumer.accept(url, this.responseWrapper);
     return responseWrapper;
   }
 
   @Override
   public HTTPResponse post(URL url, InputStream inputStream, String s) throws IOException {
     this.responseWrapper = new TeeHTTPResponseWrapper(wrapped.post(url, inputStream, s));
     requestConsumer.accept(url, this.responseWrapper);
     return responseWrapper;
   }
 
   @Override
   public HTTPResponse get(URL url) throws IOException {
     this.responseWrapper = new TeeHTTPResponseWrapper(wrapped.get(url));
     requestConsumer.accept(url, this.responseWrapper);
     return responseWrapper;
   }
 
   public HTTPResponse getLatestResponse() {
     return responseWrapper;
   }
 
   public byte[] getLatestResponseCopy() {
     return responseWrapper == null ? null : responseWrapper.getCopy();
   }
 
   // <editor-fold desc="methods directly delegated to wrapped object">
   @Override
   public String getUser() {
     return wrapped.getUser();
   }
 
   @Override
   public void setUser(String user) {
     wrapped.setUser(user);
   }
 
   @Override
   public String getPassword() {
     return wrapped.getPassword();
   }
 
   @Override
   public void setPassword(String password) {
     wrapped.setPassword(password);
   }
 
   @Override
   public Map<String, String> getExtraParams() {
     return wrapped.getExtraParams();
   }
 
   @Override
   public void setExtraParams(Map<String, String> extraParams) {
     wrapped.setExtraParams(extraParams);
   }
 
   @Override
   public int getConnectTimeout() {
     return wrapped.getConnectTimeout();
   }
 
   @Override
   public void setConnectTimeout(int connectTimeout) {
     wrapped.setConnectTimeout(connectTimeout);
   }
 
   @Override
   public int getReadTimeout() {
     return wrapped.getReadTimeout();
   }
 
   @Override
   public void setReadTimeout(int readTimeout) {
     wrapped.setReadTimeout(readTimeout);
   }
 
   @Override
   public void setTryGzip(boolean tryGZIP) {
     wrapped.setTryGzip(tryGZIP);
   }
 
   @Override
   public boolean isTryGzip() {
     return wrapped.isTryGzip();
   }
   // </editor-fold>
 }