/*
 * 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.http.resource;

import static org.apache.juneau.common.utils.Utils.*;

import java.io.*;
import java.util.function.*;

import org.apache.http.*;
import org.apache.juneau.annotation.*;
import org.apache.juneau.assertions.*;
import org.apache.juneau.http.entity.*;
import org.apache.juneau.http.header.*;
import org.apache.juneau.internal.*;

/**
 * A basic {@link org.apache.juneau.http.resource.HttpResource} implementation with additional features.
 *
 * Provides the following features:
 * <ul class='spaced-list'>
 *    <li>
 *       Caching.
 *    <li>
 *       Fluent setters.
 *    <li>
 *       Fluent assertions.
 *    <li>
 *       Externally-supplied/dynamic content.
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a>
 * </ul>
 */
@BeanIgnore  /* Use toString() to serialize */
public class BasicResource implements HttpResource {

   //-----------------------------------------------------------------------------------------------------------------
   // Instance
   //-----------------------------------------------------------------------------------------------------------------

   BasicHttpEntity entity;
   HeaderList headers = HeaderList.create();
   boolean unmodifiable;

   /**
    * Constructor.
    *
    * @param entity The entity that makes up this resource content.
    */
   public BasicResource(BasicHttpEntity entity) {
      this.entity = entity;
   }

   /**
    * Copy constructor.
    *
    * @param copyFrom The bean bean copied.
    */
   public BasicResource(BasicResource copyFrom) {
      this.entity = copyFrom.entity.copy();
      this.headers = copyFrom.headers.copy();
   }


   /**
    * Constructor.
    *
    * <p>
    * This is the constructor used when parsing an HTTP response.
    *
    * @param response The HTTP response to copy from.  Must not be <jk>null</jk>.
    * @throws IOException Rethrown from {@link HttpEntity#getContent()}.
    */
   public BasicResource(HttpResponse response) throws IOException {
      this(new StreamEntity());
      copyFrom(response);
   }

   /**
    * Creates a builder for this class initialized with the contents of this bean.
    *
    * <p>
    * Allows you to create a modifiable copy of this bean.
    *
    * @return A new builder bean.
    */
   public BasicResource copy() {
      return new BasicResource(this);
   }

   /**
    * Copies the contents of the specified HTTP response to this builder.
    *
    * @param response The response to copy from.  Must not be null.
    * @return This object.
    * @throws IOException If content could not be retrieved.
    */
   public BasicResource copyFrom(HttpResponse response) throws IOException {
      addHeaders(response.getAllHeaders());
      setContent(response.getEntity().getContent());
      return this;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Properties
   //-----------------------------------------------------------------------------------------------------------------


   /**
    * Specifies whether this bean should be unmodifiable.
    * <p>
    * When enabled, attempting to set any properties on this bean will cause an {@link UnsupportedOperationException}.
    *
    * @return This object.
    */
   public BasicResource setUnmodifiable() {
      unmodifiable = true;
      entity.setUnmodifiable();
      headers.setUnmodifiable();
      return this;
   }

   /**
    * Returns <jk>true</jk> if this bean is unmodifiable.
    *
    * @return <jk>true</jk> if this bean is unmodifiable.
    */
   public boolean isUnmodifiable() {
      return unmodifiable;
   }

   /**
    * Throws an {@link UnsupportedOperationException} if the unmodifiable flag is set on this bean.
    */
   protected final void assertModifiable() {
      if (unmodifiable)
         throw new UnsupportedOperationException("Bean is read-only");
   }

   /**
    * Returns access to the underlying builder for the HTTP entity.
    *
    * @return The underlying builder for the HTTP entity.
    */
   public HttpEntity getEntity() {
      return entity;
   }

   /**
    * Sets the content on this entity bean.
    *
    * @param value The entity content, can be <jk>null</jk>.
    * @return This object.
    */
   public BasicResource setContent(Object value) {
      entity.setContent(value);
      return this;
   }

   /**
    * Sets the content on this entity bean from a supplier.
    *
    * <p>
    * Repeatable entities such as {@link StringEntity} use this to allow the entity content to be resolved at
    * serialization time.
    *
    * @param value The entity content, can be <jk>null</jk>.
    * @return This object.
    */
   public BasicResource setContent(Supplier<?> value) {
      entity.setContent(value);
      return this;
   }

   /**
    * Sets the content type on this entity bean.
    *
    * @param value The new <c>Content-Type</c> header, or <jk>null</jk> to unset.
    * @return This object.
    */
   public BasicResource setContentType(String value) {
      entity.setContentType(value);
      return this;
   }

   /**
    * Sets the content type on this entity bean.
    *
    * @param value The new <c>Content-Type</c> header, or <jk>null</jk> to unset.
    * @return This object.
    */
   public BasicResource setContentType(ContentType value) {
      entity.setContentType(value);
      return this;
   }

   /**
    * Sets the content length on this entity bean.
    *
    * @param value The new <c>Content-Length</c> header value, or <c>-1</c> to unset.
    * @return This object.
    */
   public BasicResource setContentLength(long value) {
      entity.setContentLength(value);
      return this;
   }

   /**
    * Sets the content encoding header on this entity bean.
    *
    * @param value The new <c>Content-Encoding</c> header, or <jk>null</jk> to unset.
    * @return This object.
    */
   public BasicResource setContentEncoding(String value) {
      entity.setContentEncoding(value);
      return this;
   }

   /**
    * Sets the content encoding header on this entity bean.
    *
    * @param value The new <c>Content-Encoding</c> header, or <jk>null</jk> to unset.
    * @return This object.
    */
   public BasicResource setContentEncoding(ContentEncoding value) {
      entity.setContentEncoding(value);
      return this;
   }

   /**
    * Sets the 'chunked' flag value to <jk>true</jk>.
    *
    * <h5 class='section'>Notes:</h5><ul>
    *    <li>If the {@link HttpEntity#getContentLength()} method returns a negative value, the HttpClient code will always
    *       use chunked encoding.
    * </ul>
    *
    * @return This object.
    */
   public BasicResource setChunked() {
      entity.setChunked();
      return this;
   }

   /**
    * Sets the 'chunked' flag value.
    *
    * <h5 class='section'>Notes:</h5><ul>
    *    <li class='note'>If the {@link HttpEntity#getContentLength()} method returns a negative value, the HttpClient code will always
    *       use chunked encoding.
    * </ul>
    *
    * @param value The new value for this flag.
    * @return This object.
    */
   public BasicResource setChunked(boolean value) {
      entity.setChunked(value);
      return this;
   }

   /**
    * Specifies that the contents of this resource should be cached into an internal byte array so that it can
    * be read multiple times.
    *
    * @return This object.
    * @throws IOException If entity could not be read into memory.
    */
   public BasicResource setCached() throws IOException {
      entity.setCached();
      return this;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // BasicHeaderGroup setters.
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Sets the specified header in this builder.
    *
    * <p>
    * This is a no-op if either the name or value is <jk>null</jk>.
    *
    * @param name The header name.
    * @param value The header value.
    * @return This object.
    */
   public BasicResource setHeader(String name, String value) {
      if (name != null && value != null)
         headers.set(name, value);
      return this;
   }

   /**
    * Appends the specified header to the end of the headers in this builder.
    *
    * <p>
    * This is a no-op if either the name or value is <jk>null</jk>.
    *
    * @param name The header name.
    * @param value The header value.
    * @return This object.
    */
   public BasicResource addHeader(String name, String value) {
      if (name != null && value != null)
         headers.append(name, value);
      return this;
   }

   /**
    * Sets the specified headers in this builder.
    *
    * @param value The new value.
    * @return This object.
    */
   public BasicResource setHeaders(HeaderList value) {
      headers = value.copy();
      return this;
   }

   /**
    * Sets the specified headers in this builder.
    *
    * @param values The headers to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public BasicResource setHeaders(Header...values) {
      for (Header h : values) {
         if (h != null) {
            String n = h.getName();
            String v = h.getValue();
            if (isNotEmpty(n)) {
               if (n.equalsIgnoreCase("content-type"))
                  setContentType(v);
               else if (n.equalsIgnoreCase("content-encoding"))
                  setContentEncoding(v);
               else if (n.equalsIgnoreCase("content-length"))
                  setContentLength(Long.parseLong(v));
               else
                  headers.set(h);
            }
         }
      }
      return this;
   }

   /**
    * Appends the specified headers to the end of the headers in this builder.
    *
    * @param values The headers to set.  <jk>null</jk> headers and headers with <jk>null</jk> names or values are ignored.
    * @return This object.
    */
   public BasicResource addHeaders(Header...values) {
      for (Header h : values) {
         if (h != null) {
            String n = h.getName();
            String v = h.getValue();
            if (isNotEmpty(n)) {
               if (n.equalsIgnoreCase("content-type"))
                  setContentType(v);
               else if (n.equalsIgnoreCase("content-encoding"))
                  setContentEncoding(v);
               else if (n.equalsIgnoreCase("content-length"))
                  setContentLength(Long.parseLong(v));
               else
                  headers.append(h);
            }
         }
      }
      return this;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Other methods
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Converts the contents of the entity of this resource as a string.
    *
    * <p>
    * Note that this may exhaust the content on non-repeatable, non-cached entities.
    *
    * @return The contents of this entity as a string.
    * @throws IOException If a problem occurred while trying to read the content.
    */
   public String asString() throws IOException {
      return entity.asString();
   }

   /**
    * Converts the contents of the entity of this resource as a byte array.
    *
    * <p>
    * Note that this may exhaust the content on non-repeatable, non-cached entities.
    *
    * @return The contents of this entity as a byte array.
    * @throws IOException If a problem occurred while trying to read the content.
    */
   public byte[] asBytes() throws IOException {
      return entity.asBytes();
   }

   /**
    * Returns an assertion on the contents of the entity of this resource.
    *
    * <p>
    * Note that this may exhaust the content on non-repeatable, non-cached entities.
    *
    * @return A new fluent assertion.
    * @throws IOException If a problem occurred while trying to read the byte array.
    */
   public FluentStringAssertion<BasicResource> assertString() throws IOException {
      return new FluentStringAssertion<>(asString(), this);
   }

   /**
    * Returns an assertion on the contents of the entity of this resource.
    *
    * <p>
    * Note that this may exhaust the content on non-repeatable, non-cached entities.
    *
    * @return A new fluent assertion.
    * @throws IOException If a problem occurred while trying to read the byte array.
    */
   public FluentByteArrayAssertion<BasicResource> assertBytes() throws IOException {
      return new FluentByteArrayAssertion<>(asBytes(), this);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Path-through methods.
   //-----------------------------------------------------------------------------------------------------------------

   @Override /* HttpEntity */
   public long getContentLength() {
      return entity.getContentLength();
   }

   @Override /* HttpEntity */
   public boolean isRepeatable() {
      return entity.isRepeatable();
   }

   @Override /* HttpEntity */
   public boolean isChunked() {
      return entity.isChunked();
   }

   @Override /* HttpEntity */
   public Header getContentType() {
      return entity.getContentType();
   }

   @Override /* HttpEntity */
   public Header getContentEncoding() {
      return entity.getContentEncoding();
   }

   @Override /* HttpEntity */
   public boolean isStreaming() {
      return entity.isStreaming();
   }

   @Override
   public void consumeContent() throws IOException {}

   @Override /* HttpEntity */
   public InputStream getContent() throws IOException, UnsupportedOperationException {
      return entity.getContent();
   }

   @Override /* HttpEntity */
   public void writeTo(OutputStream outStream) throws IOException {
      entity.writeTo(outStream);
   }

   @Override /* HttpResource */
   public HeaderList getHeaders() {
      return headers;
   }
}