/*
 * 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.classic.response;

import static org.apache.juneau.commons.utils.Shorts.*;
import static org.apache.juneau.http.classic.HttpEntities.*;

import java.net.*;
import java.util.*;

import org.apache.http.*;
import org.apache.http.Header;
import org.apache.http.impl.*;
import org.apache.http.params.*;
import org.apache.juneau.http.*;
import org.apache.juneau.http.classic.*;
import org.apache.juneau.http.classic.header.*;
import org.apache.juneau.marshall.*;

/**
 * Basic implementation of the {@link HttpResponse} interface.
 *
 * <p>
 * Although this class implements the various setters defined on the {@link HttpResponse} interface, it's in general
 * going to be more efficient to set the status/headers/content of this bean through the builder.
 *
 * <p>
 * Immutability is expressed with the "funnel + nested {@code Unmodifiable} snapshot" paradigm: every mutator (fluent
 * setter and {@code void} interface mutator) routes through the single protected {@link #modify(Runnable)} choke-point,
 * and each concrete leaf gets a nested {@code X.Unmodifiable} whose only behavioral override is a throwing
 * {@code modify(...)}.  A leaf's {@link #unmodifiable()} factory returns a point-in-time snapshot of type
 * {@code X.Unmodifiable}; any attempt to set a property on it throws an {@link UnsupportedOperationException}.
 *
 * <p>
 * This is a self-typed (CRTP) root: a leaf declares <c>class Ok <jk>extends</jk> BasicHttpResponse&lt;Ok&gt;</c> and
 * inherits leaf-typed fluent setters with no covariant overrides.
 *
 * <h5 class='section'>Notes:</h5><ul>
 *    <li class='warn'>Beans are not thread safe unless they're marked as unmodifiable.
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommon">juneau-rest-common</a>
 * </ul>
 *
 * @param <SELF> The self type for fluent setters.
 */
@Marshalled(as=MarshalledAs.STRING)
@SuppressWarnings({
   "deprecation", // Uses deprecated HttpMessage API
   "java:S119", // 'SELF' (CRTP self-type) is intentional and clearer than a single-letter name.
   "java:S1192" // Duplicated literals (argument/property names) read more clearly inline than as constants
})
public abstract class BasicHttpResponse<SELF extends BasicHttpResponse<SELF>> implements HttpResponse {

   BasicStatusLine statusLine = new BasicStatusLine();
   HeaderList headers = HeaderList.create();
   HttpEntity content;

   /**
    * Copy constructor.
    *
    * @param copyFrom The bean to copy from.  Must not be <jk>null</jk>.
    */
   protected BasicHttpResponse(BasicHttpResponse<?> copyFrom) {
      statusLine = copyFrom.statusLine.copy();
      headers = copyFrom.headers.copy();
      content = copyFrom.content;
   }

   /**
    * Constructor.
    *
    * @param statusLine The HTTP status line.  Must not be <jk>null</jk>.
    */
   protected BasicHttpResponse(BasicStatusLine statusLine) {
      setStatusLine(statusLine.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>.
    */
   protected BasicHttpResponse(HttpResponse response) {
      reqnn("response", response);
      setHeaders(response.getAllHeaders());
      setContent(response.getEntity());
      setStatusLine(response.getStatusLine());
   }

   @Override /* Overridden from HttpMessage */
   public void addHeader(Header value) {
      modify(() -> headers.append(value));
   }

   @Override /* Overridden from HttpMessage */
   public void addHeader(String name, String value) {
      modify(() -> headers.append(name, value));
   }

   @Override /* Overridden from HttpMessage */
   public boolean containsHeader(String name) {
      return headers.contains(name);
   }

   @Override /* Overridden from HttpMessage */
   public Header[] getAllHeaders() { return headers.getAll(); }

   @Override /* Overridden from HttpMessage */
   public HttpEntity getEntity() {
      // Constructing a StringEntity is somewhat expensive, so don't create it unless it's needed.
      if (content == null)
         content = stringEntity(getStatusLine().getReasonPhrase());
      return content;
   }

   @Override /* Overridden from HttpMessage */
   public Header getFirstHeader(String name) {
      return headers.getFirst(name).orElse(null);
   }

   /**
    * Returns access to the underlying builder for the headers.
    *
    * @return The underlying builder for the headers.
    */
   public HeaderList getHeaders() { return headers; }

   @Override /* Overridden from HttpMessage */
   public Header[] getHeaders(String name) {
      return headers.getAll(name);
   }

   @Override /* Overridden from HttpMessage */
   public Header getLastHeader(String name) {
      return headers.getLast(name).orElse(null);
   }

   @Override /* Overridden from HttpMessage */
   public Locale getLocale() { return statusLine.getLocale(); }

   @Override /* Overridden from HttpMessage */
   public HttpParams getParams() { return null; }

   @Override /* Overridden from HttpMessage */
   public ProtocolVersion getProtocolVersion() { return statusLine.getProtocolVersion(); }

   @Override /* Overridden from HttpMessage */
   public StatusLine getStatusLine() { return statusLine; }

   @Override /* Overridden from HttpMessage */
   public HeaderIterator headerIterator() {
      return headers.headerIterator();
   }

   @Override /* Overridden from HttpMessage */
   public HeaderIterator headerIterator(String name) {
      return headers.headerIterator(name);
   }

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

   @Override /* Overridden from HttpMessage */
   public void removeHeader(Header value) {
      modify(() -> headers.remove(value));
   }

   @Override /* Overridden from HttpMessage */
   public void removeHeaders(String name) {
      modify(() -> headers.remove(name));
   }

   /**
    * Sets the body on this response.
    *
    * @param value The body on this response.  Can be <jk>null</jk> to unset the property.
    * @return This object.
    */
   public SELF setContent(HttpEntity value) {
      return modify(() -> content = value);
   }

   /**
    * Sets the body on this response.
    *
    * @param value The body on this response.  Can be <jk>null</jk> (treated as an empty string).
    * @return This object.
    */
   public SELF setContent(String value) {
      return modify(() -> content = stringEntity(value));
   }

   @Override /* Overridden from HttpMessage */
   public void setEntity(HttpEntity entity) {
      modify(() -> content = entity);
   }

   @Override /* Overridden from HttpMessage */
   public void setHeader(Header value) {
      modify(() -> headers.set(value));
   }

   @Override /* Overridden from HttpMessage */
   public void setHeader(String name, String value) {
      modify(() -> headers.set(name, value));
   }

   /**
    * Sets the specified header to the end of the headers in this builder.
    *
    * @param value The header to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public SELF setHeader2(Header value) {
      return modify(() -> headers.set(value));
   }

   /**
    * Sets the specified header to the end of the headers in this builder.
    *
    * @param name The header name.
    * @param value The header value.
    * @return This object.
    */
   public SELF setHeader2(String name, String value) {
      return modify(() -> headers.set(name, value));
   }

   @Override /* Overridden from HttpMessage */
   public void setHeaders(Header[] values) {
      modify(() -> headers.removeAll().append(values));
   }

   /**
    * Sets the specified headers on this response.
    *
    * @param value The new value.  Must not be <jk>null</jk>.
    * @return This object.
    */
   public SELF setHeaders(HeaderList value) {
      return modify(() -> headers = value.copy());
   }

   /**
    * Sets the specified headers to the end of the headers in this builder.
    *
    * @param values The headers to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public SELF setHeaders(List<Header> values) {
      return modify(() -> headers.set(values));
   }

   /**
    * Sets the specified headers to the end of the headers in this builder.
    *
    * @param values The headers to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public SELF setHeaders2(Header...values) {
      return modify(() -> headers.set(values));
   }

   @Override /* Overridden from HttpMessage */
   public void setLocale(Locale loc) {
      modify(() -> statusLine.setLocale(loc));
   }

   /**
    * Sets the locale used to retrieve reason phrases.
    *
    * <p>
    * If not specified, uses {@link Locale#getDefault()}.
    *
    * @param value The new value.  Can be <jk>null</jk>.  The effect is implementation-dependent, depending on the configured {@link ReasonPhraseCatalog} (e.g. ignored by {@link EnglishReasonPhraseCatalog}).
    * @return This object.
    */
   public SELF setLocale2(Locale value) {
      return modify(() -> statusLine.setLocale(value));
   }

   /**
    * Specifies the value for the <c>Location</c> header.
    *
    * @param value The new header location.  Can be <jk>null</jk> (no-op; the header is left unchanged).
    * @return This object.
    */
   public SELF setLocation(String value) {
      return modify(() -> headers.set(Location.of(value)));
   }

   /**
    * Specifies the value for the <c>Location</c> header.
    *
    * @param value The new header location.  Can be <jk>null</jk> (no-op; the header is left unchanged).
    * @return This object.
    */
   public SELF setLocation(URI value) {
      return modify(() -> headers.set(Location.of(value)));
   }

   @Override /* Overridden from HttpMessage */
   public void setParams(HttpParams params) {
      // Deprecated optional interface method; routed through the funnel so it is frozen on unmodifiable snapshots.
      modify(() -> { /* No-op */ });
   }

   /**
    * Sets the protocol version on the status line.
    *
    * <p>
    * If not specified, <js>"HTTP/1.1"</js> will be used.
    *
    * @param value The new value.  Can be <jk>null</jk>, in which case the default protocol version is cleared and {@link BasicStatusLine#getProtocolVersion()} returns <jk>null</jk>.
    * @return This object.
    */
   public SELF setProtocolVersion(ProtocolVersion value) {
      return modify(() -> statusLine.setProtocolVersion(value));
   }

   @Override /* Overridden from HttpMessage */
   public void setReasonPhrase(String reason) throws IllegalStateException {
      modify(() -> statusLine.setReasonPhrase(reason));
   }

   /**
    * Sets the reason phrase on the status line.
    *
    * <p>
    * If not specified, the reason phrase will be retrieved from the reason phrase catalog
    * using the locale on this builder.
    *
    * @param value The new value.  Can be <jk>null</jk> to fall back to the reason phrase catalog.
    * @return This object.
    */
   public SELF setReasonPhrase2(String value) {
      return modify(() -> statusLine.setReasonPhrase(value));
   }

   /**
    * Sets the reason phrase catalog used to retrieve reason phrases.
    *
    * <p>
    * If not specified, uses {@link EnglishReasonPhraseCatalog}.
    *
    * @param value The new value.  Can be <jk>null</jk> to fall back to {@link EnglishReasonPhraseCatalog#INSTANCE}.
    * @return This object.
    */
   public SELF setReasonPhraseCatalog(ReasonPhraseCatalog value) {
      return modify(() -> statusLine.setReasonPhraseCatalog(value));
   }

   @Override /* Overridden from HttpMessage */
   public void setStatusCode(int code) throws IllegalStateException {
      modify(() -> statusLine.setStatusCode(code));
   }

   /**
    * Sets the status code on the status line.
    *
    * <p>
    * If not specified, <c>0</c> will be used.
    *
    * @param value The new value.
    * @return This object.
    */
   public SELF setStatusCode2(int value) {
      return modify(() -> statusLine.setStatusCode(value));
   }

   /**
    * Sets the protocol version on the status line.
    *
    * <p>
    * If not specified, <js>"HTTP/1.1"</js> will be used.
    *
    * @param value The new value.  Must not be <jk>null</jk>.
    * @return This object.
    */
   public SELF setStatusLine(BasicStatusLine value) {
      return modify(() -> statusLine = value.copy());
   }

   @Override /* Overridden from HttpMessage */
   public void setStatusLine(ProtocolVersion ver, int code) {
      modify(() -> statusLine.setProtocolVersion(ver).setStatusCode(code));
   }

   @Override /* Overridden from HttpMessage */
   public void setStatusLine(ProtocolVersion ver, int code, String reason) {
      modify(() -> statusLine.setProtocolVersion(ver).setReasonPhrase(reason).setStatusCode(code));
   }

   @Override /* Overridden from HttpMessage */
   public void setStatusLine(StatusLine value) {
      modify(() -> statusLine.setProtocolVersion(value.getProtocolVersion()).setReasonPhrase(value.getReasonPhrase()).setStatusCode(value.getStatusCode()));
   }

   /**
    * Returns an unmodifiable snapshot of this bean.
    *
    * <p>
    * The returned instance is a point-in-time copy of the leaf's nested {@code Unmodifiable} type; any attempt to set a
    * property on it throws an {@link UnsupportedOperationException}.  This method is idempotent: if this bean is already
    * unmodifiable it returns itself rather than taking another snapshot.  The receiver is left unchanged (and still
    * modifiable unless it was already unmodifiable).
    *
    * @return An unmodifiable snapshot of this bean, or this bean if it is already unmodifiable.
    */
   public abstract SELF unmodifiable();

   @Override /* Overridden from Object */
   public String toString() {
      var sb = new StringBuilder().append(statusLine).append(' ').append(headers);
      if (nn(content))
         sb.append(' ').append(content);
      return sb.toString();
   }

   @Override /* Overridden from Object */
   public boolean equals(Object o) {
      return o instanceof BasicHttpResponse<?> other && eq(this, other, (x, y) ->
         eq(x.statusLine, y.statusLine) && eq(x.headers, y.headers) && eq(x.content, y.content));
   }

   @Override /* Overridden from Object */
   public int hashCode() {
      return h(statusLine, headers, content);
   }

   /**
    * Returns this object cast to the self type.
    *
    * @return This object.
    */
   @SuppressWarnings({
      "unchecked" // CRTP self-type cast is safe: SELF is bound to the concrete leaf type.
   })
   protected final SELF self() { return (SELF) this; }

   /**
    * Single mutation funnel — the only choke-point through which all state changes on this bean flow.
    *
    * <p>
    * Every mutator (fluent setter and {@code void} interface mutator) routes through this method.  The nested
    * {@code Unmodifiable} snapshot overrides only this method to throw, which freezes the entire mutation surface with
    * a single override.
    *
    * @param mutation The state change to apply.
    * @return This object.
    */
   protected SELF modify(Runnable mutation) {
      mutation.run();
      return self();
   }

   /**
    * Deep-freeze hook invoked from the nested {@code Unmodifiable} constructor after the snapshot copy completes.
    *
    * <p>
    * The mutable sub-beans are frozen here by <b>direct field assignment</b> (never via a setter, which would route
    * through the throwing {@link #modify(Runnable)} and blow up during construction).  A leaf that adds its own mutable
    * sub-bean overrides this method (calling {@code super.freeze()} first).
    */
   protected void freeze() {
      statusLine = statusLine.unmodifiable();   // DIRECT field write — must NOT use setStatusLine(...)
      headers = headers.unmodifiable();         // DIRECT field write — snapshot the copied HeaderList.
   }

   /**
    * Verifies that the specified HTTP response has the expected status code and returns it.
    *
    * @param response The HTTP response to check.  Must not be <jk>null</jk>.
    * @param expected The status code the response is required to have.
    * @return The same response.
    * @throws IllegalArgumentException If the response status code is not what was expected.
    */
   static HttpResponse requireStatus(HttpResponse response, int expected) throws IllegalArgumentException {
      return BasicHttpException.requireStatus(response, expected);
   }

   /**
    * Asserts that the specified HTTP response has the same status code as the one on the status line of this bean.
    *
    * @param response The HTTP response to check.  Must not be <jk>null</jk>.
    * @throws IllegalArgumentException If status code is not what was expected.
    */
   protected void assertStatusCode(HttpResponse response) throws IllegalArgumentException {
      requireStatus(response, getStatusLine().getStatusCode());
   }
}