/*
 * Copyright 2013 Netflix, Inc.
 *
 * Licensed 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 feign;

import java.io.ByteArrayInputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;

import static feign.Util.UTF_8;
import static feign.Util.checkNotNull;
import static feign.Util.checkState;
import static feign.Util.decodeOrDefault;
import static feign.Util.valuesOrEmpty;

/**
 * An immutable response to an http invocation which only returns string content.
 */
public final class Response implements Closeable {

  private final int status;
  private final String reason;
  private final Map<String, Collection<String>> headers;
  private final Body body;

  private Response(int status, String reason, Map<String, Collection<String>> headers, Body body) {
    checkState(status >= 200, "Invalid status code: %s", status);
    this.status = status;
    this.reason = reason; //nullable
    this.headers = Collections.unmodifiableMap(caseInsensitiveCopyOf(headers));
    this.body = body; //nullable
  }

  public static Response create(int status, String reason, Map<String, Collection<String>> headers,
                                InputStream inputStream, Integer length) {
    return new Response(status, reason, headers, InputStreamBody.orNull(inputStream, length));
  }

  public static Response create(int status, String reason, Map<String, Collection<String>> headers,
                                byte[] data) {
    return new Response(status, reason, headers, ByteArrayBody.orNull(data));
  }

  public static Response create(int status, String reason, Map<String, Collection<String>> headers,
                                String text, Charset charset) {
    return new Response(status, reason, headers, ByteArrayBody.orNull(text, charset));
  }

  public static Response create(int status, String reason, Map<String, Collection<String>> headers,
                                Body body) {
    return new Response(status, reason, headers, body);
  }

  /**
   * status code. ex {@code 200}
   *
   * See <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html" >rfc2616</a>
   */
  public int status() {
    return status;
  }

  /**
   * Nullable and not set when using http/2
   *
   * See https://github.com/http2/http2-spec/issues/202
   */
  public String reason() {
    return reason;
  }

  /**
   * Returns a case-insensitive mapping of header names to their values.
   */
  public Map<String, Collection<String>> headers() {
    return headers;
  }

  /**
   * if present, the response had a body
   */
  public Body body() {
    return body;
  }

  @Override
  public String toString() {
    StringBuilder builder = new StringBuilder("HTTP/1.1 ").append(status);
    if (reason != null) builder.append(' ').append(reason);
    builder.append('\n');
    for (String field : headers.keySet()) {
      for (String value : valuesOrEmpty(headers, field)) {
        builder.append(field).append(": ").append(value).append('\n');
      }
    }
    if (body != null) builder.append('\n').append(body);
    return builder.toString();
  }

  @Override
  public void close() {
    Util.ensureClosed(body);
  }

  public interface Body extends Closeable {

    /**
     * length in bytes, if known. Null if unknown or greater than {@link Integer#MAX_VALUE}.
     *
     * <br><br><br><b>Note</b><br> This is an integer as
     * most implementations cannot do bodies greater than 2GB.
     */
    Integer length();

    /**
     * True if {@link #asInputStream()} and {@link #asReader()} can be called more than once.
     */
    boolean isRepeatable();

    /**
     * It is the responsibility of the caller to close the stream.
     */
    InputStream asInputStream() throws IOException;

    /**
     * It is the responsibility of the caller to close the stream.
     */
    Reader asReader() throws IOException;
  }

  private static final class InputStreamBody implements Response.Body {

    private final InputStream inputStream;
    private final Integer length;
    private InputStreamBody(InputStream inputStream, Integer length) {
      this.inputStream = inputStream;
      this.length = length;
    }

    private static Body orNull(InputStream inputStream, Integer length) {
      if (inputStream == null) {
        return null;
      }
      return new InputStreamBody(inputStream, length);
    }

    @Override
    public Integer length() {
      return length;
    }

    @Override
    public boolean isRepeatable() {
      return false;
    }

    @Override
    public InputStream asInputStream() throws IOException {
      return inputStream;
    }

    @Override
    public Reader asReader() throws IOException {
      return new InputStreamReader(inputStream, UTF_8);
    }

    @Override
    public void close() throws IOException {
      inputStream.close();
    }
  }

  private static final class ByteArrayBody implements Response.Body {

    private final byte[] data;

    public ByteArrayBody(byte[] data) {
      this.data = data;
    }

    private static Body orNull(byte[] data) {
      if (data == null) {
        return null;
      }
      return new ByteArrayBody(data);
    }

    private static Body orNull(String text, Charset charset) {
      if (text == null) {
        return null;
      }
      checkNotNull(charset, "charset");
      return new ByteArrayBody(text.getBytes(charset));
    }

    @Override
    public Integer length() {
      return data.length;
    }

    @Override
    public boolean isRepeatable() {
      return true;
    }

    @Override
    public InputStream asInputStream() throws IOException {
      return new ByteArrayInputStream(data);
    }

    @Override
    public Reader asReader() throws IOException {
      return new InputStreamReader(asInputStream(), UTF_8);
    }

    @Override
    public void close() throws IOException {
    }

    @Override
    public String toString() {
      return decodeOrDefault(data, UTF_8, "Binary data");
    }
  }

  private static Map<String, Collection<String>> caseInsensitiveCopyOf(Map<String, Collection<String>> headers) {
    Map<String, Collection<String>> result = new TreeMap<String, Collection<String>>(String.CASE_INSENSITIVE_ORDER);

    for (Map.Entry<String, Collection<String>> entry : headers.entrySet()) {
      String headerName = entry.getKey();
      if (!result.containsKey(headerName)) {
        result.put(headerName.toLowerCase(Locale.ROOT), new LinkedList<String>());
      }
      result.get(headerName).addAll(entry.getValue());
    }
    return result;
  }
}