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/*
 * Copyright DataStax, 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 com.datastax.driver.core;

import com.datastax.driver.core.exceptions.DriverInternalError;
import com.datastax.driver.core.exceptions.UnsupportedFeatureException;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.util.AttributeKey;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.EnumSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** A message from the CQL binary protocol. */
abstract class Message {

  protected static final Logger logger = LoggerFactory.getLogger(Message.class);

  static AttributeKey CODEC_REGISTRY_ATTRIBUTE_KEY =
      AttributeKey.valueOf("com.datastax.driver.core.CodecRegistry");

  interface Coder {
    void encode(R request, ByteBuf dest, ProtocolVersion version);

    int encodedSize(R request, ProtocolVersion version);
  }

  interface Decoder {
    R decode(ByteBuf body, ProtocolVersion version, CodecRegistry codecRegistry);
  }

  private volatile int streamId = -1;

  /**
   * A generic key-value custom payload. Custom payloads are simply ignored by the default
   * QueryHandler implementation server-side.
   *
   * @since Protocol V4
   */
  private volatile Map customPayload;

  protected Message() {}

  Message setStreamId(int streamId) {
    this.streamId = streamId;
    return this;
  }

  int getStreamId() {
    return streamId;
  }

  Map getCustomPayload() {
    return customPayload;
  }

  Message setCustomPayload(Map customPayload) {
    this.customPayload = customPayload;
    return this;
  }

  abstract static class Request extends Message {

    enum Type {
      STARTUP(1, Requests.Startup.coder),
      CREDENTIALS(4, Requests.Credentials.coder),
      OPTIONS(5, Requests.Options.coder),
      QUERY(7, Requests.Query.coder),
      PREPARE(9, Requests.Prepare.coder),
      EXECUTE(10, Requests.Execute.coder),
      REGISTER(11, Requests.Register.coder),
      BATCH(13, Requests.Batch.coder),
      AUTH_RESPONSE(15, Requests.AuthResponse.coder);

      final int opcode;
      final Coder coder;

      Type(int opcode, Coder coder) {
        this.opcode = opcode;
        this.coder = coder;
      }
    }

    final Type type;
    private final boolean tracingRequested;

    protected Request(Type type) {
      this(type, false);
    }

    protected Request(Type type, boolean tracingRequested) {
      this.type = type;
      this.tracingRequested = tracingRequested;
    }

    @Override
    Request setStreamId(int streamId) {
      // JAVA-1179: defensively guard against reusing the same Request object twice.
      // If no streamId was ever set we can use this object directly, otherwise make a copy.
      if (getStreamId() < 0) return (Request) super.setStreamId(streamId);
      else {
        Request copy = this.copy();
        copy.setStreamId(streamId);
        return copy;
      }
    }

    boolean isTracingRequested() {
      return tracingRequested;
    }

    ConsistencyLevel consistency() {
      switch (this.type) {
        case QUERY:
          return ((Requests.Query) this).options.consistency;
        case EXECUTE:
          return ((Requests.Execute) this).options.consistency;
        case BATCH:
          return ((Requests.Batch) this).options.consistency;
        default:
          return null;
      }
    }

    ConsistencyLevel serialConsistency() {
      switch (this.type) {
        case QUERY:
          return ((Requests.Query) this).options.serialConsistency;
        case EXECUTE:
          return ((Requests.Execute) this).options.serialConsistency;
        case BATCH:
          return ((Requests.Batch) this).options.serialConsistency;
        default:
          return null;
      }
    }

    long defaultTimestamp() {
      switch (this.type) {
        case QUERY:
          return ((Requests.Query) this).options.defaultTimestamp;
        case EXECUTE:
          return ((Requests.Execute) this).options.defaultTimestamp;
        case BATCH:
          return ((Requests.Batch) this).options.defaultTimestamp;
        default:
          return 0;
      }
    }

    ByteBuffer pagingState() {
      switch (this.type) {
        case QUERY:
          return ((Requests.Query) this).options.pagingState;
        case EXECUTE:
          return ((Requests.Execute) this).options.pagingState;
        default:
          return null;
      }
    }

    Request copy() {
      Request request = copyInternal();
      request.setCustomPayload(this.getCustomPayload());
      return request;
    }

    protected abstract Request copyInternal();

    Request copy(ConsistencyLevel newConsistencyLevel) {
      Request request = copyInternal(newConsistencyLevel);
      request.setCustomPayload(this.getCustomPayload());
      return request;
    }

    protected Request copyInternal(ConsistencyLevel newConsistencyLevel) {
      throw new UnsupportedOperationException();
    }
  }

  abstract static class Response extends Message {

    enum Type {
      ERROR(0, Responses.Error.decoder),
      READY(2, Responses.Ready.decoder),
      AUTHENTICATE(3, Responses.Authenticate.decoder),
      SUPPORTED(6, Responses.Supported.decoder),
      RESULT(8, Responses.Result.decoder),
      EVENT(12, Responses.Event.decoder),
      AUTH_CHALLENGE(14, Responses.AuthChallenge.decoder),
      AUTH_SUCCESS(16, Responses.AuthSuccess.decoder);

      final int opcode;
      final Decoder decoder;

      private static final Type[] opcodeIdx;

      static {
        int maxOpcode = -1;
        for (Type type : Type.values()) maxOpcode = Math.max(maxOpcode, type.opcode);
        opcodeIdx = new Type[maxOpcode + 1];
        for (Type type : Type.values()) {
          if (opcodeIdx[type.opcode] != null) throw new IllegalStateException("Duplicate opcode");
          opcodeIdx[type.opcode] = type;
        }
      }

      Type(int opcode, Decoder decoder) {
        this.opcode = opcode;
        this.decoder = decoder;
      }

      static Type fromOpcode(int opcode) {
        if (opcode < 0 || opcode >= opcodeIdx.length)
          throw new DriverInternalError(String.format("Unknown response opcode %d", opcode));
        Type t = opcodeIdx[opcode];
        if (t == null)
          throw new DriverInternalError(String.format("Unknown response opcode %d", opcode));
        return t;
      }
    }

    final Type type;
    protected volatile UUID tracingId;
    protected volatile List warnings;

    protected Response(Type type) {
      this.type = type;
    }

    Response setTracingId(UUID tracingId) {
      this.tracingId = tracingId;
      return this;
    }

    UUID getTracingId() {
      return tracingId;
    }

    Response setWarnings(List warnings) {
      this.warnings = warnings;
      return this;
    }
  }

  @ChannelHandler.Sharable
  static class ProtocolDecoder extends MessageToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, Frame frame, List