/*
 * Copyright contributors to Hyperledger Besu.
 *
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
package org.hyperledger.besu.ethereum.api.jsonrpc.ipc;

import static org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcError.INVALID_REQUEST;

import org.hyperledger.besu.ethereum.api.jsonrpc.execution.JsonRpcExecutor;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequest;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcError;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcErrorResponse;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponse;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponseType;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicBoolean;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import io.vertx.core.Future;
import io.vertx.core.Vertx;
import io.vertx.core.buffer.Buffer;
import io.vertx.core.json.DecodeException;
import io.vertx.core.json.Json;
import io.vertx.core.json.JsonArray;
import io.vertx.core.json.JsonObject;
import io.vertx.core.net.NetServer;
import io.vertx.core.net.NetServerOptions;
import io.vertx.core.net.NetSocket;
import io.vertx.core.net.SocketAddress;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class JsonRpcIpcService {

  private static final Logger LOG = LoggerFactory.getLogger(JsonRpcIpcService.class);
  private static final ObjectWriter JSON_OBJECT_WRITER =
      new ObjectMapper()
          .registerModule(new Jdk8Module()) // Handle JDK8 Optionals (de)serialization
          .writer()
          .without(JsonGenerator.Feature.FLUSH_PASSED_TO_STREAM)
          .with(JsonGenerator.Feature.AUTO_CLOSE_TARGET);

  private final Vertx vertx;
  private final Path path;
  private final JsonRpcExecutor jsonRpcExecutor;
  private NetServer netServer;

  public JsonRpcIpcService(final Vertx vertx, final Path path, final JsonRpcExecutor rpcExecutor) {
    this.vertx = vertx;
    this.path = path;
    this.jsonRpcExecutor = rpcExecutor;
  }

  public Future<NetServer> start() {
    netServer = vertx.createNetServer(buildNetServerOptions());
    netServer.connectHandler(
        socket -> {
          AtomicBoolean closedSocket = new AtomicBoolean(false);
          socket
              .closeHandler(unused -> closedSocket.set(true))
              .handler(
                  buffer -> {
                    if (buffer.length() == 0) {
                      errorReturn(socket, null, JsonRpcError.INVALID_REQUEST);
                    } else {
                      try {
                        final JsonObject jsonRpcRequest = buffer.toJsonObject();
                        vertx
                            .<JsonRpcResponse>executeBlocking(
                                promise -> {
                                  final JsonRpcResponse jsonRpcResponse =
                                      jsonRpcExecutor.execute(
                                          Optional.empty(),
                                          null,
                                          null,
                                          closedSocket::get,
                                          jsonRpcRequest,
                                          req -> req.mapTo(JsonRpcRequest.class));
                                  promise.complete(jsonRpcResponse);
                                })
                            .onSuccess(
                                jsonRpcResponse -> {
                                  try {
                                    socket.write(
                                        JSON_OBJECT_WRITER.writeValueAsString(jsonRpcResponse)
                                            + '\n');
                                  } catch (JsonProcessingException e) {
                                    LOG.error("Error streaming JSON-RPC response", e);
                                  }
                                })
                            .onFailure(
                                throwable -> {
                                  try {
                                    final Integer id = jsonRpcRequest.getInteger("id", null);
                                    errorReturn(socket, id, JsonRpcError.INTERNAL_ERROR);
                                  } catch (ClassCastException idNotIntegerException) {
                                    errorReturn(socket, null, JsonRpcError.INTERNAL_ERROR);
                                  }
                                });
                      } catch (DecodeException jsonObjectDecodeException) {
                        try {
                          final JsonArray batchJsonRpcRequest = buffer.toJsonArray();
                          if (batchJsonRpcRequest.isEmpty()) {
                            errorReturn(socket, null, JsonRpcError.INVALID_REQUEST);
                          } else {
                            vertx
                                .<List<JsonRpcResponse>>executeBlocking(
                                    promise -> {
                                      List<JsonRpcResponse> responses = new ArrayList<>();
                                      for (int i = 0; i < batchJsonRpcRequest.size(); i++) {
                                        final JsonObject jsonRequest;
                                        try {
                                          jsonRequest = batchJsonRpcRequest.getJsonObject(i);
                                        } catch (ClassCastException e) {
                                          responses.add(
                                              new JsonRpcErrorResponse(null, INVALID_REQUEST));
                                          continue;
                                        }
                                        responses.add(
                                            jsonRpcExecutor.execute(
                                                Optional.empty(),
                                                null,
                                                null,
                                                closedSocket::get,
                                                jsonRequest,
                                                req -> req.mapTo(JsonRpcRequest.class)));
                                      }
                                      promise.complete(responses);
                                    })
                                .onSuccess(
                                    jsonRpcBatchResponse -> {
                                      try {
                                        final JsonRpcResponse[] completed =
                                            jsonRpcBatchResponse.stream()
                                                .filter(
                                                    jsonRpcResponse ->
                                                        jsonRpcResponse.getType()
                                                            != JsonRpcResponseType.NONE)
                                                .toArray(JsonRpcResponse[]::new);

                                        socket.write(
                                            JSON_OBJECT_WRITER.writeValueAsString(completed)
                                                + '\n');
                                      } catch (JsonProcessingException e) {
                                        LOG.error("Error streaming JSON-RPC response", e);
                                      }
                                    })
                                .onFailure(
                                    throwable ->
                                        errorReturn(socket, null, JsonRpcError.INTERNAL_ERROR));
                          }
                        } catch (DecodeException jsonArrayDecodeException) {
                          errorReturn(socket, null, JsonRpcError.PARSE_ERROR);
                        }
                      }
                    }
                  });
        });
    return netServer
        .listen(SocketAddress.domainSocketAddress(path.toString()))
        .onSuccess(successServer -> LOG.info("IPC endpoint opened: {}", path))
        .onFailure(throwable -> LOG.error("Unable to open IPC endpoint", throwable));
  }

  public Future<Void> stop() {
    if (netServer == null) {
      return Future.succeededFuture();
    } else {
      return netServer
          .close()
          .onComplete(
              closeResult -> {
                try {
                  Files.deleteIfExists(path);
                } catch (IOException e) {
                  LOG.error("Unable to delete IPC file", e);
                }
              });
    }
  }

  private Future<Void> errorReturn(
      final NetSocket socket, final Integer id, final JsonRpcError rpcError) {
    return socket.write(Buffer.buffer(Json.encode(new JsonRpcErrorResponse(id, rpcError)) + '\n'));
  }

  private NetServerOptions buildNetServerOptions() {
    return new NetServerOptions();
  }
}
