// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The SFC 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.openqa.selenium.devtools;

import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Multimap;
import org.openqa.selenium.devtools.idealized.target.model.SessionID;
import org.openqa.selenium.internal.Require;
import org.openqa.selenium.json.Json;
import org.openqa.selenium.json.JsonInput;
import org.openqa.selenium.remote.http.HttpClient;
import org.openqa.selenium.remote.http.HttpRequest;
import org.openqa.selenium.remote.http.WebSocket;

import java.io.Closeable;
import java.io.StringReader;
import java.time.Duration;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Consumer;
import java.util.logging.Level;
import java.util.logging.Logger;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.openqa.selenium.json.Json.MAP_TYPE;
import static org.openqa.selenium.remote.http.HttpMethod.GET;

public class Connection implements Closeable {

  private static final Logger LOG = Logger.getLogger(Connection.class.getName());
  private static final Json JSON = new Json();
  private static final Executor EXECUTOR = Executors.newCachedThreadPool(r -> {
    Thread thread = new Thread(r, "CDP Connection");
    thread.setDaemon(true);
    return thread;
  });
  private static final AtomicLong NEXT_ID = new AtomicLong(1L);
  private final WebSocket socket;
  private final Map<Long, Consumer<JsonInput>> methodCallbacks = new LinkedHashMap<>();
  private final Multimap<Event<?>, Consumer<?>> eventCallbacks = HashMultimap.create();

  public Connection(HttpClient client, String url) {
    Require.nonNull("HTTP client", client);
    Require.nonNull("URL to connect to", url);

    socket = client.openSocket(new HttpRequest(GET, url), new Listener());
  }

  private static class NamedConsumer<X> implements Consumer<X> {

    private final String name;
    private final Consumer<X> delegate;

    private NamedConsumer(String name, Consumer<X> delegate) {
      this.name = name;
      this.delegate = delegate;
    }

    public static <X> Consumer<X> of(String name, Consumer<X> delegate) {
      return new NamedConsumer<>(name, delegate);
    }

    @Override
    public void accept(X x) {
      delegate.accept(x);
    }

    @Override
    public String toString() {
      return "Consumer for " + name;
    }
  }

  public <X> CompletableFuture<X> send(SessionID sessionId, Command<X> command) {
    long id = NEXT_ID.getAndIncrement();

    CompletableFuture<X> result = new CompletableFuture<>();
    if (command.getSendsResponse()) {
      methodCallbacks.put(id, NamedConsumer.of(command.getMethod(), input -> {
        try {
          X value = command.getMapper().apply(input);
          result.complete(value);
        } catch (Throwable e) {
          LOG.log(Level.WARNING, String.format("Unable to map result for %s", command.getMethod()), e);
          result.completeExceptionally(e);
        }
      }));
    }

    ImmutableMap.Builder<String, Object> serialized = ImmutableMap.builder();
    serialized.put("id", id);
    serialized.put("method", command.getMethod());
    serialized.put("params", command.getParams());
    if (sessionId != null) {
      serialized.put("sessionId", sessionId);
    }

    LOG.fine(() -> String.format("-> %s", JSON.toJson(serialized.build())));
    socket.sendText(JSON.toJson(serialized.build()));

    if (!command.getSendsResponse() ) {
      result.complete(null);
    }

    return result;
  }

  public <X> X sendAndWait(SessionID sessionId, Command<X> command, Duration timeout) {
    try {
      CompletableFuture<X> future = send(sessionId, command);
      return future.get(timeout.toMillis(), MILLISECONDS);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      throw new IllegalStateException("Thread has been interrupted", e);
    } catch (ExecutionException e) {
      Throwable cause = e;
      if (e.getCause() != null) {
        cause = e.getCause();
      }
      throw new DevToolsException(cause);
    } catch (TimeoutException e) {
      throw new org.openqa.selenium.TimeoutException(e);
    }
  }

  public <X> void addListener(Event<X> event, Consumer<X> handler) {
    Require.nonNull("Event to listen for", event);
    Require.nonNull("Handler to call", handler);

    synchronized (eventCallbacks) {
      eventCallbacks.put(event, handler);
    }
  }

  public void clearListeners() {
    synchronized (eventCallbacks) {
      eventCallbacks.clear();
    }
  }

  @Override
  public void close() {
    socket.close();
  }

  private class Listener implements WebSocket.Listener {

    @Override
    public void onText(CharSequence data) {
      EXECUTOR.execute(() -> {
        try {
          handle(data);
        } catch (Throwable t) {
          LOG.log(Level.WARNING, "Unable to process: " + data, t);
        }
      });
    }
  }

  private void handle(CharSequence data) {
    // It's kind of gross to decode the data twice, but this lets us get started on something
    // that feels nice to users.
    // TODO: decode once, and once only

    String asString = String.valueOf(data);
    LOG.fine(() -> String.format("<- %s", asString));

    Map<String, Object> raw = JSON.toType(asString, MAP_TYPE);
    if (raw.get("id") instanceof Number && raw.get("result") != null) {
      Consumer<JsonInput> consumer = methodCallbacks.remove(((Number) raw.get("id")).longValue());
      if (consumer == null) {
        return;
      }

      try (StringReader reader = new StringReader(asString);
           JsonInput input = JSON.newInput(reader)) {
        input.beginObject();
        while (input.hasNext()) {
          switch (input.nextName()) {
            case "result":
              consumer.accept(input);
              break;

            default:
              input.skipValue();
          }
        }
        input.endObject();
      }
    } else if (raw.get("method") instanceof String && raw.get("params") instanceof Map) {
      synchronized (eventCallbacks) {
        // TODO: Also only decode once.
        eventCallbacks.keySet().stream()
          .filter(event -> raw.get("method").equals(event.getMethod()))
          .forEach(event -> {
            // TODO: This is grossly inefficient. I apologise, and we should fix this.
            try (StringReader reader = new StringReader(asString);
                 JsonInput input = JSON.newInput(reader)) {
              Object value = null;
              input.beginObject();
              while (input.hasNext()) {
                switch (input.nextName()) {
                  case "params":
                    value = event.getMapper().apply(input);
                    break;

                  default:
                    input.skipValue();
                    break;
                }
              }
              input.endObject();

              if (value == null) {
                // Do nothing.
                return;
              }

              final Object finalValue = value;

              for (Consumer<?> action : eventCallbacks.get(event)) {
                @SuppressWarnings("unchecked") Consumer<Object> obj = (Consumer<Object>) action;
                obj.accept(finalValue);
              }
            }
          });
      }
    } else {
      LOG.warning("Unhandled type: " + data);
    }
  }
}

@@ -5928,24 +5928,66 @@
 + data, t);%0A
+          throw new DevToolsException(t);%0A
         %7D%0A  

Throw an exception if unable to process a message