/*
    * Copyright 2017 LINE Corporation
    *
    * LINE Corporation 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:
    *
    *   https://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.linecorp.centraldogma.server.internal.thrift;
  
  import static java.util.Objects.requireNonNull;
  
  import java.net.InetSocketAddress;
  import java.time.Clock;
  import java.time.Instant;
  import java.time.temporal.ChronoUnit;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.regex.Pattern;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.common.annotations.VisibleForTesting;
  
  import com.linecorp.armeria.common.HttpHeaderNames;
  import com.linecorp.armeria.common.HttpRequest;
  import com.linecorp.armeria.common.HttpResponse;
  import com.linecorp.armeria.server.HttpService;
  import com.linecorp.armeria.server.ServiceRequestContext;
  import com.linecorp.armeria.server.SimpleDecoratingHttpService;
  
  public class TokenlessClientLogger extends SimpleDecoratingHttpService {
  
      private static final Logger logger = LoggerFactory.getLogger(TokenlessClientLogger.class);
  
      private static final Pattern PATTERN = Pattern.compile("\\s*[Bb][Ee][Aa][Rr][Ee][Rr]\\s+anonymous\\s*");
  
      private final Clock clock;
      private final ConcurrentMap<String, Instant> reportedAddresses = new ConcurrentHashMap<>();
  
      public TokenlessClientLogger(HttpService delegate) {
          this(delegate, Clock.systemUTC());
      }
  
      @VisibleForTesting
      TokenlessClientLogger(HttpService delegate, Clock clock) {
          super(delegate);
          this.clock = requireNonNull(clock, "clock");
      }
  
      @Override
      public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) throws Exception {
          final String authorization = req.headers().get(HttpHeaderNames.AUTHORIZATION);
          if (authorization == null || !PATTERN.matcher(authorization).matches()) {
              final InetSocketAddress raddr = ctx.remoteAddress();
              final String ip = raddr.getAddress().getHostAddress();
              final Instant now = Instant.now(clock);
              final Instant lastReport = reportedAddresses.putIfAbsent(ip, now);
              final boolean report;
              if (lastReport == null) {
                  report = true;
              } else if (ChronoUnit.DAYS.between(lastReport, now) >= 1) {
                  report = reportedAddresses.replace(ip, lastReport, now);
              } else {
                  report = false;
              }
  
              if (report) {
                  report(raddr.getHostString(), ip);
              }
          }
  
          return unwrap().serve(ctx, req);
      }
  
      @VisibleForTesting
      void report(String hostname, String ip) {
          logger.debug("Received a request without 'authorization' header from: {}/{}", hostname, ip);
      }
  }