juplo.de Git - demos/kafka/chat/blob - src/main/java/de/juplo/kafka/chat/backend/domain/ChatRoom.java

   1 package de.juplo.kafka.chat.backend.domain;
   2
   3 import lombok.EqualsAndHashCode;
   4 import lombok.Getter;
   5 import lombok.ToString;
   6 import lombok.extern.slf4j.Slf4j;
   7 import reactor.core.publisher.Flux;
   8 import reactor.core.publisher.Mono;
   9 import reactor.core.publisher.Sinks;
  10
  11 import java.time.Clock;
  12 import java.time.LocalDateTime;
  13 import java.util.*;
  14 import java.util.regex.Matcher;
  15 import java.util.regex.Pattern;
  16
  17
  18 @Slf4j
  19 @EqualsAndHashCode(of = { "id" })
  20 @ToString(of = { "id", "name" })
  21 public class ChatRoom
  22 {
  23   public final static Pattern VALID_USER = Pattern.compile("^[a-z0-9-]{2,}$");
  24   @Getter
  25   private final UUID id;
  26   @Getter
  27   private final String name;
  28   private final Clock clock;
  29   private final ChatRoomService service;
  30   private final int bufferSize;
  31   private Sinks.Many<Message> sink;
  32
  33
  34   public ChatRoom(
  35       UUID id,
  36       String name,
  37       Clock clock,
  38       ChatRoomService service,
  39       int bufferSize)
  40   {
  41     this.id = id;
  42     this.name = name;
  43     this.clock = clock;
  44     this.service = service;
  45     this.bufferSize = bufferSize;
  46     // @RequiredArgsConstructor unfortunately not possible, because
  47     // the `bufferSize` is not set, if `createSink()` is called
  48     // from the variable declaration!
  49     this.sink = createSink();
  50   }
  51
  52
  53   synchronized public Mono<Message> addMessage(
  54       Long id,
  55       String user,
  56       String text)
  57   {
  58     Matcher matcher = VALID_USER.matcher(user);
  59     if (!matcher.matches())
  60       throw new InvalidUsernameException(user);
  61
  62     Message.MessageKey key = Message.MessageKey.of(user, id);
  63     return service
  64         .getMessage(key)
  65         .flatMap(existing -> text.equals(existing.getMessageText())
  66             ? Mono.just(existing)
  67             : Mono.error(() -> new MessageMutationException(existing, text)))
  68         .switchIfEmpty(
  69             Mono
  70                 .fromSupplier(() ->service.persistMessage(key, LocalDateTime.now(clock), text))
  71                 .doOnNext(m ->
  72                 {
  73                   Sinks.EmitResult result = sink.tryEmitNext(m);
  74                   if (result.isFailure())
  75                   {
  76                     log.warn("Emitting of message failed with {} for {}", result.name(), m);
  77                   }
  78                 }));
  79   }
  80
  81
  82   public Mono<Message> getMessage(String username, Long messageId)
  83   {
  84     Message.MessageKey key = Message.MessageKey.of(username, messageId);
  85     return service.getMessage(key);
  86   }
  87
  88   synchronized public Flux<Message> listen()
  89   {
  90     return sink
  91         .asFlux()
  92         .doOnCancel(() -> sink = createSink()); // Sink hast to be recreated on auto-cancel!
  93   }
  94
  95   public Flux<Message> getMessages()
  96   {
  97     return getMessages(0, Long.MAX_VALUE);
  98   }
  99
 100   public Flux<Message> getMessages(long first, long last)
 101   {
 102     return service.getMessages(first, last);
 103   }
 104
 105   private Sinks.Many<Message> createSink()
 106   {
 107     return Sinks
 108         .many()
 109         .multicast()
 110         .onBackpressureBuffer(bufferSize);
 111   }
 112 }