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   1 /**
   2  * Copyright (c) 2010-2023 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.mielecloud.internal.webservice.sse;
  14
  15 import java.io.BufferedReader;
  16 import java.io.IOException;
  17 import java.io.InputStream;
  18 import java.io.InputStreamReader;
  19 import java.nio.charset.StandardCharsets;
  20 import java.util.function.Consumer;
  21
  22 import org.eclipse.jdt.annotation.NonNullByDefault;
  23 import org.eclipse.jdt.annotation.Nullable;
  24 import org.openhab.binding.mielecloud.internal.webservice.exception.MieleWebserviceDisconnectSseException;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * Parses events from the SSE event stream and emits them via the given dispatcher.
  30  *
  31  * @author Björn Lange - Initial Contribution
  32  */
  33 @NonNullByDefault
  34 class SseStreamParser {
  35     private static final String SSE_KEY_EVENT = "event:";
  36     private static final String SSE_KEY_DATA = "data:";
  37
  38     private final Logger logger = LoggerFactory.getLogger(SseStreamParser.class);
  39
  40     private final BufferedReader reader;
  41     private final Consumer<ServerSentEvent> onServerSentEventCallback;
  42     private final Consumer<@Nullable Throwable> onStreamClosedCallback;
  43
  44     private @Nullable String event;
  45
  46     SseStreamParser(InputStream inputStream, Consumer<ServerSentEvent> onServerSentEventCallback,
  47             Consumer<@Nullable Throwable> onStreamClosedCallback) {
  48         this.reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
  49         this.onServerSentEventCallback = onServerSentEventCallback;
  50         this.onStreamClosedCallback = onStreamClosedCallback;
  51     }
  52
  53     void parseAndDispatchEvents() {
  54         try {
  55             String line = null;
  56             while ((line = reader.readLine()) != null) {
  57                 onLineReceived(line);
  58             }
  59
  60             silentlyCloseReader();
  61             logger.debug("SSE stream ended. Closing stream.");
  62             onStreamClosedCallback.accept(null);
  63         } catch (IOException exception) {
  64             silentlyCloseReader();
  65
  66             if (!(exception.getCause() instanceof MieleWebserviceDisconnectSseException)) {
  67                 logger.warn("SSE connection failed unexpectedly: {}", exception.getMessage());
  68                 onStreamClosedCallback.accept(exception.getCause());
  69             }
  70         }
  71         logger.debug("SSE stream closed.");
  72     }
  73
  74     private void silentlyCloseReader() {
  75         try {
  76             reader.close();
  77         } catch (IOException e) {
  78             logger.warn("Failed to clean up SSE connection resources!", e);
  79         }
  80     }
  81
  82     private void onLineReceived(String line) {
  83         if (line.isEmpty()) {
  84             return;
  85         }
  86
  87         if (line.startsWith(SSE_KEY_EVENT)) {
  88             event = line.substring(SSE_KEY_EVENT.length()).trim();
  89         } else if (line.startsWith(SSE_KEY_DATA)) {
  90             String event = this.event;
  91             String data = line.substring(SSE_KEY_DATA.length()).trim();
  92
  93             if (event == null) {
  94                 logger.warn("Received data payload without prior event payload.");
  95             } else {
  96                 onServerSentEventCallback.accept(new ServerSentEvent(event, data));
  97             }
  98         } else {
  99             logger.warn("Unable to parse line from SSE stream: {}", line);
 100         }
 101     }
 102 }