/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.juneau.marshall.sse;

import static org.apache.juneau.commons.utils.Shorts.*;
import static org.apache.juneau.commons.utils.StringUtils.*;

import java.io.*;
import java.util.*;
import java.util.stream.*;

import org.apache.juneau.marshall.serializer.*;
import org.apache.juneau.marshall.stream.*;

/**
 * Session object that lives for the duration of a single use of {@link SseSerializer}.
 *
 * <h5 class='section'>Notes:</h5><ul>
 *    <li class='warn'>This class is not thread safe and is typically discarded after one use.
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/Sse">SSE</a>
 * </ul>
 */
@SuppressWarnings({
   "java:S110", // Inheritance depth acceptable for session hierarchy
   "java:S1192", // Duplicated literals (argument/property names) read more clearly inline than as constants
   "resource" // Closeable resources are owned by the caller's serializer session; Eclipse JDT @Owning warning is by design.
})
public class SseSerializerSession extends WriterSerializerSession implements RecordWritable {

   /**
    * Builder class.
    */
   public static class Builder extends WriterSerializerSession.Builder<Builder> {

      /**
       * Constructor.
       *
       * @param ctx The context creating this session. Cannot be <jk>null</jk>.
       */
      protected Builder(SseSerializer ctx) {
         super(reqnn("ctx", ctx));
      }

      @Override
      public SseSerializerSession build() {
         return new SseSerializerSession(this);
      }
   }

   /**
    * Creates a new builder for this object.
    *
    * @param ctx The context creating this session. Cannot be <jk>null</jk>.
    * @return A new builder.
    */
   public static Builder create(SseSerializer ctx) {
      return new Builder(reqnn("ctx", ctx));
   }

   /**
    * Constructor.
    *
    * @param builder The builder for this object.
    */
   protected SseSerializerSession(Builder builder) {
      super(builder);
   }

   @Override /* RecordWritable */
   public RecordWriter writeRecords(Object output) throws IOException {
      return RecordAdapter.arrayWriter(this, output);
   }

   @Override /* RecordWritable */
   public boolean isRecordStreaming() {
      return false;
   }

   @Override /* Overridden from SerializerSession */
   @SuppressWarnings({
      "java:S2095" // Writer is owned by SerializerPipe/caller and must not be closed by this session.
   })
   protected void doWrite(SerializerPipe pipe, Object o) throws IOException, SerializeException {
      var w = pipe.getWriter();
      if (o == null)
         return;
      if (o instanceof SseEvent o2) {
         writeEvent(w, o2);
      } else if (o instanceof Iterable<?> o2) {
         for (var item : o2)
            writeIfEvent(w, item);
      } else if (o instanceof Stream<?> o2) {
         try (var s2 = o2) {
            s2.forEach(item -> writeIfEventUnchecked(w, item));
         }
      } else if (o instanceof SseEvent[] o2) {
         for (var e : o2)
            writeEvent(w, e);
      } else if (o.getClass().isArray()) {
         var arr = (Object[]) o;
         for (var item : arr)
            writeIfEvent(w, item);
      } else {
         throw new SerializeException("SseSerializer cannot serialize objects of type '%s'.", cn(o));
      }
   }

   private static void writeIfEvent(Writer w, Object item) throws IOException, SerializeException {
      if (item == null)
         return;
      if (!(item instanceof SseEvent item2))
         throw new SerializeException("SseSerializer encountered non-SseEvent element of type '%s'.", cn(item));
      writeEvent(w, item2);
   }

   private static void writeIfEventUnchecked(Writer w, Object item) {
      try {
         writeIfEvent(w, item);
      } catch (IOException e) {
         throw new UncheckedIOException(e);
      } catch (SerializeException e) {
         throw new IllegalArgumentException(e);
      }
   }

   private static void writeEvent(Writer w, SseEvent e) throws IOException {
      if (e == null)
         return;
      if (!isEmpty(e.getEvent()))
         writeField(w, "event", e.getEvent());
      if (e.getData() != null) {
         for (var line : splitData(e.getData()))
            writeField(w, "data", line);
      }
      if (e.getId() != null)
         writeField(w, "id", e.getId());
      if (e.getRetry() != null)
         w.write("retry: " + e.getRetry() + "\n");
      w.write("\n");
      w.flush();
   }

   private static void writeField(Writer w, String name, String value) throws IOException {
      w.write(name);
      w.write(": ");
      w.write(value);
      w.write('\n');
   }

   static List<String> splitData(String s) {
      var parts = s.split("\n", -1);
      return Arrays.asList(parts);
   }
}