/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.subtitleparser.webvttparser;
  
  import static java.util.Optional.ofNullable;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.List;
  
  public class WebVTTWriter {
    private Charset charset; // Charset used to encode file
  
    public WebVTTWriter() {
      this.charset = StandardCharsets.UTF_8;
    }
  
    public WebVTTWriter(Charset charset) {
      this.charset = charset;
    }
  
    public void write(WebVTTSubtitle subtitleObject, OutputStream os) throws IOException {
      try {
        // Write header
        List<String> headerLines = subtitleObject.getHeaderLines();
        for (int i = 0; i < headerLines.size() ; i++) {
          // Ensure valid header
          if (i == 0 && !headerLines.get(i).startsWith("WEBVTT")) {
            os.write(("WEBVTT " +  headerLines.get(i) + "\n").getBytes(this.charset));
            continue;
          }
          os.write((headerLines.get(i) + "\n").getBytes(this.charset));
        }
        // Ensure valid header
        if (headerLines.size() == 0) {
          os.write(("WEBVTT" + "\n").getBytes(this.charset));
        }
        os.write("\n".getBytes(this.charset));
  
        // Write region blocks
        for (WebVTTSubtitleRegion region : subtitleObject.getRegions()) {
          for (String regionLine : region.getLines()) {
            os.write((regionLine + "\n").getBytes(this.charset));
          }
          os.write("\n".getBytes(this.charset));
        }
  
        // Write style blocks
        for (WebVTTSubtitleStyle style : subtitleObject.getStyle()) {
          for (String styleLine : style.getLines()) {
            os.write((styleLine + "\n").getBytes(this.charset));
          }
          os.write("\n".getBytes(this.charset));
        }
  
        // Write cues
        for (WebVTTSubtitleCue cue : subtitleObject.getCues()) {
          if (cue.getId() != null) {
            // Write id
            String number = String.format("%s\n", cue.getId());
            os.write(number.getBytes(this.charset));
          }
  
          // Write start and end time
          String startToEnd = String.format("%s --> %s %s\n",
                  this.formatTimeCode(cue.getStartTime()),
                  this.formatTimeCode(cue.getEndTime()),
                  ofNullable(cue.getCueSettingsList()).orElse(""));
          os.write(startToEnd.getBytes(this.charset));
  
          // Write text
          String text = String.format("%s\n", cue.getText());
          os.write(text.getBytes(this.charset));
  
          // Write empty line
          os.write("\n".getBytes(this.charset));
        }
      } catch (UnsupportedEncodingException e) {
       throw new IOException("Encoding error in input subtitle");
     }
   }
 
   private String formatTimeCode(long ms) {
     long milliseconds = ms % 1000L;
     long seconds = ms / 1000L % 60L;
     long minutes = ms / (1000L * 60L) % 60L;
     long hours = ms / (1000L * 60L * 60L);
 
     return String.format("%02d:%02d:%02d.%03d",
             hours,
             minutes,
             seconds,
             milliseconds);
   }
 }