content: /*
   * Copyright (C) 2019 The Android Open Source Project
   *
   * Licensed 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 com.google.android.exoplayer2.text.ssa;
  
  import static com.google.android.exoplayer2.text.ssa.SsaDecoder.FORMAT_LINE_PREFIX;
  
  import android.text.TextUtils;
  import androidx.annotation.Nullable;
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.util.Assertions;
  import com.google.common.base.Ascii;
  
  /**
   * Represents a {@code Format:} line from the {@code [Events]} section
   *
   * <p>The indices are used to determine the location of particular properties in each {@code
   * Dialogue:} line.
   */
  /* package */ final class SsaDialogueFormat {
  
    public final int startTimeIndex;
    public final int endTimeIndex;
    public final int styleIndex;
    public final int textIndex;
    public final int length;
  
    private SsaDialogueFormat(
        int startTimeIndex, int endTimeIndex, int styleIndex, int textIndex, int length) {
      this.startTimeIndex = startTimeIndex;
      this.endTimeIndex = endTimeIndex;
      this.styleIndex = styleIndex;
      this.textIndex = textIndex;
      this.length = length;
    }
  
    /**
     * Parses the format info from a 'Format:' line in the [Events] section.
     *
     * @return the parsed info, or null if {@code formatLine} doesn't contain both 'start' and 'end'.
     */
    @Nullable
    public static SsaDialogueFormat fromFormatLine(String formatLine) {
      int startTimeIndex = C.INDEX_UNSET;
      int endTimeIndex = C.INDEX_UNSET;
      int styleIndex = C.INDEX_UNSET;
      int textIndex = C.INDEX_UNSET;
      Assertions.checkArgument(formatLine.startsWith(FORMAT_LINE_PREFIX));
      String[] keys = TextUtils.split(formatLine.substring(FORMAT_LINE_PREFIX.length()), ",");
      for (int i = 0; i < keys.length; i++) {
        switch (Ascii.toLowerCase(keys[i].trim())) {
          case "start":
            startTimeIndex = i;
            break;
          case "end":
            endTimeIndex = i;
            break;
          case "style":
            styleIndex = i;
            break;
          case "text":
            textIndex = i;
            break;
        }
      }
      return (startTimeIndex != C.INDEX_UNSET
              && endTimeIndex != C.INDEX_UNSET
              && textIndex != C.INDEX_UNSET)
          ? new SsaDialogueFormat(startTimeIndex, endTimeIndex, styleIndex, textIndex, keys.length)
          : null;
    }
  }
  