/*
    * Copyright (c) 2002-2025 Gargoyle Software Inc.
    *
    * 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
    * https://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.htmlunit.javascript.host.css;
  
  import static org.htmlunit.javascript.host.css.CSSStyleDeclaration.isLength;
  
  import org.htmlunit.util.StringUtils;
  
  /**
   * A helper class for handling font attributes of {@link ComputedCSSStyleDeclaration}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   */
  final class ComputedFont {
  
      // static final int FONT_STYLE_INDEX = 0;
      // static final int FONT_WEIGHT_INDEX = 1;
      // static final int FONT_STRETCH_INDEX = 2;
  
      static final int FONT_SIZE_INDEX = 3;
      static final int LINE_HEIGHT_INDEX = 4;
      static final int FONT_FAMILY_INDEX = 5;
  
      static String[] getDetails(final String font) {
          String fontName = font;
          while (fontName.contains("  ")) {
              fontName = fontName.replace("  ", " ");
          }
          final String[] tokens = StringUtils.splitAtBlank(fontName);
          if (tokens.length > 1) {
              final String[] fontSizeDetails = getFontSizeDetails(tokens[tokens.length - 2]);
              if (fontSizeDetails == null) {
                  return null;
              }
              final String[] details = new String[6];
              details[FONT_SIZE_INDEX] = fontSizeDetails[0];
              details[LINE_HEIGHT_INDEX] = fontSizeDetails[1];
              details[FONT_FAMILY_INDEX] = tokens[tokens.length - 1];
              return details;
          }
          return null;
      }
  
      /**
       * @return an array of {@code fontSize} and {@code lineHeight}, or {@code null} if invalid
       */
      private static String[] getFontSizeDetails(final String fontSize) {
          final int slash = fontSize.indexOf('/');
          final String actualFontSize = slash == -1 ? fontSize : fontSize.substring(0, slash);
          if (!isLength(actualFontSize)) {
              return null;
          }
  
          String actualLineHeight = slash == -1 ? "" : fontSize.substring(slash + 1);
          if (actualLineHeight.isEmpty()) {
              actualLineHeight = null;
          }
          else if (!isValidLineHeight(actualLineHeight)) {
              return null;
          }
          return new String[] {actualFontSize, actualLineHeight};
      }
  
      private static boolean isValidLineHeight(final String lineHeight) {
          return isLength(lineHeight) || "normal".equals(lineHeight);
      }
  
      private ComputedFont() {
          // util class
      }
  
  }