/*
    * SPDX-FileCopyrightText: Copyright (c) 2011-2025 Yegor Bugayenko
    * SPDX-License-Identifier: MIT
    */
   package com.qulice.checkstyle;
   
   import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
   import com.puppycrawl.tools.checkstyle.api.FileText;
   import java.io.File;
  import org.cactoos.text.Joined;
  
  /**
   * Make sure each line indentation is either:
   * <ul>
   * <li>the same as previous one or less
   * <li>bigger than previous by exactly 4
   * </ul>
   * All other cases must cause a failure.
   *
   * @since 0.3
   */
  public final class CascadeIndentationCheck extends AbstractFileSetCheck {
      /**
       * Exact indentation increase difference.
       */
      private static final int LINE_INDENT_DIFF = 4;
  
      @Override
      public void processFiltered(final File file, final FileText lines) {
          int previous = 0;
          for (int pos = 0; pos < lines.size(); pos += 1) {
              final String line = lines.get(pos);
              final int current = CascadeIndentationCheck.indentation(line);
              if (CascadeIndentationCheck.inCommentBlock(line)
                  || line.isEmpty()) {
                  continue;
              }
              if (current > previous
                  && current != previous
                  + CascadeIndentationCheck.LINE_INDENT_DIFF) {
                  this.log(
                      pos + 1,
                      String.format(
                          new Joined(
                              "",
                              "Indentation (%d) must be same or ",
                              "less than previous line (%d), or ",
                              "bigger by exactly 4"
                          ).toString(),
                          current,
                          previous
                      )
                  );
              }
              previous = current;
          }
      }
  
      /**
       * Checks if the line belongs to a comment block.
       * @param line Input.
       * @return True if the line belongs to a comment block.
       */
      private static boolean inCommentBlock(final String line) {
          final String trimmed = line.trim();
          return !trimmed.isEmpty()
              && (trimmed.charAt(0) == '*'
                  || trimmed.startsWith("/*")
                  || trimmed.startsWith("*/")
                  );
      }
  
      /**
       * Calculates indentation of a line.
       * @param line Input line
       * @return Indentation of the given line.
       */
      private static int indentation(final String line) {
          int result = 0;
          for (int pos = 0; pos < line.length(); pos += 1) {
              if (!Character.isWhitespace(line.charAt(pos))) {
                  break;
              }
              result += 1;
          }
          return result;
      }
  
  }