/**
    * Copyright 2007 Google 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
    *
    * 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.tonicsystems.jarjar;
  
  import java.io.*;
  import java.util.*;
  
  class RulesFileParser
  {
      private RulesFileParser() {
      }
  
      public static List<PatternElement> parse(File file) throws IOException {
          return parse(new FileReader(file));
      }
  
      public static List<PatternElement> parse(String value) throws IOException {
          return parse(new java.io.StringReader(value));
      }
  
      private static String stripComment(String in) {
        int p = in.indexOf("#");
        return p < 0 ? in : in.substring(0, p);
      }
  
      private static List<PatternElement> parse(Reader r) throws IOException {
        try {
          List<PatternElement> patterns = new ArrayList<PatternElement>();
          BufferedReader br = new BufferedReader(r);
          int c = 1;
          String line;
          while ((line = br.readLine()) != null) {
              line = stripComment(line);
              if (line.length()==0)
                  continue;
              String[] parts = line.split("\\s+");
              if (parts.length < 2)
                  error(c, parts);
              String type = parts[0];
              PatternElement element = null;
              if (type.equals("rule")) {
                  if (parts.length < 3)
                      error(c, parts);
                  Rule rule = new Rule();
                  rule.setResult(parts[2]);
                  element = rule;
              } else if (type.equals("zap")) {
                  element = new Zap();
              } else if (type.equals("keep")) {
                  element = new Keep();
              } else {
                  error(c, parts);
              }
              element.setPattern(parts[1]);
              patterns.add(element);
              c++;
          }
          return patterns;
        } finally {
          r.close();
        }
      }
  
      private static void error(int line, String[] parts) {
        throw new IllegalArgumentException("Error on line " + line + ": " + Arrays.asList(parts));
      }
  }