/*
    * Copyright (C) 2010 The Guava Authors
    *
    * 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.common.base;
  
  import com.google.caliper.BeforeExperiment;
  import com.google.caliper.Benchmark;
  import com.google.caliper.Param;
  import com.google.caliper.runner.CaliperMain;
  import com.google.common.base.CharMatcher.FastMatcher;
  
  import java.util.BitSet;
  import java.util.Random;
  
  /**
   * Benchmark for the {@link CharMatcher#WHITESPACE} implementation.
   */
  public class WhitespaceMatcherBenchmark {
    private static final int STRING_LENGTH = 10000;
  
    private static final String OLD_WHITESPACE_TABLE =
        "\u0001\u0000\u00a0\u0000\u0000\u0000\u0000\u0000"
        + "\u0000\u0009\n\u000b\u000c\r\u0000\u0000\u2028\u2029\u0000\u0000\u0000\u0000\u0000\u202f"
        + "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0020\u0000\u0000\u0000\u0000\u0000"
        + "\u0000\u0000\u0000\u0000\u0000\u3000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"
        + "\u0000\u0000\u0085\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a"
        + "\u0000\u0000\u0000\u0000\u0000\u205f\u1680\u0000\u0000\u180e\u0000\u0000\u0000";
  
    public static final CharMatcher OLD_WHITESPACE = new FastMatcher("CharMatcher.WHITESPACE") {
      @Override public boolean matches(char c) {
        return OLD_WHITESPACE_TABLE.charAt(c % 79) == c;
      }
    };
  
    @Param
    private boolean useNew;
  
    @Param({"20", "50", "80"})
    private int percentMatching;
  
    private String teststring;
    private CharMatcher matcher;
  
    public static void main(String[] args) throws Exception {
      CaliperMain.main(WhitespaceMatcherBenchmark.class, new String[] {});
    }
  
    @BeforeExperiment
    protected void setUp() {
      BitSet bitSet = new BitSet();
      for (int i = 0; i < OLD_WHITESPACE_TABLE.length(); i++) {
        bitSet.set(OLD_WHITESPACE_TABLE.charAt(i));
      }
      bitSet.clear(0);
      bitSet.clear(1);
      matcher = useNew ? CharMatcher.WHITESPACE : OLD_WHITESPACE;
      teststring = newTestString(new Random(1), bitSet, percentMatching);
    }
  
    @Benchmark public int countIn(int reps) {
      int result = 0;
      CharMatcher matcher = this.matcher;
      String teststring = this.teststring;
      for (int i = 0; i < reps; i++) {
        result += matcher.countIn(teststring);
      }
      return result;
    }
  
    @Benchmark public int collapseFrom(int reps) {
      int result = 0;
      CharMatcher matcher = this.matcher;
      String teststring = this.teststring;
      for (int i = 0; i < reps; i++) {
        result += System.identityHashCode(matcher.collapseFrom(teststring, ' '));
      }
      return result;
    }
  
    private static String allMatchingChars(BitSet bitSet) {
      final char[] result = new char[bitSet.cardinality()];
      for (int j = 0, c = bitSet.nextSetBit(0); j < result.length; ++j) {
        result[j] = (char) c;
        c = bitSet.nextSetBit(c + 1);
      }
      return new String(result);
   }
 
   private static String newTestString(Random random, BitSet bitSet, int percentMatching) {
     final String allMatchingChars = allMatchingChars(bitSet);
     final char[] result = new char[STRING_LENGTH];
     // Fill with matching chars.
     for (int i = 0; i < result.length; i++) {
       result[i] = allMatchingChars.charAt(random.nextInt(allMatchingChars.length()));
     }
     // Replace some of chars by non-matching.
     int remaining = (int) ((100 - percentMatching) * result.length / 100.0 + 0.5);
     while (remaining > 0) {
       final char c = (char) random.nextInt();
       if (bitSet.get(c)) {
         final int pos = random.nextInt(result.length);
         if (bitSet.get(result[pos])) {
           result[pos] = c;
           remaining--;
         }
       }
     }
     return new String(result);
   }
 }