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/*
 * Copyright 2014-2023 Netflix, 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.netflix.spectator.impl.matcher;

import java.io.Serializable;
import java.util.Collections;
import java.util.Objects;
import java.util.SortedSet;
import java.util.function.Function;

/** Matcher that looks for a fixed number of repetitions. */
final class RepeatMatcher implements Matcher, Serializable {

  private static final long serialVersionUID = 1L;

  private final Matcher repeated;
  private final int min;
  private final int max;

  /** Create a new instance. */
  RepeatMatcher(Matcher repeated, int min, int max) {
    this.repeated = repeated;
    this.min = min;
    this.max = max;
  }

  Matcher repeated() {
    return repeated;
  }

  int min() {
    return min;
  }

  int max() {
    return max;
  }

  @Override
  public String containedString() {
    return min == 0 ? null : repeated.containedString();
  }

  @Override
  public SortedSet trigrams() {
    return min == 0 ? Collections.emptySortedSet() : repeated.trigrams();
  }

  @Override
  public int matches(String str, int start, int length) {
    final int end = start + length;
    int pos = start;
    int numMatches = 0;
    while (pos >= 0 && numMatches < max) {
      int p = repeated.matches(str, pos, end - pos);
      if (p >= 0) {
        ++numMatches;
        pos = p;
      } else {
        return (numMatches >= min) ? pos : Constants.NO_MATCH;
      }
    }
    return pos;
  }

  @Override
  public int minLength() {
    return min * repeated.minLength();
  }

  @Override
  public Matcher rewrite(Function f) {
    return new RepeatMatcher(f.apply(repeated), min, max);
  }

  @Override
  public Matcher rewriteEnd(Function f) {
    return new RepeatMatcher(f.apply(repeated), min, max);
  }

  @Override
  public String toString() {
    return min == max
        ? "(?:" + repeated + "){" + min + "}"
        : "(?:" + repeated + "){" + min + "," + max + "}";
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    RepeatMatcher that = (RepeatMatcher) o;
    return min == that.min
        && max == that.max
        && Objects.equals(repeated, that.repeated);
  }

  @Override
  public int hashCode() {
    int result = 1;
    result = 31 * result + repeated.hashCode();
    result = 31 * result + min;
    result = 31 * result + max;
    return result;
  }
}