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Public API and core implementation of Easy Rules
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/*
 * The MIT License
 *
 *  Copyright (c) 2022, Mahmoud Ben Hassine ([email protected])
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *  THE SOFTWARE.
 */
package org.jeasy.rules.api;

import java.util.Collections;
import java.util.Iterator;
import java.util.Objects;
import java.util.Set;
import java.util.TreeSet;
import org.jeasy.rules.core.RuleProxy;

/**
 * This class encapsulates a set of rules and represents a rules namespace. Rules must have a unique
 * name within a rules namespace.
 *
 * Rules will be compared to each other based on {@link Rule#compareTo(Object)} method, so {@link
 * Rule}'s implementations are expected to correctly implement {@code compareTo} to ensure unique
 * rule names within a single namespace.
 *
 * @author Mahmoud Ben Hassine ([email protected])
 */
public class Rules implements Iterable {

  private Set rules = new TreeSet<>();

  /**
   * Create a new {@link Rules} object.
   *
   * @param rules to register
   */
  public Rules(Set rules) {
    this.rules = new TreeSet<>(rules);
  }

  /**
   * Create a new {@link Rules} object.
   *
   * @param rules to register
   */
  public Rules(Rule... rules) {
    Collections.addAll(this.rules, rules);
  }

  /**
   * Create a new {@link Rules} object.
   *
   * @param rules to register
   */
  public Rules(Object... rules) {
    this.register(rules);
  }

  /**
   * Register one or more new rules.
   *
   * @param rules to register, must not be null
   */
  public void register(Object... rules) {
    Objects.requireNonNull(rules);
    for (Object rule : rules) {
      Objects.requireNonNull(rule);
      this.rules.add(RuleProxy.asRule(rule));
    }
  }

  public void register(Rule... rules) {
    Objects.requireNonNull(rules);
    for (Rule rule : rules) {
      Objects.requireNonNull(rule);
      this.rules.add(rule);
    }
  }

  public void unregister(Rules... rules) {
    Objects.requireNonNull(rules);
    for (Object rule : rules) {
      Objects.requireNonNull(rule);
      this.rules.remove(rule);
    }
  }

  /**
   * Unregister one or more rules.
   *
   * @param rules to unregister, must not be null
   */
  public void unregister(Object... rules) {
    Objects.requireNonNull(rules);
    for (Object rule : rules) {
      Objects.requireNonNull(rule);
      this.rules.remove(RuleProxy.asRule(rule));
    }
  }

  /**
   * Unregister a rule by name.
   *
   * @param ruleName name of the rule to unregister, must not be null
   */
  public void unregister(final String ruleName) {
    Objects.requireNonNull(ruleName);
    Rule rule = findRuleByName(ruleName);
    if (rule != null) {
      unregister(rule);
    }
  }

  /**
   * Check if the rule set is empty.
   *
   * @return true if the rule set is empty, false otherwise
   */
  public boolean isEmpty() {
    return rules.isEmpty();
  }

  /** Clear rules. */
  public void clear() {
    rules.clear();
  }

  /**
   * Return how many rules are currently registered.
   *
   * @return the number of rules currently registered
   */
  public int size() {
    return rules.size();
  }

  /**
   * Return an iterator on the rules set. It is not intended to remove rules using this iterator.
   *
   * @return an iterator on the rules set
   */
  @Override
  public Iterator iterator() {
    return rules.iterator();
  }

  private Rule findRuleByName(String ruleName) {
    return rules.stream()
        .filter(rule -> rule.getName().equalsIgnoreCase(ruleName))
        .findFirst()
        .orElse(null);
  }
}