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A generic CDI-based command framework
/*
* Copyright 2019 Björn Kautler
*
* 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 net.kautler.command.api.restriction;
import net.kautler.command.restriction.RestrictionLookup;
import java.util.StringJoiner;
import static java.lang.String.format;
import static java.util.Objects.requireNonNull;
/**
* A restriction chain element that can check a given restriction or combine different restrictions with boolean logic.
*/
public class RestrictionChainElement {
/**
* The restriction to check.
*/
private final Class> restriction;
/**
* Constructs a new restriction chain element.
*/
private RestrictionChainElement() {
this.restriction = null;
}
/**
* Constructs a new restriction chain element for the given restriction class.
*
* @param restriction the restriction to wrap
*/
public RestrictionChainElement(Class> restriction) {
this.restriction = requireNonNull(restriction);
}
/**
* Returns whether the command triggered by the given message should be allowed or not.
*
* @param message the message that triggered the command
* @param availableRestrictions the look up to find the actual restriction implementations
* @param the class of the message
* @return whether the command triggered by the given message should be allowed or not
*/
public boolean isCommandAllowed(M message, RestrictionLookup availableRestrictions) {
Restriction restriction = availableRestrictions.getRestriction(this.restriction);
if (restriction == null) {
throw new IllegalArgumentException(format("The restriction '%s' was not found in the given available restrictions '%s'", this.restriction, availableRestrictions));
}
return restriction.allowCommand(message);
}
/**
* Returns a restriction chain element that combines this restriction chain element with the given one using boolean
* short-circuit "and" logic.
*
* @param other the restriction chain element to be combined with this restriction chain element
* @return a restriction chain element that represents the boolean combination
*/
public RestrictionChainElement and(RestrictionChainElement other) {
return new AndCombination(this, other);
}
/**
* Returns a restriction chain element that combines this restriction chain element with the given one using boolean
* short-circuit "or" logic.
*
* @param other the restriction chain element to be combined with this restriction chain element
* @return a restriction chain element that represents the boolean combination
*/
public RestrictionChainElement or(RestrictionChainElement other) {
return new OrCombination(this, other);
}
/**
* Returns a restriction chain element that negates this restriction chain element.
*
* @return a restriction chain element that negates this restriction chain element
*/
public RestrictionChainElement negate() {
return new Negation(this);
}
@Override
public String toString() {
return new StringJoiner(", ", getClass().getSimpleName() + "[", "]")
.add("restriction=" + restriction)
.toString();
}
/**
* A restriction chain element that combines two restriction chain elements using boolean short-circuit "and" logic.
*/
private static class AndCombination extends RestrictionChainElement {
/**
* The left element of the boolean "and" logic.
*/
private final RestrictionChainElement left;
/**
* The right element of the boolean "and" logic.
*/
private final RestrictionChainElement right;
/**
* Constructs a new restriction chain element that combines the given restriction chain elements using boolean
* short-circuit "and" logic.
*
* @param left the left element of the boolean "and" logic
* @param right the right element of the boolean "and" logic
*/
private AndCombination(RestrictionChainElement left, RestrictionChainElement right) {
this.left = left;
this.right = right;
}
@Override
public boolean isCommandAllowed(M message, RestrictionLookup availableRestrictions) {
return left.isCommandAllowed(message, availableRestrictions) && right.isCommandAllowed(message, availableRestrictions);
}
@Override
public String toString() {
return new StringJoiner(", ", AndCombination.class.getSimpleName() + "[", "]")
.add("left=" + left)
.add("right=" + right)
.toString();
}
}
/**
* A restriction chain element that combines two restriction chain elements using boolean short-circuit "or" logic.
*/
private static class OrCombination extends RestrictionChainElement {
/**
* The left element of the boolean "or" logic.
*/
private final RestrictionChainElement left;
/**
* The right element of the boolean "or" logic.
*/
private final RestrictionChainElement right;
/**
* Constructs a new restriction chain element that combines the given restriction chain elements using boolean
* short-circuit "or" logic.
*
* @param left the left element of the boolean "or" logic
* @param right the right element of the boolean "or" logic
*/
private OrCombination(RestrictionChainElement left, RestrictionChainElement right) {
this.left = left;
this.right = right;
}
@Override
public boolean isCommandAllowed(M message, RestrictionLookup availableRestrictions) {
return left.isCommandAllowed(message, availableRestrictions) || right.isCommandAllowed(message, availableRestrictions);
}
@Override
public String toString() {
return new StringJoiner(", ", OrCombination.class.getSimpleName() + "[", "]")
.add("left=" + left)
.add("right=" + right)
.toString();
}
}
/**
* A restriction chain element that negates a given restriction chain element.
*/
private static class Negation extends RestrictionChainElement {
/**
* The negated restriction chain element.
*/
private final RestrictionChainElement negated;
/**
* Constructs a new restriction chain element that negates the given restriction chain element.
*
* @param negated the negated restriction chain element
*/
private Negation(RestrictionChainElement negated) {
this.negated = negated;
}
@Override
public boolean isCommandAllowed(M message, RestrictionLookup availableRestrictions) {
return !negated.isCommandAllowed(message, availableRestrictions);
}
@Override
public String toString() {
return new StringJoiner(", ", Negation.class.getSimpleName() + "[", "]")
.add("negated=" + negated)
.toString();
}
}
}