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A Java library to parse, migrate and validate crons as well as describe them in human readable
language
/*
* Copyright 2014 jmrozanec
* 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.cronutils.descriptor;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
import com.cronutils.Function;
import com.cronutils.model.field.expression.Always;
import com.cronutils.model.field.expression.And;
import com.cronutils.model.field.expression.Between;
import com.cronutils.model.field.expression.Every;
import com.cronutils.model.field.expression.FieldExpression;
import com.cronutils.model.field.expression.On;
import com.cronutils.model.field.value.FieldValue;
import com.cronutils.model.field.value.IntegerFieldValue;
import com.cronutils.utils.Preconditions;
import com.cronutils.utils.StringUtils;
/**
* Description strategy to handle cases on how to present cron information in a human readable format.
*/
abstract class DescriptionStrategy {
private static final String EVERY = "every";
private static final String WHITE_SPACE = " ";
protected Function nominalValueFunction;
protected ResourceBundle bundle;
public DescriptionStrategy(final ResourceBundle bundle) {
this.bundle = bundle;
nominalValueFunction = integer -> WHITE_SPACE + integer;
}
/**
* Provide a human readable description.
*
* @return human readable description - String
*/
public abstract String describe();
/**
* Given a {@linkplain FieldExpression}, provide a {@linkplain String} with a human readable description. Will identify
* {@linkplain FieldExpression} subclasses and delegate.
*
* @param fieldExpression - CronFieldExpression instance - not null
* @return human readable description - String
*/
protected String describe(final FieldExpression fieldExpression) {
return describe(fieldExpression, false);
}
/**
* Given a {@linkplain FieldExpression}, provide a {@linkplain String} with a human readable description. Will identify
* {@linkplain FieldExpression} subclasses and delegate.
*
* @param fieldExpression - CronFieldExpression instance - not null
* @param and - boolean expression that indicates if description should fit an "and" context
* @return human readable description - String
*/
protected String describe(final FieldExpression fieldExpression, final boolean and) {
Preconditions.checkNotNull(fieldExpression, "CronFieldExpression should not be null!");
if (fieldExpression instanceof Always) {
return describe((Always) fieldExpression, and);
}
if (fieldExpression instanceof And) {
return describe((And) fieldExpression);
}
if (fieldExpression instanceof Between) {
return describe((Between) fieldExpression, and);
}
if (fieldExpression instanceof Every) {
return describe((Every) fieldExpression, and);
}
if (fieldExpression instanceof On) {
return describe((On) fieldExpression, and);
}
return StringUtils.EMPTY;
}
/**
* Provide a human readable description for Always instance.
*
* @param always - Always
* @return human readable description - String
*/
protected String describe(final Always always, final boolean and) {
return StringUtils.EMPTY;
}
/**
* Provide a human readable description for And instance.
*
* @param and - And
* @return human readable description - String
*/
protected String describe(final And and) {
final List expressions = new ArrayList<>();
final List onExpressions = new ArrayList<>();
for (final FieldExpression fieldExpression : and.getExpressions()) {
if (fieldExpression instanceof On) {
onExpressions.add(fieldExpression);
} else {
expressions.add(fieldExpression);
}
}
final StringBuilder builder = new StringBuilder();
if (!onExpressions.isEmpty()) {
builder.append(bundle.getString("at"));
createAndDescription(builder, onExpressions).append(" %p");
}
if (!expressions.isEmpty()) {
createAndDescription(builder, expressions);
}
return builder.toString();
}
/**
* Provide a human readable description for Between instance.
*
* @param between - Between
* @return human readable description - String
*/
protected String describe(final Between between, final boolean and) {
return bundle.getString(EVERY) + " %s "
+ MessageFormat.format(bundle.getString("between_x_and_y"), nominalValue(between.getFrom()), nominalValue(between.getTo())) + WHITE_SPACE;
}
/**
* Provide a human readable description for Every instance.
*
* @param every - Every
* @return human readable description - String
*/
protected String describe(final Every every, final boolean and) {
String description;
if (every.getPeriod().getValue() > 1) {
description = String.format("%s %s ", bundle.getString(EVERY), nominalValue(every.getPeriod())) + " %p ";
} else {
description = bundle.getString(EVERY) + " %s ";
}
if (every.getExpression() instanceof Between) {
final Between between = (Between) every.getExpression();
description +=
MessageFormat.format(
bundle.getString("between_x_and_y"), nominalValue(between.getFrom()), nominalValue(between.getTo())
) + WHITE_SPACE;
}
return description;
}
/**
* Provide a human readable description for On instance.
*
* @param on - On
* @return human readable description - String
*/
protected String describe(final On on, final boolean and) {
if (and) {
return nominalValue(on.getTime());
}
return String.format("%s %s ", bundle.getString("at"), nominalValue(on.getTime())) + "%s";
}
/**
* Given an int, will return a nominal value. Example: 1 in weeks context, may mean "Monday", so nominal value for 1 would be "Monday"
* Default will return int as String
*
* @param fieldValue - some FieldValue
* @return String
*/
protected String nominalValue(final FieldValue fieldValue) {
Preconditions.checkNotNull(fieldValue, "FieldValue must not be null");
if (fieldValue instanceof IntegerFieldValue) {
return nominalValueFunction.apply(((IntegerFieldValue) fieldValue).getValue());
}
return fieldValue.toString();
}
/**
* Creates human readable description for And element.
*
* @param builder - StringBuilder instance to which description will be appended
* @param expressions - field expressions
* @return same StringBuilder instance as parameter
*/
private StringBuilder createAndDescription(final StringBuilder builder, final List expressions) {
if ((expressions.size() - 2) >= 0) {
for (int j = 0; j < expressions.size() - 2; j++) {
builder.append(String.format(" %s, ", describe(expressions.get(j), true)));
}
builder.append(String.format(" %s ", describe(expressions.get(expressions.size() - 2), true)));
}
builder.append(String.format(" %s ", bundle.getString("and")));
builder.append(describe(expressions.get(expressions.size() - 1), true));
return builder;
}
}