ConfigProperties.java

/*
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * 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 org.uberfire.commons.config;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import static org.uberfire.commons.validation.PortablePreconditions.checkNotNull;

/**
 * Encapsulates a collection of Java System Properties by name and value. Includes handy methods for providing and
 * identifying application-provided default values and converting from Strings to other common types.
 */
public class ConfigProperties {

    private final Map<String, String> configuredValues;
    private final List<ConfigProperty> configSummary = new ArrayList<ConfigProperty>();

    /**
     * Creates a new container of configured values from which specific config properties can be obtained.
     * @param configuredValues The configured values, which may have been hardcoded in a Map, read from a config file, or whatever.
     */
    public ConfigProperties(Map<String, String> configuredValues) {
        this.configuredValues = checkNotNull("configuredValues",
                                             configuredValues);
    }

    /**
     * Creates a new container of configured values from which specific config properties can be obtained.
     * @param configuredValues The configured values, which may have been read from a properties file, or obtained from
     * {@link System#getProperties()}. If the property set contains entries whose key and value are not both
     * Strings, these entries will be ignored.
     */
    public ConfigProperties(Properties configuredValues) {
        Map<String, String> stringProperties = new HashMap<String, String>();
        for (String key : configuredValues.stringPropertyNames()) {
            stringProperties.put(key,
                                 configuredValues.getProperty(key));
        }
        this.configuredValues = stringProperties;
    }

    /**
     * Returns the ConfigProperty instance corresponding to the configured value of the given property, or the default
     * if no configured value exists.
     * @param name the property name. Must not be null.
     * @param defaultValue the value to use if no configured value exists. May be null.
     * @return
     */
    public ConfigProperty get(String name,
                              String defaultValue) {
        String val = configuredValues.get(name);
        ConfigProperty cp;
        if (val == null || val.trim().length() == 0) {
            cp = new ConfigProperty(name,
                                    defaultValue,
                                    true);
        } else {
            cp = new ConfigProperty(name,
                                    val.trim(),
                                    false);
        }
        configSummary.add(cp);
        return cp;
    }

    /**
     * Returns a multi-line string containing a list of all the properties that were retrieved from this instance, in
     * the order they were retrieved. Does not list unused values from the map given in the constructor, since these may
     * contain a lot of unrelated information (for example, when using System.getProperties()). This is useful for
     * printing a summary of the configuration in a given subsystem. It also helps users learn about available
     * configuration values.
     * @param heading a line of text to print before listing the configuration values
     */
    public String getConfigurationSummary(String heading) {
        final String newLine = System.getProperty("line.separator");
        StringBuilder sb = new StringBuilder(heading);
        for (ConfigProperty cp : configSummary) {
            sb.append(newLine).append(cp);
        }
        return sb.toString();
    }

    public static class ConfigProperty {

        private final String name;
        private final String value;
        private final boolean isDefault;

        ConfigProperty(String name,
                       String value,
                       boolean isDefault) {
            this.name = name;
            this.value = value;
            this.isDefault = isDefault;
        }

        /**
         * Returns the name (map key) of this property.
         */
        public String getName() {
            return name;
        }

        /**
         * Returns the value of this property, which may or may not have been the default value.
         * @return the property value. Will be null if both the configured value was missing and the default was given
         * as null.
         * @see #isDefault()
         */
        public String getValue() {
            return value;
        }

        /**
         * Returns false if this value appeared among the user-supplied values; false if it came from the
         * application-provided default.
         * @return whether this value is a default
         */
        public boolean isDefault() {
            return isDefault;
        }

        /**
         * Returns the boolean value of this property, converting from string using the same rules as
         * {@link Boolean#valueOf(String)}.
         */
        public boolean getBooleanValue() {
            return Boolean.valueOf(value);
        }

        /**
         * Returns the integer value of this property, converting from string using the same rules as
         * {@link Integer#parseInt(String)}.
         * @throws NumberFormatException if the value cannot be parsed as an integer.
         */
        public int getIntValue() {
            return Integer.parseInt(value);
        }

        @Override
        public String toString() {
            return name + " = \"" + value + "\"" + (isDefault ? " (Defaulted)" : "");
        }
    }
}