/*
 * Copyright 2002-2016 the original author or authors.
 *
 * 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
 *
 *      https://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.taobao.arthas.core.env;

/**
 * Interface for resolving properties against any underlying source.
 *
 * @author Chris Beams
 * @author Juergen Hoeller
 * @since 3.1
 * @see Environment
 * @see PropertySourcesPropertyResolver
 */
public interface PropertyResolver {

    /**
     * Return whether the given property key is available for resolution, i.e. if
     * the value for the given key is not {@code null}.
     */
    boolean containsProperty(String key);

    /**
     * Return the property value associated with the given key, or {@code null} if
     * the key cannot be resolved.
     * 
     * @param key the property name to resolve
     * @see #getProperty(String, String)
     * @see #getProperty(String, Class)
     * @see #getRequiredProperty(String)
     */
    String getProperty(String key);

    /**
     * Return the property value associated with the given key, or
     * {@code defaultValue} if the key cannot be resolved.
     * 
     * @param key          the property name to resolve
     * @param defaultValue the default value to return if no value is found
     * @see #getRequiredProperty(String)
     * @see #getProperty(String, Class)
     */
    String getProperty(String key, String defaultValue);

    /**
     * Return the property value associated with the given key, or {@code null} if
     * the key cannot be resolved.
     * 
     * @param key        the property name to resolve
     * @param targetType the expected type of the property value
     * @see #getRequiredProperty(String, Class)
     */
    <T> T getProperty(String key, Class<T> targetType);

    /**
     * Return the property value associated with the given key, or
     * {@code defaultValue} if the key cannot be resolved.
     * 
     * @param key          the property name to resolve
     * @param targetType   the expected type of the property value
     * @param defaultValue the default value to return if no value is found
     * @see #getRequiredProperty(String, Class)
     */
    <T> T getProperty(String key, Class<T> targetType, T defaultValue);

    /**
     * Return the property value associated with the given key (never {@code null}).
     * 
     * @throws IllegalStateException if the key cannot be resolved
     * @see #getRequiredProperty(String, Class)
     */
    String getRequiredProperty(String key) throws IllegalStateException;

    /**
     * Return the property value associated with the given key, converted to the
     * given targetType (never {@code null}).
     * 
     * @throws IllegalStateException if the given key cannot be resolved
     */
    <T> T getRequiredProperty(String key, Class<T> targetType) throws IllegalStateException;

    /**
     * Resolve ${...} placeholders in the given text, replacing them with
     * corresponding property values as resolved by {@link #getProperty}.
     * Unresolvable placeholders with no default value are ignored and passed
     * through unchanged.
     * 
     * @param text the String to resolve
     * @return the resolved String (never {@code null})
     * @throws IllegalArgumentException if given text is {@code null}
     * @see #resolveRequiredPlaceholders
     * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String)
     */
    String resolvePlaceholders(String text);

    /**
     * Resolve ${...} placeholders in the given text, replacing them with
     * corresponding property values as resolved by {@link #getProperty}.
     * Unresolvable placeholders with no default value will cause an
     * IllegalArgumentException to be thrown.
     * 
     * @return the resolved String (never {@code null})
     * @throws IllegalArgumentException if given text is {@code null} or if any
     *                                  placeholders are unresolvable
     * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String,
     *      boolean)
     */
    String resolveRequiredPlaceholders(String text) throws IllegalArgumentException;

}
