/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.catalina.ssi;


import java.io.IOException;
import java.util.Collection;
import java.util.Date;

/**
 * Interface used by SSIMediator to talk to the 'outside world' ( usually a servlet ).
 */
public interface SSIExternalResolver {
    /**
     * Adds any external variables to the variableNames collection.
     *
     * @param variableNames the collection to add to
     */
    void addVariableNames(Collection<String> variableNames);


    /**
     * Returns the value of the named variable, or null if not found.
     *
     * @param name of the variable
     * @return the variable value
     */
    String getVariableValue(String name);


    /**
     * Set the named variable to the specified value. If value is null, then the variable will be removed ( ie. a call
     * to getVariableValue will return null )
     *
     * @param name  of the variable
     * @param value of the variable
     */
    void setVariableValue(String name, String value);


    /**
     * Returns the current date. This is useful for putting the SSI stuff in a regression test. Since you can make the
     * current date a constant, it makes testing easier since the output won't change.
     *
     * @return the date
     */
    Date getCurrentDate();


    /**
     * Returns the size of the specified file in bytes.
     *
     * @param path    the file path
     * @param virtual true for virtual (webapp-relative) path, false for physical path
     * @return the file size in bytes
     * @throws IOException if the file cannot be accessed
     */
    long getFileSize(String path, boolean virtual) throws IOException;


    /**
     * Returns the last modified timestamp of the specified file.
     *
     * @param path    the file path
     * @param virtual true for virtual (webapp-relative) path, false for physical path
     * @return the last modified time in milliseconds
     * @throws IOException if the file cannot be accessed
     */
    long getFileLastModified(String path, boolean virtual) throws IOException;


    /**
     * Returns the text content of the specified file.
     *
     * @param path    the file path
     * @param virtual true for virtual (webapp-relative) path, false for physical path
     * @return the file content as a string
     * @throws IOException if the file cannot be read
     */
    String getFileText(String path, boolean virtual) throws IOException;


    /**
     * Logs a message, optionally with an associated throwable.
     *
     * @param message     the log message
     * @param throwable   the associated throwable, or null
     */
    void log(String message, Throwable throwable);
}