/*
 * 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.commons.vfs2;

import java.io.File;
import java.lang.reflect.Constructor;
import java.net.URI;
import java.net.URL;
import java.net.URLStreamHandlerFactory;
import java.util.Collection;

import org.apache.commons.logging.Log;
import org.apache.commons.vfs2.operations.FileOperationProvider;

/**
 * A FileSystemManager manages a set of file systems. This interface is used to locate a {@link FileObject} by name from
 * one of those file systems.
 * <p>
 * To locate a {@link FileObject}, use one of the {@code resolveFile()} methods.
 * </p>
 *
 * <h2><a id="naming">File Naming</a></h2>
 * <p>
 * A file system manager can recognise several types of file names:
 * </p>
 * <ul>
 * <li>Absolute URI. These must start with a scheme, such as {@code file:} or {@code ftp:}, followed by a scheme
 * dependent file name. Some examples: {@code file:/c:/somefile} or {@code ftp://somewhere.org/somefile}.</li>
 * <li>Absolute local file name. For example, {@code /home/someuser/a-file} or {@code c:\dir\somefile.html}. Elements in
 * the name can be separated using any of the following characters: {@code /}, {@code \}, or the native file separator
 * character. For example, the following file names are the same: {@code c:\somedir\somefile.xml} and
 * {@code c:/somedir/somefile.xml}.</li>
 * <li>Relative path. For example: {@code ../somefile} or {@code somedir/file.txt}. The file system manager resolves
 * relative paths against its <i>base file</i>. Elements in the relative path can be separated using {@code /},
 * {@code \}, or file system specific separator characters. Relative paths may also contain {@code ..} and {@code .}
 * elements. See {@link FileObject#resolveFile} for more details.</li>
 * </ul>
 */
public interface FileSystemManager extends AutoCloseable {

    /**
     * Adds the specified FileOperationProvider for the specified scheme.
     * <p>
     * Several FileOperationProvider's might be registered for the same scheme. For example, for {@code "file"} scheme
     * we can register {@code SvnWsOperationProvider} and {@code CvsOperationProvider.}
     * </p>
     *
     * @param scheme The scheme assoicated with this provider.
     * @param operationProvider The FileOperationProvider to add.
     * @throws FileSystemException if an error occurs.
     */
    void addOperationProvider(String scheme, FileOperationProvider operationProvider) throws FileSystemException;

    /**
     * @see FileSystemManager#addOperationProvider(String, org.apache.commons.vfs2.operations.FileOperationProvider)
     *
     * @param schemes The schemes that will be associated with the provider.
     * @param operationProvider The FileOperationProvider to add.
     * @throws FileSystemException if an error occurs.
     */
    void addOperationProvider(String[] schemes, FileOperationProvider operationProvider) throws FileSystemException;

    /**
     * Determines if a layered file system can be created for a given file.
     *
     * @param file The file to check for.
     * @return true if the FileSystem can be created.
     * @throws FileSystemException if an error occurs.
     */
    boolean canCreateFileSystem(FileObject file) throws FileSystemException;

    /**
     * Closes this file system manager.
     *
     * @since 2.5.0
     */
    @Override
    default void close() {
        // noop
    }

    /**
     * Closes the given file system.
     * <p>
     * If you use VFS as singleton it is VERY dangerous to call this method.
     * </p>
     *
     * @param fileSystem The FileSystem to close.
     */
    void closeFileSystem(FileSystem fileSystem);

    /**
     * Creates a layered file system. A layered file system is a file system that is created from the contents of a
     * file, such as a zip or tar file.
     *
     * @param file The file to use to create the file system.
     * @return The root file of the new file system.
     * @throws FileSystemException On error creating the file system.
     */
    FileObject createFileSystem(FileObject file) throws FileSystemException;

    /**
     * Creates a layered file system. A layered file system is a file system that is created from the contents of a
     * file, such as a zip or tar file.
     *
     * @param provider The name of the file system provider to use. This name is the same as the scheme used in URI to
     *            identify the provider.
     * @param file The file to use to create the file system.
     * @return The root file of the new file system.
     * @throws FileSystemException On error creating the file system.
     */
    FileObject createFileSystem(String provider, FileObject file) throws FileSystemException;

    /**
     * Creates a virtual file system. The file system will contain a junction at the fs root to the supplied root file.
     *
     * @param rootFile The root file to backs the file system.
     * @return The root of the new file system.
     * @throws FileSystemException if an error occurs creating the VirtualFileSystem.
     */
    FileObject createVirtualFileSystem(FileObject rootFile) throws FileSystemException;

    /**
     * Creates an empty virtual file system. Can be populated by adding junctions to it.
     *
     * @param rootUri The root URI to use for the new file system. Can be null.
     * @return The root file of the new file system.
     * @throws FileSystemException if an error occurs creating the VirtualFileSystem.
     */
    FileObject createVirtualFileSystem(String rootUri) throws FileSystemException;

    /**
     * Returns the base file used to resolve relative paths.
     *
     * @return The base FileObject.
     * @throws FileSystemException if an error occurs.
     */
    FileObject getBaseFile() throws FileSystemException;

    /**
     * Gets the cache strategy used.
     *
     * @return the CacheStrategy.
     */
    CacheStrategy getCacheStrategy();

    /**
     * Gets the class to use to determine the content-type (mime-type).
     *
     * @return the FileContentInfoFactory.
     */
    FileContentInfoFactory getFileContentInfoFactory();

    /**
     * Gets the file object decorator used.
     *
     * @return the file object decorator Class.
     */
    Class<?> getFileObjectDecorator();

    /**
     * Gets the constructor associated to the fileObjectDecorator. We cache it here for performance reasons.
     *
     * @return the Constructor associated with the FileObjectDecorator.
     */
    Constructor<?> getFileObjectDecoratorConst();

    /**
     * Gets the cache used to cache file objects.
     *
     * @return The FilesCache.
     */
    FilesCache getFilesCache();

    /**
     * Gets the configuration builder for the given scheme.
     *
     * @param scheme The schem to use to obtain the FileSystemConfigBuidler.
     * @return A FileSystemConfigBuilder appropriate for the given scheme.
     * @throws FileSystemException if the given scheme is not konwn.
     */
    FileSystemConfigBuilder getFileSystemConfigBuilder(String scheme) throws FileSystemException;

    /**
     * Gets Providers for file operations.
     *
     * @param scheme the scheme for wich we want to get the list af registered providers.
     *
     * @return the registered FileOperationProviders for the specified scheme. If there were no providers registered for
     *         the scheme, it returns null.
     *
     * @throws FileSystemException if an error occurs.
     */
    FileOperationProvider[] getOperationProviders(String scheme) throws FileSystemException;

    /**
     * Gets the capabilities for a given scheme.
     *
     * @param scheme The scheme to use to locate the provider's capabilities.
     * @return A Collection of the various capabilities.
     * @throws FileSystemException if the given scheme is not konwn.
     */
    Collection<Capability> getProviderCapabilities(String scheme) throws FileSystemException;

    /**
     * Gets the schemes currently available.
     *
     * @return An array of available scheme names that are supported.
     */
    String[] getSchemes();

    /**
     * Returns a stream handler factory to enable URL lookup using this FileSystemManager.
     *
     * @return the URLStreamHandlerFactory.
     */
    URLStreamHandlerFactory getURLStreamHandlerFactory();

    /**
     * Returns true if this manager has a provider for a particular scheme.
     *
     * @param scheme The scheme for which a provider should be checked.
     * @return true if a provider for the scheme is available.
     */
    boolean hasProvider(String scheme);

    /**
     * Locates a file by name. See {@link #resolveFile(FileObject, String)} for details.
     *
     * @param baseFile The base file to use to resolve relative paths. Must not be {@code null}, not even if the
     *            <i>name</i> is absolute.
     * @param name The name of the file.
     * @return The file. Never returns null.
     * @throws FileSystemException On error parsing the file name.
     */
    FileObject resolveFile(File baseFile, String name) throws FileSystemException;

    /**
     * Locates a file by name. The name is resolved as described <a href="#naming">above</a>. That is, the name can be
     * either an absolute URI, an absolute file name, or a relative path to be resolved against {@code baseFile}.
     * <p>
     * Note that the file does not have to exist when this method is called.
     * </p>
     *
     * @param baseFile The base file to use to resolve relative paths. May be null if the name is an absolute file name.
     * @param name The name of the file.
     * @return The file. Never returns null.
     * @throws FileSystemException On error parsing the file name.
     */
    FileObject resolveFile(FileObject baseFile, String name) throws FileSystemException;

    /**
     * Locates a file by name. Equivalent to calling {@code resolveFile(getBaseFile(), name)}.
     *
     * @param name The name of the file.
     * @return The file. Never returns null.
     * @throws FileSystemException On error parsing the file name.
     */
    FileObject resolveFile(String name) throws FileSystemException;

    /**
     * Locates a file by name. Equivalent to calling {@code resolveFile(getBaseFile(), name)}.
     *
     * @param name The name of the file.
     * @param fileSystemOptions The FileSystemOptions used for FileSystem creation. All files that are later resolved
     *            relative to the returned {@code FileObject} share the options.
     * @return The file. Never returns null.
     * @throws FileSystemException On error parsing the file name.
     */
    FileObject resolveFile(String name, FileSystemOptions fileSystemOptions) throws FileSystemException;

    /**
     * Resolves a URI into a {@link FileObject}.
     *
     * @param uri The URI to convert.
     * @return The {@link FileObject} that represents the URI. Never returns null.
     * @throws FileSystemException On error converting the file.
     * @since 2.1
     */
    FileObject resolveFile(URI uri) throws FileSystemException;

    /**
     * Resolves a URL into a {@link FileObject}.
     *
     * @param url The URL to convert.
     * @return The {@link FileObject} that represents the URL. Never returns null.
     * @throws FileSystemException On error converting the file.
     * @since 2.1
     */
    FileObject resolveFile(URL url) throws FileSystemException;

    /**
     * Resolves a name, relative to this file name. Equivalent to calling
     * {@code resolveName( path, NameScope.FILE_SYSTEM )}.
     *
     * @param root the base file name
     * @param name The name to resolve.
     * @return A {@link FileName} object representing the resolved file name.
     * @throws FileSystemException If the name is invalid.
     */
    FileName resolveName(FileName root, String name) throws FileSystemException;

    /**
     * Resolves a name, relative to the "root" file name. Refer to {@link NameScope} for a description of how names are
     * resolved.
     *
     * @param root the base file name
     * @param name The name to resolve.
     * @param scope The {@link NameScope} to use when resolving the name.
     * @return A {@link FileName} object representing the resolved file name.
     * @throws FileSystemException If the name is invalid.
     */
    FileName resolveName(FileName root, String name, NameScope scope) throws FileSystemException;

    /**
     * Resolves the URI to a file name.
     *
     * @param uri The URI to resolve.
     * @return A FileName that matches the URI.
     * @throws FileSystemException if this is not possible.
     */
    FileName resolveURI(String uri) throws FileSystemException;

    /**
     * Sets the logger to use.
     *
     * @param log The logger to use.
     */
    void setLogger(Log log);

    /**
     * Converts a local file into a {@link FileObject}.
     *
     * @param file The file to convert.
     * @return The {@link FileObject} that represents the local file. Never returns null.
     * @throws FileSystemException On error converting the file.
     */
    FileObject toFileObject(File file) throws FileSystemException;

}