/*
 * Copyright 2002-2005 The Apache Software Foundation.
 *
 * 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.apache.commons.vfs.provider;

import org.apache.commons.vfs.FileName;
import org.apache.commons.vfs.FileSystemException;

/**
 * Implementation for any url based filesystem.<br />
 * Parses the url into user/password/host/port/path<br />
 * Does not handle a query string (after ?)
 *
 * @see URLFileNameParser URLFileNameParser for the implementation which also handles the query string too
 * @author imario@apache.org
 * @version $Revision$ $Date$
 */
public class HostFileNameParser extends AbstractFileNameParser
{
    private final int defaultPort;

    public HostFileNameParser(final int defaultPort)
    {
        this.defaultPort = defaultPort;
    }

    public int getDefaultPort()
    {
        return defaultPort;
    }

    public boolean encodeCharacter(char ch)
    {
        return super.encodeCharacter(ch);
    }

    public FileName parseUri(final VfsComponentContext context, FileName base, final String filename) throws FileSystemException
    {
        // FTP URI are generic URI (as per RFC 2396)
        final StringBuffer name = new StringBuffer();

        // Extract the scheme and authority parts
        final Authority auth = extractToPath(filename, name);

        // Decode and normalise the file name
        final String path = normalizePath(name);

        return new GenericFileName(
            auth.scheme,
            auth.hostName,
            auth.port,
            defaultPort,
            auth.userName,
            auth.password,
            path);
    }

    protected String normalizePath(final StringBuffer name)
        throws FileSystemException
    {
        UriParser.canonicalizePath(name, 0, name.length(), this);
        UriParser.normalisePath(name);
        final String path = name.toString();
        return path;
    }

    /**
     * Extracts the scheme, userinfo, hostname and port components of a
     * generic URI.
     *
     * @param uri  The absolute URI to parse.
     * @param name Used to return the remainder of the URI.
     */
    protected Authority extractToPath(final String uri,
                                      final StringBuffer name)
        throws FileSystemException
    {
        final Authority auth = new Authority();

        // Extract the scheme
        auth.scheme = UriParser.extractScheme(uri, name);

        // Expecting "//"
        if (name.length() < 2 || name.charAt(0) != '/' || name.charAt(1) != '/')
        {
            throw new FileSystemException("vfs.provider/missing-double-slashes.error", uri);
        }
        name.delete(0, 2);

        // Extract userinfo, and split into username and password
        final String userInfo = extractUserInfo(name);
        final String userName;
        final String password;
        if (userInfo != null)
        {
            int idx = userInfo.indexOf(':');
            if (idx == -1)
            {
                userName = userInfo;
                password = null;
            }
            else
            {
                userName = userInfo.substring(0, idx);
                password = userInfo.substring(idx + 1);
            }
        }
        else
        {
            userName = null;
            password = null;
        }
        auth.userName = UriParser.decode(userName);
        auth.password = UriParser.decode(password);

        // Extract hostname, and normalise (lowercase)
        final String hostName = extractHostName(name);
        if (hostName == null)
        {
            throw new FileSystemException("vfs.provider/missing-hostname.error", uri);
        }
        auth.hostName = hostName.toLowerCase();

        // Extract port
        auth.port = extractPort(name, uri);

        // Expecting '/' or empty name
        if (name.length() > 0 && name.charAt(0) != '/')
        {
            throw new FileSystemException("vfs.provider/missing-hostname-path-sep.error", uri);
        }

        return auth;
    }

    /**
     * Extracts the user info from a URI.  The scheme:// part has been removed
     * already.
     */
    protected String extractUserInfo(final StringBuffer name)
    {
        final int maxlen = name.length();
        for (int pos = 0; pos < maxlen; pos++)
        {
            final char ch = name.charAt(pos);
            if (ch == '@')
            {
                // Found the end of the user info
                String userInfo = name.substring(0, pos);
                name.delete(0, pos + 1);
                return userInfo;
            }
            if (ch == '/' || ch == '?')
            {
                // Not allowed in user info
                break;
            }
        }

        // Not found
        return null;
    }

    /**
     * Extracts the hostname from a URI.  The scheme://userinfo@ part has
     * been removed.
     */
    protected String extractHostName(final StringBuffer name)
    {
        final int maxlen = name.length();
        int pos = 0;
        for (; pos < maxlen; pos++)
        {
            final char ch = name.charAt(pos);
            if (ch == '/' || ch == ';' || ch == '?' || ch == ':'
                || ch == '@' || ch == '&' || ch == '=' || ch == '+'
                || ch == '$' || ch == ',')
            {
                break;
            }
        }
        if (pos == 0)
        {
            return null;
        }

        final String hostname = name.substring(0, pos);
        name.delete(0, pos);
        return hostname;
    }

    /**
     * Extracts the port from a URI.  The scheme://userinfo@hostname
     * part has been removed.
     *
     * @return The port, or -1 if the URI does not contain a port.
     */
    protected int extractPort(final StringBuffer name, final String uri) throws FileSystemException
    {
        if (name.length() < 1 || name.charAt(0) != ':')
        {
            return -1;
        }

        final int maxlen = name.length();
        int pos = 1;
        for (; pos < maxlen; pos++)
        {
            final char ch = name.charAt(pos);
            if (ch < '0' || ch > '9')
            {
                break;
            }
        }

        final String port = name.substring(1, pos);
        name.delete(0, pos);
        if (port.length() == 0)
        {
            throw new FileSystemException("vfs.provider/missing-port.error", uri);
        }

        return Integer.parseInt(port);
    }

    /**
     * Parsed authority info (scheme, hostname, userinfo, port)
     */
    protected static class Authority
    {
        public String scheme;
        public String hostName;
        public String userName;
        public String password;
        public int port;
    }
}