/*
 * 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
 *
 *      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 org.apache.commons.net.finger;

import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.io.Charsets;
import org.apache.commons.io.IOUtils;
import org.apache.commons.net.SocketClient;

/**
 * The FingerClient class implements the client side of the Internet Finger Protocol defined in RFC 1288. To finger a host you create a FingerClient instance,
 * connect to the host, query the host, and finally disconnect from the host. If the finger service you want to query is on a non-standard port, connect to the
 * host at that port. Here's a sample use:
 *
 * <pre>
 * FingerClient finger;
 * finger = new FingerClient();
 * try {
 *     finger.connect("foo.bar.com");
 *     System.out.println(finger.query("foobar", false));
 *     finger.disconnect();
 * } catch (IOException e) {
 *     System.err.println("Error I/O exception: " + e.getMessage());
 *     return;
 * }
 * </pre>
 */
public class FingerClient extends SocketClient {

    /**
     * The default FINGER port. Set to {@value} according to RFC 1288.
     */
    public static final int DEFAULT_PORT = 79;

    private static final String LONG_FLAG = "/W ";

    /**
     * The default FingerClient constructor. Initializes the default port to {@code DEFAULT_PORT}.
     */
    public FingerClient() {
        setDefaultPort(DEFAULT_PORT);
    }

    /**
     * Fingers the connected host and returns the input stream from the network connection of the finger query. This is equivalent to calling
     * getInputStream(longOutput, ""). You must first connect to a finger server before calling this method, and you should disconnect after finishing reading
     * the stream.
     *
     * @param longOutput Set to true if long output is requested, false if not.
     * @return The InputStream of the network connection of the finger query. Can be read to obtain finger results.
     * @throws IOException If an I/O error during the operation.
     */
    public InputStream getInputStream(final boolean longOutput) throws IOException {
        return getInputStream(longOutput, "");
    }

    /**
     * Fingers a user and returns the input stream from the network connection of the finger query. You must first connect to a finger server before calling
     * this method, and you should disconnect after finishing reading the stream.
     *
     * @param longOutput Set to true if long output is requested, false if not.
     * @param user   The name of the user to finger.
     * @return The InputStream of the network connection of the finger query. Can be read to obtain finger results.
     * @throws IOException If an I/O error during the operation.
     */
    public InputStream getInputStream(final boolean longOutput, final String user) throws IOException {
        return getInputStream(longOutput, user, null);
    }

    /**
     * Fingers a user and returns the input stream from the network connection of the finger query. You must first connect to a finger server before calling
     * this method, and you should disconnect after finishing reading the stream.
     *
     * @param longOutput Set to true if long output is requested, false if not.
     * @param user   The name of the user to finger.
     * @param encoding   the character encoding that should be used for the query, null for the platform's default encoding
     * @return The InputStream of the network connection of the finger query. Can be read to obtain finger results.
     * @throws IOException If an I/O error during the operation.
     */
    public InputStream getInputStream(final boolean longOutput, final String user, final String encoding) throws IOException {
        final DataOutputStream output;
        final StringBuilder buffer = new StringBuilder(64);
        if (longOutput) {
            buffer.append(LONG_FLAG);
        }
        buffer.append(user);
        buffer.append(NETASCII_EOL);

        // Note: Charsets.toCharset() returns the platform default for null input
        final byte[] encodedQuery = buffer.toString().getBytes(Charsets.toCharset(encoding));

        output = new DataOutputStream(new BufferedOutputStream(checkOpenOutputStream(), 1024));
        output.write(encodedQuery, 0, encodedQuery.length);
        output.flush();

        return _input_;
    }

    /**
     * Fingers the connected host and returns the output as a String. You must first connect to a finger server before calling this method, and you should
     * disconnect afterward. This is equivalent to calling {@code query(longOutput, "")}.
     *
     * @param longOutput Set to true if long output is requested, false if not.
     * @return The result of the finger query.
     * @throws IOException If an I/O error occurs while reading the socket.
     */
    public String query(final boolean longOutput) throws IOException {
        return query(longOutput, "");
    }

    /**
     * Fingers a user at the connected host and returns the output as a String. You must first connect to a finger server before calling this method, and you
     * should disconnect afterward.
     *
     * @param longOutput Set to true if long output is requested, false if not.
     * @param user   The name of the user to finger.
     * @return The result of the finger query.
     * @throws IOException If an I/O error occurs while reading the socket.
     */
    public String query(final boolean longOutput, final String user) throws IOException {
        return IOUtils.toString(() -> getInputStream(longOutput, user), getCharset());
    }

}