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/*
 * Copyright (c) 2020, Oracle and/or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, version 2.0, as published by the
 * Free Software Foundation.
 *
 * This program is also distributed with certain software (including but not
 * limited to OpenSSL) that is licensed under separate terms, as designated in a
 * particular file or component or in included license documentation. The
 * authors of MySQL hereby grant you an additional permission to link the
 * program and your derivative works with the separately licensed software that
 * they have included with MySQL.
 *
 * Without limiting anything contained in the foregoing, this file, which is
 * part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
 * version 1.0, a copy of which can be found at
 * http://oss.oracle.com/licenses/universal-foss-exception.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
 */

package com.mysql.cj.protocol.x;

import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.zip.InflaterInputStream;

import com.mysql.cj.Messages;
import com.mysql.cj.exceptions.ExceptionFactory;
import com.mysql.cj.exceptions.WrongArgumentException;

/**
 * Contains all information about a compression algorithm, its name, compression mode and classes that implement the inflating and deflating streams of data.
 */
public class CompressionAlgorithm {
    private static final Map ALIASES = new HashMap<>();
    static {
        ALIASES.put("deflate", "deflate_stream");
        ALIASES.put("lz4", "lz4_message");
        ALIASES.put("zstd", "zstd_stream");
    }

    private String algorithmIdentifier;
    private CompressionMode compressionMode;
    private String inputStreamClassFqn;
    private Class inputStreamClass = null;
    private String outputStreamClassFqn;
    private Class outputStreamClass = null;

    /**
     * Returns a list of the compression algorithms supported natively. Additional algorithms can be registered by user.
     * 
     * @return a list of the compression algorithms supported natively.
     */
    public static Map getDefaultInstances() {
        HashMap defaultInstances = new HashMap<>();
        defaultInstances.put("deflate_stream",
                new CompressionAlgorithm("deflate_stream", InflaterInputStream.class.getName(), SyncFlushDeflaterOutputStream.class.getName()));
        return defaultInstances;
    }

    /**
     * Returns the normalized compression algorithm identifier. A normalized identifier is composed by a compression algorithm name followed by '_' and then the
     * the compression operation mode ("stream" vs "message").
     * 
     * @param name
     *            the non-normalized compression algorithm identifier.
     * @return
     *         if {@code name} is an already normalized identifier or an unknown alias then the returned value is the same as the input, otherwise the
     *         normalized algorithm identifier is returned.
     */
    public static String getNormalizedAlgorithmName(String name) {
        return ALIASES.getOrDefault(name, name);
    }

    public CompressionAlgorithm(String name, String inputStreamClassFqn, String outputStreamClassFqn) {
        this.algorithmIdentifier = getNormalizedAlgorithmName(name);
        String[] nameMode = this.algorithmIdentifier.split("_");
        if (nameMode.length != 2) {
            throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("Protocol.Compression.4", new Object[] { name }));
        }
        try {
            CompressionMode mode = CompressionMode.valueOf(nameMode[1].toUpperCase());
            this.compressionMode = mode;
        } catch (IllegalArgumentException e) {
            throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("Protocol.Compression.5", new Object[] { nameMode[1] }));
        }
        this.inputStreamClassFqn = inputStreamClassFqn;
        this.outputStreamClassFqn = outputStreamClassFqn;
    }

    /**
     * Gets this algorithm's identifier.
     * 
     * @return an algorithm identifier.
     */
    public String getAlgorithmIdentifier() {
        return this.algorithmIdentifier;
    }

    /**
     * Gets this algorithm's compression mode.
     * 
     * @return an algorithm {@link CompressionMode}
     */
    public CompressionMode getCompressionMode() {
        return this.compressionMode;
    }

    /**
     * Gets this algorithm's {@link InputStream} implementation class that can be used to inflate data.
     * 
     * @return an {@link InputStream} that knows how to inflate data.
     */
    public Class getInputStreamClass() {
        if (this.inputStreamClass == null) {
            try {
                this.inputStreamClass = Class.forName(this.inputStreamClassFqn);
            } catch (ClassNotFoundException e) {
                throw ExceptionFactory.createException(WrongArgumentException.class,
                        Messages.getString("Protocol.Compression.3", new Object[] { this.inputStreamClassFqn }), e);
            }
        }
        return this.inputStreamClass;
    }

    /**
     * Gets this algorithm's {@link OutputStream} implementation class that can be used to deflate data.
     * 
     * @return an {@link OutputStream} that knows how to deflate data.
     */
    public Class getOutputStreamClass() {
        if (this.outputStreamClass == null) {
            try {
                this.outputStreamClass = Class.forName(this.outputStreamClassFqn);
            } catch (ClassNotFoundException e) {
                throw ExceptionFactory.createException(WrongArgumentException.class,
                        Messages.getString("Protocol.Compression.3", new Object[] { this.outputStreamClassFqn }), e);
            }
        }
        return this.outputStreamClass;
    }
}