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/*
 * Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.eclipse.angus.mail.handlers;

import jakarta.activation.ActivationDataFlavor;
import jakarta.activation.DataSource;
import jakarta.mail.internet.ContentType;
import jakarta.mail.internet.MimeUtility;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

/**
 * DataContentHandler for text/plain.
 */
public class text_plain extends handler_base {
    private static ActivationDataFlavor[] myDF = {
            new ActivationDataFlavor(String.class, "text/plain", "Text String")
    };

    /**
     * Creates a default {@code text_plain}.
     */
    public text_plain() {
    }

    /**
     * An OuputStream wrapper that doesn't close the underlying stream.
     */
    private static class NoCloseOutputStream extends FilterOutputStream {
        NoCloseOutputStream(OutputStream os) {
            super(os);
        }

        @Override
        public void close() {
            // do nothing
        }
    }

    @Override
    protected ActivationDataFlavor[] getDataFlavors() {
        return myDF;
    }

    @Override
    public Object getContent(DataSource ds) throws IOException {
        String enc = null;
        InputStreamReader is = null;

        try {
            enc = getCharset(ds.getContentType());
            is = new InputStreamReader(ds.getInputStream(), enc);
        } catch (IllegalArgumentException iex) {
            /*
             * An unknown charset of the form ISO-XXX-XXX will cause
             * the JDK to throw an IllegalArgumentException.  The
             * JDK will attempt to create a classname using this string,
             * but valid classnames must not contain the character '-',
             * and this results in an IllegalArgumentException, rather than
             * the expected UnsupportedEncodingException.  Yikes.
             */
            throw new UnsupportedEncodingException(enc);
        }

        try {
            int pos = 0;
            int count;
            char[] buf = new char[1024];

            while ((count = is.read(buf, pos, buf.length - pos)) != -1) {
                pos += count;
                if (pos >= buf.length) {
                    int size = buf.length;
                    size += Math.min(size, 256 * 1024);
                    char[] tbuf = new char[size];
                    System.arraycopy(buf, 0, tbuf, 0, pos);
                    buf = tbuf;
                }
            }
            return new String(buf, 0, pos);
        } finally {
            try {
                is.close();
            } catch (IOException ex) {
                // ignore it
            }
        }
    }

    /**
     * Write the object to the output stream, using the specified MIME type.
     */
    @Override
    public void writeTo(Object obj, String type, OutputStream os)
            throws IOException {
        if (!(obj instanceof String))
            throw new IOException("\"" + getDataFlavors()[0].getMimeType() +
                    "\" DataContentHandler requires String object, " +
                    "was given object of type " + obj.getClass().toString());

        String enc = null;
        OutputStreamWriter osw = null;

        try {
            enc = getCharset(type);
            osw = new OutputStreamWriter(new NoCloseOutputStream(os), enc);
        } catch (IllegalArgumentException iex) {
            /*
             * An unknown charset of the form ISO-XXX-XXX will cause
             * the JDK to throw an IllegalArgumentException.  The
             * JDK will attempt to create a classname using this string,
             * but valid classnames must not contain the character '-',
             * and this results in an IllegalArgumentException, rather than
             * the expected UnsupportedEncodingException.  Yikes.
             */
            throw new UnsupportedEncodingException(enc);
        }

        String s = (String) obj;
        osw.write(s, 0, s.length());
        /*
         * Have to call osw.close() instead of osw.flush() because
         * some charset converts, such as the iso-2022-jp converter,
         * don't output the "shift out" sequence unless they're closed.
         * The NoCloseOutputStream wrapper prevents the underlying
         * stream from being closed.
         */
        osw.close();
    }

    private String getCharset(String type) {
        try {
            ContentType ct = new ContentType(type);
            String charset = ct.getParameter("charset");
            if (charset == null)
                // If the charset parameter is absent, use US-ASCII.
                charset = "us-ascii";
            return MimeUtility.javaCharset(charset);
        } catch (Exception ex) {
            return null;
        }
    }
}