/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2020 Ziver Koc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package zutil.net.http.multipart;

import zutil.io.BufferedBoundaryInputStream;
import zutil.io.IOUtil;
import zutil.log.LogUtil;
import zutil.net.http.HttpHeader;
import zutil.net.http.HttpHeaderParser;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Parses a multipart/form-data http request,
 * saves files to temporary location.
 *
 * http://www.ietf.org/rfc/rfc1867.txt
 *
 * @author Ziver
 *
 */
public class MultipartParser implements Iterable<MultipartField>{
    private static final Logger logger = LogUtil.getLogger();
    protected static final String HEADER_CONTENT_DISPOSITION = "Content-Disposition".toUpperCase();
    protected static final String HEADER_CONTENT_TYPE        = "Content-Type".toUpperCase();

    /** This is the delimiter that will separate the fields */
    private String delimiter;
    /** The length of the HTTP Body */
    private long contentLength;
    /** This is the input stream */
    private InputStream in;

    private MultiPartIterator iterator;


    public MultipartParser(InputStream in, String delimiter, long length) {
        this.in = in;
        this.delimiter = delimiter;
        this.contentLength = length;
    }
    public MultipartParser(HttpHeader header) {
        this(header.getInputStream(),
                parseDelimiter(header.getHeader("Content-type")),
                Long.parseLong(header.getHeader("Content-Length")));
    }

    private static String parseDelimiter(String contentTypeHeader) {
        String delimiter = contentTypeHeader.split(" *; *")[1];
        delimiter = delimiter.split(" *= *")[1];
        return delimiter;
    }

    public long getContentLength() {
        return contentLength;
    }



    @Override
    public Iterator<MultipartField> iterator() {
        if (iterator == null)
            iterator = new MultiPartIterator();
        return iterator;
    }


    protected class MultiPartIterator implements Iterator<MultipartField>{
        private BufferedBoundaryInputStream boundaryIn;
        private boolean firstIteration;


        protected MultiPartIterator() {
            this.boundaryIn = new BufferedBoundaryInputStream(in);

            this.boundaryIn.setBoundary("--" +delimiter);
            firstIteration = true;
        }


        /**
         * @return if there is more data after the closest boundary.
         *          Note that if all data until the next boundary has
         *          not been read then this method can only estimate
         *          if there is a next element as the next boundary or
         *          end of stream might be out of reach.
         */
        @Override
        public boolean hasNext() {
            try {
                // check is the last characters are "--"
                if (boundaryIn.hasNext() && boundaryIn.isOnBoundary()) {
                    boundaryIn.mark(delimiter.length() + 10);
                    boundaryIn.next();
                    boolean ret = ! ('-' == boundaryIn.read() && '-' == boundaryIn.read());
                    boundaryIn.reset();
                    return ret;
                }
                // Or just guess
                return boundaryIn.hasNext();
            } catch (IOException e) {
                logger.log(Level.SEVERE, null, e);
            }
            return false;
        }


        @Override
        public MultipartField next() {
            try {
                boundaryIn.next();
                if (firstIteration) {
                    this.boundaryIn.setBoundary("\n--" +delimiter); // Add new-line to boundary after the first iteration
                    firstIteration = false;
                }
                String tmp = IOUtil.readLine(boundaryIn); // read the new line after the delimiter
                if (tmp == null || tmp.equals("--"))
                    return null;

                // Read Headers
                HashMap<String,String> headers = new HashMap<>();
                while ((tmp=IOUtil.readLine(boundaryIn)) != null && !tmp.isEmpty())
                    HttpHeaderParser.parseHeaderLine(headers, tmp);

                // Parse
                String disposition = headers.get(HEADER_CONTENT_DISPOSITION);
                if (disposition != null) {
                    HttpHeaderParser.parseCookieValues(headers, disposition);
                    if (headers.containsKey("form-data")) {
                        if (headers.containsKey("filename")) {
                            return new MultipartFileField(headers, boundaryIn);
                        }
                        else {
                            MultipartStringField field = new MultipartStringField(headers, boundaryIn);
                            return field;
                        }
                    }
                    else {
                        logger.warning("Only multipart form-data is supported");
                        return this.next(); // find next field
                    }
                }
            } catch (IOException e) {
                logger.log(Level.SEVERE, null, e);
            }
            return null;
        }


        @Override
        public void remove() {
            throw new UnsupportedOperationException("Remove not supported in read only stream.");
        }
    }
}
