/*
 * [RSSBatchExport.java]
 *
 * Summary: Convert the rss/temprssbatch.bin binary log of items into HTML.
 *
 * Copyright: (c) 2009-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.8 2009-02-06 include go package in ZIP bundle.
 */
package com.mindprod.htmlmacros.support;

import com.mindprod.common18.BigDate;
import com.mindprod.common18.EIO;
import com.mindprod.fastcat.FastCat;
import com.mindprod.htmlmacros.support.RSSSortableItem.ByDescendingDate;

import java.io.DataInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;

/**
 * Convert the rss/temprssbatch.bin binary log of items into HTML.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.8 2009-02-06 include go package in ZIP bundle.
 * @see com.mindprod.htmlmacros.macro.RSSEnd#
 * @since 2009
 */
public final class RSSBatchExport
    {
    private static final int NONE = BigDate.NULL_ORDINAL;

    /**
     * where the entire batch of RSS feeds is accumulated.
     */
    private static FastCat sb;

    /**
     * emit html needed for end of a day
     */
    private static void endDay()
        {
        sb.append( postlude() );
        }

    /**
     * emit html to describe one item
     *
     * @param feedItem           item whose previously computed HTML to expandNoRef.
     * @param fileBeingProcessed the file currently being processed.
     */
    private static void expandBatchItem( RSSSortableItem feedItem, File fileBeingProcessed )
        {
        sb.append( feedItem.asHTML( fileBeingProcessed ) );
        }

    /**
     * get HTML to tack on end  of  group of feeds for a day.
     *
     * @return xml tail for an RSS feed file
     */
    @SuppressWarnings( { "SameReturnValue" } )
    private static String postlude()
        {
        return "</ul>";
        }

    /**
     * get XML to tack on front of XML feed file.
     *
     * @param dateOrdinal BigDate ordinal of feeds in this day group
     *                    * @return html prelude to the group
     *
     * @return HTML to go on front of group of rss items for one day.
     */
    private static String prelude( int dateOrdinal )
        {
        return "<span class=\"date\">" + new BigDate( dateOrdinal ).toString() + "</span><ul>";
        }

    /**
     * read the binary RSS feed item log into an ArrayList
     *
     * @param sortableRSSFeedItems ArrayList to add items to.
     *
     * @throws java.io.IOException if problem reading binary log file.
     */
    @SuppressWarnings( { "InfiniteLoopStatement" } )
    private static void readBatch( ArrayList<RSSSortableItem> sortableRSSFeedItems ) throws IOException
        {
        DataInputStream rssBinaryLog = null;
        try
            {
            rssBinaryLog = EIO.getDataInputStream( RSSBatchLog.rssBinaryLogFile, 4 * 1024 );
            while ( true )
                {
                sortableRSSFeedItems.add( RSSSortableItem.read( rssBinaryLog ) );
                }
            }
        catch ( EOFException e )
            {
            // normal eof
            }
        finally
            {
            if ( rssBinaryLog != null )
                {
                rssBinaryLog.close();
                // no longer need the binary log file.
                //noinspection ResultOfMethodCallIgnored
                RSSBatchLog.rssBinaryLogFile.delete();
                }
            }
        }

    /**
     * emit html needed for start of day
     *
     * @param feedItem first rss item of the this day.
     */
    private static void startDay( RSSSortableItem feedItem )
        {
        sb.append( prelude( feedItem.getPublishDate() ) );
        }

    /**
     * Prepare the HTML from the combined binary batch RSS feed log. Group by days with date labels.
     * Might mix feeds. Read data from temp binary log, to create feeds for a groups of days each day
     * a <ul group.
     *
     * @param fileBeingProcessed the file currently being processed.
     *
     * @return HTML display for all items between previous RSSBegin .. RSSEnd, including <ul groups for each day.
     */
    public static String expandBatch( File fileBeingProcessed )
        {
        if ( RSSBatchLog.count == 0 )
            {
            return "<!-- no RSS items -->";
            }
        ArrayList<RSSSortableItem> sortableRSSFeedItems = new ArrayList<>( RSSBatchLog.count );
        try
            {
            readBatch( sortableRSSFeedItems );
            }
        catch ( IOException e )
            {
            throw new IllegalArgumentException( "Problems reading the RSS binary batch log. : " + e.getMessage() );
            }
        // sort items by feed/descending date.
        Collections.sort( sortableRSSFeedItems, new ByDescendingDate() );
        sb = new FastCat( RSSBatchLog.count * 3 /* start, item , end */ + 2 );
        int prevKey = NONE;
        for ( RSSSortableItem feedItem : sortableRSSFeedItems )
            {
            int thisKey = feedItem.getPublishDate();
            if ( thisKey != prevKey )
                {
                // starting a new group
                if ( prevKey != NONE )
                    {
                    endDay();
                    }
                startDay( feedItem );
                }
            // always emit the item itself.
            expandBatchItem( feedItem, fileBeingProcessed );
            prevKey = thisKey;
            } // end for
        // finish off the very last group.
        if ( prevKey != NONE )
            {
            endDay();
            }
        final String result = sb.toString();
        sb = null;
        return result;
        }
    }