/*
 * [FindAnchors.java]
 *
 * Summary: Find DT anchors and terms in a group of documents.
 *
 * Copyright: (c) 2006-2017 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:
 *  1.1 2006-01-19
 *  1.2 2014-04-18 use <dt id="xxx"> instead of <dt><a id="xxx"></a>
 */
package com.mindprod.qf;

import com.mindprod.common18.ST;
import com.mindprod.common18.Twirler;
import com.mindprod.entities.DeEntifyStrings;
import com.mindprod.hunkio.HunkIO;

import java.io.File;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.lang.System.*;

/**
 * Find DT anchors and terms in a group of documents.
 * <p/>
 * Parser is none too bright. Pays no attention to dl or dd nesting.
 * <p/>
 * Handles misc embedded HTML tags in the &lt;dt&gt;.. &lt;/dt&gt;. Demands lower case tags.
 * <p/>
 * Searches for patterns of the form:
 * <p/>
 * &lt;a name=&quot;SELFJOIN&quot;&gt;&lt;/a&gt;self join&lt;/dt&gt;
 * or
 * <p/>
 * &lt;dt&gt;&lt;a name=&quot;SELFJOIN&quot;&gt;self join&lt;/a&gt;&lt;/dt&gt;
 * Invoked by IndexMindprod
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.2 2014-04-18 use <dt id="xxx"> instead of <dt><a id="xxx"></a>
 * @since 2006
 */
final class FindAnchors
    {
    /**
     * pattern to match inner guts of an alias comment __alias__
     */
    private static final Pattern aliasPattern = Pattern.compile( "\\s*alias\\s+" );

    /**
     * pattern to match inner guts of an alias comment __cross__J__
     */
    private static final Pattern crossPattern = Pattern.compile( "\\s*cross\\s+([JBG])\\s+" );

    /**
     * pattern to match inner guts of an alias comment __macro__Image__ or generated or /generated
     */
    private static final Pattern imagePattern = Pattern.compile( "\\s*" +
                                                                 "(macro\\s+Image|generated" +
                                                                 "|/generated|cseignore|/cseignore)\\s+" );

    /**
     * pattern find the anchor <dt id="XXX">
     */
    private static final Pattern anchorPattern = Pattern.compile( "<dt\\s+id=\"([A-Z0-9_]+)\"\\s*>" );

    /**
     * rotation state of the twirling animation
     */
    private static final Twirler twirler = new Twirler();

    /**
     * parse the big file, searching out DT anchors and terms
     *
     * @param big                    A string representing the entire file to scan.
     * @param fileBeingProcessed     file we are scanning, e.g. certificate.html
     * @param glossaryBeingProcessed Glossary we are scanning.
     */
    private static void parseAllDTsOnPage( final String big, final File fileBeingProcessed, final Gloss glossaryBeingProcessed )
        {
        // prune down filename to xxx.html, without target.
        final String fileNameBeingProcessed = fileBeingProcessed.getName();
        // do a quick look to see if there are any plausible candidates, perhaps malformed
        int startLookingForNextDTAt = big.indexOf( "<dt" );
        if ( startLookingForNextDTAt < 0 )
            {
            return;
            }
        int countOfDTs = 0;
        final Matcher d = anchorPattern.matcher( big );
        // loop for each fragment
        while ( d.find( startLookingForNextDTAt ) )
            {
            // scan for beginning of new fragment and extract he ancho
            // e.g. <dt id="HANDLE">handle</dt>
            // or
            // <dt id="HTMLVALIDATOR"><a
            // href="https://www.htmlvalidator.com/">
            // <img src="image/htmlvalidatorget.png" width="88" height="31"
            // alt="get htmlvalidtor">
            // HTMLValidator</a></dt>
            final String anchor = d.group( 1 );
            final int where1 = d.end();   // points just after dt id="HANDLE">
            final int where2 = big.indexOf( "</dt>", where1 );
            if ( where2 < 0 )
                {
                err.println( "WARNING: missing </dt> in " + fileBeingProcessed );
                return;
                }
            startLookingForNextDTAt = where2 + "</dt>".length();
            // what is inside <dt..> ... </dt>
            String term = big.substring( where1, where2 ).trim();
            // there might be some <!-- alias xxx xxx xxx -> buried between <dt>...</dt>.
            // extract them.
            int commentStart;
            while ( ( commentStart = term.indexOf( "<!--" ) ) >= 0 )
                {
                // found start of a comment, might be an alias
                final int commentEnd = term.indexOf( "-->", commentStart + "<!--".length() );
                if ( commentEnd < 0 )
                    {
                    err.println( "WARNING: missing --> inside <dt> in " + fileBeingProcessed );
                    return;
                    }
                // see if innards of comment have the form __alias__xxxx xxxx xxxx
                final String aliasCandidate = term.substring( commentStart + "<!--".length(), commentEnd );
                Matcher m;
                if ( ( m = aliasPattern.matcher( aliasCandidate ) ).lookingAt() )
                    {
                    // string starts with the pattern
                    // stuff after the alias pattern is our alias.
                    final String alias = DeEntifyStrings.flattenHTML( aliasCandidate.substring( m.end() ).trim(),
                            ' ' ).trim();
                    // was it an <!-- alias #xxx abcd -->
                    final String possibleTarget = ST.firstWord( alias );
                    assert IndexEntry.indexEntries.size() < IndexEntry.MAX_SIZE_INDEX_ENTRIES : "IndexEntries overflow";
                    if ( possibleTarget.length() >= 2 && possibleTarget.charAt( 0 ) == '#' )
                        {
                        // alias
                        IndexEntry.indexEntries.add( new IndexEntry( glossaryBeingProcessed,
                                alias.substring( possibleTarget.length() ).trim()
                                /* without target */,
                                true
                                /* this is an alias */,
                                glossaryBeingProcessed,
                                fileBeingProcessed,
                                possibleTarget.substring( 1 )
                                /* without # */ ) );
                        }
                    else
                        {
                        // plain
                        countOfDTs++;
                        IndexEntry.indexEntries.add( new IndexEntry( glossaryBeingProcessed,
                                alias,
                                true/* this is an alias */,
                                glossaryBeingProcessed,
                                fileBeingProcessed,
                                anchor ) );
                        }
                    }
                else if ( imagePattern.matcher( aliasCandidate ).lookingAt() )
                    {
                    // ignore
                    }
                else if ( ( m = crossPattern.matcher( aliasCandidate ) ).lookingAt() )
                    {
                    final Gloss indexToPlaceEntry = Gloss.valueOfLetter( m.group( 1 ).charAt( 0 ) );
                    assert indexToPlaceEntry != null : "bad gloss letter";
                    // string starts with the pattern
                    // stuff after the alias pattern is our alias.
                    final String alias = DeEntifyStrings.flattenHTML( aliasCandidate.substring( m.end() ).trim(),
                            ' ' ).trim();
                    // was it an <!-- cross J #xxx abcd -->
                    final String possibleTarget = ST.firstWord( alias );
                    if ( possibleTarget.length() >= 2 && possibleTarget.charAt( 0 ) == '#' )
                        {
                        IndexEntry.indexEntries.add( new IndexEntry( indexToPlaceEntry /* index where entry appears */,
                                alias.substring( possibleTarget.length() ).trim() /* human name */,
                                true /* this is an alias */,
                                glossaryBeingProcessed /* glossary where jumps to */,
                                fileBeingProcessed /* file to  jump to */,
                                possibleTarget.substring( 1 ) /* target in file to jump to without lead # */
                        ) );
                        }
                    else
                        {
                        /* plain  alias */
                        IndexEntry.indexEntries.add( new IndexEntry( indexToPlaceEntry /* index where entry appears */,
                                alias /* human name */,
                                true /* cross counts as an alias */,
                                glossaryBeingProcessed /* glossary where jumps to */,
                                fileBeingProcessed /* file to  jump to */,
                                anchor /* target in file to jump to without lead # */ ) );
                        }
                    }
                else
                    {
                    if ( !aliasCandidate.equals( "cseignore" ) && !aliasCandidate.equals( "/cseignore" ) )
                        {
                        err.println( "WARNING: unstructured comment inside <dt>: "
                                     + fileBeingProcessed
                                     + "\n    [" + aliasCandidate + "]\n" );
                        // keep going processing rest of file.
                        }
                    }
                // remove that comment from the term, and to prepare to look for another.
                term = term.substring( 0, commentStart ) + term.substring( commentEnd + "-->".length() );
                } // end while
            // get rid of  remaining <img <a </a > etc.
            term = DeEntifyStrings.flattenHTML( term, ' ' ).trim();
            // capture the primary anchor/term pair.
            countOfDTs++;
            IndexEntry.indexEntries.add( new IndexEntry( glossaryBeingProcessed,
                    term,
                    false/* this is  not an alias */,
                    glossaryBeingProcessed,
                    fileBeingProcessed, anchor ) );
            // we are positioned past </dt> ready to look for more <dt>s.
            } // end while
        if ( countOfDTs == 0 )
            {
            err.println( "WARNING: No valid <dt entries in file " + fileBeingProcessed );
            }
        }

    /**
     * M A I N Finds anchors and terms in a group of documents. outputs anchors to a file with format like this:
     * <p/>
     * unsorted
     * <p/>
     * F = filename (where anchor was found ) e.g. F mglosssixteenbit.html
     * <p/>
     * U = anchor (associated anchor) e.g. U SIXTEENBIT
     * <p/>
     * N = term/name (term defined in English) e.g. N 16-bit
     * <p/>
     * is represented by & in *.raw files)
     *
     * @param s Customiser for the glossary we are to prepare the index for
     */
    public static void findAnchorsInGlossary( AbstractGlossCustomiser s )
        {
        try
            {
            // where to look for files with defined terms
            String inDir = s.getInputDirName();
            // read entire html file into RAM in one fell swoop.
            String prevFilename = null;
            String inFilename = s.getNextInFilename();
            while ( inFilename != null && !inFilename.equals( prevFilename ) )
                {
                prevFilename = inFilename;
                // e.g. certificate.html no lead E:\mindprod\jgloss
                final File fileBeingProcessed = new File( inDir, inFilename );
                final String big = HunkIO.readEntireFile( fileBeingProcessed, HunkIO.UTF8 );
                try
                    {
                    twirler.twirl( out );
                    parseAllDTsOnPage( big, fileBeingProcessed, s.getGlossEnum() );
                    }
                catch ( Exception e )
                    {
                    // give up entirely on first error,
                    err.println( "\n"
                                 + inFilename
                                 + " "
                                 + e.getMessage() );
                    System.exit( 1 );
                    }
                inFilename = s.getNextInFilename();
                } // end while
            }
        catch ( IOException e )
            {
            err.println();
            e.printStackTrace( err );
            err.println();
            System.exit( 1 );
            }
        }
    }