/*
 * Copyright (C) 2003-2006 Ben van Klinken and the CLucene Team
 *
 * Distributable under the terms of either the Apache License (Version 2.0) or 
 * the GNU Lesser General Public License, as specified in the COPYING file.
 *
 * Changes are Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
*/
#include "CLucene/StdHeader.h"

#include "DocumentWriter.h"
#include "FieldInfos.h"
#include "IndexWriter.h"
#include "FieldsWriter.h"
#include "Term.h"
#include "TermInfo.h"
#include "TermInfosWriter.h"

#include "CLucene/analysis/AnalysisHeader.h"

#include "CLucene/search/Similarity.h"
#include "TermInfosWriter.h"
#include "FieldsWriter.h"

CL_NS_USE(util)
CL_NS_USE(store)
CL_NS_USE(analysis)
CL_NS_USE(document)
CL_NS_DEF(index)

/*Posting*/

DocumentWriter::Posting::Posting(Term* t, const int32_t position,
    TermVectorOffsetInfo* offset)
{
    //Func - Constructor
    //Pre  - t contains a valid reference to a Term
    //Post - Instance has been created
    freq = 1;

    term = _CL_POINTER(t);
    positions.values = (int32_t*)malloc(sizeof(int32_t));
    positions.values[0] = position;
    positions.length = 1;

    if ( offset != NULL ){
        this->offsets.values =(TermVectorOffsetInfo*)malloc(sizeof(TermVectorOffsetInfo));
        this->offsets.values[0] = *offset;
        this->offsets.length = 1;
    }
}

DocumentWriter::Posting::~Posting()
{
    //Func - Destructor
    //Pre  - true
    //Post - The instance has been destroyed

    free(positions.values);
    if ( this->offsets.values != NULL )
        free(this->offsets.values);
    _CLDECDELETE(term);
}

DocumentWriter::DocumentWriter(Directory* d, Analyzer* a,
    CL_NS(search)::Similarity* sim, const int32_t mfl)
    : analyzer(a)
    , directory(d)
    , maxFieldLength(mfl)
    , fieldInfos(NULL)
    , fieldLengths(NULL)
    , similarity(sim)
    , termIndexInterval(IndexWriter::DEFAULT_TERM_INDEX_INTERVAL)
    , fieldPositions(NULL)
    , fieldBoosts(NULL)
    , termBuffer(_CLNEW Term)
{
    //Pre  - d contains a valid reference to a Directory
    //       d contains a valid reference to a Analyzer
    //       mfl > 0 and contains the maximum field length
    //Post - Instance has been created

    CND_PRECONDITION(((mfl > 0) || (mfl == IndexWriter::FIELD_TRUNC_POLICY__WARN)),
        "mfl is 0 or smaller than IndexWriter::FIELD_TRUNC_POLICY__WARN")

    fieldInfos     = NULL;
    fieldLengths   = NULL;
}

DocumentWriter::DocumentWriter(CL_NS(store)::Directory* d,
    CL_NS(analysis)::Analyzer* a, IndexWriter* writer)
    : analyzer(a)
    , directory(d)
    , maxFieldLength(writer->getMaxFieldLength())
    , fieldInfos(NULL)
    , fieldLengths(NULL)
    , similarity(writer->getSimilarity())
    , termIndexInterval(writer->getTermIndexInterval())
    , fieldPositions(NULL)
    , fieldBoosts(NULL)
    , termBuffer(_CLNEW Term)
{
    //Pre  - d contains a valid reference to a Directory
    //       d contains a valid reference to a Analyzer
    //       mfl > 0 and contains the maximum field length
    //Post - Instance has been created

    CND_PRECONDITION(((maxFieldLength > 0)
        || (maxFieldLength == IndexWriter::FIELD_TRUNC_POLICY__WARN)),
        "mfl is 0 or smaller than IndexWriter::FIELD_TRUNC_POLICY__WARN")

    fieldInfos     = NULL;
    fieldLengths   = NULL;

}

DocumentWriter::~DocumentWriter()
{
    //Func - Destructor
    //Pre  - true
    //Post - The instance has been destroyed
    clearPostingTable();
    _CLDELETE( fieldInfos );
    _CLDELETE_ARRAY(fieldLengths);
    _CLDELETE_ARRAY(fieldPositions);
    _CLDELETE_ARRAY(fieldBoosts);
    _CLDELETE_ARRAY(fieldOffsets);

    _CLDECDELETE(termBuffer);
}

void DocumentWriter::clearPostingTable()
{
	PostingTableType::iterator itr = postingTable.begin();
	while (itr != postingTable.end()){
		_CLDELETE(itr->second);
		_CLLDECDELETE(itr->first);
		++itr;
	}
	postingTable.clear();
}

void DocumentWriter::addDocument(const QString& segment, Document* doc)
{
    CND_PRECONDITION(fieldInfos == NULL, "fieldInfos!=NULL")

	// write field names
	fieldInfos = _CLNEW FieldInfos();
	fieldInfos->add(doc);
	
    QString buf = Misc::segmentname(segment, QLatin1String(".fnm"));
	fieldInfos->write(directory, buf);

	// write field values
	FieldsWriter fieldsWriter(directory, segment, fieldInfos);
	try {
		fieldsWriter.addDocument(doc);
	} _CLFINALLY (
        fieldsWriter.close()
    );
      
	// clear postingTable
	clearPostingTable();

    int32_t fieldInfoSize = fieldInfos->size();
    fieldLengths = _CL_NEWARRAY(int32_t, fieldInfoSize); // init fieldLengths
    fieldPositions = _CL_NEWARRAY(int32_t, fieldInfoSize); // init fieldPositions
	fieldOffsets = _CL_NEWARRAY(int32_t, fieldInfoSize); // init fieldOffsets
    fieldBoosts = _CL_NEWARRAY(qreal, fieldInfoSize); // init fieldBoosts

    qreal fbd = doc->getBoost();
    for (int32_t i = 0; i < fieldInfoSize; ++i) {
        fieldLengths[i] = 0;
        fieldPositions[i] = 0;
        fieldOffsets[i] = 0;
        //initialise fieldBoost array with default boost
        fieldBoosts[i] = fbd;
    }

    // invert doc into postingTable
    invertDocument(doc);

	// sort postingTable into an array
	Posting** postings = NULL;
	int32_t postingsLength = 0;
	sortPostingTable(postings, postingsLength);

	//DEBUG:
	/*for (int32_t i = 0; i < postingsLength; i++) {
		Posting* posting = postings[i];
		
		TCHAR* b = posting->term->toString();
		_cout << b << " freq=" << posting->freq;
		_CLDELETE(b);

		_cout << " pos=" << posting->positions[0];
		for (int32_t j = 1; j < posting->freq; j++)
			_cout <<"," << posting->positions[j];
		
		_cout << endl;
	}*/


	// write postings
	writePostings(postings, postingsLength, segment);

	// write norms of indexed fields
	writeNorms(segment);
	_CLDELETE_ARRAY(postings);
}

void DocumentWriter::sortPostingTable(Posting**& array, int32_t& arraySize)
{
    // copy postingTable into an array
    arraySize = postingTable.size();
    array = _CL_NEWARRAY(Posting*,arraySize);
    PostingTableType::iterator postings = postingTable.begin();
    int32_t i=0;
    while ( postings != postingTable.end() ){
        array[i] = (Posting*)postings->second;
        postings++;
        i++;
    }
    // sort the array
    quickSort(array, 0, i - 1);
}


void DocumentWriter::invertDocument(const Document* doc)
{
    DocumentFieldEnumeration* fields = doc->fields();
    try {
        while (fields->hasMoreElements()) {
            Field* field = (Field*)fields->nextElement();
            const TCHAR* fieldName = field->name();
            const int32_t fieldNumber = fieldInfos->fieldNumber(fieldName);

            int32_t length = fieldLengths[fieldNumber];     // length of field
            int32_t position = fieldPositions[fieldNumber]; // position in field
            if (length>0) 
                position+=analyzer->getPositionIncrementGap(fieldName);
            int32_t offset = fieldOffsets[fieldNumber];       // offset field

            if (field->isIndexed()) {
                if (!field->isTokenized()) { // un-tokenized field
                    //FEATURE: this is bug in java: if using a Reader, then
                    //field value will not be added. With CLucene, an untokenized
                    //field with a reader will still be added (if it isn't stored,
                    //because if it's stored, then the reader has already been read.
                    const TCHAR* charBuf = NULL;
                    int64_t dataLen = 0;

                    if (field->stringValue() == NULL && !field->isStored() ) {
                        CL_NS(util)::Reader* r = field->readerValue();
                        // this call tries to read the entire stream
                        // this may invalidate the string for the further calls
                        // it may be better to do this via a FilterReader
                        // TODO make a better implementation of this
                        dataLen = r->read(charBuf, LUCENE_INT32_MAX_SHOULDBE);
                        if (dataLen == -1)
                            dataLen = 0;
                        //todo: would be better to pass the string length, in case
                        //a null char is passed, but then would need to test the output too.
                    } else {
                        charBuf = field->stringValue();
                        dataLen = _tcslen(charBuf);
                    }

                    if(field->isStoreOffsetWithTermVector()){
                        TermVectorOffsetInfo tio;
                        tio.setStartOffset(offset);
                        tio.setEndOffset(offset + dataLen);
                        addPosition(fieldName, charBuf, position++, &tio );
                    }else
                        addPosition(fieldName, charBuf, position++, NULL);
                    offset += dataLen;
                    length++;
                } else { // field must be tokenized
                    CL_NS(util)::Reader* reader; // find or make Reader
                    bool delReader = false;
                    if (field->readerValue() != NULL) {
                        reader = field->readerValue();
                    } else if (field->stringValue() != NULL) {
                        reader = _CLNEW CL_NS(util)::StringReader(
                            field->stringValue(),_tcslen(field->stringValue()),
                            false);
                        delReader = true;
                    } else {
                        _CLTHROWA(CL_ERR_IO,"field must have either String or Reader value");
                    }

                    try {
                        // Tokenize field and add to postingTable.
                        CL_NS(analysis)::TokenStream* stream =
                            analyzer->tokenStream(fieldName, reader);

                        try {
                            CL_NS(analysis)::Token t;
                            int32_t lastTokenEndOffset = -1;
                            while (stream->next(&t)) {
                                position += (t.getPositionIncrement() - 1);

                                if(field->isStoreOffsetWithTermVector()){
                                    TermVectorOffsetInfo tio;
                                    tio.setStartOffset(offset + t.startOffset());
                                    tio.setEndOffset(offset + t.endOffset());
                                    addPosition(fieldName, t.termText(), position++, &tio);
                                } else
                                    addPosition(fieldName, t.termText(), position++, NULL);

                                lastTokenEndOffset = t.endOffset();
                                length++;
                                // Apply field truncation policy.
                                if (maxFieldLength != IndexWriter::FIELD_TRUNC_POLICY__WARN) {
                                    // The client programmer has explicitly authorized us to
                                    // truncate the token stream after maxFieldLength tokens.
                                    if ( length > maxFieldLength)
                                        break;
                                } else if (length > IndexWriter::DEFAULT_MAX_FIELD_LENGTH) {
                                    const TCHAR* errMsgBase = 
                                        _T("Indexing a huge number of tokens from a single")
                                        _T(" field (\"%s\", in this case) can cause CLucene")
                                        _T(" to use memory excessively.")
                                        _T("  By default, CLucene will accept only %s tokens")
                                        _T(" tokens from a single field before forcing the")
                                        _T(" client programmer to specify a threshold at")
                                        _T(" which to truncate the token stream.")
                                        _T("  You should set this threshold via")
                                        _T(" IndexReader::maxFieldLength (set to LUCENE_INT32_MAX")
                                        _T(" to disable truncation, or a value to specify maximum number of fields).");

                                    TCHAR defaultMaxAsChar[34];
                                    _i64tot(IndexWriter::DEFAULT_MAX_FIELD_LENGTH,
                                        defaultMaxAsChar, 10
                                        );
                                    int32_t errMsgLen = _tcslen(errMsgBase)
                                        + _tcslen(fieldName)
                                        + _tcslen(defaultMaxAsChar);
                                    TCHAR* errMsg = _CL_NEWARRAY(TCHAR,errMsgLen+1);

                                    _sntprintf(errMsg, errMsgLen,errMsgBase, fieldName, defaultMaxAsChar);

                                    _CLTHROWT_DEL(CL_ERR_Runtime,errMsg);
                                }
                            } // while token->next

                            if(lastTokenEndOffset != -1 )
                                offset += lastTokenEndOffset + 1;
                        } _CLFINALLY (
                            stream->close();
                            _CLDELETE(stream);
                        );
                    } _CLFINALLY (
                        if (delReader) {
                            _CLDELETE(reader);
                        }
                    );
                } // if/else field is to be tokenized
                fieldLengths[fieldNumber] = length; // save field length
                fieldPositions[fieldNumber] = position;	  // save field position
                fieldBoosts[fieldNumber] *= field->getBoost();
                fieldOffsets[fieldNumber] = offset;
            } // if field is to beindexed
        } // while more fields available
    } _CLFINALLY (
        _CLDELETE(fields);
    );
}

void DocumentWriter::addPosition(const TCHAR* field, const TCHAR* text,
    const int32_t position, TermVectorOffsetInfo* offset)
{
	termBuffer->set(field,text,false);

	Posting* ti = postingTable.get(termBuffer);
	if (ti != NULL) {				  // word seen before
		int32_t freq = ti->freq;
		if (ti->positions.length == freq) {
            // positions array is full, realloc its size
            ti->positions.length = freq*2;
            ti->positions.values = (int32_t*)realloc(ti->positions.values, ti->positions.length * sizeof(int32_t));
		}
		ti->positions.values[freq] = position;		  // add new position
		
		if (offset != NULL) {
			if (ti->offsets.length == freq){
				ti->offsets.length = freq*2;
                ti->offsets.values = (TermVectorOffsetInfo*)realloc(ti->offsets.values, ti->offsets.length * sizeof(TermVectorOffsetInfo));
            }
			ti->offsets[freq] = *offset;
		}

		ti->freq = freq + 1;			  // update frequency
	} else {					  // word not seen before
		Term* term = _CLNEW Term( field, text, false);
		postingTable.put(term, _CLNEW Posting(term, position, offset));
	}
}

//static
void DocumentWriter::quickSort(Posting**& postings, const int32_t lo, const int32_t hi)
{
	if(lo >= hi)
		return;

	int32_t mid = (lo + hi) / 2;

	if(postings[lo]->term->compareTo(postings[mid]->term) > 0) {
		 Posting* tmp = postings[lo];
		postings[lo] = postings[mid];
		postings[mid] = tmp;
	}

	if(postings[mid]->term->compareTo(postings[hi]->term) > 0) {
		Posting* tmp = postings[mid];
		postings[mid] = postings[hi];
		postings[hi] = tmp;
	      
		if(postings[lo]->term->compareTo(postings[mid]->term) > 0) {
			Posting* tmp2 = postings[lo];
			postings[lo] = postings[mid];
			postings[mid] = tmp2;
		}
	}

	int32_t left = lo + 1;
	int32_t right = hi - 1;

	if (left >= right)
		return; 

	const Term* partition = postings[mid]->term; //not kept, so no need to finalize
    
	for( ;; ) {
		while(postings[right]->term->compareTo(partition) > 0)
		--right;
	      
		while(left < right && postings[left]->term->compareTo(partition) <= 0)
			++left;
		      
		if(left < right) {
			Posting* tmp = postings[left];
			postings[left] = postings[right];
			postings[right] = tmp;
			--right;
		} else {
			break;
		}
	}

	quickSort(postings, lo, left);
	quickSort(postings, left + 1, hi);
}

void DocumentWriter::writePostings(Posting** postings,
    const int32_t postingsLength, const QString& segment)
{
	#define __DOCLOSE(obj)                                          \
        if (obj!=NULL) {                                            \
            try {                                                   \
                obj->close();                                       \
                _CLDELETE(obj);                                     \
            } catch(CLuceneError &e) {                              \
                ierr = e.number();                                  \
                err = e.what();                                     \
            } catch(...) {                                          \
                err = "Unknown error while closing posting tables"; \
            }                                                       \
        }

    IndexOutput* freq = NULL;
    IndexOutput* prox = NULL;
    TermInfosWriter* tis = NULL;
    TermVectorsWriter* termVectorWriter = NULL;
    try {
        //open files for inverse index storage
        QString buf = Misc::segmentname(segment, QLatin1String(".frq"));
        freq = directory->createOutput(buf);

        buf = Misc::segmentname(segment, QLatin1String(".prx"));
        prox = directory->createOutput(buf);

        tis = _CLNEW TermInfosWriter(directory, segment, fieldInfos,
            termIndexInterval);
        TermInfo* ti = _CLNEW TermInfo();
        const TCHAR* currentField = NULL;
        for (int32_t i = 0; i < postingsLength; i++) {
            Posting* posting = postings[i];

            // add an entry to the dictionary with pointers to prox and freq files
            ti->set(1, freq->getFilePointer(), prox->getFilePointer(), -1);
            tis->add(posting->term, ti);

            // add an entry to the freq file
            int32_t postingFreq = posting->freq;
            if (postingFreq == 1)				  // optimize freq=1
                freq->writeVInt(1);			  // set low bit of doc num.
            else {
                freq->writeVInt(0);			  // the document number
                freq->writeVInt(postingFreq);			  // frequency in doc
            }

            int32_t lastPosition = 0;			  // write positions
            for (int32_t j = 0; j < postingFreq; ++j) {		  // use delta-encoding
                prox->writeVInt(posting->positions.values[j] - lastPosition);
                lastPosition = posting->positions.values[j];
            }

            // check to see if we switched to a new field
            const TCHAR* termField = posting->term->field();
            if ( currentField == NULL || _tcscmp(currentField,termField) != 0 ) {
                //todo, can we do an intern'd check?
                // changing field - see if there is something to save
                currentField = termField;
                FieldInfo* fi = fieldInfos->fieldInfo(currentField);

                if (fi->storeTermVector) {
                    if (termVectorWriter == NULL) {
                        termVectorWriter = _CLNEW TermVectorsWriter(directory,
                            segment, fieldInfos);
                        termVectorWriter->openDocument();
                    }
                    termVectorWriter->openField(currentField);
                } else if (termVectorWriter != NULL) {
                    termVectorWriter->closeField();
                }
            }
            if (termVectorWriter != NULL && termVectorWriter->isFieldOpen()) {
                termVectorWriter->addTerm(posting->term->text(), postingFreq,
                    &posting->positions, &posting->offsets);
            }
        }
        if (termVectorWriter != NULL)
            termVectorWriter->closeDocument();
        _CLDELETE(ti);
    } _CLFINALLY ( 
        const char* err = NULL;
        int32_t ierr = 0;

        // make an effort to close all streams we can but remember and re-throw
        // the first exception encountered in this process
        __DOCLOSE(freq);
        __DOCLOSE(prox);
        __DOCLOSE(tis);
        __DOCLOSE(termVectorWriter);
        if (err != NULL)
            _CLTHROWA(ierr,err);
    );
}

void DocumentWriter::writeNorms(const QString& segment)
{
    for(int32_t n = 0; n < fieldInfos->size(); n++){
        FieldInfo* fi = fieldInfos->fieldInfo(n);
        if(fi->isIndexed && !fi->omitNorms) {
            qreal norm = fieldBoosts[n] * similarity->lengthNorm(
                fi->name, fieldLengths[n]);

            QString fn(segment + QLatin1String(".f%1"));
            IndexOutput* norms = directory->createOutput(fn.arg(n));
            try {
                norms->writeByte(CL_NS(search)::Similarity::encodeNorm(norm));
            }_CLFINALLY ( 
                norms->close();
                _CLDELETE(norms);
            )
        }
    }
}

CL_NS_END
