/*
 *  Copyright (C) 2016 Enrico Mariotti <enricomariotti@yahoo.it>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 or (at your option)
 *  version 3 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <QTextCodec>
#include <QObject>
#include "core/Tools.h"
#include "CsvParser.h"

CsvParser::CsvParser()
    : m_ch(0)
    , m_comment('#')
    , m_currCol(1)
    , m_currRow(1)
    , m_isBackslashSyntax(false)
    , m_isEof(false)
    , m_isFileLoaded(false)
    , m_isGood(true)
    , m_lastPos(-1)
    , m_maxCols(0)
    , m_qualifier('"')
    , m_separator(',')
    , m_statusMsg("")
{
    m_csv.setBuffer(&m_array);
    m_ts.setDevice(&m_csv);
    m_csv.open(QIODevice::ReadOnly);
    m_ts.setCodec("UTF-8");
}

CsvParser::~CsvParser() {
    m_csv.close();
}

bool CsvParser::isFileLoaded() {
    return m_isFileLoaded;
}

bool CsvParser::reparse() {
    reset();
    return parseFile();
}


bool CsvParser::parse(QFile *device) {
    clear();
    if (nullptr == device) {
        m_statusMsg += QObject::tr("NULL device\n");
        return false;
    }
    if (!readFile(device)) {
        return false;
    }
    return parseFile();
}

bool CsvParser::readFile(QFile *device) {
    if (device->isOpen()) {
        device->close();
    }

    device->open(QIODevice::ReadOnly);
    if (!Tools::readAllFromDevice(device, m_array)) {
        m_statusMsg += QObject::tr("Error reading from device\n");
        m_isFileLoaded = false;
    }
    else {
    device->close();

    m_array.replace("\r\n", "\n");
    m_array.replace("\r", "\n");
    if (0 == m_array.size()) {
        m_statusMsg += QObject::tr("File empty\n");
    }
    m_isFileLoaded = true;
    }
    return m_isFileLoaded;
}

void CsvParser::reset() {
    m_ch = 0;
    m_currCol = 1;
    m_currRow = 1;
    m_isEof = false;
    m_isGood = true;
    m_lastPos = -1;
    m_maxCols = 0;
    m_statusMsg = "";
    m_ts.seek(0);
    m_table.clear();
    //the following are users' concern :)
    //m_comment = '#';
    //m_backslashSyntax = false;
    //m_comment = '#';
    //m_qualifier = '"';
    //m_separator = ',';
}

void CsvParser::clear() {
    reset();
    m_isFileLoaded = false;
    m_array.clear();
}

bool CsvParser::parseFile() {
    parseRecord();
    while (!m_isEof)
    {
        if (!skipEndline()) {
            appendStatusMsg(QObject::tr("malformed string"));
        }
        m_currRow++;
        m_currCol = 1;
        parseRecord();
    }
    fillColumns();
    return m_isGood;
}

void CsvParser::parseRecord() {
    csvrow row;
    if (isComment()) {
        skipLine();
        return;
    }
    else {
        do {
            parseField(row);
            getChar(m_ch);
        } while (isSeparator(m_ch) && !m_isEof);

        if (!m_isEof) {
            ungetChar();
        }
        if (isEmptyRow(row)) {
            row.clear();
            return;
        }
        m_table.push_back(row);
        if (m_maxCols < row.size()) {
            m_maxCols = row.size();
        }
        m_currCol++;
    }
}

void CsvParser::parseField(csvrow& row) {
    QString field;
    peek(m_ch);
    if (!isTerminator(m_ch))
    {
        if (isQualifier(m_ch)) {
             parseQuoted(field);
        }
        else {
             parseSimple(field);
        }
    }
    row.push_back(field);
}

void CsvParser::parseSimple(QString &s) {
    QChar c;
    getChar(c);
    while ((isText(c)) && (!m_isEof))
    {
        s.append(c);
        getChar(c);
    }
    if (!m_isEof) {
        ungetChar();
    }
}

void CsvParser::parseQuoted(QString &s) {
    //read and discard initial qualifier (e.g. quote)
    getChar(m_ch);
    parseEscaped(s);
    //getChar(m_ch);
    if (!isQualifier(m_ch)) {
        appendStatusMsg(QObject::tr("missing closing quote"));
    }
}

void CsvParser::parseEscaped(QString &s) {
    parseEscapedText(s);
    while (processEscapeMark(s, m_ch)) {
        parseEscapedText(s);
    }
    if (!m_isEof) {
        ungetChar();
    }
}

void CsvParser::parseEscapedText(QString &s) {
    getChar(m_ch);
    while ((!isQualifier(m_ch)) && !m_isEof)
    {
        s.append(m_ch);
        getChar(m_ch);
    }
}

bool CsvParser::processEscapeMark(QString &s, QChar c) {
    QChar buf;
    peek(buf);
    QChar c2;
    //escape-character syntax, e.g. \"
    if (true == m_isBackslashSyntax)
    {
        if (c != '\\') {
            return false;
        }
        //consume (and append) second qualifier
        getChar(c2);
        if (m_isEof){
            c2='\\';
            s.append('\\');
            return false;
        }
        else {
            s.append(c2);
            return true;
        }
    }
    //double quote syntax, e.g. ""
    else
    {
        if (!isQualifier(c)) {
            return false;
        }
        peek(c2);
        if (!m_isEof) { //not EOF, can read one char
            if (isQualifier(c2)) {
                s.append(c2);
                getChar(c2);
                return true;
            }
        }
        return false;
    }
}

void CsvParser::fillColumns() {
    //fill the rows with lesser columns with empty fields

    for (int i=0; i<m_table.size(); ++i) {
        int gap = m_maxCols-m_table.at(i).size();
        if (gap > 0) {
            csvrow r = m_table.at(i);
            for (int j=0; j<gap; ++j) {
                r.append(QString(""));
            }
            m_table.replace(i, r);
        }
    }
}

void CsvParser::skipLine() {
    m_ts.readLine();
    m_ts.seek(m_ts.pos()-1);
}

bool CsvParser::skipEndline() {
    getChar(m_ch);
    return (m_ch == '\n');
}


void CsvParser::getChar(QChar& c) {
    m_isEof = m_ts.atEnd();
    if (!m_isEof) {
        m_lastPos = m_ts.pos();
        m_ts >> c;
    }
}

void CsvParser::ungetChar() {
    if (!m_ts.seek(m_lastPos))
        m_statusMsg += QObject::tr("Internal: unget lower bound exceeded");
}

void CsvParser::peek(QChar& c) {
    getChar(c);
    if (!m_isEof) {
        ungetChar();
    }
}

bool CsvParser::isQualifier(const QChar c) const {
    if (true == m_isBackslashSyntax && (c != m_qualifier)) {
        return (c == '\\');
    }
    else {
    return (c == m_qualifier);
    }
}

bool CsvParser::isComment() {
    bool result = false;
    QChar c2;
    qint64 pos = m_ts.pos();

    do {
        getChar(c2);
    } while ((isSpace(c2) || isTab(c2)) && (!m_isEof));

    if (c2 == m_comment) {
        result = true;
    }
    m_ts.seek(pos);
    return result;
}

bool CsvParser::isText(QChar c) const {
     return !( (isCRLF(c)) || (isSeparator(c)) );
}

bool CsvParser::isEmptyRow(csvrow row) const {
    csvrow::const_iterator it = row.constBegin();
    for (; it != row.constEnd(); ++it) {
        if ( ((*it) != "\n") && ((*it) != "") )
            return false;
    }
    return true;
}

bool CsvParser::isCRLF(const QChar c) const {
    return (c == '\n');
}

bool CsvParser::isSpace(const QChar c) const {
    return (c == 0x20);
}

bool CsvParser::isTab(const QChar c) const {
    return (c == '\t');
}

bool CsvParser::isSeparator(const QChar c) const {
    return (c == m_separator);
}

bool CsvParser::isTerminator(const QChar c) const {
    return (isSeparator(c) || (c == '\n') || (c == '\r'));
}

void CsvParser::setBackslashSyntax(bool set) {
    m_isBackslashSyntax = set;
}

void CsvParser::setComment(const QChar c) {
    m_comment = c.unicode();
}

void CsvParser::setCodec(const QString s) {
    m_ts.setCodec(QTextCodec::codecForName(s.toLocal8Bit()));
}

void CsvParser::setFieldSeparator(const QChar c) {
    m_separator = c.unicode();
}

void CsvParser::setTextQualifier(const QChar c) {
    m_qualifier = c.unicode();
}

int CsvParser::getFileSize() const {
    return m_csv.size();
}

const csvtable CsvParser::getCsvTable() const {
    return m_table;
}

QString CsvParser::getStatus() const {
    return m_statusMsg;
}

int CsvParser::getCsvCols() const {
    if ((m_table.size() > 0) && (m_table.at(0).size() > 0))
        return m_table.at(0).size();
    else return 0;
}

int CsvParser::getCsvRows() const {
    return m_table.size();
}


void CsvParser::appendStatusMsg(QString s) {
    m_statusMsg += s
      .append(" @" + QString::number(m_currRow))
      .append(",")
      .append(QString::number(m_currCol))
      .append("\n");
    m_isGood = false;
}