/*
 * Copyright (C) 2008-2012 The QXmpp developers
 *
 * Authors:
 *  Manjeet Dahiya
 *  Jeremy Lainé
 *
 * Source:
 *  http://code.google.com/p/qxmpp
 *
 * This file is a part of QXmpp library.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 */


#include <QBuffer>
#include <QByteArray>
#include <QCryptographicHash>
#include <QDateTime>
#include <QDebug>
#include <QDomElement>
#include <QRegExp>
#include <QString>
#include <QStringList>
#include <QXmlStreamWriter>

#include "QXmppUtils.h"
#include "QXmppLogger.h"

// adapted from public domain source by Ross Williams and Eric Durbin
// FIXME : is this valid for big-endian machines?
static quint32 crctable[256] =
{
    0x00000000L, 0x77073096L, 0xEE0E612CL, 0x990951BAL,
    0x076DC419L, 0x706AF48FL, 0xE963A535L, 0x9E6495A3L,
    0x0EDB8832L, 0x79DCB8A4L, 0xE0D5E91EL, 0x97D2D988L,
    0x09B64C2BL, 0x7EB17CBDL, 0xE7B82D07L, 0x90BF1D91L,
    0x1DB71064L, 0x6AB020F2L, 0xF3B97148L, 0x84BE41DEL,
    0x1ADAD47DL, 0x6DDDE4EBL, 0xF4D4B551L, 0x83D385C7L,
    0x136C9856L, 0x646BA8C0L, 0xFD62F97AL, 0x8A65C9ECL,
    0x14015C4FL, 0x63066CD9L, 0xFA0F3D63L, 0x8D080DF5L,
    0x3B6E20C8L, 0x4C69105EL, 0xD56041E4L, 0xA2677172L,
    0x3C03E4D1L, 0x4B04D447L, 0xD20D85FDL, 0xA50AB56BL,
    0x35B5A8FAL, 0x42B2986CL, 0xDBBBC9D6L, 0xACBCF940L,
    0x32D86CE3L, 0x45DF5C75L, 0xDCD60DCFL, 0xABD13D59L,
    0x26D930ACL, 0x51DE003AL, 0xC8D75180L, 0xBFD06116L,
    0x21B4F4B5L, 0x56B3C423L, 0xCFBA9599L, 0xB8BDA50FL,
    0x2802B89EL, 0x5F058808L, 0xC60CD9B2L, 0xB10BE924L,
    0x2F6F7C87L, 0x58684C11L, 0xC1611DABL, 0xB6662D3DL,
    0x76DC4190L, 0x01DB7106L, 0x98D220BCL, 0xEFD5102AL,
    0x71B18589L, 0x06B6B51FL, 0x9FBFE4A5L, 0xE8B8D433L,
    0x7807C9A2L, 0x0F00F934L, 0x9609A88EL, 0xE10E9818L,
    0x7F6A0DBBL, 0x086D3D2DL, 0x91646C97L, 0xE6635C01L,
    0x6B6B51F4L, 0x1C6C6162L, 0x856530D8L, 0xF262004EL,
    0x6C0695EDL, 0x1B01A57BL, 0x8208F4C1L, 0xF50FC457L,
    0x65B0D9C6L, 0x12B7E950L, 0x8BBEB8EAL, 0xFCB9887CL,
    0x62DD1DDFL, 0x15DA2D49L, 0x8CD37CF3L, 0xFBD44C65L,
    0x4DB26158L, 0x3AB551CEL, 0xA3BC0074L, 0xD4BB30E2L,
    0x4ADFA541L, 0x3DD895D7L, 0xA4D1C46DL, 0xD3D6F4FBL,
    0x4369E96AL, 0x346ED9FCL, 0xAD678846L, 0xDA60B8D0L,
    0x44042D73L, 0x33031DE5L, 0xAA0A4C5FL, 0xDD0D7CC9L,
    0x5005713CL, 0x270241AAL, 0xBE0B1010L, 0xC90C2086L,
    0x5768B525L, 0x206F85B3L, 0xB966D409L, 0xCE61E49FL,
    0x5EDEF90EL, 0x29D9C998L, 0xB0D09822L, 0xC7D7A8B4L,
    0x59B33D17L, 0x2EB40D81L, 0xB7BD5C3BL, 0xC0BA6CADL,
    0xEDB88320L, 0x9ABFB3B6L, 0x03B6E20CL, 0x74B1D29AL,
    0xEAD54739L, 0x9DD277AFL, 0x04DB2615L, 0x73DC1683L,
    0xE3630B12L, 0x94643B84L, 0x0D6D6A3EL, 0x7A6A5AA8L,
    0xE40ECF0BL, 0x9309FF9DL, 0x0A00AE27L, 0x7D079EB1L,
    0xF00F9344L, 0x8708A3D2L, 0x1E01F268L, 0x6906C2FEL,
    0xF762575DL, 0x806567CBL, 0x196C3671L, 0x6E6B06E7L,
    0xFED41B76L, 0x89D32BE0L, 0x10DA7A5AL, 0x67DD4ACCL,
    0xF9B9DF6FL, 0x8EBEEFF9L, 0x17B7BE43L, 0x60B08ED5L,
    0xD6D6A3E8L, 0xA1D1937EL, 0x38D8C2C4L, 0x4FDFF252L,
    0xD1BB67F1L, 0xA6BC5767L, 0x3FB506DDL, 0x48B2364BL,
    0xD80D2BDAL, 0xAF0A1B4CL, 0x36034AF6L, 0x41047A60L,
    0xDF60EFC3L, 0xA867DF55L, 0x316E8EEFL, 0x4669BE79L,
    0xCB61B38CL, 0xBC66831AL, 0x256FD2A0L, 0x5268E236L,
    0xCC0C7795L, 0xBB0B4703L, 0x220216B9L, 0x5505262FL,
    0xC5BA3BBEL, 0xB2BD0B28L, 0x2BB45A92L, 0x5CB36A04L,
    0xC2D7FFA7L, 0xB5D0CF31L, 0x2CD99E8BL, 0x5BDEAE1DL,
    0x9B64C2B0L, 0xEC63F226L, 0x756AA39CL, 0x026D930AL,
    0x9C0906A9L, 0xEB0E363FL, 0x72076785L, 0x05005713L,
    0x95BF4A82L, 0xE2B87A14L, 0x7BB12BAEL, 0x0CB61B38L,
    0x92D28E9BL, 0xE5D5BE0DL, 0x7CDCEFB7L, 0x0BDBDF21L,
    0x86D3D2D4L, 0xF1D4E242L, 0x68DDB3F8L, 0x1FDA836EL,
    0x81BE16CDL, 0xF6B9265BL, 0x6FB077E1L, 0x18B74777L,
    0x88085AE6L, 0xFF0F6A70L, 0x66063BCAL, 0x11010B5CL,
    0x8F659EFFL, 0xF862AE69L, 0x616BFFD3L, 0x166CCF45L,
    0xA00AE278L, 0xD70DD2EEL, 0x4E048354L, 0x3903B3C2L,
    0xA7672661L, 0xD06016F7L, 0x4969474DL, 0x3E6E77DBL,
    0xAED16A4AL, 0xD9D65ADCL, 0x40DF0B66L, 0x37D83BF0L,
    0xA9BCAE53L, 0xDEBB9EC5L, 0x47B2CF7FL, 0x30B5FFE9L,
    0xBDBDF21CL, 0xCABAC28AL, 0x53B39330L, 0x24B4A3A6L,
    0xBAD03605L, 0xCDD70693L, 0x54DE5729L, 0x23D967BFL,
    0xB3667A2EL, 0xC4614AB8L, 0x5D681B02L, 0x2A6F2B94L,
    0xB40BBE37L, 0xC30C8EA1L, 0x5A05DF1BL, 0x2D02EF8DL
};

/// Parses a date-time from a string according to
/// XEP-0082: XMPP Date and Time Profiles.

QDateTime QXmppUtils::datetimeFromString(const QString &str)
{
    QRegExp tzRe("(Z|([+-])([0-9]{2}):([0-9]{2}))");
    int tzPos = tzRe.indexIn(str, 19);
    if (str.size() < 20 || tzPos < 0)
        return QDateTime();

    // process date and time
    QDateTime dt = QDateTime::fromString(str.left(19), "yyyy-MM-ddThh:mm:ss");
    dt.setTimeSpec(Qt::UTC);

    // process milliseconds
    if (tzPos > 20 && str.at(19) == '.')
    {
        QString millis = (str.mid(20, tzPos - 20) + "000").left(3);
        dt = dt.addMSecs(millis.toInt());
    }

    // process time zone
    if (tzRe.cap(1) != "Z")
    {
        int offset = tzRe.cap(3).toInt() * 3600 + tzRe.cap(4).toInt() * 60;
        if (tzRe.cap(2) == "+")
            dt = dt.addSecs(-offset);
        else
            dt = dt.addSecs(offset);
    }
    return dt;
}

/// Serializes a date-time to a string according to
/// XEP-0082: XMPP Date and Time Profiles.

QString QXmppUtils::datetimeToString(const QDateTime &dt)
{
    QDateTime utc = dt.toUTC();
    if (utc.time().msec())
        return utc.toString("yyyy-MM-ddThh:mm:ss.zzzZ");
    else
        return utc.toString("yyyy-MM-ddThh:mm:ssZ");
}

/// Parses a timezone offset (in seconds) from a string according to
/// XEP-0082: XMPP Date and Time Profiles.

int QXmppUtils::timezoneOffsetFromString(const QString &str)
{
    QRegExp tzRe("(Z|([+-])([0-9]{2}):([0-9]{2}))");
    if (!tzRe.exactMatch(str))
        return 0;

    // No offset from UTC
    if (tzRe.cap(1) == "Z")
        return 0;

    // Calculate offset
    const int offset = tzRe.cap(3).toInt() * 3600 +
                       tzRe.cap(4).toInt() * 60;
    if (tzRe.cap(2) == "-")
        return -offset;
    else
        return offset;
}

/// Serializes a timezone offset (in seconds) to a string according to
/// XEP-0082: XMPP Date and Time Profiles.

QString QXmppUtils::timezoneOffsetToString(int secs)
{
    if (!secs)
        return QString::fromLatin1("Z");

    const QTime tzoTime = QTime(0, 0, 0).addSecs(qAbs(secs));
    return (secs < 0 ? "-" : "+") + tzoTime.toString("hh:mm");
}

/// Returns the domain for the given \a jid.

QString QXmppUtils::jidToDomain(const QString &jid)
{
    return jidToBareJid(jid).split("@").last();
}

/// Returns the resource for the given \a jid.

QString QXmppUtils::jidToResource(const QString& jid)
{
    const int pos = jid.indexOf(QChar('/'));
    if (pos < 0)
        return QString();
    return jid.mid(pos+1);
}

/// Returns the user for the given \a jid.

QString QXmppUtils::jidToUser(const QString &jid)
{
    const int pos = jid.indexOf(QChar('@'));
    if (pos < 0)
        return QString();
    return jid.left(pos);
}

/// Returns the bare jid (i.e. without resource) for the given \a jid.

QString QXmppUtils::jidToBareJid(const QString& jid)
{
    const int pos = jid.indexOf(QChar('/'));
    if (pos < 0)
        return jid;
    return jid.left(pos);
}

/// Calculates the CRC32 checksum for the given input.

quint32 QXmppUtils::generateCrc32(const QByteArray &in)
{
    quint32 result = 0xffffffff;
    for(int n = 0; n < in.size(); ++n)
        result = (result >> 8) ^ (crctable[(result & 0xff) ^ (quint8)in[n]]);
    return result ^= 0xffffffff;
}

static QByteArray generateHmac(QCryptographicHash::Algorithm algorithm, const QByteArray &key, const QByteArray &text)
{
    QCryptographicHash hasher(algorithm);

    const int B = 64;
    QByteArray kpad = key + QByteArray(B - key.size(), 0);

    QByteArray ba;
    for (int i = 0; i < B; ++i)
        ba += kpad[i] ^ 0x5c;

    QByteArray tmp;
    for (int i = 0; i < B; ++i)
        tmp += kpad[i] ^ 0x36;
    hasher.addData(tmp);
    hasher.addData(text);
    ba += hasher.result();

    hasher.reset();
    hasher.addData(ba);
    return hasher.result();
}

/// Generates the MD5 HMAC for the given \a key and \a text.

QByteArray QXmppUtils::generateHmacMd5(const QByteArray &key, const QByteArray &text)
{
    return generateHmac(QCryptographicHash::Md5, key, text);
}

/// Generates the SHA1 HMAC for the given \a key and \a text.

QByteArray QXmppUtils::generateHmacSha1(const QByteArray &key, const QByteArray &text)
{
    return generateHmac(QCryptographicHash::Sha1, key, text);
}

/// Generates a random integer x between 0 and N-1.
///
/// \param N

int QXmppUtils::generateRandomInteger(int N)
{
    Q_ASSERT(N > 0 && N <= RAND_MAX);
    int val;
    while (N <= (val = qrand() / (RAND_MAX/N))) {};
    return val;
}

/// Returns a random byte array of the specified size.
///
/// \param length

QByteArray QXmppUtils::generateRandomBytes(int length)
{
    QByteArray bytes(length, 'm');
    for (int i = 0; i < length; ++i)
        bytes[i] = (char)generateRandomInteger(256);
    return bytes;
}

/// Returns a random alphanumerical string of the specified size.
///
/// \param length

QString QXmppUtils::generateStanzaHash(int length)
{
    const QString somechars = "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    const int N = somechars.size();
    QString hashResult;
    for ( int idx = 0; idx < length; ++idx )
        hashResult += somechars[generateRandomInteger(N)];
    return hashResult;
}

void helperToXmlAddAttribute(QXmlStreamWriter* stream, const QString& name,
                             const QString& value)
{
    if(!value.isEmpty())
        stream->writeAttribute(name,value);
}

void helperToXmlAddTextElement(QXmlStreamWriter* stream, const QString& name,
                           const QString& value)
{
    if(!value.isEmpty())
        stream->writeTextElement( name, value);
    else
        stream->writeEmptyElement(name);
}

