//  dataprotocol.cpp
// ==================
//
// Implementation of the data protocol (rfc 2397)
//
// Author: Leo Savernik
// Email: l.savernik@aon.at
// Copyright (C) 2002, 2003 by Leo Savernik <l.savernik@aon.at>
// Created: Sam Dez 28 14:11:18 CET 2002

/***************************************************************************
 *                                                                         *
 *   This program 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; version 2.                 *
 *                                                                         *
 ***************************************************************************/

#include "dataprotocol_p.h"

#include "global.h"

#include <QtCore/QByteArray>
#include <QtCore/QCharRef>
#include <QtCore/QMutableStringListIterator>
#include <QtCore/QTextCodec>

#ifdef DATAKIOSLAVE
#  include <kinstance.h>
#  include <stdlib.h>
#endif

#if !defined(DATAKIOSLAVE)
#  define DISPATCH(f) dispatch_##f
#else
#  define DISPATCH(f) f
#endif

using namespace KIO;
#ifdef DATAKIOSLAVE
extern "C" {

    int kdemain(int argc, char **argv)
    {
        //qDebug() << "*** Starting kio_data ";

        if (argc != 4) {
            //qDebug() << "Usage: kio_data  protocol domain-socket1 domain-socket2";
            exit(-1);
        }

        DataProtocol slave(argv[2], argv[3]);
        slave.dispatchLoop();

        //qDebug() << "*** kio_data Done";
        return 0;
    }
}
#endif

/** structure containing header information */
struct DataHeader {
    QString mime_type;        // mime type of content (lowercase)
    MetaData attributes;      // attribute/value pairs (attribute lowercase,
    //  value unchanged)
    bool is_base64;       // true if data is base64 encoded
    QByteArray url;       // reference to decoded url
    int data_offset;      // zero-indexed position within url
    // where the real data begins. May point beyond
    // the end to indicate that there is no data
};

/** returns the position of the first occurrence of any of the given
  * characters @p c1 or comma (',') or semicolon (';') or buf.length()
  * if none is contained.
  *
  * @param buf buffer where to look for c
  * @param begin zero-indexed starting position
  * @param c1 character to find or '\0' to ignore
  */
static int find(const QByteArray &buf, int begin, const char c1)
{
    static const char comma = ',';
    static const char semicolon = ';';
    int pos = begin;
    int size = buf.length();
    while (pos < size) {
        const char ch = buf[pos];
        if (ch == comma || ch == semicolon || (c1 != '\0' && ch == c1)) {
            break;
        }
        pos++;
    }/*wend*/
    return pos;
}

/** extracts the string between the current position @p pos and the first
 * occurrence of either @p c1 or comma (',') or semicolon (';') exclusively
 * and updates @p pos to point at the found delimiter or at the end of the
 * buffer if neither character occurred.
 * @param buf buffer where to look for
 * @param pos zero-indexed position within buffer
 * @param c1 character to find or '\0' to ignore
 */
static inline QString extract(const QByteArray &buf, int &pos,
                              const char c1 = '\0')
{
    int oldpos = pos;
    pos = find(buf, oldpos, c1);
    return buf.mid(oldpos, pos - oldpos);
}

/** ignores all whitespaces
 * @param buf buffer to operate on
 * @param pos position to shift to first non-whitespace character
 *  Upon return @p pos will either point to the first non-whitespace
 *  character or to the end of the buffer.
 */
static inline void ignoreWS(const QString &buf, int &pos)
{
    int size = buf.length();
    while (pos < size && buf[pos].isSpace()) {
        ++pos;
    }
}

/** parses a quoted string as per rfc 822.
 *
 * If trailing quote is missing, the whole rest of the buffer is returned.
 * @param buf buffer to operate on
 * @param pos position pointing to the leading quote
 * @return the extracted string. @p pos will be updated to point to the
 *  character following the trailing quote.
 */
static QString parseQuotedString(const QString &buf, int &pos)
{
    int size = buf.length();
    QString res;
    res.reserve(size);    // can't be larger than buf
    pos++;        // jump over leading quote
    bool escaped = false; // if true means next character is literal
    bool parsing = true;  // true as long as end quote not found
    while (parsing && pos < size) {
        const QChar ch = buf[pos++];
        if (escaped) {
            res += ch;
            escaped = false;
        } else {
            switch (ch.unicode()) {
            case '"': parsing = false; break;
            case '\\': escaped = true; break;
            default: res += ch; break;
            }/*end switch*/
        }/*end if*/
    }/*wend*/
    res.squeeze();
    return res;
}

/** parses the header of a data url
 * @param url the data url
 * @param mimeOnly if the only interesting information is the mime type
 * @return DataHeader structure with the header information
 */
static DataHeader parseDataHeader(const QUrl &url, const bool mimeOnly)
{
    DataHeader header_info;

    // initialize header info members
    header_info.mime_type = QStringLiteral("text/plain");
    header_info.attributes.insert(QStringLiteral("charset"), QStringLiteral("us-ascii"));
    header_info.is_base64 = false;

    // decode url and save it
    const QByteArray &raw_url = header_info.url = QByteArray::fromPercentEncoding(url.path(QUrl::FullyEncoded).toLatin1());
    const int raw_url_len = raw_url.length();

    header_info.data_offset = 0;

    // read mime type
    if (raw_url_len == 0) {
        return header_info;
    }
    const QString mime_type = extract(raw_url, header_info.data_offset).trimmed();
    if (!mime_type.isEmpty()) {
        header_info.mime_type = mime_type;
    }
    if (mimeOnly) {
        return header_info;
    }

    if (header_info.data_offset >= raw_url_len) {
        return header_info;
    }
    // jump over delimiter token and return if data reached
    if (raw_url[header_info.data_offset++] == QLatin1Char(',')) {
        return header_info;
    }

    // read all attributes and store them
    bool data_begin_reached = false;
    while (!data_begin_reached && header_info.data_offset < raw_url_len) {
        // read attribute
        const QString attribute = extract(raw_url, header_info.data_offset, '=').trimmed();
        if (header_info.data_offset >= raw_url_len
                || raw_url[header_info.data_offset] != QLatin1Char('=')) {
            // no assigment, must be base64 option
            if (attribute == QLatin1String("base64")) {
                header_info.is_base64 = true;
            }
        } else {
            header_info.data_offset++; // jump over '=' token

            // read value
            ignoreWS(raw_url, header_info.data_offset);
            if (header_info.data_offset >= raw_url_len) {
                return header_info;
            }

            QString value;
            if (raw_url[header_info.data_offset] == QLatin1Char('"')) {
                value = parseQuotedString(raw_url, header_info.data_offset);
                ignoreWS(raw_url, header_info.data_offset);
            } else {
                value = extract(raw_url, header_info.data_offset).trimmed();
            }

            // add attribute to map
            header_info.attributes[attribute.toLower()] = value;

        }/*end if*/
        if (header_info.data_offset < raw_url_len
                && raw_url[header_info.data_offset] == QLatin1Char(',')) {
            data_begin_reached = true;
        }
        header_info.data_offset++; // jump over separator token
    }/*wend*/

    return header_info;
}

#ifdef DATAKIOSLAVE
DataProtocol::DataProtocol(const QByteArray &pool_socket, const QByteArray &app_socket)
    : SlaveBase("kio_data", pool_socket, app_socket)
{
#else
DataProtocol::DataProtocol()
{
#endif
    //qDebug();
}

/* --------------------------------------------------------------------- */

DataProtocol::~DataProtocol()
{
    //qDebug();
}

/* --------------------------------------------------------------------- */

void DataProtocol::get(const QUrl &url)
{
    ref();
    //qDebug() << this;

    const DataHeader hdr = parseDataHeader(url, false);

    const int size = hdr.url.length();
    const int data_ofs = qMin(hdr.data_offset, size);
    // FIXME: string is copied, would be nice if we could have a reference only
    const QByteArray url_data = hdr.url.mid(data_ofs);
    QByteArray outData;

    if (hdr.is_base64) {
        // base64 stuff is expected to contain the correct charset, so we just
        // decode it and pass it to the receiver
        outData = QByteArray::fromBase64(url_data);
    } else {
        QTextCodec *codec = QTextCodec::codecForName(hdr.attributes[QStringLiteral("charset")].toLatin1());
        if (codec != 0) {
            outData = codec->toUnicode(url_data).toUtf8();
        } else {
            outData = url_data;
        }/*end if*/
    }/*end if*/

    //qDebug() << "emit mimeType@"<<this;
    mimeType(hdr.mime_type);
    //qDebug() << "emit totalSize@"<<this;
    totalSize(outData.size());

    //qDebug() << "emit setMetaData@"<<this;
#if defined(DATAKIOSLAVE)
    MetaData::ConstIterator it;
    for (it = hdr.attributes.constBegin(); it != hdr.attributes.constEnd(); ++it) {
        setMetaData(it.key(), it.value());
    }/*next it*/
#else
    setAllMetaData(hdr.attributes);
#endif

    //qDebug() << "emit sendMetaData@"<<this;
    sendMetaData();
//qDebug() << "(1) queue size " << dispatchQueue.size();
    // empiric studies have shown that this shouldn't be queued & dispatched
    data(outData);
//qDebug() << "(2) queue size " << dispatchQueue.size();
    DISPATCH(data(QByteArray()));
//qDebug() << "(3) queue size " << dispatchQueue.size();
    DISPATCH(finished());
//qDebug() << "(4) queue size " << dispatchQueue.size();
    deref();
}

/* --------------------------------------------------------------------- */

void DataProtocol::mimetype(const QUrl &url)
{
    ref();
    mimeType(parseDataHeader(url, true).mime_type);
    finished();
    deref();
}

/* --------------------------------------------------------------------- */
