/* $Id: EbmlWriter.cpp 65197 2017-01-09 11:40:46Z vboxsync $ */
/** @file
 * EbmlWriter.cpp - EBML writer + WebM container
 */

/*
 * Copyright (C) 2013-2017 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 */


#include <list>
#include <stack>
#include <iprt/string.h>
#include <iprt/file.h>
#include <iprt/asm.h>
#include <iprt/cdefs.h>
#include <iprt/err.h>
#include <VBox/log.h>
#include "EbmlWriter.h"
#include "EbmlIDs.h"


class Ebml
{
public:
    typedef uint32_t EbmlClassId;

private:

    struct EbmlSubElement
    {
        uint64_t offset;
        EbmlClassId classId;
        EbmlSubElement(uint64_t offs, EbmlClassId cid) : offset(offs), classId(cid) {}
    };

    std::stack<EbmlSubElement> m_Elements;
    RTFILE m_File;

public:

    /** Creates EBML output file. */
    inline int create(const char *a_pszFilename)
    {
      return RTFileOpen(&m_File, a_pszFilename, RTFILE_O_CREATE | RTFILE_O_WRITE | RTFILE_O_DENY_NONE);
    }

    /** Returns file size. */
    inline uint64_t getFileSize()
    {
        return RTFileTell(m_File);
    }

    /** Get reference to file descriptor */
    inline const RTFILE &getFile()
    {
        return m_File;
    }

    /** Returns available space on storage. */
    inline uint64_t getAvailableSpace()
    {
        RTFOFF pcbFree;
        int rc = RTFileQueryFsSizes(m_File, NULL, &pcbFree, 0, 0);
        return (RT_SUCCESS(rc)? (uint64_t)pcbFree : UINT64_MAX);
    }

    /** Closes the file. */
    inline void close()
    {
        RTFileClose(m_File);
    }

    /** Starts an EBML sub-element. */
    inline Ebml &subStart(EbmlClassId classId)
    {
        writeClassId(classId);
        /* store the current file offset. */
        m_Elements.push(EbmlSubElement(RTFileTell(m_File), classId));
        /* Indicates that size of the element
         * is unkown (as according to EBML specs).
         */
        writeUnsignedInteger(UINT64_C(0x01FFFFFFFFFFFFFF));
        return *this;
    }

    /** Ends an EBML sub-element. */
    inline Ebml &subEnd(EbmlClassId classId)
    {
        /* Class ID on the top of the stack should match the class ID passed
         * to the function. Otherwise it may mean that we have a bug in the code.
         */
        if(m_Elements.empty() || m_Elements.top().classId != classId) throw VERR_INTERNAL_ERROR;

        uint64_t uPos = RTFileTell(m_File);
        uint64_t uSize = uPos - m_Elements.top().offset - 8;
        RTFileSeek(m_File, m_Elements.top().offset, RTFILE_SEEK_BEGIN, NULL);

        /* make sure that size will be serialized as uint64 */
        writeUnsignedInteger(uSize | UINT64_C(0x0100000000000000));
        RTFileSeek(m_File, uPos, RTFILE_SEEK_BEGIN, NULL);
        m_Elements.pop();
        return *this;
    }

    /** Serializes a null-terminated string. */
    inline Ebml &serializeString(EbmlClassId classId, const char *str)
    {
        writeClassId(classId);
        uint64_t size = strlen(str);
        writeSize(size);
        write(str, size);
        return *this;
    }

    /* Serializes an UNSIGNED integer
     * If size is zero then it will be detected automatically. */
    inline Ebml &serializeUnsignedInteger(EbmlClassId classId, uint64_t parm, size_t size = 0)
    {
        writeClassId(classId);
        if (!size) size = getSizeOfUInt(parm);
        writeSize(size);
        writeUnsignedInteger(parm, size);
        return *this;
    }

    /** Serializes a floating point value.
     *
     * Only 8-bytes double precision values are supported
     * by this function.
     */
    inline Ebml &serializeFloat(EbmlClassId classId, double value)
    {
        writeClassId(classId);
        writeSize(sizeof(double));
        writeUnsignedInteger(*reinterpret_cast<uint64_t*>(&value));
        return *this;
    }

    /** Writes raw data to file. */
    inline void write(const void *data, size_t size)
    {
        int rc = RTFileWrite(m_File, data, size, NULL);
        if (!RT_SUCCESS(rc)) throw rc;
    }

    /** Writes an unsigned integer of variable of fixed size. */
    inline void writeUnsignedInteger(uint64_t value, size_t size = sizeof(uint64_t))
    {
        /* convert to big-endian */
        value = RT_H2BE_U64(value);
        write(reinterpret_cast<uint8_t*>(&value) + sizeof(value) - size, size);
    }

    /** Writes EBML class ID to file.
     *
     * EBML ID already has a UTF8-like represenation
     * so getSizeOfUInt is used to determine
     * the number of its bytes.
     */
    inline void writeClassId(EbmlClassId parm)
    {
        writeUnsignedInteger(parm, getSizeOfUInt(parm));
    }

    /** Writes data size value. */
    inline void writeSize(uint64_t parm)
    {
        /* The following expression defines the size of the value that will be serialized
         * as an EBML UTF-8 like integer (with trailing bits represeting its size):
          1xxx xxxx                                                                              - value 0 to  2^7-2
          01xx xxxx  xxxx xxxx                                                                   - value 0 to 2^14-2
          001x xxxx  xxxx xxxx  xxxx xxxx                                                        - value 0 to 2^21-2
          0001 xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx                                             - value 0 to 2^28-2
          0000 1xxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx                                  - value 0 to 2^35-2
          0000 01xx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx                       - value 0 to 2^42-2
          0000 001x  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx            - value 0 to 2^49-2
          0000 0001  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx - value 0 to 2^56-2
         */
        size_t size = 8 - ! (parm & (UINT64_MAX << 49)) - ! (parm & (UINT64_MAX << 42)) -
                          ! (parm & (UINT64_MAX << 35)) - ! (parm & (UINT64_MAX << 28)) -
                          ! (parm & (UINT64_MAX << 21)) - ! (parm & (UINT64_MAX << 14)) -
                          ! (parm & (UINT64_MAX << 7));
        /* One is subtracted in order to avoid loosing significant bit when size = 8. */
        uint64_t mask = RT_BIT_64(size * 8 - 1);
        writeUnsignedInteger((parm & (((mask << 1) - 1) >> size)) | (mask >> (size - 1)), size);
    }

    /** Size calculation for variable size UNSIGNED integer.
     *
     * The function defines the size of the number by trimming
     * consequent trailing zero bytes starting from the most significant.
     * The following statement is always true:
     * 1 <= getSizeOfUInt(arg) <= 8.
     *
     * Every !(arg & (UINT64_MAX << X)) expression gives one
     * if an only if all the bits from X to 63 are set to zero.
     */
    static inline size_t getSizeOfUInt(uint64_t arg)
    {
        return 8 - ! (arg & (UINT64_MAX << 56)) - ! (arg & (UINT64_MAX << 48)) -
                   ! (arg & (UINT64_MAX << 40)) - ! (arg & (UINT64_MAX << 32)) -
                   ! (arg & (UINT64_MAX << 24)) - ! (arg & (UINT64_MAX << 16)) -
                   ! (arg & (UINT64_MAX << 8));
    }

private:
    void operator=(const Ebml &);

};

class WebMWriter_Impl
{
    struct CueEntry
    {
        uint32_t    time;
        uint64_t    loc;
        CueEntry(uint32_t t, uint64_t l) : time(t), loc(l) {}
    };

    /** Operation mode. */
    WebMWriter::Mode m_enmMode;

    bool            m_fDebug;
    int64_t         m_iLastPtsMs;
    int64_t         m_iInitialPtsMs;
    vpx_rational_t  m_Framerate;

    uint64_t        m_uPositionReference;
    uint64_t        m_uSeekInfoPos;
    uint64_t        m_uSegmentInfoPos;
    uint64_t        m_uTrackPos;
    uint64_t        m_uCuePos;
    uint64_t        m_uClusterPos;

    uint64_t        m_uTrackIdPos;

    uint64_t        m_uStartSegment;

    uint32_t        m_uClusterTimecode;
    bool            m_bClusterOpen;

    std::list<CueEntry> m_CueList;

    Ebml                m_Ebml;

public:

    WebMWriter_Impl() :
        m_enmMode(WebMWriter::Mode_Unknown),
        m_fDebug(false),
        m_iLastPtsMs(-1),
        m_iInitialPtsMs(-1),
        m_Framerate(),
        m_uPositionReference(0),
        m_uSeekInfoPos(0),
        m_uSegmentInfoPos(0),
        m_uTrackPos(0),
        m_uCuePos(0),
        m_uClusterPos(0),
        m_uTrackIdPos(0),
        m_uStartSegment(0),
        m_uClusterTimecode(0),
        m_bClusterOpen(false) {}

    void writeHeader(const vpx_codec_enc_cfg_t *a_pCfg, const struct vpx_rational *a_pFps)
    {
        m_Ebml.subStart(EBML)
              .serializeUnsignedInteger(EBMLVersion, 1)
              .serializeUnsignedInteger(EBMLReadVersion, 1)
              .serializeUnsignedInteger(EBMLMaxIDLength, 4)
              .serializeUnsignedInteger(EBMLMaxSizeLength, 8)
              .serializeString(DocType, "webm")
              .serializeUnsignedInteger(DocTypeVersion, 2)
              .serializeUnsignedInteger(DocTypeReadVersion, 2)
              .subEnd(EBML);

        m_Ebml.subStart(Segment);

        m_uPositionReference = RTFileTell(m_Ebml.getFile());
        m_Framerate = *a_pFps;

        writeSeekInfo();

        m_uTrackPos = RTFileTell(m_Ebml.getFile());

        m_Ebml.subStart(Tracks);

        /* Write video? */
        if (   m_enmMode == WebMWriter::Mode_Video
            || m_enmMode == WebMWriter::Mode_AudioVideo)
        {
            /*
             * Video track.
             */
            m_Ebml.subStart(TrackEntry);
            m_Ebml.serializeUnsignedInteger(TrackNumber, 1);

            m_uTrackIdPos = RTFileTell(m_Ebml.getFile());

            m_Ebml.serializeUnsignedInteger(TrackUID, 0 /* UID */, 4)
                  .serializeUnsignedInteger(TrackType, 1 /* Video */)
                  .serializeString(CodecID, "V_VP8")
                  .subStart(Video)
                  .serializeUnsignedInteger(PixelWidth, a_pCfg->g_w)
                  .serializeUnsignedInteger(PixelHeight, a_pCfg->g_h)
                  .serializeFloat(FrameRate, (double) a_pFps->num / a_pFps->den)
                  .subEnd(Video)
                  .subEnd(TrackEntry);
        }

#ifdef VBOX_WITH_AUDIO_VIDEOREC
        if (   m_enmMode == WebMWriter::Mode_Audio
            || m_enmMode == WebMWriter::Mode_AudioVideo)
        {
            /*
             * Audio track.
             */
            m_Ebml.subStart(TrackEntry);
            m_Ebml.serializeUnsignedInteger(TrackNumber, 2);
            /** @todo Implement track's "Language" property? Currently this defaults to English ("eng"). */

            m_Ebml.serializeUnsignedInteger(TrackUID, 1 /* UID */, 4)
                  .serializeUnsignedInteger(TrackType, 2 /* Audio */)
                  .serializeString(CodecID, "A_OPUS")
                  .subStart(Audio)
                  .serializeFloat(SamplingFrequency, 44100.0)
                  .serializeFloat(OutputSamplingFrequency, 44100.0)
                  .serializeUnsignedInteger(Channels, 2)
                  .serializeUnsignedInteger(BitDepth, 16)
                  .subEnd(Audio)
                  .subEnd(TrackEntry);
        }
#endif

        m_Ebml.subEnd(Tracks);
    }

    void writeBlock(const vpx_codec_enc_cfg_t *a_pCfg, const vpx_codec_cx_pkt_t *a_pPkt)
    {
        uint16_t uBlockTimecode = 0;
        int64_t  iPtsMs;
        bool     bStartCluster = false;

        /* Calculate the PTS of this frame in milliseconds. */
        iPtsMs = a_pPkt->data.frame.pts * 1000
                 * (uint64_t) a_pCfg->g_timebase.num / a_pCfg->g_timebase.den;
        if (iPtsMs <= m_iLastPtsMs)
            iPtsMs = m_iLastPtsMs + 1;
        m_iLastPtsMs = iPtsMs;

        if (m_iInitialPtsMs < 0)
          m_iInitialPtsMs = m_iLastPtsMs;

        /* Calculate the relative time of this block. */
        if (iPtsMs - m_uClusterTimecode > 65536)
            bStartCluster = 1;
        else
            uBlockTimecode = static_cast<uint16_t>(iPtsMs - m_uClusterTimecode);

        int fKeyframe = (a_pPkt->data.frame.flags & VPX_FRAME_IS_KEY);
        if (bStartCluster || fKeyframe)
        {
            if (m_bClusterOpen)
                m_Ebml.subEnd(Cluster);

            /* Open a new cluster. */
            uBlockTimecode = 0;
            m_bClusterOpen = true;
            m_uClusterTimecode = (uint32_t)iPtsMs;
            m_uClusterPos = RTFileTell(m_Ebml.getFile());
            m_Ebml.subStart(Cluster)
                  .serializeUnsignedInteger(Timecode, m_uClusterTimecode);

            /* Save a cue point if this is a keyframe. */
            if (fKeyframe)
            {
                CueEntry cue(m_uClusterTimecode, m_uClusterPos);
                m_CueList.push_back(cue);
            }
        }

        /* Write a "Simple Block". */
        m_Ebml.writeClassId(SimpleBlock);
        m_Ebml.writeUnsignedInteger(0x10000000u | (4 + a_pPkt->data.frame.sz), 4);
        m_Ebml.writeSize(1);
        m_Ebml.writeUnsignedInteger(uBlockTimecode, 2);
        m_Ebml.writeUnsignedInteger((fKeyframe ? 0x80 : 0) | (a_pPkt->data.frame.flags & VPX_FRAME_IS_INVISIBLE ? 0x08 : 0), 1);
        m_Ebml.write(a_pPkt->data.frame.buf, a_pPkt->data.frame.sz);
    }

    void writeFooter(uint32_t a_u64Hash)
    {
        if (m_bClusterOpen)
            m_Ebml.subEnd(Cluster);

        m_uCuePos = RTFileTell(m_Ebml.getFile());
        m_Ebml.subStart(Cues);
        for (std::list<CueEntry>::iterator it = m_CueList.begin(); it != m_CueList.end(); ++it)
        {
          m_Ebml.subStart(CuePoint)
                .serializeUnsignedInteger(CueTime, it->time)
                .subStart(CueTrackPositions)
                .serializeUnsignedInteger(CueTrack, 1)
                .serializeUnsignedInteger(CueClusterPosition, it->loc - m_uPositionReference, 8)
                .subEnd(CueTrackPositions)
                .subEnd(CuePoint);
        }

        m_Ebml.subEnd(Cues)
              .subEnd(Segment);

        writeSeekInfo();

        int rc = RTFileSeek(m_Ebml.getFile(), m_uTrackIdPos, RTFILE_SEEK_BEGIN, NULL);
        if (!RT_SUCCESS(rc)) throw rc;

        m_Ebml.serializeUnsignedInteger(TrackUID, (m_fDebug ? 0xDEADBEEF : a_u64Hash), 4);

        rc = RTFileSeek(m_Ebml.getFile(), 0, RTFILE_SEEK_END, NULL);
        if (!RT_SUCCESS(rc)) throw rc;
    }

    friend class WebMWriter;

private:

    void writeSeekInfo()
    {
        uint64_t uPos = RTFileTell(m_Ebml.getFile());
        if (m_uSeekInfoPos)
            RTFileSeek(m_Ebml.getFile(), m_uSeekInfoPos, RTFILE_SEEK_BEGIN, NULL);
        else
            m_uSeekInfoPos = uPos;

        m_Ebml.subStart(SeekHead)

              .subStart(Seek)
              .serializeUnsignedInteger(SeekID, Tracks)
              .serializeUnsignedInteger(SeekPosition, m_uTrackPos - m_uPositionReference, 8)
              .subEnd(Seek)

              .subStart(Seek)
              .serializeUnsignedInteger(SeekID, Cues)
              .serializeUnsignedInteger(SeekPosition, m_uCuePos - m_uPositionReference, 8)
              .subEnd(Seek)

              .subStart(Seek)
              .serializeUnsignedInteger(SeekID, Info)
              .serializeUnsignedInteger(SeekPosition, m_uSegmentInfoPos - m_uPositionReference, 8)
              .subEnd(Seek)

              .subEnd(SeekHead);

        int64_t iFrameTime = (int64_t)1000 * m_Framerate.den / m_Framerate.num;
        m_uSegmentInfoPos = RTFileTell(m_Ebml.getFile());

        char szVersion[64];
        RTStrPrintf(szVersion, sizeof(szVersion), "vpxenc%s",
                    m_fDebug ? "" : vpx_codec_version_str());

        m_Ebml.subStart(Info)
              .serializeUnsignedInteger(TimecodeScale, 1000000)
              .serializeFloat(Segment_Duration, m_iLastPtsMs + iFrameTime - m_iInitialPtsMs)
              .serializeString(MuxingApp, szVersion)
              .serializeString(WritingApp, szVersion)
              .subEnd(Info);
    }
};

WebMWriter::WebMWriter() : m_Impl(new WebMWriter_Impl()) {}

WebMWriter::~WebMWriter()
{
    delete m_Impl;
}

int WebMWriter::create(const char *a_pszFilename, WebMWriter::Mode a_enmMode)
{
    m_Impl->m_enmMode = a_enmMode;

    return m_Impl->m_Ebml.create(a_pszFilename);
}

void WebMWriter::close()
{
    m_Impl->m_Ebml.close();
}

int WebMWriter::writeHeader(const vpx_codec_enc_cfg_t *a_pCfg, const vpx_rational *a_pFps)
{
    try
    {
        m_Impl->writeHeader(a_pCfg, a_pFps);
    }
    catch(int rc)
    {
        return rc;
    }
    return VINF_SUCCESS;
}

int WebMWriter::writeBlock(const vpx_codec_enc_cfg_t *a_pCfg, const vpx_codec_cx_pkt_t *a_pPkt)
{
    try
    {
        m_Impl->writeBlock(a_pCfg, a_pPkt);
    }
    catch(int rc)
    {
        return rc;
    }
    return VINF_SUCCESS;
}

int WebMWriter::writeFooter(uint32_t a_u64Hash)
{
    try
    {
        m_Impl->writeFooter(a_u64Hash);
    }
    catch(int rc)
    {
        return rc;
    }
    return VINF_SUCCESS;
}

uint64_t WebMWriter::getFileSize()
{
    return m_Impl->m_Ebml.getFileSize();
}

uint64_t WebMWriter::getAvailableSpace()
{
    return m_Impl->m_Ebml.getAvailableSpace();
}