/*M///////////////////////////////////////////////////////////////////////////////////////
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//                 For Open Source Computer Vision Library
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#include <cerrno>

#include "precomp.hpp"
#include "utils.hpp"
#include "grfmt_pam.hpp"

/* the PAM related fields */
#define MAX_PAM_HEADER_IDENITFIER_LENGTH 8
#define MAX_PAM_HEADER_VALUE_LENGTH 255

/* PAM header fileds */
typedef enum {
    PAM_HEADER_NONE,
    PAM_HEADER_COMMENT,
    PAM_HEADER_ENDHDR,
    PAM_HEADER_HEIGHT,
    PAM_HEADER_WIDTH,
    PAM_HEADER_DEPTH,
    PAM_HEADER_MAXVAL,
    PAM_HEADER_TUPLTYPE,
} PamHeaderFieldType;

struct pam_header_field {
    PamHeaderFieldType type;
    char identifier[MAX_PAM_HEADER_IDENITFIER_LENGTH+1];
};

const static struct pam_header_field fields[] = {
    {PAM_HEADER_ENDHDR,   "ENDHDR"},
    {PAM_HEADER_HEIGHT,   "HEIGHT"},
    {PAM_HEADER_WIDTH,    "WIDTH"},
    {PAM_HEADER_DEPTH,    "DEPTH"},
    {PAM_HEADER_MAXVAL,   "MAXVAL"},
    {PAM_HEADER_TUPLTYPE, "TUPLTYPE"},
};
#define PAM_FIELDS_NO (sizeof (fields) / sizeof ((fields)[0]))

typedef bool (*cvtFunc) (void *src, void *target, int width, int target_channels,
    int target_depth);

struct channel_layout {
    uint rchan, gchan, bchan, graychan;
};

struct pam_format {
    uint fmt;
    char name[MAX_PAM_HEADER_VALUE_LENGTH+1];
    cvtFunc cvt_func;
    /* the channel layout that should be used when
     * imread_ creates a 3 channel or 1 channel image
     * used when no conversion function is available
     */
    struct channel_layout layout;
};

static bool rgb_convert (void *src, void *target, int width, int target_channels,
    int target_depth);

const static struct pam_format formats[] = {
    {CV_IMWRITE_PAM_FORMAT_NULL, "", NULL, {0, 0, 0, 0} },
    {CV_IMWRITE_PAM_FORMAT_BLACKANDWHITE, "BLACKANDWHITE", NULL, {0, 0, 0, 0} },
    {CV_IMWRITE_PAM_FORMAT_GRAYSCALE, "GRAYSCALE", NULL, {0, 0, 0, 0} },
    {CV_IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA, "GRAYSCALE_ALPHA", NULL, {0, 0, 0, 0} },
    {CV_IMWRITE_PAM_FORMAT_RGB, "RGB", rgb_convert, {0, 1, 2, 0} },
    {CV_IMWRITE_PAM_FORMAT_RGB_ALPHA, "RGB_ALPHA", NULL, {0, 1, 2, 0} },
};
#define PAM_FORMATS_NO (sizeof (fields) / sizeof ((fields)[0]))

/*
 * conversion functions
 */

static bool
rgb_convert (void *src, void *target, int width, int target_channels, int target_depth)
{
    bool ret = false;
    if (target_channels == 3) {
        switch (target_depth) {
            case CV_8U:
                icvCvt_RGB2BGR_8u_C3R( (uchar*) src, 0, (uchar*) target, 0,
                    cvSize(width,1) );
                ret = true;
                break;
            case CV_16U:
                icvCvt_RGB2BGR_16u_C3R( (ushort *)src, 0, (ushort *)target, 0,
                    cvSize(width,1) );
                ret = true;
                break;
            default:
                break;
        }
    } else if (target_channels == 1) {
        switch (target_depth) {
            case CV_8U:
                icvCvt_BGR2Gray_8u_C3C1R( (uchar*) src, 0, (uchar*) target, 0,
                    cvSize(width,1), 2 );
                ret = true;
                break;
            case CV_16U:
                icvCvt_BGRA2Gray_16u_CnC1R( (ushort *)src, 0, (ushort *)target, 0,
                    cvSize(width,1), 3, 2 );
                ret = true;
                break;
            default:
                break;
        }
    }
    return ret;
}

/*
 * copy functions used as a fall back for undefined formats
 * or simpler conversion options
 */

static void
basic_conversion (void *src, const struct channel_layout *layout, int src_sampe_size,
    int src_width, void *target, int target_channels, int target_depth)
{
    switch (target_depth) {
        case CV_8U:
        {
            uchar *d = (uchar *)target, *s = (uchar *)src,
                *end = ((uchar *)src) + src_width;
            switch (target_channels) {
                case 1:
                    for( ; s < end; d += 3, s += src_sampe_size )
                        d[0] = d[1] = d[2] = s[layout->graychan];
                    break;
                case 3:
                    for( ; s < end; d += 3, s += src_sampe_size ) {
                        d[0] = s[layout->bchan];
                        d[1] = s[layout->gchan];
                        d[2] = s[layout->rchan];
                    }
                    break;
                default:
                    assert (0);
            }
            break;
        }
        case CV_16U:
        {
            ushort *d = (ushort *)target, *s = (ushort *)src,
                *end = ((ushort *)src) + src_width;
            switch (target_channels) {
                case 1:
                    for( ; s < end; d += 3, s += src_sampe_size )
                        d[0] = d[1] = d[2] = s[layout->graychan];
                    break;
                case 3:
                    for( ; s < end; d += 3, s += src_sampe_size ) {
                        d[0] = s[layout->bchan];
                        d[1] = s[layout->gchan];
                        d[2] = s[layout->rchan];
                    }
                    break;
                default:
                    assert (0);
            }
            break;
        }
        default:
            assert (0);
    }
}


static bool ReadPAMHeaderLine (cv::RLByteStream& strm,
                PamHeaderFieldType &fieldtype,
                char value[MAX_PAM_HEADER_VALUE_LENGTH+1])
{
    int code, pos;
    bool ident_found = false;
    uint i;
    char ident[MAX_PAM_HEADER_IDENITFIER_LENGTH+1] = { 0 };

    do {
        code = strm.getByte();
    } while ( isspace(code) );

    if (code == '#') {
        /* we are in a comment, eat characters until linebreak */
        do
        {
            code = strm.getByte();
        } while( code != '\n' && code != '\r' );
        fieldtype = PAM_HEADER_COMMENT;
        return true;
    } else if (code == '\n' || code == '\r' ) {
        fieldtype = PAM_HEADER_NONE;
        return true;
    }

    /* nul-ify buffers before writing to them */
    memset (ident, '\0', sizeof(char) * MAX_PAM_HEADER_IDENITFIER_LENGTH);
    for (i=0; i<MAX_PAM_HEADER_IDENITFIER_LENGTH; i++) {
        if (!isspace(code))
            ident[i] = (char) code;
        else
            break;
        code = strm.getByte();
    }

    /* we may have filled the buffer and still have data */
    if (!isspace(code))
        return false;

    for (i=0; i<PAM_FIELDS_NO; i++) {
        if (strncmp(fields[i].identifier, ident, MAX_PAM_HEADER_IDENITFIER_LENGTH+1) == 0) {
            fieldtype = fields[i].type;
            ident_found = true;
        }
    }

    if (!ident_found)
        return false;

    memset (value, '\0', sizeof(char) * MAX_PAM_HEADER_VALUE_LENGTH);
    /* we may have an identifier that has no value */
    if (code == '\n' || code == '\r')
        return true;

    do {
        code = strm.getByte();
    } while ( isspace(code) );



    /* read identifier value */
    for (i=0; i<MAX_PAM_HEADER_VALUE_LENGTH; i++) {
        if (code != '\n' && code != '\r') {
            value[i] = (char) code;
        } else if (code != '\n' || code != '\r')
            break;
        code = strm.getByte();
    }
    pos = i;

    /* should be terminated */
    if (code != '\n' && code != '\r')
        return false;

    /* remove trailing white spaces */
    while (pos >= 0 && isspace(value[pos]))
        value[pos--] = '\0';

    return true;
}

static bool ParseNumber (char *str, int *retval)
{
  char *endptr;
  long lval = strtol (str, &endptr, 0);

  if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
        || (errno != 0 && lval == 0)) {
    return false;
  }
  if (endptr == str) {
    return false;
  }

  *retval = (int) lval;

  return true;
}

namespace cv
{

PAMDecoder::PAMDecoder()
{
    m_offset = -1;
    m_buf_supported = true;
    bit_mode = false;
    selected_fmt = CV_IMWRITE_PAM_FORMAT_NULL;
    m_maxval = 0;
    m_channels = 0;
    m_sampledepth = 0;
}


PAMDecoder::~PAMDecoder()
{
    m_strm.close();
}

size_t PAMDecoder::signatureLength() const
{
    return 3;
}

bool PAMDecoder::checkSignature( const String& signature ) const
{
    return signature.size() >= 3 && signature[0] == 'P' &&
           signature[1] == '7' &&
           isspace(signature[2]);
}

ImageDecoder PAMDecoder::newDecoder() const
{
    return makePtr<PAMDecoder>();
}

struct parsed_fields
{
    bool endhdr, height, width, depth, maxval;
};

#define HEADER_READ_CORRECT(pf) (pf.endhdr && pf.height && pf.width \
    && pf.depth && pf.maxval)


bool  PAMDecoder::readHeader()
{
    PamHeaderFieldType fieldtype = PAM_HEADER_NONE;
    char value[MAX_PAM_HEADER_VALUE_LENGTH+1];
    int byte;
    struct parsed_fields flds;
    if( !m_buf.empty() )
    {
        if( !m_strm.open(m_buf) )
            return false;
    }
    else if( !m_strm.open( m_filename ))
        return false;
    CV_TRY
    {
        byte = m_strm.getByte();
        if( byte != 'P' )
            CV_THROW( RBS_BAD_HEADER );

        byte = m_strm.getByte();
        if (byte != '7')
            CV_THROW( RBS_BAD_HEADER );

        byte = m_strm.getByte();
        if (byte != '\n' && byte != '\r')
            CV_THROW( RBS_BAD_HEADER );

        uint i;
        memset (&flds, 0x00, sizeof (struct parsed_fields));
        do {
            if (!ReadPAMHeaderLine(m_strm, fieldtype, value))
                CV_THROW( RBS_BAD_HEADER );
            switch (fieldtype) {
                case PAM_HEADER_NONE:
                case PAM_HEADER_COMMENT:
                    continue;
                case PAM_HEADER_ENDHDR:
                    flds.endhdr = true;
                    break;
                case PAM_HEADER_HEIGHT:
                    if (flds.height)
                        CV_THROW( RBS_BAD_HEADER );
                    if (!ParseNumber (value, &m_height))
                        CV_THROW( RBS_BAD_HEADER );
                    flds.height = true;
                    break;
                case PAM_HEADER_WIDTH:
                    if (flds.width)
                        CV_THROW( RBS_BAD_HEADER );
                    if (!ParseNumber (value, &m_width))
                        CV_THROW( RBS_BAD_HEADER );
                    flds.width = true;
                    break;
                case PAM_HEADER_DEPTH:
                    if (flds.depth)
                        CV_THROW( RBS_BAD_HEADER );
                    if (!ParseNumber (value, &m_channels))
                        CV_THROW( RBS_BAD_HEADER );
                    flds.depth = true;
                    break;
                case PAM_HEADER_MAXVAL:
                    if (flds.maxval)
                        CV_THROW( RBS_BAD_HEADER );
                    if (!ParseNumber (value, &m_maxval))
                        CV_THROW( RBS_BAD_HEADER );
                    if ( m_maxval > 65535 )
                        CV_THROW( RBS_BAD_HEADER );
                    if ( m_maxval > 255 ) {
                        m_sampledepth = CV_16U;
                    }
                    else
                        m_sampledepth = CV_8U;
                    if (m_maxval == 1)
                        bit_mode = true;
                    flds.maxval = true;
                    break;
                case PAM_HEADER_TUPLTYPE:
                    for (i=0; i<PAM_FORMATS_NO; i++) {
                        if (strncmp(formats[i].name,
                                value, MAX_PAM_HEADER_VALUE_LENGTH+1) == 0) {
                            selected_fmt = formats[i].fmt;
                        }
                    }
                    break;
                default:
                    CV_THROW( RBS_BAD_HEADER );
            }
        } while (fieldtype != PAM_HEADER_ENDHDR);

        if (HEADER_READ_CORRECT(flds)) {
            if (selected_fmt == CV_IMWRITE_PAM_FORMAT_NULL) {
                if (m_channels == 1 && m_maxval == 1)
                    selected_fmt = CV_IMWRITE_PAM_FORMAT_BLACKANDWHITE;
                else if (m_channels == 1 && m_maxval < 256)
                    selected_fmt = CV_IMWRITE_PAM_FORMAT_GRAYSCALE;
                else if (m_channels == 3 && m_maxval < 256)
                    selected_fmt = CV_IMWRITE_PAM_FORMAT_RGB;
            }
            m_type = CV_MAKETYPE(m_sampledepth, m_channels);
            m_offset = m_strm.getPos();

            return true;
        }
    } CV_CATCH_ALL
    {
    }

    m_offset = -1;
    m_width = m_height = -1;
    m_strm.close();
    return false;
}


bool  PAMDecoder::readData( Mat& img )
{
    uchar* data = img.ptr();
    int target_channels = img.channels();
    size_t imp_stride = img.step;
    int sample_depth = CV_ELEM_SIZE1(m_type);
    int src_elems_per_row = m_width*m_channels;
    int src_stride = src_elems_per_row*sample_depth;
    int x, y;
    bool res = false, funcout;
    PaletteEntry palette[256];
    const struct pam_format *fmt = NULL;
    struct channel_layout layout = { 0, 0, 0, 0 }; // normalized to 1-channel grey format

    /* setting buffer to max data size so scaling up is possible */
    AutoBuffer<uchar> _src(src_elems_per_row * 2);
    uchar* src = _src;
    AutoBuffer<uchar> _gray_palette;
    uchar* gray_palette = _gray_palette;

    if( m_offset < 0 || !m_strm.isOpened())
        return false;

    if (selected_fmt != CV_IMWRITE_PAM_FORMAT_NULL)
        fmt = &formats[selected_fmt];
    else {
        /* default layout handling */
        if (m_channels >= 3) {
            layout.bchan = 0;
            layout.gchan = 1;
            layout.rchan = 2;
        }
    }

    CV_TRY
    {
        m_strm.setPos( m_offset );

        /* the case where data fits the opencv matrix */
        if (m_sampledepth == img.depth() && target_channels == m_channels && !bit_mode) {
            /* special case for 16bit images with wrong endianess */
            if (m_sampledepth == CV_16U && !isBigEndian())
            {
                for (y = 0; y < m_height; y++, data += imp_stride )
                {
                    m_strm.getBytes( src, src_stride );
                    for( x = 0; x < src_elems_per_row; x++ )
                    {
                        uchar v = src[x * 2];
                        data[x * 2] = src[x * 2 + 1];
                        data[x * 2 + 1] = v;
                    }
                }
            }
            else {
                m_strm.getBytes( data, src_stride * m_height );
            }

        }
        else {
            /* black and white mode */
            if (bit_mode) {
                if( target_channels == 1 )
                {
                    _gray_palette.allocate(2);
                    gray_palette = _gray_palette;
                    gray_palette[0] = 0;
                    gray_palette[1] = 255;
                    for( y = 0; y < m_height; y++, data += imp_stride )
                    {
                        m_strm.getBytes( src, src_stride );
                        FillGrayRow1( data, src, m_width, gray_palette );
                    }
                } else if ( target_channels == 3 )
                {
                    FillGrayPalette( palette, 1 , false );
                    for( y = 0; y < m_height; y++, data += imp_stride )
                    {
                        m_strm.getBytes( src, src_stride );
                        FillColorRow1( data, src, m_width, palette );
                    }
                }
            } else {
                for (y = 0; y < m_height; y++, data += imp_stride )
                {
                    m_strm.getBytes( src, src_stride );

                    /* endianess correction */
                    if( m_sampledepth == CV_16U && !isBigEndian() )
                    {
                        for( x = 0; x < src_elems_per_row; x++ )
                        {
                            uchar v = src[x * 2];
                            src[x * 2] = src[x * 2 + 1];
                            src[x * 2 + 1] = v;
                        }
                    }

                    /* scale down */
                    if( img.depth() == CV_8U && m_sampledepth == CV_16U )
                    {
                        for( x = 0; x < src_elems_per_row; x++ )
                        {
                            int v = ((ushort *)src)[x];
                            src[x] = (uchar)(v >> 8);
                        }
                    }

                    /* if we are only scaling up/down then we can then copy the data */
                    if (target_channels == m_channels) {
                        memcpy (data, src, imp_stride);
                    }
                    /* perform correct conversion based on format */
                    else if (fmt) {
                        funcout = false;
                        if (fmt->cvt_func)
                            funcout = fmt->cvt_func (src, data, m_width, target_channels,
                                img.depth());
                        /* fall back to default if there is no conversion function or it
                         * can't handle the specified characteristics
                         */
                        if (!funcout)
                            basic_conversion (src, &fmt->layout, m_channels,
                                m_width, data, target_channels, img.depth());

                    /* default to selecting the first available channels */
                    } else {
                        basic_conversion (src, &layout, m_channels,
                            m_width, data, target_channels, img.depth());
                    }
                }
            }
        }

        res = true;
    } CV_CATCH_ALL
    {
    }

    return res;
}


//////////////////////////////////////////////////////////////////////////////////////////

PAMEncoder::PAMEncoder()
{
    m_description = "Portable arbitrary format (*.pam)";
    m_buf_supported = true;
}


PAMEncoder::~PAMEncoder()
{
}


ImageEncoder PAMEncoder::newEncoder() const
{
    return makePtr<PAMEncoder>();
}


bool PAMEncoder::isFormatSupported( int depth ) const
{
    return depth == CV_8U || depth == CV_16U;
}


bool PAMEncoder::write( const Mat& img, const std::vector<int>& params )
{

    WLByteStream strm;

    int width = img.cols, height = img.rows;
    int stride = width*(int)img.elemSize();
    const uchar* data = img.ptr();
    const struct pam_format *fmt = NULL;
    int x, y, tmp, bufsize = 256;

    /* parse save file type */
    for( size_t i = 0; i < params.size(); i += 2 )
        if( params[i] == CV_IMWRITE_PAM_TUPLETYPE ) {
            if ( params[i+1] > CV_IMWRITE_PAM_FORMAT_NULL &&
                 params[i+1] < (int) PAM_FORMATS_NO)
                fmt = &formats[params[i+1]];
        }

    if( m_buf )
    {
        if( !strm.open(*m_buf) )
            return false;
        m_buf->reserve( alignSize(256 + stride*height, 256));
    }
    else if( !strm.open(m_filename) )
        return false;

    tmp = width * (int)img.elemSize();

    if (bufsize < tmp)
        bufsize = tmp;

    AutoBuffer<char> _buffer(bufsize);
    char* buffer = _buffer;

    /* write header */
    tmp = 0;
    tmp += sprintf( buffer, "P7\n");
    tmp += sprintf( buffer + tmp, "WIDTH %d\n", width);
    tmp += sprintf( buffer + tmp, "HEIGHT %d\n", height);
    tmp += sprintf( buffer + tmp, "DEPTH %d\n", img.channels());
    tmp += sprintf( buffer + tmp, "MAXVAL %d\n", (1 << img.elemSize1()*8) - 1);
    if (fmt)
        tmp += sprintf( buffer + tmp, "TUPLTYPE %s\n", fmt->name );
    tmp += sprintf( buffer + tmp, "ENDHDR\n" );

    strm.putBytes( buffer, (int)strlen(buffer) );
    /* write data */
    if (img.depth() == CV_8U)
        strm.putBytes( data, stride*height );
    else if (img.depth() == CV_16U) {
        /* fix endianess */
        if (!isBigEndian()) {
            for( y = 0; y < height; y++ ) {
                memcpy( buffer, img.ptr(y), stride );
                for( x = 0; x < stride; x += 2 )
                {
                    uchar v = buffer[x];
                    buffer[x] = buffer[x + 1];
                    buffer[x + 1] = v;
                }
                strm.putBytes( buffer, stride );
            }
        } else
            strm.putBytes( data, stride*height );
    } else
        assert (0);

    strm.close();
    return true;
}

}