/******************************************************************************
 *
 * Project:  CEOS Translator
 * Purpose:  Implementation of non-GDAL dependent CEOS support.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 * Copyright (c) 2007-2012, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "ceosopen.h"

CPL_INLINE static void CPL_IGNORE_RET_VAL_INT(CPL_UNUSED int unused)
{
}

/************************************************************************/
/*                            CEOSScanInt()                             */
/*                                                                      */
/*      Read up to nMaxChars from the passed string, and interpret      */
/*      as an integer.                                                  */
/************************************************************************/

static int CEOSScanInt(const char *pszString, int nMaxChars)

{
    char szWorking[33] = {0};
    int i;

    if (nMaxChars > 32 || nMaxChars == 0)
        nMaxChars = 32;

    for (i = 0; i < nMaxChars && pszString[i] != '\0'; i++)
        szWorking[i] = pszString[i];

    szWorking[i] = '\0';

    return (atoi(szWorking));
}

/************************************************************************/
/*                           CEOSReadRecord()                           */
/*                                                                      */
/*      Read a single CEOS record at the current point in the file.     */
/*      Return NULL after reporting an error if it fails, otherwise     */
/*      return the record.                                              */
/************************************************************************/

CEOSRecord *CEOSReadRecord(CEOSImage *psImage)

{
    GByte abyHeader[12];
    CEOSRecord *psRecord;
    GUInt32 nRecordNumUInt32, nLengthUInt32;

    /* -------------------------------------------------------------------- */
    /*      Read the standard CEOS header.                                  */
    /* -------------------------------------------------------------------- */
    if (VSIFEofL(psImage->fpImage))
        return NULL;

    if (VSIFReadL(abyHeader, 1, 12, psImage->fpImage) != 12)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Ran out of data reading CEOS record.");
        return NULL;
    }

    /* -------------------------------------------------------------------- */
    /*      Extract this information.                                       */
    /* -------------------------------------------------------------------- */
    psRecord = (CEOSRecord *)CPLMalloc(sizeof(CEOSRecord));
    if (psImage->bLittleEndian)
    {
        CPL_SWAP32PTR(abyHeader + 0);
        CPL_SWAP32PTR(abyHeader + 8);
    }

    nRecordNumUInt32 = ((unsigned)abyHeader[0] << 24) + (abyHeader[1] << 16) +
                       (abyHeader[2] << 8) + abyHeader[3];

    psRecord->nRecordType = ((unsigned)abyHeader[4] << 24) +
                            (abyHeader[5] << 16) + (abyHeader[6] << 8) +
                            abyHeader[7];

    nLengthUInt32 = ((unsigned)abyHeader[8] << 24) + (abyHeader[9] << 16) +
                    (abyHeader[10] << 8) + abyHeader[11];

    /* -------------------------------------------------------------------- */
    /*      Does it look reasonable?  We assume there can't be too many     */
    /*      records and that the length must be between 12 and 200000.      */
    /* -------------------------------------------------------------------- */
    if (nRecordNumUInt32 > 200000 || nLengthUInt32 < 12 ||
        nLengthUInt32 > 200000)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "CEOS record leader appears to be corrupt.\n"
                 "Record Number = %u, Record Length = %u\n",
                 nRecordNumUInt32, nLengthUInt32);
        CPLFree(psRecord);
        return NULL;
    }

    psRecord->nRecordNum = (int)nRecordNumUInt32;
    psRecord->nLength = (int)nLengthUInt32;

    /* -------------------------------------------------------------------- */
    /*      Read the remainder of the record into a buffer.  Ensure that    */
    /*      the first 12 bytes gets moved into this buffer as well.         */
    /* -------------------------------------------------------------------- */
    psRecord->pachData = (char *)VSI_MALLOC_VERBOSE(psRecord->nLength);
    if (psRecord->pachData == NULL)
    {
        CPLFree(psRecord);
        return NULL;
    }

    memcpy(psRecord->pachData, abyHeader, 12);

    if ((int)VSIFReadL(psRecord->pachData + 12, 1, psRecord->nLength - 12,
                       psImage->fpImage) != psRecord->nLength - 12)
    {
        CPLError(CE_Failure, CPLE_FileIO, "Short read on CEOS record data.\n");
        CPLFree(psRecord->pachData);
        CPLFree(psRecord);
        return NULL;
    }

    return psRecord;
}

/************************************************************************/
/*                         CEOSDestroyRecord()                          */
/*                                                                      */
/*      Free a record.                                                  */
/************************************************************************/

void CEOSDestroyRecord(CEOSRecord *psRecord)

{
    if (psRecord)
    {
        CPLFree(psRecord->pachData);
        CPLFree(psRecord);
    }
}

/************************************************************************/
/*                              CEOSOpen()                              */
/************************************************************************/

/**
 * Open a CEOS transfer.
 *
 * @param pszFilename The name of the CEOS imagery file (i.e. imag_01.dat).
 * @param pszAccess An fopen() style access string.  Should be either "rb" for
 * read-only access, or "r+b" for read, and update access.
 *
 * @return A CEOSImage pointer as a handle to the image.  The CEOSImage also
 * has various information about the image available.  A NULL is returned
 * if an error occurs.
 */

CEOSImage *CEOSOpen(const char *pszFilename, const char *pszAccess)

{
    VSILFILE *fp;
    CEOSRecord *psRecord;
    CEOSImage *psImage;
    int nSeqNum, i;
    GByte abyHeader[16];

    /* -------------------------------------------------------------------- */
    /*      Try to open the imagery file.                                   */
    /* -------------------------------------------------------------------- */
    fp = VSIFOpenL(pszFilename, pszAccess);

    if (fp == NULL)
    {
        CPLError(CE_Failure, CPLE_OpenFailed,
                 "Failed to open CEOS file `%s' with access `%s'.\n",
                 pszFilename, pszAccess);
        return NULL;
    }

    /* -------------------------------------------------------------------- */
    /*      Create a CEOSImage structure, and initialize it.                */
    /* -------------------------------------------------------------------- */
    psImage = (CEOSImage *)CPLCalloc(1, sizeof(CEOSImage));
    psImage->fpImage = fp;

    psImage->nPixels = psImage->nLines = psImage->nBands = 0;

    /* -------------------------------------------------------------------- */
    /*      Preread info on the first record, to establish if it is         */
    /*      little endian.                                                  */
    /* -------------------------------------------------------------------- */
    if (VSIFReadL(abyHeader, 16, 1, fp) != 1 || VSIFSeekL(fp, 0, SEEK_SET) < 0)
    {
        CEOSClose(psImage);
        return NULL;
    }

    if (abyHeader[0] != 0 || abyHeader[1] != 0)
        psImage->bLittleEndian = TRUE;

    /* -------------------------------------------------------------------- */
    /*      Try to read the header record.                                  */
    /* -------------------------------------------------------------------- */
    psRecord = CEOSReadRecord(psImage);
    if (psRecord == NULL || psRecord->nLength < 288 + 4)
    {
        CEOSDestroyRecord(psRecord);
        CEOSClose(psImage);
        return NULL;
    }

    char format_doc[13] = {0};
    memcpy(format_doc, psRecord->pachData + 16, 12);
    if (strncmp("CEOS-SAR-CCT", format_doc, 12) == 0)
    {
        CEOSDestroyRecord(psRecord);
        CEOSClose(psImage);
        return NULL;
    }

    if (psRecord->nRecordType != CRT_IMAGE_FDR)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Got a %X type record, instead of the expected\n"
                 "file descriptor record on file %s.\n",
                 psRecord->nRecordType, pszFilename);

        CEOSDestroyRecord(psRecord);
        CEOSClose(psImage);
        return NULL;
    }

    /* -------------------------------------------------------------------- */
    /*      The sequence number should be 2 indicating this is the          */
    /*      imagery file.                                                   */
    /* -------------------------------------------------------------------- */
    nSeqNum = CEOSScanInt(psRecord->pachData + 44, 4);
    if (nSeqNum != 2)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Got a %d file sequence number, instead of the expected\n"
                 "2 indicating imagery on file %s.\n"
                 "Continuing to access anyways.\n",
                 nSeqNum, pszFilename);
    }

    /* -------------------------------------------------------------------- */
    /*      Extract various information.                                    */
    /* -------------------------------------------------------------------- */
    psImage->nImageRecCount = CEOSScanInt(psRecord->pachData + 180, 6);
    psImage->nImageRecLength = CEOSScanInt(psRecord->pachData + 186, 6);
    psImage->nBitsPerPixel = CEOSScanInt(psRecord->pachData + 216, 4);
    psImage->nBands = CEOSScanInt(psRecord->pachData + 232, 4);
    psImage->nLines = CEOSScanInt(psRecord->pachData + 236, 8);
    psImage->nPixels = CEOSScanInt(psRecord->pachData + 248, 8);

    psImage->nPrefixBytes = CEOSScanInt(psRecord->pachData + 276, 4);
    psImage->nSuffixBytes = CEOSScanInt(psRecord->pachData + 288, 4);

    if (psImage->nImageRecLength <= 0 || psImage->nPrefixBytes < 0 ||
        psImage->nBands > INT_MAX / psImage->nImageRecLength ||
        (size_t)psImage->nBands > INT_MAX / sizeof(int))
    {
        CEOSDestroyRecord(psRecord);
        CEOSClose(psImage);
        return NULL;
    }

    /* -------------------------------------------------------------------- */
    /*      Try to establish the layout of the imagery data.                */
    /* -------------------------------------------------------------------- */
    psImage->nLineOffset = psImage->nBands * psImage->nImageRecLength;

    psImage->panDataStart = (int *)VSIMalloc(sizeof(int) * psImage->nBands);
    if (psImage->panDataStart == NULL)
    {
        CEOSDestroyRecord(psRecord);
        CEOSClose(psImage);
        return NULL;
    }

    for (i = 0; i < psImage->nBands; i++)
    {
        psImage->panDataStart[i] = psRecord->nLength +
                                   i * psImage->nImageRecLength + 12 +
                                   psImage->nPrefixBytes;
    }

    CEOSDestroyRecord(psRecord);

    return psImage;
}

/************************************************************************/
/*                          CEOSReadScanline()                          */
/************************************************************************/

/**
 * Read a scanline of image.
 *
 * @param psCEOS The CEOS dataset handle returned by CEOSOpen().
 * @param nBand The band number (i.e. 1, 2, 3).
 * @param nScanline The scanline requested, one based.
 * @param pData The data buffer to read into.  Must be at least nPixels *
 * nBitesPerPixel bits long.
 *
 * @return CPLErr Returns error indicator or CE_None if the read succeeds.
 */

CPLErr CEOSReadScanline(CEOSImage *psCEOS, int nBand, int nScanline,
                        void *pData)

{
    int nOffset, nBytes;

    /*
     * As a short cut, I currently just seek to the data, and read it
     * raw, rather than trying to read ceos records properly.
     */

    nOffset =
        psCEOS->panDataStart[nBand - 1] + (nScanline - 1) * psCEOS->nLineOffset;

    if (VSIFSeekL(psCEOS->fpImage, nOffset, SEEK_SET) != 0)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Seek to %d for scanline %d failed.\n", nOffset, nScanline);
        return CE_Failure;
    }

    /* -------------------------------------------------------------------- */
    /*      Read the data.                                                  */
    /* -------------------------------------------------------------------- */
    nBytes = psCEOS->nPixels * psCEOS->nBitsPerPixel / 8;
    if ((int)VSIFReadL(pData, 1, nBytes, psCEOS->fpImage) != nBytes)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Read of %d bytes for scanline %d failed.\n", nBytes,
                 nScanline);
        return CE_Failure;
    }

    return CE_None;
}

/************************************************************************/
/*                             CEOSClose()                              */
/************************************************************************/

/**
 * Close a CEOS transfer.  Any open files are closed, and memory deallocated.
 *
 * @param psCEOS The CEOSImage handle from CEOSOpen to be closed.
 */

void CEOSClose(CEOSImage *psCEOS)

{
    CPLFree(psCEOS->panDataStart);
    CPL_IGNORE_RET_VAL_INT(VSIFCloseL(psCEOS->fpImage));
    CPLFree(psCEOS);
}