/******************************************************************************
 *
 * Project:  FITS Driver
 * Purpose:  Implement FITS raster read/write support
 * Author:   Simon Perkins, s.perkins@lanl.gov
 *
 ******************************************************************************
 * Copyright (c) 2001, Simon Perkins
 * Copyright (c) 2008-2012, Even Rouault <even dot rouault at mines-paris dot org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "cpl_string.h"
#include "gdal_frmts.h"
#include "gdal_pam.h"
#include <string.h>
#include <fitsio.h>

CPL_CVSID("$Id: fitsdataset.cpp 36501 2016-11-25 14:09:24Z rouault $");

/************************************************************************/
/* ==================================================================== */
/*                              FITSDataset                             */
/* ==================================================================== */
/************************************************************************/

class FITSRasterBand;

class FITSDataset : public GDALPamDataset {

  friend class FITSRasterBand;

  fitsfile* hFITS;

  GDALDataType gdalDataType;   // GDAL code for the image type
  int fitsDataType;   // FITS code for the image type

  bool isExistingFile;
  long highestOffsetWritten;  // How much of image has been written

  FITSDataset();     // Others should not call this constructor explicitly

  CPLErr Init(fitsfile* hFITS_, bool isExistingFile_);

public:
  ~FITSDataset();

  static GDALDataset* Open( GDALOpenInfo* );
  static GDALDataset* Create( const char* pszFilename,
                              int nXSize, int nYSize, int nBands,
                              GDALDataType eType,
                              char** papszParmList );
};

/************************************************************************/
/* ==================================================================== */
/*                            FITSRasterBand                           */
/* ==================================================================== */
/************************************************************************/

class FITSRasterBand : public GDALPamRasterBand {

  friend class  FITSDataset;

public:

  FITSRasterBand(FITSDataset*, int);
  virtual ~FITSRasterBand();

  virtual CPLErr IReadBlock( int, int, void * ) override;
  virtual CPLErr IWriteBlock( int, int, void * ) override;
};

/************************************************************************/
/*                          FITSRasterBand()                           */
/************************************************************************/

FITSRasterBand::FITSRasterBand( FITSDataset *poDSIn, int nBandIn )
{
  poDS = poDSIn;
  nBand = nBandIn;
  eDataType = poDSIn->gdalDataType;
  nBlockXSize = poDSIn->nRasterXSize;
  nBlockYSize = 1;
}

/************************************************************************/
/*                          ~FITSRasterBand()                           */
/************************************************************************/

FITSRasterBand::~FITSRasterBand()
{
    FlushCache();
}

/************************************************************************/
/*                             IReadBlock()                             */
/************************************************************************/

CPLErr FITSRasterBand::IReadBlock(CPL_UNUSED int nBlockXOff, int nBlockYOff,
                                  void* pImage ) {
  // A FITS block is one row (we assume BSQ formatted data)
  FITSDataset* dataset = (FITSDataset*) poDS;
  fitsfile* hFITS = dataset->hFITS;
  int status = 0;

  // Since a FITS block is a whole row, nBlockXOff must be zero
  // and the row number equals the y block offset. Also, nBlockYOff
  // cannot be greater than the number of rows
  CPLAssert(nBlockXOff == 0);
  CPLAssert(nBlockYOff < nRasterYSize);

  // Calculate offsets and read in the data. Note that FITS array offsets
  // start at 1...
  long offset = (nBand - 1) * nRasterXSize * nRasterYSize +
    nBlockYOff * nRasterXSize + 1;
  long nElements = nRasterXSize;

  // If we haven't written this block to the file yet, then attempting
  // to read causes an error, so in this case, just return zeros.
  if (!dataset->isExistingFile && offset > dataset->highestOffsetWritten) {
    memset(pImage, 0, nBlockXSize * nBlockYSize
           * GDALGetDataTypeSize(eDataType) / 8);
    return CE_None;
  }

  // Otherwise read in the image data
  fits_read_img(hFITS, dataset->fitsDataType, offset, nElements,
                NULL, pImage, NULL, &status);
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Couldn't read image data from FITS file (%d).", status);
    return CE_Failure;
  }

  return CE_None;
}

/************************************************************************/
/*                            IWriteBlock()                             */
/*                                                                      */
/************************************************************************/

CPLErr FITSRasterBand::IWriteBlock( CPL_UNUSED int nBlockXOff, int nBlockYOff,
                                    void* pImage )
{
  FITSDataset* dataset = (FITSDataset*) poDS;
  fitsfile* hFITS = dataset->hFITS;
  int status = 0;

  // Since a FITS block is a whole row, nBlockXOff must be zero
  // and the row number equals the y block offset. Also, nBlockYOff
  // cannot be greater than the number of rows

  // Calculate offsets and read in the data. Note that FITS array offsets
  // start at 1...
  long offset = (nBand - 1) * nRasterXSize * nRasterYSize +
    nBlockYOff * nRasterXSize + 1;
  long nElements = nRasterXSize;
  fits_write_img(hFITS, dataset->fitsDataType, offset, nElements,
                 pImage, &status);

  // Capture special case of non-zero status due to data range
  // overflow Standard GDAL policy is to silently truncate, which is
  // what CFITSIO does, in addition to returning NUM_OVERFLOW (412) as
  // the status.
  if (status == NUM_OVERFLOW)
    status = 0;

  // Check for other errors
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Error writing image data to FITS file (%d).", status);
    return CE_Failure;
  }

  // When we write a block, update the offset counter that we've written
  if (offset > dataset->highestOffsetWritten)
    dataset->highestOffsetWritten = offset;

  return CE_None;
}

/************************************************************************/
/* ==================================================================== */
/*                             FITSDataset                             */
/* ==================================================================== */
/************************************************************************/

// Some useful utility functions

// Simple static function to determine if FITS header keyword should
// be saved in meta data.
static const int ignorableHeaderCount = 15;
static const char* const ignorableFITSHeaders[ignorableHeaderCount] = {
  "SIMPLE", "BITPIX", "NAXIS", "NAXIS1", "NAXIS2", "NAXIS3", "END",
  "XTENSION", "PCOUNT", "GCOUNT", "EXTEND", "CONTINUE",
  "COMMENT", "", "LONGSTRN"
};
static bool isIgnorableFITSHeader(const char* name) {
  for (int i = 0; i < ignorableHeaderCount; ++i) {
    if (strcmp(name, ignorableFITSHeaders[i]) == 0)
      return true;
  }
  return false;
}

/************************************************************************/
/*                            FITSDataset()                            */
/************************************************************************/

FITSDataset::FITSDataset():
    hFITS(NULL)
{}

/************************************************************************/
/*                           ~FITSDataset()                            */
/************************************************************************/

FITSDataset::~FITSDataset() {

  int status;
  if( hFITS )
  {
    if(eAccess == GA_Update)
    {
      // Only do this if we've successfully opened the file and update
      // capability.  Write any meta data to the file that's compatible with
      // FITS.
      status = 0;
      fits_movabs_hdu(hFITS, 1, NULL, &status);
      fits_write_key_longwarn(hFITS, &status);
      if (status) {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Couldn't move to first HDU in FITS file %s (%d).\n",
                 GetDescription(), status);
      }
      char** metaData = GetMetadata();
      int count = CSLCount(metaData);
      for (int i = 0; i < count; ++i) {
        const char* field = CSLGetField(metaData, i);
        if (strlen(field) == 0)
            continue;
        else {
            char* key = NULL;
            const char* value = CPLParseNameValue(field, &key);
            // FITS keys must be less than 8 chars
            if (key != NULL && strlen(key) <= 8 && !isIgnorableFITSHeader(key))
            {
                // Although FITS provides support for different value
                // types, the GDAL Metadata mechanism works only with
                // string values. Prior to about 2003-05-02, this driver
                // would attempt to guess the value type from the metadata
                // value string amd then would use the appropriate
                // type-specific FITS keyword update routine. This was
                // found to be troublesome (e.g. a numeric version string
                // with leading zeros would be interpreted as a number
                // and might get those leading zeros stripped), and so now
                // the driver writes every value as a string. In practice
                // this is not a problem since most FITS reading routines
                // will convert from strings to numbers automatically, but
                // if you want finer control, use the underlying FITS
                // handle. Note: to avoid a compiler warning we copy the
                // const value string to a non const one.
                char* valueCpy = CPLStrdup(value);
                fits_update_key_longstr(hFITS, key, valueCpy, NULL, &status);
                CPLFree(valueCpy);

                // Check for errors.
                if (status)
                {
                    CPLError(CE_Warning, CPLE_AppDefined,
                             "Couldn't update key %s in FITS file %s (%d).",
                             key, GetDescription(), status);
                    return;
                }
            }
            // Must free up key
            CPLFree(key);
        }
      }

      // Make sure we flush the raster cache before we close the file!
      FlushCache();
    }

    // Close the FITS handle - ignore the error status
    status = 0;
    fits_close_file(hFITS, &status);
  }
}

/************************************************************************/
/*                           Init()                                     */
/************************************************************************/

CPLErr FITSDataset::Init(fitsfile* hFITS_, bool isExistingFile_) {

  hFITS = hFITS_;
  isExistingFile = isExistingFile_;
  highestOffsetWritten = 0;
  int status = 0;

  // Move to the primary HDU
  fits_movabs_hdu(hFITS, 1, NULL, &status);
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Couldn't move to first HDU in FITS file %s (%d).\n",
             GetDescription(), status);
    return CE_Failure;
  }

  // The cftsio driver automatically rescales data on read and write
  // if BSCALE and BZERO are defined as header keywords. This behavior
  // causes overflows with GDAL and is slightly mysterious, so we
  // disable this rescaling here.
  fits_set_bscale(hFITS, 1.0, 0.0, &status);

  // Get the image info for this dataset (note that all bands in a FITS dataset
  // have the same type)
  int bitpix;
  int naxis;
  const int maxdim = 3;
  long naxes[maxdim];
  fits_get_img_param(hFITS, maxdim, &bitpix, &naxis, naxes, &status);
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Couldn't determine image parameters of FITS file %s (%d).",
             GetDescription(), status);
    return CE_Failure;
  }

  // Determine data type
  if (bitpix == BYTE_IMG) {
     gdalDataType = GDT_Byte;
     fitsDataType = TBYTE;
  }
  else if (bitpix == SHORT_IMG) {
    gdalDataType = GDT_Int16;
    fitsDataType = TSHORT;
  }
  else if (bitpix == LONG_IMG) {
    gdalDataType = GDT_Int32;
    fitsDataType = TINT;
  }
  else if (bitpix == FLOAT_IMG) {
    gdalDataType = GDT_Float32;
    fitsDataType = TFLOAT;
  }
  else if (bitpix == DOUBLE_IMG) {
    gdalDataType = GDT_Float64;
    fitsDataType = TDOUBLE;
  }
  else {
    CPLError(CE_Failure, CPLE_AppDefined,
             "FITS file %s has unknown data type: %d.", GetDescription(),
             bitpix);
    return CE_Failure;
  }

  // Determine image dimensions - we assume BSQ ordering
  if (naxis == 2) {
    nRasterXSize = static_cast<int>(naxes[0]);
    nRasterYSize = static_cast<int>(naxes[1]);
    nBands = 1;
  }
  else if (naxis == 3) {
    nRasterXSize = static_cast<int>(naxes[0]);
    nRasterYSize = static_cast<int>(naxes[1]);
    nBands = static_cast<int>(naxes[2]);
  }
  else {
    CPLError(CE_Failure, CPLE_AppDefined,
             "FITS file %s does not have 2 or 3 dimensions.",
             GetDescription());
    return CE_Failure;
  }

  // Create the bands
  for (int i = 0; i < nBands; ++i)
    SetBand(i+1, new FITSRasterBand(this, i+1));

  // Read header information from file and use it to set metadata
  // This process understands the CONTINUE standard for long strings.
  // We don't bother to capture header names that duplicate information
  // already captured elsewhere (e.g. image dimensions and type)
  int keyNum;
  char key[100];
  char value[100];

  int nKeys = 0;
  int nMoreKeys = 0;
  fits_get_hdrspace(hFITS, &nKeys, &nMoreKeys, &status);
  for(keyNum = 1; keyNum <= nKeys; keyNum++)
  {
    fits_read_keyn(hFITS, keyNum, key, value, NULL, &status);
    if (status) {
      CPLError(CE_Failure, CPLE_AppDefined,
               "Error while reading key %d from FITS file %s (%d)",
               keyNum, GetDescription(), status);
      return CE_Failure;
    }
    if (strcmp(key, "END") == 0) {
        // We should not get here in principle since the END
        // keyword shouldn't be counted in nKeys, but who knows.
        break;
    }
    else if (isIgnorableFITSHeader(key)) {
      // Ignore it!
    }
    else {   // Going to store something, but check for long strings etc
      // Strip off leading and trailing quote if present
      char* newValue = value;
      if (value[0] == '\'' && value[strlen(value) - 1] == '\'')
      {
          newValue = value + 1;
          value[strlen(value) - 1] = '\0';
      }
      // Check for long string
      if (strrchr(newValue, '&') == newValue + strlen(newValue) - 1)
      {
          // Value string ends in "&", so use long string conventions
          char* longString = NULL;
          fits_read_key_longstr(hFITS, key, &longString, NULL, &status);
          // Note that read_key_longstr already strips quotes
          if( status )
          {
              CPLError(CE_Failure, CPLE_AppDefined,
                       "Error while reading long string for key %s from "
                       "FITS file %s (%d)", key, GetDescription(), status);
              return CE_Failure;
          }
          SetMetadataItem(key, longString);
          free(longString);
      }
      else
      {  // Normal keyword
          SetMetadataItem(key, newValue);
      }
    }
  }

  return CE_None;
}

/************************************************************************/
/*                                Open()                                */
/************************************************************************/

GDALDataset* FITSDataset::Open(GDALOpenInfo* poOpenInfo) {

  const char* fitsID = "SIMPLE  =                    T";  // Spaces important!
  size_t fitsIDLen = strlen(fitsID);  // Should be 30 chars long

  if ((size_t)poOpenInfo->nHeaderBytes < fitsIDLen)
    return NULL;
  if (memcmp(poOpenInfo->pabyHeader, fitsID, fitsIDLen))
    return NULL;

  // Get access mode and attempt to open the file
  int status = 0;
  fitsfile* hFITS = NULL;
  if (poOpenInfo->eAccess == GA_ReadOnly)
    fits_open_file(&hFITS, poOpenInfo->pszFilename, READONLY, &status);
  else
    fits_open_file(&hFITS, poOpenInfo->pszFilename, READWRITE, &status);
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Error while opening FITS file %s (%d).\n",
             poOpenInfo->pszFilename, status);
    fits_close_file(hFITS, &status);
    return NULL;
  }

  // Create a FITSDataset object and initialize it from the FITS handle
  FITSDataset* dataset = new FITSDataset();
  dataset->eAccess = poOpenInfo->eAccess;

  // Set up the description and initialize the dataset
  dataset->SetDescription(poOpenInfo->pszFilename);
  if (dataset->Init(hFITS, true) != CE_None) {
    delete dataset;
    return NULL;
  }
  else
  {
/* -------------------------------------------------------------------- */
/*      Initialize any PAM information.                                 */
/* -------------------------------------------------------------------- */
      dataset->SetDescription( poOpenInfo->pszFilename );
      dataset->TryLoadXML();

/* -------------------------------------------------------------------- */
/*      Check for external overviews.                                   */
/* -------------------------------------------------------------------- */
      dataset->oOvManager.Initialize( dataset, poOpenInfo->pszFilename, poOpenInfo->GetSiblingFiles() );

      return dataset;
  }
}

/************************************************************************/
/*                               Create()                               */
/*                                                                      */
/*      Create a new FITS file.                                         */
/************************************************************************/

GDALDataset *FITSDataset::Create( const char* pszFilename,
                                  int nXSize, int nYSize,
                                  int nBands, GDALDataType eType,
                                  CPL_UNUSED char** papszParmList )
{
  int status = 0;

  // No creation options are defined. The BSCALE/BZERO options were
  // removed on 2002-07-02 by Simon Perkins because they introduced
  // excessive complications and didn't really fit into the GDAL
  // paradigm.

  // Create the file - to force creation, we prepend the name with '!'
  char* extFilename = new char[strlen(pszFilename) + 10];  // 10 for margin!
  snprintf(extFilename, strlen(pszFilename) + 10, "!%s", pszFilename);
  fitsfile* hFITS = NULL;
  fits_create_file(&hFITS, extFilename, &status);
  delete[] extFilename;
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Couldn't create FITS file %s (%d).\n", pszFilename, status);
    return NULL;
  }

  // Determine FITS type of image
  int bitpix;
  if (eType == GDT_Byte)
    bitpix = BYTE_IMG;
  else if (eType == GDT_Int16)
    bitpix = SHORT_IMG;
  else if (eType == GDT_Int32)
    bitpix = LONG_IMG;
  else if (eType == GDT_Float32)
    bitpix = FLOAT_IMG;
  else if (eType == GDT_Float64)
    bitpix = DOUBLE_IMG;
  else {
    CPLError(CE_Failure, CPLE_AppDefined,
             "GDALDataType (%d) unsupported for FITS", eType);
    fits_close_file(hFITS, &status);
    return NULL;
  }

  // Now create an image of appropriate size and type
  long naxes[3] = {nXSize, nYSize, nBands};
  int naxis = (nBands == 1) ? 2 : 3;
  fits_create_img(hFITS, bitpix, naxis, naxes, &status);

  // Check the status
  if (status) {
    CPLError(CE_Failure, CPLE_AppDefined,
             "Couldn't create image within FITS file %s (%d).",
             pszFilename, status);
    fits_close_file(hFITS, &status);
    return NULL;
  }

  FITSDataset* dataset = new FITSDataset();
  dataset->nRasterXSize = nXSize;
  dataset->nRasterYSize = nYSize;
  dataset->eAccess = GA_Update;
  dataset->SetDescription(pszFilename);

  // Init recalculates a lot of stuff we already know, but...
  if (dataset->Init(hFITS, false) != CE_None) {
    delete dataset;
    return NULL;
  }
  else {
    return dataset;
  }
}

/************************************************************************/
/*                          GDALRegister_FITS()                         */
/************************************************************************/

void GDALRegister_FITS()

{
    if( GDALGetDriverByName( "FITS" ) != NULL )
        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription( "FITS" );
    poDriver->SetMetadataItem( GDAL_DCAP_RASTER, "YES" );
    poDriver->SetMetadataItem( GDAL_DMD_LONGNAME,
                               "Flexible Image Transport System" );
    poDriver->SetMetadataItem( GDAL_DMD_HELPTOPIC,
                               "frmt_various.html#FITS" );
    poDriver->SetMetadataItem( GDAL_DMD_CREATIONDATATYPES,
                               "Byte Int16 Int32 Float32 Float64" );

    poDriver->pfnOpen = FITSDataset::Open;
    poDriver->pfnCreate = FITSDataset::Create;
    poDriver->pfnCreateCopy = NULL;

    GetGDALDriverManager()->RegisterDriver(poDriver);
}
