/**********************************************************************
 *
 *  geo_simpletags.c  TIFF Interface module that just keeps track of the
 *                    tags in memory, without depending on libtiff.
 *
 **********************************************************************/
 
#include "geotiff.h"    /* public GTIFF interface */
#include "geo_simpletags.h"

#include "geo_tiffp.h"  /* Private TIFF interface */
#include "geo_keyp.h"   /* Private GTIFF interface */

static int ST_TypeSize( int st_type );

static int        _GTIFGetField (tiff_t *tif, pinfo_t tag, int *count, void *value );
static int        _GTIFSetField (tiff_t *tif, pinfo_t tag, int  count, void *value );
static tagtype_t  _GTIFTagType  (tiff_t *tif, pinfo_t tag);

/*
 * Set up default TIFF handlers. 
 */
void GTIFSetSimpleTagsMethods(TIFFMethod *method)
{
	if (!method) return;
	
	method->get = _GTIFGetField;
	method->set = _GTIFSetField;
	method->type = _GTIFTagType;
}

/* returns the value of TIFF tag <tag>, or if
 * the value is an array, returns an allocated buffer
 * containing the values. Allocate a copy of the actual
 * buffer, sized up for updating.
 */
static int _GTIFGetField (tiff_t *tif, pinfo_t tag, int *count, void *val )
{
    int item_size, data_type;
    void *internal_value, *ret_value;

    if( !ST_GetKey( (ST_TIFF*) tif, (int) tag, count, &data_type, 
                    &internal_value ) )
        return 0;

    if( data_type != ST_TagType( tag ) )
        return 0;

    item_size = ST_TypeSize( data_type );

    ret_value = (char *)_GTIFcalloc( *count * item_size );
    if (!ret_value) return 0;

    _TIFFmemcpy( ret_value, internal_value,  item_size * *count );
	
    *(void **)val = ret_value;
    return 1;
}

/* 
 * Set a GeoTIFF TIFF field.
 */
static int _GTIFSetField (tiff_t *tif, pinfo_t tag, int count, void *value )
{
    int st_type = ST_TagType( tag );

    return ST_SetKey( (ST_TIFF *) tif, (int) tag, count, st_type, value );
}

/*
 *  This routine is supposed to return the TagType of the <tag>
 *  TIFF tag. Unfortunately, "libtiff" does not provide this
 *  service by default, so we just have to "know" what type of tags
 *  we've got, and how many. We only define the ones Geotiff
 *  uses here, and others return UNKNOWN. The "tif" parameter
 *  is provided for those TIFF implementations that provide
 *  for tag-type queries.
 */
static tagtype_t  _GTIFTagType  (tiff_t *tif, pinfo_t tag)
{
	tagtype_t ttype;

	(void) tif; /* dummy reference */
	
	switch (tag)
	{
		case GTIFF_ASCIIPARAMS:    ttype=TYPE_ASCII; break;
		case GTIFF_PIXELSCALE:
		case GTIFF_TRANSMATRIX:
		case GTIFF_TIEPOINTS:
		case GTIFF_DOUBLEPARAMS:   ttype=TYPE_DOUBLE; break;
		case GTIFF_GEOKEYDIRECTORY: ttype=TYPE_SHORT; break;
		default: ttype = TYPE_UNKNOWN;
	}
	
	return ttype;
}

/************************************************************************/
/*                             ST_TagType()                             */
/************************************************************************/

int ST_TagType( int tag )
{
    switch (tag)
    {
      case GTIFF_ASCIIPARAMS:    
        return STT_ASCII;

      case GTIFF_PIXELSCALE:
      case GTIFF_TRANSMATRIX:
      case GTIFF_TIEPOINTS:
      case GTIFF_DOUBLEPARAMS:   
        return STT_DOUBLE;

      case GTIFF_GEOKEYDIRECTORY:
        return STT_SHORT;
    }
    
    return -1;
}


/************************************************************************/
/*                            ST_TypeSize()                             */
/************************************************************************/

static int ST_TypeSize( int st_type )

{
    if( st_type == STT_ASCII )
        return 1;
    else if( st_type == STT_SHORT )
        return 2;
    else if( st_type == STT_DOUBLE )
        return 8;
    else
        return 8;
}

/************************************************************************/
/*                             ST_Create()                              */
/************************************************************************/

ST_TIFF *ST_Create()

{
    return (ST_TIFF *) calloc(1,sizeof(ST_TIFF));
}

/************************************************************************/
/*                             ST_Destroy()                             */
/************************************************************************/

void ST_Destroy( ST_TIFF *st )

{
    int i;

    for( i = 0; i < st->key_count; i++ )
        free( st->key_list[i].data );

    if( st->key_list )
        free( st->key_list );
    free( st );
}

/************************************************************************/
/*                             ST_SetKey()                              */
/************************************************************************/

int ST_SetKey( ST_TIFF *st, int tag, int count, int st_type, void *data )

{
    int i, item_size = ST_TypeSize( st_type );

/* -------------------------------------------------------------------- */
/*      If we already have a value for this tag, replace it.            */
/* -------------------------------------------------------------------- */
    for( i = 0; i < st->key_count; i++ )
    {
        if( st->key_list[i].tag == tag )
        {
            free( st->key_list[i].data );
            st->key_list[i].count = count;
            st->key_list[i].type = st_type;
            st->key_list[i].data = malloc(item_size*count);
            memcpy( st->key_list[i].data, data, count * item_size );
            return 1;
        }
    }

/* -------------------------------------------------------------------- */
/*      Otherwise, add a new entry.                                     */
/* -------------------------------------------------------------------- */
    st->key_count++;
    st->key_list = (ST_KEY *) realloc(st->key_list,
                                      sizeof(ST_KEY) * st->key_count);
    st->key_list[st->key_count-1].tag = tag;
    st->key_list[st->key_count-1].count = count;
    st->key_list[st->key_count-1].type = st_type;
    st->key_list[st->key_count-1].data = malloc(item_size * count);
    memcpy( st->key_list[st->key_count-1].data, data, item_size * count );
    
    return 1;
}

/************************************************************************/
/*                             ST_GetKey()                              */
/************************************************************************/

int ST_GetKey( ST_TIFF *st, int tag, int *count, 
               int *st_type, void **data_ptr )

{
    int i;

    for( i = 0; i < st->key_count; i++ )
    {
        if( st->key_list[i].tag == tag )
        {
            if( count )
                *count = st->key_list[i].count;
            if( st_type )
                *st_type = st->key_list[i].type;
            if( data_ptr )
                *data_ptr = st->key_list[i].data;
            return 1;
        }
    }

    return 0;
}

