/*********************************************************************************
 *
 *  File: getcat-2001.c
 *
 *  Remaps the NLCD 2001 urban land use categories to the indices expected by
 *  the WRF UCM; all non-urban categories are discarded.
 *
 *********************************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/stat.h>


int main(int argc, char ** argv)
{
    size_t datlen, i;
    struct stat st;
    int fdin, fdout;
    unsigned char * dat;

    if (argc != 2) {
        fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
        return 1;
    }

    printf("Opening input file %s\n", argv[1]);

    if ((fdin = open(argv[1], O_RDONLY)) == -1) {
        fprintf(stderr, "Error opening input file %s\n", argv[1]);
        return 1;
    }

    /* Get size of the input file */
    i = fstat(fdin, &st);
    datlen = (size_t)st.st_size;
    fprintf(stderr, "Reading %ld bytes from %s\n", (long)datlen, argv[1]);

    /* Allocate working array */
    dat = (unsigned char *)malloc(datlen);

    read(fdin,dat,datlen); 

    close(fdin); 


    /*
     *  Remap urban categories
     */
    for(i=0; i<datlen; i++) {
        switch( dat[i] ) {
            case (unsigned char)21 :
                dat[i] = (unsigned char)31;
                break;

            case (unsigned char)22 :
                dat[i] = (unsigned char)31;
                break;

            case (unsigned char)23 :
                dat[i] = (unsigned char)32;
                break;

            case (unsigned char)24 :
                dat[i] = (unsigned char)33;
                break;

            default :
                dat[i] = (unsigned char)0;
        }
    }

    if ((fdout = open(argv[1], O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1) {
        fprintf(stderr, "Error opening %s for output\n", argv[1]);
        return 1;
    }

    write(fdout,dat,datlen); 

    free(dat);

    close(fdout); 

    printf("Successfully converted urban categories in %s\n", argv[1]);

    return 0;
}