/*********************************************************************************
 *
 *  File: uf.c
 *
 *  Creates an urban fraction dataset from a dominant land category data set.
 *
 *  The name of the input land category file is read from the command line, and
 *  the resulting urban fraction field for the corresponding tile is written to
 *  and output file named 'outfile.dat'.
 *
 *  The mapping between land category and urban fraction is specified 
 *  programmatically with a case block in the program code, below, and the urban 
 *  fractions themselves can be specified on the command-line.
 *
 *  NOTES: It is assumed that the dominant land category data use 1 byte of storage
 *         for each category.
 *
 *
 *  Michael G. Duda, NCAR/MMM
 *  Initial version: 11 July 2012
 *
 *  Updated 26 March 2012: added command-line arguments to specify urban fractions
 *      for different categories.
 *
 *********************************************************************************/

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


void help_mesg(char * cmd_name)
{
    fprintf(stderr, "Usage: %s [options] <filename>\n", cmd_name);
    fprintf(stderr, "       where options are any of:\n"); 
    fprintf(stderr, "       -L <integer>     set the urban percentage (0 to 100) for low-density residential areas\n");
    fprintf(stderr, "       -H <integer>     set the urban percentage (0 to 100) for high-density residential areas\n");
    fprintf(stderr, "       -I <integer>     set the urban percentage (0 to 100) for commercial/industrial areas\n");
    fprintf(stderr, "       -h               print this help message and quit\n");
}


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


    /* Set default percentages for low-density residential, high-density residential, and commercial/industrial areas */
    l_pct = 50;
    h_pct = 90;
    i_pct = 95;


    if (argc < 2) {
        help_mesg(argv[0]);
        return 1;
    }

    /* Scan command-line arguments */
    while ((o = getopt(argc, argv, "L:H:I:h")) != -1) {
        switch( o ) {
            case (int)'L':
                sscanf(optarg, "%i", &l_pct);
                break;
            case (int)'H':
                sscanf(optarg, "%i", &h_pct);
                break;
            case (int)'I':
                sscanf(optarg, "%i", &i_pct);
                break;
            case (int)'h':
                help_mesg(argv[0]);
                return 0;
            case (int)'?':
                if (optopt == (int)'L')
                    fprintf(stderr, "Error: the -L option requires an argument\n");
                else if (optopt == (int)'H')
                    fprintf(stderr, "Error: the -H option requires an argument\n");
                else if (optopt == (int)'I')
                    fprintf(stderr, "Error: the -I option requires an argument\n");
                else 
                    fprintf(stderr, "Error: unrecognized option -%c\n", optopt);
    
                return 1;
        }
    }

    if (optind >= argc) {
       help_mesg(argv[0]);
       return 1;
    }

    printf("Using low-density residential urban percentage of %i%%\n",  l_pct);
    printf("Using high-density residential urban percentage of %i%%\n", h_pct);
    printf("Using commercial/industrial urban percentage of %i%%\n",    i_pct);

    printf("Opening %s\n", argv[optind]);

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

    if ((fdout = open("outfile.dat", O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1) {
        fprintf(stderr, "Error opening output file outfile.dat\n");
        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[optind]);

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

    read(fdin,dat,datlen); 


    /*
     * Urban fractions are assigned in the range [0,100] (i.e., as a percentage),
     *   which is converted to the range [0,1] in geogrid by specifying 
     *   scale_factor=0.01 in the index file for the urban fraction data set 
     */
    for(i=0; i<datlen; i++) {
        switch( dat[i] ) {
            case (unsigned char)31 :
                dat[i] = (unsigned char)l_pct;
                break;

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

            case (unsigned char)33 :
                dat[i] = (unsigned char)i_pct;
                 printf(" acctually assigned %f\n", dat[i]);
                 printf(" want to asign %f\n",  i_pct);
                 printf(" I met urban %s\n", dat[i]);
                break;

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


    write(fdout,dat,datlen); 

    free(dat);

    close(fdin); 
    close(fdout); 

    return 0;
}