#include <stdio.h>
#include "dbg.h"

#define MAX_FILENAME 2048


int main(int argc, char *argv[])
{
    int rc = -1;
    char *filename;
    int nchars = 0;
    int nlines = 0;
    int i;
    long seekpos;
    char c;
    FILE *fp;

    check(argc > 1, "You must provide a filename as arg 1");
    filename = argv[1];

    fp = fopen(filename, "r");
    check(fp != NULL, "Failed to open \"%s\".", filename);

    while((c = fgetc(fp)) != EOF) {
        nchars++;
        if (c == '\n') {
            nlines++;
            if (nlines % 10 == 0) {
                printf("At line %d of \"%s\"\n", nlines, filename);
            }
        }
    }

    printf("\"%s\" contains %d chars\n", filename, nchars);

    printf("Current position of \"%s\" is %ld\n", filename, ftell(fp));
    printf("Writing out \"%s\" in reverse:\n", filename);

    for (i = 0; i < nchars; i++) {
        seekpos = (long)nchars - (i + 1);
        rc = fseek(fp, seekpos, SEEK_SET);
        check(rc != -1, "Failed to seek to %ld", seekpos);
        c = fgetc(fp);
        check(c != EOF, "Failed to read char at %ld", seekpos);
        putc(c, stdout);
    }

    rewind(fp);
    printf("\n\nRewound \"%s\" to position %ld\n", filename, ftell(fp));

    rc = fclose(fp);
    check(rc != -1, "Failed to close \"%s\".", filename);


    return 1;

error:
    return 0;
}