/*
 * hello.c - A simple hello world program.
 */

#include <stdio.h>
#include <string.h>

#include "greeter.h"

#define startswith(str, prefix) (!strncmp(str, prefix, strlen(prefix)))

const char *description = "hello - A simple hello world program";
const char *usage =
  "Usage: hello <flags...>\n"
  "Flags:\n"
  "    --help|-h          Print this message and exit\n"
  "    --name=|-n <name>  The name being greeted";

int main(int argc, char *argv[])
{
    // Variables that get set by command line flags:
    char *name = "world";

    // Loop over command line arguments:
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--help") == 0) {
          print_help:
            printf("%s\n%s\n", description, usage);
            return 0;
        } else if (startswith(argv[i], "--name=")) {
            name = &argv[i][strlen("--name=")];
        } else if (argv[i][0] == '-' && argv[i][1] != '-') {
            // Single-char flags:
            for (char *c = &argv[i][1]; *c; c++) {
                switch (*c) {
                    case 'h': goto print_help;
                    case 'n':
                        name = (i+1 < argc) ? argv[++i] : "";
                        break;
                    default:
                        printf("Unknown flag: -%c\n%s\n",
                               *c, usage);
                        return 1;
                }
            }
        } else {
            printf("Unknown flag: %s\n%s\n", argv[i], usage);
            return 1;
        }
    }
    
    // Do the business logic:
    greet(name);

    return 0;
}