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

void get_short_option(int argc, char **argv)
{
    int c;
    int i;

    opterr = 0;

    for (i = 0; i < argc; i++)
    {
        // check short option format (with length of 2)
        if (strstr(argv[i], "-") != NULL && strlen(argv[i]) != 2)
        {
            puts("wrong option format");
            return;
        }
    }

    // multiple short options
    while(1)
    {
        c = getopt(argc, argv, "hs:m:");

        if (c == -1)
        {
           break;
        }

        switch (c)
        {
            // allow no argument
            case 'h':
                printf("option %c\n", c);
                break;

            // allow single argument
            case 's':
                printf("option %c with arg '%s'\n", c, optarg);
                break;

            // allow unlimitted arguments
            case 'm':
                optind--;
                while (optind < argc)
                {
                    if (strstr(argv[optind], "-") != NULL)
                    {
                        break;
                    }
                    printf("option %c with arg '%s'\n", c, argv[optind++]);
                }
                break;

            case '?':
                puts("invalid option");
                return;

            default:
                printf("?? getopt returned character code 0%o ??\n", c);
        }
    }

    if (optind < argc)
    {
        printf("non-option ARGV-elements: ");
        while (optind < argc)
        {
            printf("%s ", argv[optind++]);
        }
        printf("\n");
    }

    return;
}

void get_long_option(int argc, char **argv)
{
    int c;
    int i;
    int index = 0;
    int do_add, do_append, do_delete, flag;   /* flag variables */

    // struct option {
    //     const char *name;
    //     int has_arg;
    //     int *flag;
    //     int val;
    // };

    struct option long_options[] = {
        {"add",     no_argument,        &do_add,    1    }, // set do_add to 1
        {"append",  required_argument,  &do_append, 1    }, // set do_append to 1
        {"delete",  optional_argument,  &do_delete, 1    }, // set do_delete to 1
        {"setflag", no_argument,        &flag,      1    }, // set flag to 1
        {"clrfalg", no_argument,        &flag,      0    }, // set flag to 0
        {"verbose", no_argument,        0,          'v'  }, // "--verbose" returns "-v"
        {"file",    required_argument,  0,          'f'  }, // "--file" returns "-f"
        {0,         0,                  0,          0    }  // null termination
    };

    opterr = 0;

    for (i = 0; i < argc; i++)
    {
        // check short option format (with length of 2)
        if (strstr(argv[i], "--") == NULL && strstr(argv[i], "-") != NULL && strlen(argv[i]) != 2)
        {
            puts("wrong option format");
            return;
        }
    }

    while(1)
    {
        c = getopt_long(argc, argv, ":v:f:", long_options, &index);

        if (c == -1)
        {
            break;
        }

        switch (c)
        {
            case 0:
                printf("option %s", long_options[index].name);
                if (optarg)
                {
                    printf(" with arg:");
                    optind--;
                    while (optind < argc)
                    {
                        if (strstr(argv[optind], "-") != NULL)
                        {
                            break;
                        }
                        printf(" %s", argv[optind++]);
                    }
                }
                if (long_options[index].flag != NULL)
                {
                    printf(" (flag is set to %d)", long_options[index].val);
                }
                printf("\n");
                break;

            case 'v':
            case 'f':
                printf("option %c", c);
                if (optarg)
                {
                    printf(" with arg:");
                    optind--;
                    while (optind < argc)
                    {
                        if (strstr(argv[optind], "-") != NULL)
                        {
                            break;
                        }
                        printf(" %s", argv[optind++]);
                    }
                }
                printf("\n");
                break;

            case ':':
                puts("missing argument");
                return;

            case '?':
                puts("invalid option");
                return;

            default:
                printf("?? getopt returned character code 0%o ??\n", c);
        }
    }

    if (optind < argc)
    {
        printf("non-option ARGV-elements: ");
        while (optind < argc)
        {
            printf("%s ", argv[optind++]);
        }
        printf("\n");
    }

    return;
}

int main(int argc, char **argv)
{
    get_short_option(argc, argv);
    // get_long_option(argc, argv);

    return 0;
}