/*
 * check_password_rules.c
 */

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

#define MAX_PASSWORD_SIZE 256



/*
Given a string, check whether it meets the quality rules for
UMD Directory passwords

Implement:
   * A password must be at least 8 and no more than 32 characters
     in length.
   * A password must contain at least one uppercase letter.
   * A password must contain at least one lowercase letter.
   * A password must contain at least one character
     from the set of digits or punctuation characters
     (such as # @ $ & among others).
   * A password may not begin or end with the space character.
   * A password may not contain more than two consecutive identical
     characters.

Do not implement
   * A password may not be (or be a variation of) a dictionary word
     in English or many other languages. This includes making simple
     substitutions of digits or punctuation that resemble alphabetic
     characters (such as replacing the letter S in a common word with
     the $ symbol).
   * You may not reuse a password you have already used.
*/
int
check_password_rules(char s[])
{
    int length      = 0;        // stores the password length
    int uppercase   = 0;        // count of uppercase characters
    int lowercase   = 0;        // count of lowercase characters
    int special     = 0;        // count of special characters
    int digit       = 0;        // count of digits
    int begin_space = 0;        // the string begins with a space
    int end_space   = 0;        // the string ends with a space
    int consecutive = 0;        // the string has consecutive identical chars
    char c, old_c;
    int i;

    i = 0;
    while (i < MAX_PASSWORD_SIZE && (c = s[i]) != '\0') {

        if (c >= 'A' && c <= 'Z') {
            // Could also use isupper()
            uppercase++;
        } else if (c >= 'a' && c <= 'z') {
            // Could also use islower()
            lowercase++;
        } else if (c >= '0' && c <= '9') {
            // Could also use isdigit()
            digit++;
        } else {

            // Could also use isspecial()
            switch (c) {
                // Count special characters
                case '#':
                case '@':
                case '$':
                case '&':
                    // and so on
                    special++;
                    break;

                // Check space at the beginning
                case ' ':
                    if (i==0) {
                        begin_space = 1;
                    }
                    break;
            }
        }  // if-else

        // Check consecutive characters
        if (i > 0 && old_c == c) {
            consecutive = 1;
        }

        old_c = c;

        i++;
    }

    // Check space at the end
    end_space = (old_c == ' ');

    // Update the length
    length = i;

    // Print debugging info
	printf ("length = %d\nuppercase = %d\nlowercase = %d\ndigit = %d\nspecial = %d\nbegin_space = %d\nend_space = %d\nconsecutive = %d\n",
			length, uppercase, lowercase, digit, special, begin_space, end_space, consecutive);

    return  length >= 8 && length <= 32 &&
            uppercase > 0 &&
            lowercase > 0 &&
            (digit > 0 || special > 0) &&
            !begin_space &&
            !end_space &&
            !consecutive;
}


int
main ()
{
    char password[MAX_PASSWORD_SIZE];

    // Read password and check UMD rules
    printf("Enter your password: ");
    fgets(password, MAX_PASSWORD_SIZE, stdin);

    // Remove the final '\n' returned by fgets
    password[strlen(password) - 1] = '\0';

    printf("The string '%s' %s the UMD password requirements",
           password,
           check_password_rules(password) ? "meets" : "does not meet");

    return 0;
}