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

char next_char(char texto[25], int *longitud){
    char caracter;
    caracter = texto[*longitud];
    (*longitud)++;
    return caracter;
}

char char_class(char caracter){  //mide que digito es
    if (isupper(caracter)){
    	return 1; //UPPERCASE
    }else if (islower(caracter)){
	    return 2; //LOWERCASE
    }else if (isdigit(caracter)){
	    return 3; //NUMBER
    }else{
        return 4; //OTHER
    }
}

int next_state(int tipoCaracter, int old_state){
    switch (old_state){
	case 0:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            return 1;
            break;
		case 2: //LOWERCASE
            return 2;
            break;
        case 3: //DIGIT
            return 3;
            break;
		}
	break;
	case 1:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            return 6;
            break;
		case 2: //LOWERCASE
            return 2;
            break;
        case 3: //DIGIT
            return 5;
            break;
		}
	break;
	case 2:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            return 3;
            break;
		}
	break;
	case 3:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            return 7;
            break;
		}
	break;
	case 5:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            return 8;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            return 7;
            break;
		}
	break;
	case 6:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            return 7;
            break;
		}
	break;
	case 7:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            return 8;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            //return ;
            break;
		}
	break;
	case 8:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            return 9;
            break;
        case 3: //DIGIT
            //return ;
            break;
		}
	break;
	case 9:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            //return ;
            break;
        case 4: //OTHER
            return 10;
            break;
		}
	break;
	case 10:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            //return ;
            break;
		case 2: //LOWERCASE
            //return ;
            break;
        case 3: //DIGIT
            return 11;
            break;
		}
	break;
	/*case 11:
            switch (tipoCaracter){
		case 1: //UPPERCASE
            return 1;
            break;
		case 2: //LOWERCASE
            return 3;
            break;
        case 3: //DIGIT
            return 3;
            break;
		}
	break;*/
}
}

/*
 *
 */
int main(int argc, char** argv) {

    int state;
    int token_type; // {password=1, error=0};
    char input[25];
    int longitud = 0;
    char character;
    int class;	// {UPPERCASE=1, ...};

    printf ("Please write your password (+ENTER): ");
    scanf("%s",&input);

    character = next_char(input, &longitud);
    state = 0; /* code for state 0 */

    while (1){
      class = char_class(character);
	state = next_state(class, state);
	switch(state){
            case 1: /* building a password */
		      printf ("%c", character);
                  break;
            case 2: /* accept state */ // caso 11
		      token_type = 1; //identifier
                  break;
            case 3: /* error */
		      token_type = 0; //error
                  break;
            }
      character = next_char(input, &longitud);
	}

	if (token_type==1)
		printf ("\nYour password IS VALID\n");
	else
		printf ("\nPassword NOT VALID \n");

	return (0);
}