PasswordStrength enum for a tutorial on the SSaurel's Channel

PasswordStrength.java

package com.ssaurel.passwordstrength;

import android.graphics.Color;

public enum PasswordStrength {

  // we use some color in green tint => 
  //more secure is the password, more darker is the color associated
  WEAK(R.string.weak, Color.parseColor("#61ad85")),
  MEDIUM(R.string.medium, Color.parseColor("#4d8a6a")),
  STRONG(R.string.strong, Color.parseColor("#3a674f")),
  VERY_STRONG(R.string.very_strong, Color.parseColor("#264535"));

  public int msg;
  public int color;
  private static int MIN_LENGTH = 8;
  private static int MAX_LENGTH = 15;

  PasswordStrength(int msg, int color) {
    this.msg = msg;
    this.color = color;
  }

  public static PasswordStrength calculate(String password) {
    int score = 0;
	// boolean indicating if password has an upper case
    boolean upper = false;
	// boolean indicating if password has a lower case
    boolean lower = false;
	// boolean indicating if password has at least one digit
    boolean digit = false;
	// boolean indicating if password has a leat one special char
    boolean specialChar = false;

    for (int i = 0; i < password.length(); i++) {
      char c = password.charAt(i);

      if (!specialChar  &&  !Character.isLetterOrDigit(c)) {
        score++;
        specialChar = true;
      } else {
        if (!digit  &&  Character.isDigit(c)) {
          score++;
          digit = true;
        } else {
          if (!upper || !lower) {
            if (Character.isUpperCase(c)) {
              upper = true;
            } else {
              lower = true;
            }

            if (upper && lower) {
              score++;
            }
          }
        }
      }
    }

    int length = password.length();

    if (length > MAX_LENGTH) {
      score++;
    } else if (length < MIN_LENGTH) {
      score = 0;
    }

    // return enum following the score
    switch(score) {
      case 0 : return WEAK;
      case 1 : return MEDIUM;
      case 2 : return STRONG;
      case 3 : return VERY_STRONG;
      default:
    }

    return VERY_STRONG;
  }
}