// Main function
function showPWStrength()
	{		
	// load username and password into local variables
	var sUsername = document.MainForm.username.value;
	var sPassword = document.MainForm.password.value;
	// do we have a password?
	if (sPassword.length==0)
		{
		// hide the rating box
		PasswordRating.style.display='none';
		return;
		}
	else
		{
		// show the rating box
		PasswordRating.style.display='block';
		// check password length
		if (passwordLengthCheck(sPassword)=='short')
			{
			displayPasswordWeak();
			return;
			}
		else
			{
			//Do we have a user name?
			if (sUsername.length>0)
				{
				// check that the username is not related to the password
				if (passwordSubsetUsername(sUsername.toLowerCase(),sPassword.toLowerCase()))
					{
					displayPasswordWeak();
					return false;
					}
				}
			// okay, so we don't have a WEAK password, but check it's either intermediate or strong.
			var specialCharacterCounter = 0;
			
			//alert(specialCharacterCounter);
			
			
			// Does it contain lower case characters?
			if (passwordHasLowerCaseLetters(document.MainForm.password.value))
				{
				specialCharacterCounter++;
				}
			// Does it contain upper case characters?
			if (passwordHasUpperCaseLetters(document.MainForm.password.value))
				{
				specialCharacterCounter++;
				}
			// does it contain numerics
			if (passwordHasNumerics(document.MainForm.password.value))
				{
				specialCharacterCounter++;
				}
			// does it contain "special characters"
			if (passwordHasSpecialCharacters(document.MainForm.password.value))
				{
				specialCharacterCounter++;
				}
				
			// What are we to display?
			if (specialCharacterCounter >= 3)
				{
				displayPasswordStrong();
				}
			else
				{
				displayPasswordIntermediate();
				}			
			}			
		}
	}

// Display functions
function displayPasswordStrong()
	{
	// Set colour green
	PasswordSecurityStrength.innerText="Password is strong";
	PasswordSecurityStrength.bgColor="#ccffcc";
	}	
function displayPasswordIntermediate()
	{
	PasswordSecurityStrength.innerHTML="<a href=\"javascript:openWindow();\" title=\"Click for suggestions on how to generate a strong password\" >[?]</a> Password is intermediate strength";
	PasswordSecurityStrength.bgColor="#ffffcc";
	}	
function displayPasswordWeak()
	{
	PasswordSecurityStrength.innerHTML="<a href=\"javascript:openWindow();\" title=\"Click for suggestions on how to generate a strong password\" >[?]</a> Password is weak";
	PasswordSecurityStrength.bgColor="#ff3333";
	}
function openWindow()
	{
	var url = 'passwordStrengthSuggestion.htm';
	var refWin;		
	refWin = window.open(url,'PasswordStrengthExplanation');
	}
	
// Check functions
function passwordLengthCheck(password)
	{
	if (password.length<8)
		{
		return 'short';
		}
	else
		{
		return 'long';
		}
	}
function passwordSubsetUsername(sUsername, sPassword)
	{
	// Only want to check this if the username is not exactly equal to the password
	if (sUsername != sPassword)
		{
		// Username and password are different, if more than 3 characters different then it's okay
		if (Math.abs(sUsername.length - sPassword.length) > 3)
			{
			// these differ by at more than three characters, so okay
			return false
			}
		else
			{
			// Is the password a substring of the username
			if (sUsername.indexOf(sPassword) != -1)
				{
				// The password is a subset of the username
				return true;		
				}
			// Is the username a subset of the password
			else if (sPassword.indexOf(sUsername) != -1)
				{
				// The username is a subset of the password
				return true;		
				}
			else
				{
				return false;
				}
			}
		}
	else
		{
		// Password is username
		return true;
		}	
	}
function passwordHasLowerCaseLetters(sPassword)
	{
	var RegularExpression = /[a-z]/
	
	if (sPassword.search(RegularExpression)==-1)
		{
		return false;
		}
	else
		{
		return true;
		}
	}
function passwordHasUpperCaseLetters(sPassword)
	{
	var RegularExpression = /[A-Z]/
	
	if (sPassword.search(RegularExpression)==-1)
		{
		return false;
		}
	else
		{
		return true;
		}
	}
function passwordHasNumerics(sPassword)
	{
	var RegularExpression = /[0-9]/
	
	if (sPassword.search(RegularExpression)==-1)
		{
		return false;
		}
	else
		{
		return true;
		}	
	}
function passwordHasSpecialCharacters(sPassword)
	{
	// Array of special characters
	var specialCharacters = new Array('£','€','/','?',',','.','<','>',';','\`','"','~','!','@','#','$','%','^','&','*','(',')','_','+','-','=','{','}','|','[',']','\\',':');

	//  );
	var bFound=false;
	// Iterate through the array of special characters
	
	for(var i=0; i<specialCharacters.length; i++)
		{
		if (sPassword.indexOf(specialCharacters[i])!=-1)
			{
			bFound=true;
			}
		}
	return bFound;	
	}