// email
function checkEmail(strng) {
    "use strict";
    var error, emailFilter, illegalChars;

    error = "";
    if (strng === "") {
        error = "Email: Enter an email address.\n";
    }

    //emailFilter = /^.+@.+\..{2,3}$/;
    emailFilter = /^(([^<>()\[\]\\.,;:\s@\"]+(\.[^<>()\[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    if (!(emailFilter.test(strng))) {
        error = "Email: Enter a valid email address.\n";
    } else {
        //test email for illegal characters
        illegalChars = /[\(\)\><\,\;\:\\\"\[\]]/;
        if (strng.match(illegalChars)) {
            error = "Email: Email address contains illegal characters.\n";
        }
    }
    return error;
}


// phone number - strip out delimiters and check for 10 digits
function checkPhone(strng) {
    "use strict";
	var error, stripped;
	error = "";
	if (strng === "") {
	    error = "Phone: Enter a phone number.\n";
	}

	stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
	if (isNaN(parseInt(stripped, 10))) {
	    error = "Phone: The number contains illegal characters.";
	}
	if (stripped.length !== 10) {
	    error = "Phone: Incorrect length. Ensure you include an area code.\n";
	}
	return error;
}


// password - between 6-8 chars, uppercase, lowercase, and numeral
function checkPassword(strng) {
    "use strict";
	var error, illegalChars;
	error = "";
	if (strng === "") {
	    error = "Password: You didn't enter a password.\n";
	}

	illegalChars = /[\W_]/; // allow only letters and numbers		
	if ((strng.length < 6) || (strng.length > 8)) {
	    error = "Password: The password is the wrong length.\n";
	} else if (illegalChars.test(strng)) {
	    error = "Password: The password contains illegal characters.\n";
	} else if (!((strng.search(/(a-z)+/)) && (strng.search(/(A-Z)+/)) && (strng.search(/(0-9)+/)))) {
	    error = "Password: The password must contain at least one uppercase letter, one lowercase letter, and one numeral.\n";
	}  
	return error;    
}    


// username - 4-10 chars, uc, lc, and underscore only.
function checkUsername(strng) {
    "use strict";
	var error, illegalChars;
	error = "";
	if (strng === "") {
	    error = "UserName: You didn't enter a username.\n";
	}
	
	illegalChars = /\W/; // allow letters, numbers, and underscores
	if ((strng.length < 4) || (strng.length > 10)) {
	    error = "UserName: The username is the wrong length.\n";
	} else if (illegalChars.test(strng)) {
	    error = "UserName: The username contains illegal characters.\n";
	} 
	return error;
}       


// non-empty textbox
function isEmpty(strng) {
    "use strict";
	var error = "";
	if (strng.length === 0) {
	    error = "The mandatory text area has not been filled in.\n";
	}
	return error;	  
}

// was textbox altered
function isDifferent(strng) {
    "use strict";
	var error = ""; 
	if (strng !== "Can\'t touch this!") {
	    error = "You altered the inviolate text area.\n";
	}
	return error;
}

// exactly one radio button is chosen
function checkRadio(checkvalue) {
    "use strict";
	var error = "";
	if (!(checkvalue)) {
	    error = "Please check a radio button.\n";
	}
	return error;
}

// valid selector from dropdown list
function checkDropdown(choice) {
    "use strict";
	var error = "";
	if (choice === 0) {
	    error = "You didn't choose an option from the drop-down list.\n";
	}    
	return error;
}