/************************************************************
+	form functions
*************************************************************/

// finds if a string is blank (nothing but spaces)
function isblank(v) {
	var blank = true;
	for (i = 0; i < v.length; i++) {
		if (v.charAt(i) != ' ') { blank = false; }
	}
	return blank;
}

// finds if a form value is empty
function isempty(x) {
	if (x.value == "" || isblank(x.value)) { return true; }
	else { return false; }
}

// finds if a select box has not been changed
function unchanged(x) {
	if (x.selectedIndex == 0) { return true; }
	else { return false; }
}

// validates a join crew submission
function vJoinCrew(form) {
	var response = "";
	var valid = true;
	// check if any dates were selected
	var checked = 0;
	for (i = 0; i < form.length; i++) {
		if (form[i].type == "checkbox" && form[i].checked) { checked++; }
	}
	if (checked == 0) { response += "Please select one or more dates to join the crew for.\n"; }
	// check crew fields
	if (document.getElementById("past-yes").checked) {
		if (unchanged(form.past_yes_name)) { response += "Please enter your name.\n"; }
		if (isempty(form.past_yes_email)) { response += "Please enter a valid e-mail address.\n"; }
	}
	else {
		if (isempty(form.past_no_fname)) { response += "Please enter a first name.\n"; }
		if (isempty(form.past_no_lname)) { response += "Please enter a last name.\n"; }
		if (isempty(form.past_no_email)) { response += "Please enter a valid e-mail address.\n"; }
	}
	// alert user
	if (response != "") {
		alert(response);
		valid = false;
	}
	return valid;
}