String.prototype.trim = function() { return this.replace(/^\s+|\s+$/g, ''); };

function toggleUnitLessons(unitId) {
	var unitLessons = document.getElementById('ul' + unitId);
	var unitExpImg = document.getElementById('uei' + unitId);
	
	if(unitLessons.style.display == 'none') {
		// open lessons
		unitLessons.style.display = '';
		unitExpImg.src = unitExpImg.oSrc;
	}
	else {
		unitLessons.style.display = 'none';
		unitExpImg.src = unitExpImg.cSrc;
	}
}

function toggleAccountDetails(unitId) {
	var accountDetails = document.getElementById('accntDetails');
	var accountDetailstExpImg = document.getElementById('accntDetailsExp');
	
	if(accountDetails.style.display == 'none') {
		// open lessons
		accountDetails.style.display = '';
		accountDetailstExpImg.src = accountDetailstExpImg.oSrc;
	}
	else {
		accountDetails.style.display = 'none';
		accountDetailstExpImg.src = accountDetailstExpImg.cSrc;
	}
}


function toggleDisplayVisibility(elementId) {
	var element = document.getElementById(elementId);
	if(element.style.display == 'none')
		element.style.display = '';
	else
		element.style.display = 'none';
}

function courseEditToggle(courseId) {
	toggleDisplayVisibility('tagCourse' + courseId);
	toggleDisplayVisibility('tagCourseEdit' + courseId); 
	return false;
}

function deleteCourse(courseName, courseId, courseUnitsCount) {
	if(courseUnitsCount == 0) {
		if (confirm('Are you sure you want to delete course ' + courseName + ' ?')) {
			document.frmDeleteCourse.id.value = courseId;
			document.frmDeleteCourse.submit();		}
	}
	else {
		alert('Course contains units and cannot be deleted. Please delete course units first.');
	}
}

function unitEditToggle(unitId) {
	toggleDisplayVisibility('tagUnit' + unitId);
	toggleDisplayVisibility('tagUnitEdit' + unitId); 
	return false;
}

function deleteUnit(unitName, unitId, unitLessonsCount) {
	if(unitLessonsCount == 0) {
		if (confirm('Are you sure you want to delete unit ' + unitName + ' ?')) {
			document.frmDeleteUnit.id.value = unitId;
			document.frmDeleteUnit.submit();		
		}
	}
	else {
		alert('Unit contains lessons and cannot be deleted. Please delete unit lessons first.');
	}
}

function deleteLesson(lessonNumber, lessonId) {
	if (confirm('Are you sure you want to delete lesson #' + lessonNumber + ' ?')) {
		document.frmDeleteLesson.id.value = lessonId;
		document.frmDeleteLesson.submit();		
	}
}

function confirmFileDelete() {
	return confirm('Are you sure you want to delete this file?');
}

function confirmDelete() {
	return confirm('Are you sure you want to delete?');
}

function isEnter(evt, tf, button) {
	evt = (evt) ? evt : (window.event) ? event : null;
	if (evt) {
	    var charCode = (evt.charCode) ? evt.charCode :
	                   ((evt.keyCode) ? evt.keyCode :
	                   ((evt.which) ? evt.which : 0));
	    if (charCode == 13) {
			button.click();
	    }
  	} 					
}

function openWin(link, name, width, height, scrollbars) {
	   if(!width) width = 500;
	   if(!height) height = 800;
	   if(!name) name = 'popup';
	   if(!scrollbars) scrollbars = 'yes';
	   var win = window.open(link.href, name,'height=' + height + ',width=' + width + ', scrollbars=' + scrollbars + ', resizable=yes');
	   win.focus();
	   return false;
	}