// global variables
var _Debug = false;   // set this to false to turn debugging off and get rid of the alert boxes

// define exception/error codes
var _NoError                   = 0;
var _GeneralError              = 101;
var _ServerBusy                = 102;
var _InvalidArgumentError      = 201;
var _ElementCannotHaveChildren = 202;
var _ElementIsNotAnArray       = 203;
var _NotInitialized            = 301;
var _NotImplementedError       = 401;
var _InvalidSetValue           = 402;
var _ElementIsReadOnly         = 403;
var _ElementIsWriteOnly        = 404;
var _IncorrectDataType         = 405;

// CMI Data Model constants
var _CMICreditYes                = 'credit';
var _CMICreditNo                 = 'no-credit';
var _CMILessonStatusPassed       = 'passed';
var _CMILessonStatusCompleted    = 'completed';
var _CMILessonStatusFailed       = 'failed';
var _CMILessonStatusIncomplete   = 'incomplete';
var _CMILessonStatusBrowsed      = 'browsed';
var _CMILessonStatusNotAttempted = 'not attempted';
var _CMILessonModeBrowse         = 'browse';
var _CMILessonModeNormal         = 'normal';
var _CMILessonModeReview         = 'review';
var _CMIExitTimeout              = 'time-out';
var _CMIExitSuspend              = 'suspend';
var _CMIExitLogout               = 'logout';
var _CMIExitNormal               = '';

// local variable definitions
var apiHandle    = null;
var API          = null;
var findAPITries = 0;


/*******************************************************************************
**
** Function doLMSInitialize()
** Inputs:  None
** Return:  CMIBoolean true if the initialization was successful, or
**          CMIBoolean false if the initialization failed.
**
** Description:
** Initialize communication with LMS by calling the LMSInitialize
** function which will be implemented by the LMS.
**
*******************************************************************************/
function doLMSInitialize()
{
	var api, result;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSInitialize was not successful.');

		return 'false';
	}

	result = api.LMSInitialize('');
	return result.toString();
}

/*******************************************************************************
**
** Function doLMSFinish()
** Inputs:  None
** Return:  CMIBoolean true if successful
**          CMIBoolean false if failed.
**
** Description:
** Close communication with LMS by calling the LMSFinish
** function which will be implemented by the LMS
**
*******************************************************************************/
function doLMSFinish()
{
	var api, result;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSFinish was not successful.');

		return 'false';
	}
	else
	{
		// call the LMSFinish function that should be implemented by the API
		result = api.LMSFinish('');
		return result.toString();
	}
}

/*******************************************************************************
**
** Function doLMSGetValue(name)
** Inputs:  name - string representing the cmi data model defined category or
**          element (e.g. cmi.core.student_id)
** Return:  The value presently assigned by the LMS to the cmi data model
**          element defined by the element or category identified by the name
**          input value.
**
** Description:
** Wraps the call to the LMS LMSGetValue method
**
*******************************************************************************/
function doLMSGetValue(name)
{
	var api, value;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSGetValue was not successful.');

		return '';
	}
	else
	{
		value = api.LMSGetValue(name);
		return value.toString();
	}
}

/*******************************************************************************
**
** Function doLMSSetValue(name, value)
** Inputs:  name -string representing the data model defined category or element
**          value -the value that the named element or category will be assigned
** Return:  CMIBoolean true if successful
**          CMIBoolean false if failed.
**
** Description:
** Wraps the call to the LMS LMSSetValue function
**
*******************************************************************************/
function doLMSSetValue(name, value)
{
	var api;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSSetValue was not successful.');

		return;
	}
	else
	{
		api.LMSSetValue(name, value);
		return;
	}
}

/*******************************************************************************
**
** Function doLMSCommit()
** Inputs:  None
** Return:  None
**
** Description:
** Call the LMSCommit function 
**
*******************************************************************************/
function doLMSCommit()
{
	var api, result;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSCommit was not successful.');

		return 'false';
	}
	else
	{
		result = api.LMSCommit('');
		return result.toString();
	}
}

/*******************************************************************************
**
** Function doLMSGetLastError()
** Inputs:  None
** Return:  The error code that was set by the last LMS function call
**
** Description:
** Call the LMSGetLastError function 
**
*******************************************************************************/
function doLMSGetLastError()
{
	var api;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSGetLastError was not successful.');

		//since we can't get the error code from the LMS, return a general error
		return _GeneralError;
	}

	return api.LMSGetLastError().toString();
}

/*******************************************************************************
**
** Function doLMSGetErrorString(errorCode)
** Inputs:  errorCode - Error Code
** Return:  The textual description that corresponds to the input error code
**
** Description:
** Call the LMSGetErrorString function 
**
********************************************************************************/
function doLMSGetErrorString(errorCode)
{
	var api;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSGetErrorString was not successful.');

		return '';
	}

	return api.LMSGetErrorString(errorCode).toString();
}

/*******************************************************************************
**
** Function doLMSGetDiagnostic(errorCode)
** Inputs:  errorCode - Error Code(integer format), or null
** Return:  The vendor specific textual description that corresponds to the 
**          input error code
**
** Description:
** Call the LMSGetDiagnostic function
**
*******************************************************************************/
function doLMSGetDiagnostic(errorCode)
{
	var api;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSGetDiagnostic was not successful.');

		return '';
	}

	return api.LMSGetDiagnostic(errorCode).toString();
}

/*******************************************************************************
**
** Function LMSIsInitialized()
** Inputs:  none
** Return:  true if the LMS API is currently initialized, otherwise false
**
** Description:
** Determines if the LMS API is currently initialized or not.
**
*******************************************************************************/
function LMSIsInitialized()
{
	// there is no direct method for determining if the LMS API is initialized
	// for example an LMSIsInitialized function defined on the API so we'll try
	// a simple LMSGetValue and trap for the LMS Not Initialized Error

	var api, value, errCode;

	api = getAPIHandle();
	if (api == null)
	{
		if (_Debug)
			alert('Unable to locate the LMS\'s API Implementation.\nLMSIsInitialized() failed.');

		return false;
	}
	else
	{
		value = api.LMSGetValue('cmi.core.student_name');
		errCode = api.LMSGetLastError().toString();
		return (errCode == _NotInitialized) ? false : true;
	}
}

/******************************************************************************
**
** Function getAPIHandle()
** Inputs:  None
** Return:  value contained by APIHandle
**
** Description:
** Returns the handle to API object if it was previously set,
** otherwise it returns null
**
*******************************************************************************/
function getAPIHandle()
{
	if (apiHandle == null)
		apiHandle = getAPI();

	return apiHandle;
}

/*******************************************************************************
**
** Function getAPI()
** Inputs:  none
** Return:  If an API object is found, it's returned, otherwise null is returned
**
** Description:
** This function looks for an object named API, first in the current window's 
** frame hierarchy and then, if necessary, in the current window's opener window
** hierarchy (if there is an opener window).
**
*******************************************************************************/
function getAPI()
{
	var theAPI;

	theAPI = findAPI(window);
	if ((theAPI == null) && (window.opener != null) && (typeof(window.opener) != 'undefined'))
		theAPI = findAPI(window.opener);
	if (theAPI == null)
		if (_Debug)
			alert('Unable to find an API adapter');

	return theAPI;
}

/*******************************************************************************
**
** Function findAPI(win)
** Inputs:  win - a Window Object
** Return:  If an API object is found, it's returned, otherwise null is returned
**
** Description:
** This function looks for an object named API in parent and opener windows
**
*******************************************************************************/
function findAPI(win)
{
	while ((win.API == null) && (win.parent != null) && (win.parent != win))
	{
		findAPITries++;
		if (findAPITries > 7)   // Note: 7 is an arbitrary number, but should be more than sufficient
		{
			if (_Debug)
				alert('Error finding API -- too deeply nested.');

			return null;
		}
      
		win = win.parent;
	}

	return win.API;
}