var SCORM_API = null,
    unloaded = false,
    isInitialized = false,
    isTerminated = false,
    courseStatus,
    value_store = [],
    lastCommand,
    setValueWasSuccessful = true,
    CaptivateSWF; //Cache the reference to the SWF to avoid future lookups


/*
   cmiCache(property, value)
   Caches CMI value to help prevent sending duplicate data to LMS

   Parameters: property (CMI property name), value (CMI value, normally a string)
   Returns:    property value if cached version found, false if not cached.
*/

var cmiCache = function(property, value){

    //Ensure we have a valid property to work with
    if(typeof property === "undefined"){ return false; }

    //Replace all periods in CMI property names so we don't run into JS errors
    property = property.replace(/\./g,'_');

    //If cached value exists, return it
    if(typeof value_store[property] !== "undefined"){
        return value_store[property];
    }

    //Otherwise add to cache
    if(typeof value !== "undefined"){
        value_store[property] = value;
    }

    return false;

};


/*
   findAPI(window)
   Adapted from pipwerks SCORM wrapper
   https://github.com/pipwerks/scorm-api-wrapper

   Looks for an object named API in parent and opener windows

   Parameters: window (the browser window object).
   Returns:    Object if API is found, null if no API found
*/

var findAPI = function(win){

    var API,
        findAttempts = 0,
        findAttemptLimit = 500;

    while (!win.API_1484_11 && win.parent && win.parent != win && findAttempts <= findAttemptLimit){
        findAttempts++;
        win = win.parent;
    }

    API = win.API_1484_11 || null;

    /*
    if(!API){
        alert("Error finding API. \nFind attempts: " +findAttempts +". \nFind attempt limit: " +findAttemptLimit);
    }
    */

    return API;

};


/*
   getAPI()
   Adapted from pipwerks SCORM wrapper
   https://github.com/pipwerks/scorm-api-wrapper

   Looks for an object named API_1484_11, 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).

   Parameters:  None.
   Returns:     Object if API found, null if no API found
*/

var getAPI = function(){

    var API = null,
        win = window;

    //Look in parent windows first
    if(win.parent && win.parent != win){
        API = findAPI(win.parent);
    }

    //Look in opener windows next
    if(!API && win.top.opener){
        API = findAPI(win.top.opener);
    }

    //Plateau LMS needs special hand-holding
    if(!API && win.top.opener && win.top.opener.document) {
        API = findAPI(win.top.opener.document);
    }

    //if(!API){ alert("getAPI failed: Can't find the API!"); }

    return API;

};


var Captivate_DoExternalInterface = function (command, parameter, value, variable) {

    console.log("Captivate_DoExternalInterface: " +command +", " +parameter +", " +value);

    var strErr = "true",
        intercept = false;

    //Ensure SCORM API was initialized
    if(!isInitialized){ return; }

    if(command === "Initialize"){

        //We already initialized, just nod politely
        //and tell the SWF everything is okay!

    } else if(command === "SetValue"){

        if(parameter === "completion_status"){ courseStatus = value; }

        //Check to see if value is already cached
        var cached_value = cmiCache(parameter, value);

        //Only send value to LMS if it hasn't already been sent;
        //If value is cached and matches what is about to be sent
        //to the LMS, prevent value from being sent a second time.
        if(!cached_value || cached_value !== value){
            console.log(parameter +"(" +value +") is not cached. Sending to LMS.");
            strErr = SCORM_API.SetValue(parameter, value);
            setValueWasSuccessful = (strErr === "true");
        } else {
            console.log(parameter +"(" +value +") has already been sent. Preventing redundant LMS communication.");
            //Fakin' it for Captivate's sake.
            setValueWasSuccessful = true;
        }

    } else if(command === "Terminate"){

        strErr = SCORM_API.Terminate("");
        isTerminated = (strErr === "true");

    } else if(command === "Commit"){

        strErr = SCORM_API.Commit("");

    } else if(command === "GetLastError"){

        if(lastCommand === "SetValue" && setValueWasSuccessful){
            strErr = "";
            console.log("Last Get/Set was successful. Preventing pointless GetLastError invocation.");
        } else {
            strErr = SCORM_API.GetLastError();
        }

    } else if(value && value.length > 0){

        strErr = SCORM_API[command](parameter);

    }

    CaptivateSWF.SetScormVariable(variable, strErr);

    lastCommand = command;

    return strErr;

};


var initializeSCORM = function (){

    isInitialized = SCORM_API.Initialize("");

    if(isInitialized){

        console.log("SCORM initialized. Ready to go!");
        courseStatus = SCORM_API.GetValue("cmi.completion_status");

        if(courseStatus === "not attempted"){
            SCORM_API.SetValue("cmi.completion_status", "incomplete");
        }

    }

};

//Used by SWFObject
var callbackFn = function (e){
    //e.ref is the <object> aka SWF file. No need for getElementById
    if(e.success && e.ref){
        CaptivateSWF = e.ref;
        CaptivateSWF.tabIndex = -1; //Set tabIndex to enable focus on non-form elements
        CaptivateSWF.focus();

        //Initialze the SCORM API, don't wait for the SWF to do it.
        initializeSCORM();
    }
};

var unloadHandler = function (){
    if(!unloaded && isInitialized && !isTerminated){
        var exit_status = (courseStatus === "incomplete") ? "suspend" : "normal";
        SCORM_API.SetValue("cmi.exit", exit_status); //Set exit to whatever is needed
        SCORM_API.Commit(""); //Ensure that LMS saves all data
        isTerminated = (SCORM_API.Terminate("") === "true"); //close the SCORM API connection properly
        unloaded = true; //Ensure we don't invoke unloadHandler more than once.
    }
};

window.onbeforeunload = unloadHandler;
window.onunload = unloadHandler;

//Initialize SCORM API
SCORM_API = getAPI();

//Only embed SWF if SCORM API is found
if(SCORM_API){

    swfobject.embedSWF(CONFIG.FILEPATH + "?SCORM_API=1.0&SCORM_TYPE=0", CONFIG.TARGET, CONFIG.WIDTH, CONFIG.HEIGHT, CONFIG.FPVERSION, false, flashvars, params, attributes, callbackFn);

} else {

    //Provide a useful error message for the learner. Will only show up if SCORM API is not found!
    swfobject.addDomLoadEvent(function(){
	document.getElementById(CONFIG.TARGET).innerHTML = CONFIG.NOSCORM;
    });

}