log.js

/*


AUTHOR: LAURA
PROJECT: ACCENTURE FABRIC THAT REMEMBERS
DESC: THIS CODE READS FROM AND WRITES DATA TO CHROME LOCAL STORAGE. ALSO MANAGES IT
SO ITS ALWAYS THE MOST RECENT DATA. 

TO SEE THE DATA OPEN CHROME CODE INSPECTOR -> APPLICATION -> LOCAL STORAGE
SAVES VALUES FOR ALL SESSIONS (EVEN IF YOU CLOSE AND REOPEN)

*/


var LOGMAX = 650000;


//Update to Write to Local Storage.
 function logData(data){


  //get date in seconds
  var timestamp = Math.floor(Date.now() / 1000);
  timestamp = "aftr:"+timestamp+":"+data.region
  let value = data.scale;

  let min = timestamp;
  let min_x = -1;
  //pop the last value from the list and write a new one. 
  //this ensures that the last 650000 values will be recorded and displayed
  if(localStorage.length >= LOGMAX){

  	console.log("LOCAL STORAGE FULL, OVERWRITING PREVIOUS DATA");
  	
  	//remove the oldest entry // write the 
  	for(var x in localStorage){
  		var ts = split(x, ":")

  		if(ts[0] < min){
  			min = ts[0];
  			min_x = x;
  		}
  	}
  	
  	localStorage.removeItem(min_x);
  }

  localStorage.setItem(timestamp, value);
 }


 //prints the size of each entry and total use of the local store
//each entry is ~ 0.000008 MB 
//store has max of 5MB
// we can safely store 625000 entries before we over run
function calculateLocalStoreUsage(){

	var total = 0;
	for(var x in localStorage) {
	  var amount = (localStorage[x].length * 2) / 1024 / 1024;
	  total += amount;
	  console.log( x + " = " + amount.toFixed(8) + " MB");
	}
	//console.log( "Total: " + total.toFixed(8) + " MB");
}


//careful! calling this from console will clear all data in local storage
function clearLocalStorage(){

	var total = 0;
	for(var x in localStorage) {
	  localStorage.removeItem(x);
	}
	console.log( "LOCAL STORAGE CLEARED");
	console.log("local storage size now "+localStorage.length);
}


//call this from console when you want to write a file of the data
function downloadLocalStorage(){
	let d_log = loadRawLog();

	let oldest_stamp = d_log[0].timestamp;
   	let newest_stamp =   d_log[0].timestamp


	for(var d in d_log){
		if(d_log[d].timestamp > newest_stamp) newest_stamp = d_log[d].timestamp;
		if(d_log[d].timestamp < oldest_stamp) oldest_stamp = d_log[d].timestamp;
	}

	let writer = createWriter(oldest_stamp+"_"+newest_stamp+".csv");
	writer.write(["timestamp", "region", "value"]);
	writer.write('\n');

	for(var d in d_log){
		writer.write([d_log[d].timestamp, d_log[d].region, d_log[d].value]);
		writer.write('\n');
	}
	writer.close();


}



//load raw log into memory so we can process it for the visualization
//this will be called once everytime we switch into vis mode, though log entries may be
//accumulated in the backgroudn that won't affect this
function loadRawLog(){
	//clear the log so we can load it fresh

	var d_log = [];
	//console.log(localStorage.length);

	for(var x in localStorage) {
		if(typeof(localStorage[x]) == "string"){
			time_region = x.split(":")
			if(time_region[0].localeCompare("aftr") === 0){
				value = localStorage[x];
				d_log.push({
				timestamp: time_region[1],
				region: time_region[2],
				value: value}
				);
			}
		}
	}

	return d_log;

}