SatelliteImageDate

// Test mapping function
//
// area
// fileID, satID, timestamp


// The Hawaiian Islands
//var geom = ee.Geometry.Point(Map.getCenter().coordinates().get(0), Map.getCenter().coordinates().get(1))
/*
  Declaration of all variables to be used
  which can be initialized and cleared
*/
var HotMap = function(){
  this.name = "HotMap";

  //UI components
  this.dateBoxStart = null;
  this.dateBoxEnd = null;
  this.reRunAnalysis = null;
  this.addPrecipitation = null;

  //Object Variables
  this.startDate = null;
  this.endDate = null;
  this.ic = null;
  this.init();
};



HotMap.prototype.init = function(){
  /*
  Generates UI components as global variables
  */
  var thisObject = this;
  // date textbox
  this.dateBoxStart = ui.Textbox({
     placeholder: 'Enter start date (YYYY-MM-DD)',
     onChange: function(){thisObject.startDateChanged()}
   });

   this.dateBoxEnd = ui.Textbox({
     placeholder: 'Enter end date (YYYY-MM-DD)',
     onChange: function(){thisObject.endDateChanged()}
   });

   //Rerun for selection
   this.reRunAnalysis = ui.Button({
     label: 'Re-Run Analysis',
     onClick: function(target){thisObject.onReRunClick()}
   });

   this.addPrecipitation = ui.Button({
     label: 'Add Precipitation',
     onClick: function(target){thisObject.addPrecipitationLayer(thisObject.startDate, thisObject.endDate)}
   });
   /*
   End of global ui components
   */
}

HotMap.prototype.show = function(){
  this.setupSidePannel();
  //this.onReRunClick();
}

/*
  *********************** Handlers of UI call back functions ***********************
  */
HotMap.prototype.startDateChanged = function(date){
  print(date)
  this.startDate = date;
}

HotMap.prototype.endDateChanged = function(date){
    print(date)
    this.endDate = date;
}

HotMap.prototype.onReRunClick = function(){
  var geom = Map.getCenter();
  // Landsat 8 collection
  var ic = ee.ImageCollection('LANDSAT/LC8_L1T_TOA')
    .filterBounds(geom)
    //.filterDate('2016-01-01','2016-01-5')
    .select(['B2','B3','B4','B5','B6','B7'],['blue','green','red','nir','swir1','swir2']);

  if(this.startDate != null && this.startDate != ''){
    ic = ic.filterDate(this.startDate)
  }else{
    ic = ic.sort('system:time-start')
  }

  // SINGLE IMAGE
  var img = ee.Image(ic.first())
  Map.addLayer(img.select(['swir1','swir2','nir']),{min:0,max:0.4},'infrared')
  var hot = this.runHotMapAnalysis(img)
  Map.addLayer(hot,{color:'FF0000'},'hot_vectors')
}
/*
  *********************** END ***********************
  */





// Generates the side pannel
HotMap.prototype.setupSidePannel = function(){
  // PANELS
  // ********************************************************************************************
  // main panel
  var panel = ui.Panel({style: {width: '400px'}})
  panel.widgets().set(0,ui.Label('Controls',{fontWeight:'bold'}))
  panel.widgets().set(1,this.dateBoxStart)
  panel.widgets().set(2,this.dateBoxEnd)
  panel.widgets().set(3,this.reRunAnalysis)
  panel.widgets().set(4, this.addPrecipitation)
  ui.root.add(panel);

}

/**
  Fancy pants function to do the actual SCIENCE!!!
*/
// HOTMAP detection (returns hot pixel clusters, i.e. a feature collection per image)
HotMap.prototype.runHotMapAnalysis = function(img) {

  // wavebands
  var n  = img.select('nir')
  var s1 = img.select('swir1')
  var s2 = img.select('swir2')

  // alpha detection
  var a1 = s2.divide(s1).gt(1.4)
  var a2 = s2.divide(n).gt(1.4)
  var a3 = s2.gt(0.15)
  var alpha = a1.and(a2).and(a3).rename('alpha')

  // beta detection
  var b1 = s1.divide(n).gt(2)
  var b2 = s1.gt(0.5)
  var beta = b1.and(b2).rename('beta')

  // potential hot pixels
  var potentialHot = alpha.or(beta)
  var hotPixels = potentialHot.updateMask(potentialHot)

  // hot pixel clusters (count alpha pixels)
  var hotClusters = hotPixels.addBands(alpha).reduceToVectors({
    eightConnected:true,
    maxPixels:2e8,//might seem like a lot but MOST pixels are masked
    reducer:ee.Reducer.count()
  })

  // hot pixel clusters must contain alpha pixels
  var validHotClusters = hotClusters.filter(ee.Filter.gt('count', 0));

  // Image properties
  var fileID = img.get('system:index')
  var satID = ee.String(fileID).slice(0,3)
  var timestamp = img.get('system:time_start')

  // Assign properties
  var clusters = validHotClusters.map(function(feature) {
    var clusterGeom = feature.geometry()
    var clusterArea = feature.geometry().area(1) // i.e. to within 1 m2
    var cluster = ee.Feature(clusterGeom,{
      fileID:fileID,
      satID:satID,
      timestamp:timestamp,
      area:clusterArea
    })
    return cluster
  })

  return clusters
}

/**
  Grabs precipitation data and plots it on map
**/
// function addPrecipitationLayer(dateStart, dateEnd)
// Parameters:
// string dateStart, indicating start of data range (e.g. '2017-03-01')
// string dateEnd, indicating end of datarange (e.g. '2017-03-27')
// Return values:
// like any good function, this function returns void and just has tons of side effects
HotMap.prototype.addPrecipitationLayer = function(dateStart, dateEnd) {
    var s = dateStart;
    var e = dateEnd;
    if(s == null){
      s = '2017-03-01';
      e = '2017-03-27';
    }
    this.ic = ee.ImageCollection('UCSB-CHG/CHIRPS/PENTAD')
    //.filterDate('2017-03-01', '2017-03-27');
    .filterDate(s, e);
    var meanPrecip = this.ic.reduce(ee.Reducer.mean());
    
    Map.addLayer(meanPrecip, {min:0,max:10, palette: ['FF0000', '0000FF']}, 'precipitation', true, 0.40);
}



// declare the hot object to be used
var hot = new HotMap();
hot.show();