// imports

var l8Reflectance = ee.ImageCollection("LANDSAT/LC08/C01/T1_TOA"),
    l8Collection = ee.ImageCollection("LANDSAT/LC08/C01/T1_RT"),
    Copiapo = /* color: #0b4a8b */ee.Geometry.Point([-70.740966796875, -27.790491224830877]),
    DEM = ee.Image("USGS/SRTMGL1_003"),
    cloudVisParam = {"opacity":1,"bands":["B1"],"min":1,"palette": ["3888ff","ff0000"]};
var borders = ee.FeatureCollection('ft:1Li-jBAaNhqKaW2WxAPJspU9mvZp4qTtBIuHqOkpB').geometry();
var digitalElevation = ee.Image("USGS/SRTMGL1_003");

//filtering image collection to region of choice

var chileanLayers = l8Collection.filterBounds(borders);

//using the simpleCloudScore function to find areas with clouds

var cloudLayers = chileanLayers.map(function(image) {
  var cloud = ee.Algorithms.Landsat.simpleCloudScore(image).select('cloud');
  return(cloud);
})

//selecting images with a cloud score of 60 or more and adding them into 1 image

var cloudScoredLayers = cloudLayers.map(function(image) {
  var cloudScore = image.select(['cloud']).gte(60);
  return(cloudScore);
})
var cloudSum = cloudScoredLayers.sum();

//using a different method to create a cloud image by using high reflectance
//values

var maxReflectance = l8Reflectance.map(function(image) {
  var cloud1Reflectance = image.select('B1');
  var cloud2Reflectance = image.select('B2');
  var cloud3Reflectance = image.select('B3');
  var cloud4Reflectance = image.select('B4');
  var cloud5Reflectance = image.select('B5');
    var possibleClouds = cloud1Reflectance.add(cloud2Reflectance)
  .add(cloud3Reflectance).add(cloud4Reflectance).add(cloud5Reflectance);
    var onlyClouds = possibleClouds.gte(4);
  return(onlyClouds);
});
var cloudReflectance = maxReflectance.sum();

//creating a mask of altitude for the altitude range I want

var DEM = DEM.clip(borders);
var desiredMinAltitude = DEM.gte(650);
var desiredMaxAltitude = DEM.gte(900);
var desiredAltitude = desiredMinAltitude.subtract(desiredMaxAltitude);
var desiredAltitude = desiredAltitude.mask(desiredAltitude);

//creating 2 binary images for both methods used to calculate clouds, then
//adding them creating an image where a value of 1 shows clouds in either of
//the methods, and a value of 2 shows clouds found in both methods

var cloudsAltitude = cloudReflectance.gte(3).mask(desiredAltitude);
var cloudSumAltitude = cloudSum.gte(75).mask(desiredAltitude);
var cloudMean = cloudsAltitude.add(cloudSumAltitude);
var cloudsMasked = cloudMean.eq(0).not();
var cloudResult = cloudMean.mask(cloudsMasked);

//centres image and applies visualisation parameters

Map.centerObject(Copiapo, 7);
Map.addLayer(cloudResult, cloudVisParam, "Cloud Layer");

//with this I tried to calculate the area of all cloud pixels in the
//cloudResult image, this is where the problem begins

var area = ee.Image.pixelArea().mask(cloudResult);
var cloudArea = area.multiply(cloudResult.gte(1));
var cloudAreaSqkm = cloudArea.divide(1000000);
var totalCloudArea = cloudAreaSqkm.reduceRegion({
  reducer: ee.Reducer.sum(),
  geometry: borders,
  scale: 1000,
  maxPixels: 1e9
});
print("Total Cloud Area: ", totalCloudArea.get('area'), 'sq. km');

//this calculates the area of a smaller altitude range than the one before,
//this also causes me some problems

var optimalMinAltitude = DEM.gte(700);
var optimalMaxAltitude = DEM.gte(800);
var optimalAltitude = optimalMinAltitude.subtract(optimalMaxAltitude);
var optimalAltitude = optimalAltitude.mask(optimalAltitude);

var optimalClouds = cloudResult.mask(optimalAltitude);

var optimalCloudArea = area.multiply(optimalClouds.gte(1));
var optimalCloudAreaSqkm = optimalCloudArea.divide(1000000);
var optimalTotalCloudArea = optimalCloudAreaSqkm.reduceRegion({
  reducer: ee.Reducer.sum(),
  geometry: borders,
  scale: 1000,
  maxPixels: 1e9
});
    print("Optimal Cloud Area:", optimalTotalCloudArea.get('area'), 'sq. km');