// Enter a country name and set parameters for forest definition.
// County name must match an entry in Large Scale International Boundary (LSIB) dataset.
var country = 'Haiti'; // selected country (e.g. Haiti)

// Load country features from Large Scale International Boundary (LSIB) dataset.
var countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017');
//var selected = countries.filter(ee.Filter.eq('country_na', ee.String(country)));
var selected = geometry;
// Center the map to the selected country.
Map.centerObject(selected, 6);

print('country: ', country);


var imageVisParam =  {
		"opacity":1,
		"bands":["loss","treecover2000","gain"],
		"min":[0,120,0],
		"max":[1, 0 ,1],
		"gamma":1
};

var imageVisParamLossYear =  {
		"opacity":1,
		"bands":["lossyear"],
		"min":[1],
		"max":[18],
		"palette" : ['red']
};



var setProperties = function(img){
	img = img.set("class0", "FF0000,\"Tree Cover Loss 2000-2018\"" );
	img = img.set("class1", "0000FF,\"Tree Cover Gain 2000-2012\"" );
	img = img.set("class2", "FF00FF,\"Tree Cover Loss and Gain\"" );
	img = img.set("palette", "[\"00FF00\",\"000000\"]" );
	img = img.set("unit", "% Tree Cover 2000");
	img = img.set("min", "10" );
	img = img.set("max", "100" );
	return img;
};

var setPropertiesLossYear = function(img, year){
	img = img.set("class0", "FF0000,\"Tree Cover Loss - \"" + year);
	return img;
};

var getHansenMap = function( label, pixScale, region  ){

	var treeCoverImage = hansenImage;
	//treeCoverImage = treeCoverImage.clip(region);
	// Threshold to determine if there is forest cover : 10% cover or there was a gain
	treeCoverImage = treeCoverImage.mask( treeCoverImage.select('treecover2000').gt(10).or( treeCoverImage.select('gain').gt(0) ) );
	
	if( region )
		treeCoverImage = treeCoverImage.clip( region );

	var treeCoverImageVisualized = treeCoverImage.visualize( imageVisParam );
	treeCoverImageVisualized = setProperties(treeCoverImageVisualized);

	return treeCoverImageVisualized;
};


var getHansenLossYearMap = function( year, region ){
	var treeCoverImage = hansenImage;
	
	year = year - 2000;
	//treeCoverImage = treeCoverImage.clip(region);
	// Threshold to determine if there is forest cover : 10% cover or there was a gain
	treeCoverImage = treeCoverImage.mask( treeCoverImage.select('loss').eq(1).and( treeCoverImage.select('lossyear').eq(year) ) );
	
	if( region )
		treeCoverImage = treeCoverImage.clip( region );

	var treeCoverImageVisualized = treeCoverImage.visualize( imageVisParamLossYear );
	treeCoverImageVisualized = setPropertiesLossYear(treeCoverImageVisualized, year +2000);

	return treeCoverImageVisualized;
};


//returns JSON object with properties total, area, density
var getAreaData= function( geometry  ){
	var treeCoverImage = hansenImage;

	treeCoverImage = treeCoverImage.clip(geometry);
	var forestCoverMask = treeCoverImage.expression(
			'treecover2000>25?1:gain>0?1:0', 
			{ treecover2000 : treeCoverImage.select('treecover2000'), gain : treeCoverImage.select('gain') }
	).rename("tree_presence");

	// Threshold to determine if there is forest cover : 10% cover or there was a gain
	var lossGainImage = treeCoverImage.addBands(forestCoverMask  ).select(["loss","gain", "tree_presence"]).multiply(ee.Image.pixelArea());

	var statsLossGain = lossGainImage.reduceRegion({
		reducer: ee.Reducer.sum(),
		geometry: geometry,
		maxPixels: 1e10
	});

	var averageTreeCover = treeCoverImage.select("treecover2000").reduceRegion({
		reducer: ee.Reducer.mean(),
		geometry: geometry,
		maxPixels: 1e10
	});

	var totalArea = geometry.area().divide( 10000 );
	var areaTreeCover = ee.Number( statsLossGain.get('tree_presence') ).divide( 10000 );
	var areaLost = ee.Number( statsLossGain.get('loss')).divide( 10000 );
	var areaGain = ee.Number( statsLossGain.get('gain')).divide(  10000 );
	var avgTreeCover = averageTreeCover.get("treecover2000");
	var percentageTreeCoveredArea = areaTreeCover.divide(totalArea).multiply(100);
	var percentageTreeCoveredLoss = areaLost.divide(areaTreeCover).multiply(100);
	var percentageTreeCoveredGain = areaGain.divide(areaTreeCover).multiply(100);

	var listOfYears = ee.List.sequence(1,18,1);
	var lossCoverImage = treeCoverImage.mask( treeCoverImage.select('loss').gt(0));
	var lossByYear = listOfYears.map( 
			function(year){
				var lossInYear = lossCoverImage.select(['lossyear']).eq( ee.Number(year).toInt() );
				var areaImage = lossInYear.multiply(ee.Image.pixelArea()).divide( 10000);
				var lostArea = areaImage.reduceRegion({
					reducer: ee.Reducer.sum(),
					geometry: geometry,
					maxPixels: 1e10
				});

				return ee.Dictionary(["year", ee.Number(year).add( 2000 ), "lostArea", lostArea.get('lossyear')]);
			}
	);
	
	// Get a histogram of the tree cover 2000 distribution in steps of 10%
	var treeCover2000Histogram = treeCoverImage.select("treecover2000").reduceRegion({
		reducer: ee.Reducer.fixedHistogram({ min:0, max :100, steps:10 }),
		geometry: geometry,
		maxPixels:1e10
	});

	var data = ee.Dictionary( {
		treeCover2000 : areaTreeCover,
		treeCoverLoss : areaLost,
		treeCoverGain : areaGain,
		treeCoverAverage : avgTreeCover,
		totalArea : totalArea,
		percentageTreeCoveredArea : percentageTreeCoveredArea,
		percentageTreeCoveredLoss : percentageTreeCoveredLoss,
		percentageTreeCoveredGain : percentageTreeCoveredGain,
		lossByYear : lossByYear,
		histogram : treeCover2000Histogram
	} );
	return data;

};


var testPublicFunctions = function(){
  var p = getAreaData( geometry );
   
  print ("Hansen tree cover data ( cover, loss and gain) in Hectares", p);
  getHansenMap("Test Polygon", 100, geometry );
  Map.addLayer( getHansenLossYearMap(2000) ,null, " Loss 2000" );
  Map.addLayer( getHansenLossYearMap(2005) ,null, " Loss 2005", false );
  Map.addLayer( getHansenMap("Test map", 30), null, "Hansen map 2000-2018");
};

testPublicFunctions();