// Script for extracting GEE data

// Set projection
var wkt = ' \
  PROJCS["World_Mollweide", \
    GEOGCS["GCS_WGS_1984", \
      DATUM["WGS_1984", \
        SPHEROID["WGS_1984",6378137,298.257223563]], \
      PRIMEM["Greenwich",0], \
      UNIT["Degree",0.017453292519943295]], \
    PROJECTION["Mollweide"], \
    PARAMETER["False_Easting",0], \
    PARAMETER["False_Northing",0], \
    PARAMETER["Central_Meridian",0], \
    UNIT["Meter",1], \
    AUTHORITY["EPSG","54009"]]';
    
var mollw = ee.Projection(wkt);
var pa = ee.FeatureCollection("projects/ee-user/assets/TigerReserves");

Map.addLayer(pa)

// 1. Generate forest layer
var hansen = ee.Image("UMD/hansen/global_forest_change_2021_v1_9");
var forest2000 = hansen.select('treecover2000').gt(25);
var lossyr = hansen.select('lossyear');

// 2. Calculate forest within each buffered region
 var calcFor = function(feat) {
  var forested = forest2000.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.sum(),
    scale:30,
    maxPixels: 1e13,
    tileScale:16,
    crs: mollw
  }).get('treecover2000');
  return feat.set('Forest sq km',ee.Number(forested).multiply(0.0009));
 };

// 3. Calculate forest loss year
var yrs = ee.List.sequence(1,22);
var calcLoss = function(feat){
  var loss = yrs.map(function(y){
    var this_yr_loss = lossyr.eq(ee.Number(y)).reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.sum(),
    scale:30,
    maxPixels: 1e13,
    tileScale:16,
    crs: mollw
  }).get('lossyear');
  return ee.Number(this_yr_loss).multiply(0.0009);
  });
return feat.set('loss sq km',loss);
};


// 4. Travel time / distance
var img= ee.Image("projects/earthengine-legacy/assets/users/One_Engine_Man/acc_50k");

var calcDist = function(feat) {
  var dist = img.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:30,
    maxPixels: 1e13,
    crs: mollw
  });
  return feat.set("distance",ee.Number(dist));
};

// 5. Rainfall
var dataset = ee.ImageCollection("UCSB-CHG/CHIRPS/PENTAD");
var yr = ee.List.sequence(2000,2020);
var calcRain = function(feat){
  var rainfall = yr.map(function(y){
    var image = dataset.filterDate(y).first();
    var startDate = ee.Date.fromYMD(y, 1, 1)
    var endDate = startDate.advance(1, 'year')
    var filtered = dataset.filter(ee.Filter.date(startDate, endDate))
    var total = filtered.reduce(ee.Reducer.sum())
    var this_yr = total.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:1000,
    maxPixels: 1e13,
    crs: mollw
  }).get('precipitation_sum');
  return ee.Number(this_yr);
  });
return feat.set('Total rainfall',rainfall);
};

// 6. Population
var data = ee.ImageCollection("WorldPop/GP/100m/pop").filterMetadata('country', 'equals', 'LAO');
var ye = ee.List(['2000','2001','2002','2003','2004','2005','2006','2007','2008','2009','2010','2011','2012','2013','2014','2015','2016','2017','2018','2019','2020']);
var calcPop = function(feat){
  var population = ye.map(function(y){
    var image = data.filterDate(y).first();
    var this_yr = image.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(), // Changed mean from sum
    scale:100,
    maxPixels: 1e13,
    crs: mollw
  }).get('population');
  return ee.Number(this_yr);
  });
return feat.set('Total Populations',population);
};

//7. PPP
var im= ee.Image("projects/earthengine-legacy/assets/users/One_Engine_Man/PPP2000sum");

var calcPPP = function(feat) {
  var p = im.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:30,
    maxPixels: 1e13,
    crs: mollw
  });
  return feat.set("PPP2000",ee.Number(p));
};

// 8. Elevation
var d = ee.Image('CGIAR/SRTM90_V4');
var elev = d.select('elevation');
var slopes = ee.Terrain.slope(elev);
var aspects = ee.Terrain.aspect(elev);

var calcElev = function(feat) {
  var elevation = elev.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:100,
    crs: mollw
  })//.get('elevation');
  return feat.set('elevation',elevation);
};

var calcSlope = function(feat) {
  var slope = slopes.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:100,
    crs: mollw
  })//.get('elevation');
  return feat.set('slope',slope);
};

var calcAspect = function(feat) {
  var aspect = aspects.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:100,
    crs: mollw
  })//.get('elevation');
  return feat.set('aspect',aspect);
};

// 9. AGBC
var agb = ee.ImageCollection("NASA/ORNL/biomass_carbon_density/v1").filterMetadata('system:index','equals','2010').select('agb').first();
var ucr = ee.ImageCollection("NASA/ORNL/biomass_carbon_density/v1").filterMetadata('system:index','equals','2010').select('agb_uncertainty').first();

var calcAGB = function(feat) {
  var biomass = agb.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:300,
    crs: mollw
  })//.get('elevation');
  return feat.set('biomass',biomass);
};

var calcUCR = function(feat) {
  var uncertainty = ucr.reduceRegion({
    geometry:feat.geometry(),
    reducer:ee.Reducer.mean(),
    scale:300,
    crs: mollw
  })//.get('elevation');
  return feat.set('uncertainty',uncertainty);
};

// 10. Run calculations
var results = pa.map(calcFor).map(calcLoss).map(calcDist).map(calcRain).map(calcPop).map(calcPPP).map(calcElev).map(calcSlope).map(calcAspect).map(calcAGB).map(calcUCR);

Export.table.toDrive({
  collection: results,
  description:'TRsOuputs',
  folder: 'Syn',
  fileFormat: 'CSV',
  selectors: ['WDPAID','Forest sq km', 'loss sq km','Total rainfall','Total Populations','distance',"PPP2000", 'aspect', 'slope', 'elevation','biomass', 'uncertainty' , 'STATUS_YR','IUCN_CAT','area_km2','NAME','Zone']
});