// CREATE CLOUD-FREE ICE MASK

// Use this script to create the cloud free ice mask that is used in the lake mapping script
// Requires a shapefile to define the area over which to create the ice mask (same as used for mapping script)
// Specific pathways/filenames will need changing by the user

// Pete Tuckett 2021
// patuckett1@sheffield.ac.uk
// Tuckett, P. A., Ely, J. C., Sole, A. J., Lea, J. M., Livingstone, S. J., Jones, J. M., & van Wessem, J. M. (2021). 
// Automated mapping of the seasonal evolution of surface meltwater and its links to climate on the Amery Ice Shelf, Antarctica. The Cryosphere. 1-35.

// ################################################################################################################

// Define the asset pathway containing the region shapefile
var assetPath='users/patuckett1/Regions/Amery';

var catchments=ee.FeatureCollection(assetPath);
print(catchments)

Map.centerObject(catchments, 6);
Map.addLayer(catchments,[],'RoIs');

// Specifiy the Data products to by used:
var L8 = 'LANDSAT/LC08/C01/T2_TOA';

var icemaskstart = '2017-01-01'; // Keep fixed to 2018 even when not mapping that year
var icemaskend = '2018-12-31';
var sunElev = 20; // Minimum sun elevation angle (Moussavi, 2020)
var L8bandsUsed = ['B2','B3','B4','B6','B10'];
var L7bandsUsed = ['B1','B2','B3','B5','B6_VCID_1'];

// Create Colour palettes for MapDisplay
var RedColour = {palette: ['FF0000'], max: 1};
var BlueColour = {palette: ['0000FF'], max: 1};
var GreenColour = {palette: ['00FF00'], max: 1};

//############################################ INITIAL LOOP TO CHECK NUMBER OF IMAGES #############################################

// Open massive loop that loops through different catchments ('returns' at very end of script)
var NumImages_Collection=catchments.map(function(feat){
  
var filteredRoiGeometry1=ee.Feature(feat).geometry(); 

// Create a mask for the ROI in order to be able to use .updateMask(ROIRask) to clip images to ROI
var ROImask1 = ee.Image.constant(1).clip(filteredRoiGeometry1)

// Collection for IceMask
var Collection_for_ice_mask1 = ee.ImageCollection(L8)
		.filterBounds(filteredRoiGeometry1)
		.filterDate(icemaskstart, icemaskend)
		.sort('DATE_ACQUIRED')
	  .filterMetadata('SUN_ELEVATION', 'greater_than', sunElev)
	  .filter(ee.Filter.lt('CLOUD_COVER', 5)) // Only uses cloud free images (<5% cloud)
	  .select(L8bandsUsed)
  .map(function(image){
  return image.rename(['BLUE','GREEN','RED','SWIR','TIR']).updateMask(ROImask1);
  });
  
  // Identify the number of images used for the each ROI tile & set as property of feature
var NumImageColl = Collection_for_ice_mask1.size();
var NumImages_Property = feat.set('NumImages', NumImageColl);

// Close loop to return a collection that has the number of images used per tile attached as property
return NumImages_Property
})

// Create an updated collection that removes any tile that does not have any images (gets around count error)
var UpdatedCollection = NumImages_Collection.filterMetadata('NumImages','not_equals',0)
print(UpdatedCollection, 'Updated Catchments')

Map.addLayer(UpdatedCollection,[],'RoIs');

//############################################ LOOP THROUGH CATCHMENTS #############################################

// Open massive loop that loops through different catchments ('returns' at very end of script)
var ImageColl=ee.ImageCollection(UpdatedCollection.map(function(feat){ //!! I've changed this to map over the catchments FC

var filteredRoiGeometry=ee.Feature(feat).geometry();  //changed this line to get the geometry of the feature
var ROImask = ee.Image.constant(1).clip(filteredRoiGeometry)

//###############################################################################


// Collection for IceMask
var Collection_for_ice_mask = ee.ImageCollection(L8)
		.filterBounds(filteredRoiGeometry)
		.filterDate(icemaskstart, icemaskend)
		.sort('DATE_ACQUIRED')
    .filterMetadata('SUN_ELEVATION', 'greater_than', sunElev)
    .filter(ee.Filter.lt('CLOUD_COVER', 5)) // Only uses cloud free images (<5% cloud)
    .select(L8bandsUsed)
  .map(function(image){
  return image.rename(['BLUE','GREEN','RED','SWIR','TIR']).updateMask(ROImask);
  });
		
//print('Collection for Ice Mask', Collection_for_ice_mask)

// Create L8 RockMask function
var Landsat_RockMask_Func = function(image){
  var Diff = image.select('TIR').divide(image.select('BLUE'));
  var BLUE = image.select('BLUE')
  var RockSeawater = Diff.gt(650).and(BLUE.lt(0.35));
  var RockArea = RockSeawater.eq(1);
  var RockAreav2 = RockArea.updateMask(RockArea).rename('YearlyRockArea')
  
  return image.addBands(RockAreav2);//updateMask(RockMaskv2).addBands(RockAreav2).addBands(RockMaskv2);
};

// Apply RockSea function and isolate areas of rock in each image
var L8_RockMasked_Collection = Collection_for_ice_mask.map(Landsat_RockMask_Func);
var L8_Yearly_rock_only = L8_RockMasked_Collection.select(['YearlyRockArea']);
//print('2018 Rock Bands', L8_rock_areas_only)

// Stack rock areas, then create ice mask based on areas NOT covered by rock. Clip to ROI.
var YearIce = L8_Yearly_rock_only.reduce(ee.Reducer.max()).mask().not();
var YearIceMask = YearIce.updateMask(YearIce).rename('YearIceMask').updateMask(ROImask);
//print('2018 Ice Mask', YearIceMask)

//Map.addLayer(YearIceMask,RedColour, 'YearIceMask')

// Close big loop for each ROI by returning the output for each tile
return YearIceMask
}))

print(ImageColl)

// Display an individual IceMask image
var Images = ImageColl.toList(ImageColl.size());
var ToDisplay = ee.Image(Images.get(1));

//Map.addLayer(ToDisplay, RedColour, 'YearIceMask')

var Mosaic = ImageColl.mosaic();
print(Mosaic)

Map.addLayer(Mosaic, RedColour, 'Mosaic')


//#####################################################################################################
//Export the ice mask to assets
Export.image.toAsset({   
  image: Mosaic,
  description:'Amery_2017_2018_Icemask_60m',
  assetId: 'Amery_2017_2018_Icemask_60m',
  crs: 'EPSG:3031',
  scale: 60, //60
  region: ee.Feature(ee.FeatureCollection(UpdatedCollection.union()).first()).geometry(), 
  maxPixels: 1e13
})

// Export the image, specifying scale and region.
//Export.image.toDrive({
 // image: Mosaic,
 // description: 'QueenMary_IceMask_2018',
 // scale: 60,
 // crs: 'EPSG:3031',
 // maxPixels: 1e12,
 // region: catchments_collection,
//});