/**** Start of imports. If edited, may not auto-convert in the playground. ****/
var imageCollection = ee.ImageCollection("projects/sat-io/open-datasets/us-drought-monitor");
/***** End of imports. If edited, may not auto-convert in the playground. *****/
/*
Category	Description
DO	Abnormally Dry
D1	Moderate Drought
D2	Severe Drought
D3	Extreme Drought
D4	Exceptional Drought
*/

var usdm = ee.Image(imageCollection.toList(imageCollection.size()).get(-1))

// Define a dictionary which will be used to make legend and visualize image on map
var dict = {
  "names": [
    "DO	Abnormally Dry", //1
    "D1 Moderate Drought", //2
    "D2 Severe Drought", //3
    "D3 Extreme Drought",//4
    "D4 Exceptional Drought", //5
  ],
  "colors": [
    "#FFFF00", 
    "#FCD37F", 
    "#FFAA00",
    "#E60000", 
    "#730000"
  ]};

// Create a panel to hold the legend widget
var legend = ui.Panel({
  style: {
    position: 'bottom-left',
    padding: '8px 15px'
  }
});

// Function to generate the legend
function addCategoricalLegend(panel, dict, title) {
  
  // Create and add the legend title.
  var legendTitle = ui.Label({
    value: title,
    style: {
      fontWeight: 'bold',
      fontSize: '18px',
      margin: '0 0 4px 0',
      padding: '0'
    }
  });
  panel.add(legendTitle);
  
  var loading = ui.Label('Loading legend...', {margin: '2px 0 4px 0'});
  panel.add(loading);
  
  // Creates and styles 1 row of the legend.
  var makeRow = function(color, name) {
    // Create the label that is actually the colored box.
    var colorBox = ui.Label({
      style: {
        backgroundColor: color,
        // Use padding to give the box height and width.
        padding: '8px',
        margin: '0 0 4px 0'
      }
    });
  
    // Create the label filled with the description text.
    var description = ui.Label({
      value: name,
      style: {margin: '0 0 4px 6px'}
    });
  
    return ui.Panel({
      widgets: [colorBox, description],
      layout: ui.Panel.Layout.Flow('horizontal')
    });
  };
  
  // Get the list of palette colors and class names from the image.
  var palette = dict['colors'];
  var names = dict['names'];
  loading.style().set('shown', false);
  
  for (var i = 0; i < names.length; i++) {
    panel.add(makeRow(palette[i], names[i]));
  }
  
  Map.add(panel);
  
}


/*
  // Display map and legend ///////////////////////////////////////////////////////////////////////////////
*/

// Add the legend to the map
addCategoricalLegend(legend, dict, 'US Drought Monitor');

// Add USDM Image image to the map
Map.addLayer(usdm, {min:0, max:4, palette:dict['colors']}, usdm.get('system:index').getInfo())
