downLoadImagery

//downLoadImagery_Beta20150213

//Set the start date and enddate for the full time period you want images
var startdate = new Date("October 1, 2013");
var enddate = new Date("January 30, 2015");
//Set the length and type of temporal units for each picture (e.g., 1 picture for every 1 month, 1 picture for every 15 days)
var intervalType = 'month';
var intervalLength = 1;
//Set a base name for the image names
var imageBaseName = "Romero";


//--------------------
/////CHOOSE DATA TYPE

var imageType = 'NDVI'
//var imageType = 'Raw'
//var imageType = 'Wetness'
//var imageType = 'NDWI'
var imageType = 'Veg'





//---------------------
//CHOOSE REGION
var West = -119.74170684814453  //Longitude
var North = 34.05607276338369  //Latitude 
var East = -119.66754913330078  //Longitude
var South = 34.00969645770158   //Latitude 


var coords1 = '[[' + West + "," + North + '], ['+ West + "," + South + '], ['+ East + "," + South + '], ['+ East + "," + North + ']]';   
//print(coords1);  



//----------------------
// IMAGERY SOURCES - LANDSAT
// Code will use:
//      -Landsat 5 if interval end date is before May 8 2012
//      -Landsat 7 if interval end date is after May 9 2012 and interval start is after april 7 2013
//      -Landsat 8 if interval start date is after April 7 2013
var landsat8startDate =  new Date("April 7, 2013");
var landsat5endDate =  new Date("May 8, 2012"); 


//----------------------
//A date function to increment dates by the temporal units given above
function dateAdd(date, interval, units) {
  var ret = new Date(date); //don't change original date
  switch(interval.toLowerCase()) {
    case 'year'   :  ret.setFullYear(ret.getFullYear() + units);  break;
    case 'quarter':  ret.setMonth(ret.getMonth() + 3*units);  break;
    case 'month'  :  ret.setMonth(ret.getMonth() + units);  break;
    case 'week'   :  ret.setDate(ret.getDate() + 7*units);  break;
    case 'day'    :  ret.setDate(ret.getDate() + units);  break;
    case 'hour'   :  ret.setTime(ret.getTime() + units*3600000);  break;
    case 'minute' :  ret.setTime(ret.getTime() + units*60000);  break;
    case 'second' :  ret.setTime(ret.getTime() + units*1000);  break;
    default       :  ret = undefined;  break;
  }
  return ret;
}

//a formatting function to convert a date to a text string for a filename (e.g. "2014_06_01")
function dateFormat(date) {
  var fYear = date.getFullYear();
  var tempMonth = date.getMonth() + 1
  var fMonth;
  if (tempMonth<10) {
    fMonth = "0"+tempMonth;
  } else {
    fMonth = tempMonth.toString();
  }
  var tempDate = date.getDate()
  var fDate;
  if (tempDate<10) {
    fDate = "0"+tempDate;
  } else {
    fDate = tempDate.toString();
  }
  var fDateString = fYear.toString()+"_"+fMonth+"_"+fDate;
  return fDateString;
}


//Establish variables for the loop
var i;
var intervalEndDate = startdate;
print("Generating image URLs...")

//Loop to iterate through the dates.  Loop continues while the end of the interval is less than the end date for the full period
for (i=0;intervalEndDate < enddate;i=i+intervalLength) {
  var intervalStartDate = dateAdd(startdate,intervalType,i);
  var intervalEndDate = dateAdd(startdate,intervalType,i+intervalLength);
  //print('START DATE  ' + intervalStartDate.toString());
  //print('END DATE  ' + intervalEndDate.toString());

  //Choose landsat 5, landsat 7, or landsat 8 based on interval range  
  if (intervalStartDate > landsat8startDate) {
      var landsatNum = "LC8";
  } else if (intervalEndDate < landsat5endDate) {
      var landsatNum = "LT5";
  } else {
     var landsatNum = "LE7";
  }

 //print(landsatNum);
  
  
  //get image collection.  Note that Landsat 8 collection starts April 7th, 2013

  switch(imageType) {
      case 'NDVI':
          var landsat8 = ee.ImageCollection('LANDSAT/' + landsatNum +'_L1T_8DAY_NDVI');
          break;
      case 'Raw':
          var landsat8 = ee.ImageCollection('LANDSAT/' + landsatNum +'_L1T');
          break;
      case 'Wetness':
          var landsat8 = ee.ImageCollection('LANDSAT/' + landsatNum +'_L1T');
          break;
      case 'NDWI':
          var landsat8 = ee.ImageCollection('LANDSAT/' + landsatNum +'_L1T_8DAY_NDWI');
          break;
      case 'Veg':
          var landsat8 = ee.ImageCollection('LANDSAT/' + landsatNum +'_L1T');
          break;
    }

  
  
  //Filter the image collection to a smaller image collection based on the interval start and end date
  var intervalImageCollection = landsat8.filterDate(intervalStartDate, intervalEndDate);
  //Reduce the interval image collection to a single image using a median reducer
  var median1 = intervalImageCollection.median();
  //Set the bands to visualize the image
  //var map1 = median1.visualize({'bands': ['B4', 'B3', 'B2'], 'min': 5000, 'max': 18000});
  switch(imageType) {
    case 'NDVI':
        var NDVI_PALETTE = ['663300', 'CC7A00', 'B8B800', '009900'];
        var map1 = median1.visualize({'bands': "NDVI", 'palette': NDVI_PALETTE});
        break;
    case 'Wetness':
        var map1 = median1.visualize({'bands': ['B7', 'B5', 'B1'], 'min': 5000, 'max': 18000});
        break;
    case 'Raw':
        var map1 = median1.visualize({'bands': ['B4', 'B3', 'B2'], 'min': 5000, 'max': 18000});
        break;
    case 'NDWI':
        var NDWI_PALETTE = ['FFFFCC', '0066FF'];
        var map1 = median1.visualize({'bands': "NDWI", 'palette': NDWI_PALETTE});
        break;
    case 'Veg':
        var map1 = median1.visualize({'bands': ['B5', 'B6', 'B2'], 'min': 5000, 'max': 18000});
        break;
  }
  //Generate file name for download
  var imageName = imageBaseName+"_"+ imageType + "_" +dateFormat(intervalStartDate)+"_to_"+dateFormat(intervalEndDate);
  //Generate a URL to download the image
  var path = map1.getDownloadURL({'name':imageName, 'scale': 30, 'region': coords1, 'crs':'EPSG:4326', 'filePerBand': 'False'});
  // gonzales zoom [[-121.493, 36.497], [-121.493, 36.464], [-121.44, 36.464], [-121.44, 36.497]]
  // whole region '[[-121.59, 36.6], [-121.59, 36.4], [-121.38, 36.4], [-121.38, 36.6]]'
  print(path);
}