# Script to get MCD14ML MODIS data
library(RCurl)
library(dplyr)

# fetch_MCD14ML() downloads all of the zipped data files for the
# MODIS MCD14ML data product
#
# args:
#   dir: the name of a directory to store the zip files (string)
#   overwrite: should existing data be overrwitten? (logical)
#
# returns:
#   none, but downloads all of the zip files in "dir"
#
# example:
#   fetch_MCD14ML('mcd_test')

fetch_MCD14ML <- function(dir, overwrite = FALSE) {
  if (!dir.exists(dir)) {
    dir.create(dir, recursive = TRUE)
  }

  ftp_prefix <- 'ftp://fire:burnt@fuoco.geog.umd.edu/modis/C6/mcd14ml/'

  # make vector of filenames on ftp server
  files <- getURL(ftp_prefix, dirlistonly = TRUE) %>%
    strsplit(split = '\n') %>%
    unlist()

  # make ftp paths to each file
  to_download <- lapply(files, FUN = function(x) paste0(ftp_prefix, x)) %>%
    unlist()

  # download each
  destination_files <- file.path(dir, files)
  pb <- txtProgressBar(max = length(destination_files))
  for (i in seq_along(destination_files)) {
    if (!file.exists(destination_files[i]) | overwrite) {
      download.file(to_download[i], destination_files[i])
    }
    setTxtProgressBar(pb, i)
  }
  close(pb)
}