R/load_binpaths.R

In pobsteta/theia2r: An R toolbox to find, download and preprocess Sentinel-2 data

#' @title Load the paths of external executables
#' @description Internal function to load the paths of executables 
#'  from the JSON where they are saved when installed.
#' @param bins Character vector with one of more of the following values:
#'  'gdal', sen2cor', 'wget', 'aria2', 'python'.
#'  If an executable corresponding to the passed `bins` value is not found
#'  in the JSON, it is installed (Windows) or checked (Linux).
#' @return The list of the paths
#'
#' @author Luigi Ranghetti, phD (2018) \email{ranghetti.l@@irea.cnr.it}
#' @note License: GPL 3.0
#' @importFrom jsonlite fromJSON
#' @examples
#' \dontrun{
#'
#' # Load only existing paths
#' binpaths <- load_binpaths()
#' 
#' # Load paths, forcing to check GDAL and sen2cor
#' binpaths <- load_binpaths(c('gdal', 'sen2cor'))
#' }


load_binpaths <- function(bins = NULL) {
    
    # Define where the JSON with the paths is
    binpaths_file <- file.path(system.file("extdata", package = "theia2r"), "paths.json")
    
    # If it exists, load it; otherwise, create empty
    binpaths <- if (file.exists(binpaths_file)) {
        jsonlite::fromJSON(binpaths_file)
    } else {
        list()
    }
    
    ## Check that the required binaries are present
    
    # Check GDAL
    if ("gdal" %in% bins & is.null(binpaths$gdalinfo)) {
        check_gdal()
        binpaths <- jsonlite::fromJSON(binpaths_file)
    }
    
    # Check sen2cor
    if ("sen2cor" %in% bins & is.null(binpaths$sen2cor)) {
        if (interactive()) {
            print_message(type = "waiting", "sen2cor was not found in your system; press ENTER to install, ESC to escape.")
        } else {
            print_message(type = "message", "sen2cor was not found in your system and will be installed.")
        }
        install_sen2cor() %>% suppressMessages()
        binpaths <- jsonlite::fromJSON(binpaths_file)
    }
    
    # Check wget
    if ("wget" %in% bins & is.null(binpaths$wget)) {
        if (Sys.info()["sysname"] == "Windows") {
            suppressMessages(install_wget())
        } else if (Sys.which("wget") != "") {
            binpaths$wget <- normalizePath(Sys.which("wget"))
            writeLines(jsonlite::toJSON(binpaths, pretty = TRUE), binpaths_file)
            binpaths <- jsonlite::fromJSON(binpaths_file)
        }
    }
    
    # Check aria2
    if ("aria2" %in% bins & is.null(binpaths$aria2c)) {
        if (Sys.info()["sysname"] == "Windows") {
            suppressMessages(install_aria2())
        } else if (Sys.which("aria2c") != "") {
            binpaths$aria2c <- normalizePath(Sys.which("aria2c"))
            writeLines(jsonlite::toJSON(binpaths, pretty = TRUE), binpaths_file)
            binpaths <- jsonlite::fromJSON(binpaths_file)
        }
    }
    
    # Check python
    if ("python" %in% bins & is.null(binpaths$python)) {
        init_python()
        binpaths <- jsonlite::fromJSON(binpaths_file)
    }
    
    # Return the list
    attr(binpaths, "path") <- binpaths_file
    binpaths
    
}