R/search-saga.R

In stevenpawley/RSAGA5: Linking R with the Open-Source 'SAGA-GIS' Software

#' Automatic search for the path to a SAGA-GIS installation
#'
#' Returns the path to the saga_cmd executable.
#' 
#' @details
#' On Microsoft Windows, automatic searching will occur first in 'C:/Program
#' Files/SAGA-GIS'; 'C:/Program Files (x86)/SAGA-GIS'; 'C:/SAGA-GIS';
#' 'C:/OSGeo4W'; and 'C:/OSGeo4W64'.
#' 
#' On Linux, saga_cmd is usually included in PATH, if not an automatic search is
#' performed in the '/usr/' folder.
#' 
#' For macOS, since version 8.5, SAGA-GIS is available as an standalone macOS
#' app from \href{https://sourceforge.net/projects/saga-gis/}{SourceForge}. The
#' 'SAGA.app' package is searched first (assuming that it is installed in the
#' '/Applications/' folder). Other macOS locations that are searched include
#' '/usr/local/bin/' (for Homebrew installations) and within the QGIS application
#' (SAGA-GIS is bundled with the QGIS application on macOS by default).
#' 
#' If multiple versions of SAGA-GIS are installed on the system, the path to the
#' newest version is returned.
#'
#' @return The path to installed saga_cmd binary.
#'
#' @export
search_saga <- function() {
  # check to see if saga_cmd is recognized (i.e. has been added to path)
  saga_cmd <- if (nchar(Sys.which(names = "saga_cmd")) > 0) "saga_cmd" else NULL

  if (is.null(saga_cmd)) {

    # define search paths
    if (Sys.info()["sysname"] == "Windows") {
      search_paths <- c(
        "C:/Program Files/SAGA-GIS",
        "C:/Program Files (x86)/SAGA-GIS",
        "C:/SAGA-GIS",
        "C:/OSGeo4W",
        "C:/OSGeo4W64"
      )
      saga_executable <- "saga_cmd.exe"
      
    } else if (Sys.info()["sysname"] == "Linux") {
      search_paths <- c("/usr")
      saga_executable <- "saga_cmd$"
      
    } else if (Sys.info()["sysname"] == "Darwin") {
      search_paths <- c(
        "/Applications/SAGA.app/Contents/MacOS",
        "/usr/local/bin",
        "/Applications/QGIS.app/Contents/MacOS/bin"
      )

      saga_executable <- "^saga_cmd$"
    }

    # search for saga_cmd executable
    saga_cmd <- c()
    for (f in search_paths) {
      saga_cmd <- c(saga_cmd, list.files(
        path = f,
        pattern = saga_executable,
        recursive = TRUE,
        full.names = TRUE
      ))
    }
  }

  # error is saga_cmd not found
  if (length(saga_cmd) == 0) {
    rlang::abort(
      paste(
        "SAGA-GIS installation not found. Need to supply a valid path",
        "to the saga_cmd executable"
      )
    )

    return(NULL)

    # automatically use newest version if multiple installations are found
  } else if (length(saga_cmd) > 1) {
    message("Multiple installations of SAGA-GIS were found at:")
    message(paste(saga_cmd, collapse = "\n"))
    message(paste(
      "Choosing newest version. Manually specify the location when",
      "calling saga_gis() to use an older version"
    ))

    saga_vers <- list()

    for (saga_inst in saga_cmd) {
      saga_vers <- append(saga_vers, saga_version(saga_inst))
    }

    saga_cmd <- saga_cmd[which(saga_vers == max(saga_vers))]
  }

  return(saga_cmd)
}