httr authentication functions for fitbit API

oauth-functions.R

# edited from init_oauth2.0 to:
# * add trailing slash to callback
# * add base64 encoded client_id:client_secret to request when exchanging

init_oauth2.0_fitbit <- function(endpoint, app, scope = NULL, type = NULL,
  use_oob = getOption("httr_oob_default"),
  is_interactive = interactive()) {
  if (!use_oob && !httr:::is_installed("httpuv")) {
    message("httpuv not installed, defaulting to out-of-band authentication")
    use_oob <- TRUE
  }
  
  if (isTRUE(use_oob)) {
    stopifnot(interactive())
    redirect_uri <- "urn:ietf:wg:oauth:2.0:oob"
    state <- NULL
  } else {
    redirect_uri <- paste0(oauth_callback(), "/")
    state <- httr:::nonce()
  }
  
  scope_arg <- paste(scope, collapse = ' ')
  
  authorize_url <- modify_url(endpoint$authorize, 
    query = httr:::compact(list(
      client_id = app$key,
      scope = scope_arg,
      redirect_uri = redirect_uri,
      response_type = "code",
      state = state))
    )
  
  if (isTRUE(use_oob)) {
    code <- oauth_exchanger(authorize_url)$code
  } else {
    code <- oauth_listener(authorize_url, is_interactive)$code
  }

  auth <- paste0("Basic ", 
    base64enc::base64encode(charToRaw(paste0(app$key, ":", app$secret))))
    
  # Use authorisation code to get (temporary) access token
  req <- POST(endpoint$access, encode = "form",
    add_headers("Authorization" = auth),
    body = list(
      client_id = app$key,
      redirect_uri = redirect_uri,
      grant_type = "authorization_code",
      code = code))
  content(req, type = type)
}

# edited from refresh_oauth2.0 to:
# * add base64 encoded client_id:client_secret to request when exchanging

refresh_oauth2.0_fitbit <- function(endpoint, app, credentials) {
  if (is.null(credentials$refresh_token)) {
    stop("Refresh token not available", call. = FALSE)
  }
  
  refresh_url <- endpoint$access

    # Use authorisation code to get (temporary) access token
  body <- list(
    refresh_token = credentials$refresh_token,
    client_id = app$key,
    client_secret = app$secret,
    grant_type = "refresh_token"
  )
  
  auth <- paste0("Basic ", 
    base64enc::base64encode(charToRaw(paste0(app$key, ":", app$secret))))
  
  response <- POST(refresh_url, body = body, encode = "form", 
    add_headers("Authorization" = auth))
  stop_for_status(response)
  
  refresh_data <- content(response)
  modifyList(credentials, refresh_data)
}

oauth2.0_token_fitbit <- function(endpoint, app, scope = NULL, type = NULL,
  use_oob = getOption("httr_oob_default"),
  as_header = TRUE,
  cache = getOption("httr_oauth_cache")) {
  params <- list(scope = scope, type = type, use_oob = use_oob,
    as_header = as_header)
  Token2.0_fitbit$new(app = app, endpoint = endpoint, params = params,
    cache_path = cache)
}

Token2.0_fitbit <- R6::R6Class("Token2.0_fitbit", inherit = Token2.0, list(
  init_credentials = function() {
    self$credentials <- init_oauth2.0_fitbit(self$endpoint, self$app,
      scope = self$params$scope, type = self$params$type,
      use_oob = self$params$use_oob)
  },
  refresh = function() {
    self$credentials <- refresh_oauth2.0_fitbit(self$endpoint, self$app, self$credentials)
    self$cache()
    self
  }
))