R/crypto_helpers.R

In heguevel/Crypto: Cryptocurrency Market Data

#' CoinMarketCap Professional API Call
#'
#' @param url CoinMarketCap API URL
#' @importFrom httr 'content' 'GET' 'add_headers' 'accept_json'
#' @importFrom rstudioapi askForSecret
#' @return api results
#' @export
#' @examples
#' \dontrun{
#' cmc_api('https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest')
#' }
cmc_api <- function(url) {
  safely_read_json(httr::content(httr::GET(url, httr::add_headers(`X-CMC_PRO_API_KEY` = rstudioapi::askForSecret("coinmarketcap-apikey")),
    httr::accept_json()), "text"))
}

#' Get Updated Coinlist
#' @description Gets updated coin listing from CoinMarketCap professional API
#' and prompts user to provide CMC API key using the keyring package.
#' @importFrom dplyr select
#' @export
#' @return dataframe
#' @examples
#' \dontrun{
#' get_coinlist_api()
#'  }
get_coinlist_api <- function() {
  id <- ""
  name <- ""
  symbol <- ""
  slug <- ""
  cmc_rank <- ""
  packages <- c(is.element("keyring", utils::installed.packages()[, 1]), is.element("rstudioapi",
    utils::installed.packages()[, 1]))

  if (!any(packages)) {
    message("Crypto highly recommends you install keyring `install.packages(\"keyring\")` to manage your API keys.",
      appendLF = TRUE)
  }

  base <- "https://pro-api.coinmarketcap.com"
  endpoint <- "/v1/cryptocurrency/listings/latest"
  params <- "?start=1&limit=5000&convert=USD"
  url <- paste0(base, endpoint, params)

  listings <- cmc_api(url)$data %>% as.data.frame() %>% dplyr::select(id, name,
    symbol, slug, cmc_rank)
  names(listings) <- c("id", "name", "symbol", "slug", "rank")
  return(listings)
}

#' Get Updated Coinlist
#' @description Gets updated coin listing from local data
#' @export
#' @return dataframe
#' @examples
#' \dontrun{
#' get_coinlist_static()
#'  }
get_coinlist_static <- function() {
  listings <- coin_list
  return(listings)
}

#' Check locale encoding
#'
#' Helper function to ensure encoding is UTF-8
#'
#' @param sys_locale string system locale
#' @return Sets system variable to UTF-8
#'
#' @export
#' @name replace_encoding
#'
#' @examples
#' \dontrun{
#' sys_locale <- Sys.getlocale(category = 'LC_TIME')
#' replace_encoding(sys_locale)
#' }
replace_encoding <- function(sys_locale) {
  new_locale <- "en_US.UTF-8"
  if (!endsWith(sys_locale, "UTF-8")) {
    if (!endsWith(sys_locale, "1252")) {
      msg <- paste("Temporarily changing locale encoding from", sys_locale,
        "to UTF-8. Will reset back to", sys_locale)
      warning(msg, call. = TRUE, immediate. = TRUE)
      sys_os <- .Platform$OS.type
      ifelse(sys_os == "unix", new_locale <- Sys.setlocale(category = "LC_ALL",
        locale = "en_US.UTF-8"), new_locale <- Sys.setlocale(category = "LC_ALL",
        locale = "English_United States.1252"))
    }
  }
  return(new_locale)
}

#' Reset locale encoding
#'
#' Helper function to reset encoding from UTF-8 back
#' to R sessions original locale value.
#'
#' @param sys_locale string Original system locale
#' @return Sets locale back to original value
#'
#' @export
#' @name reset_encoding
#'
#' @examples
#' \dontrun{
#' sys_locale <- Sys.getlocale(category = 'LC_TIME')
#' reset_encoding(sys_locale)
#' }
reset_encoding <- function(sys_locale) {
  reset_enc <- sys_locale
  if (Sys.getlocale(category = "LC_TIME") != sys_locale) {
    message("Resetting to your local encoding standard.", appendLF = TRUE)
    reset_enc <- Sys.setlocale(category = "LC_ALL", locale = sys_locale)
  }
  return(reset_enc)
}

#' Platform Locale
#'
#' Helper function to identify locale to use for date encoding
#' based on source platform being unix based or windows
#'
#' @return locale
#' @export
#'
#' @examples {
#' platform_locale()
#' }
platform_locale <- function() {
  sys_os <- .Platform$OS.type
  locale <- ifelse(sys_os == "unix", "en_US.UTF-8", "English_United States.1252")
  return(locale)
}


#' @title Safely read json API
#' @description This will attempt to safely retrieve data and return a elegant error message to the user if the data is unavailable.
#'
#' @param json_url json API URL
#' @importFrom httr 'content' 'modify_url' 'GET' 'http_type' 'user_agent' 'parse_media' 'status_code'
#' @importFrom jsonlite fromJSON
#'
#' @return parsed dataset or a elegant error message
#'
#' @examples {
#' json_url <- 'https://s2.coinmarketcap.com/generated/search/quick_search.json'
#' result <- safely_read_json(json_url)
#' }
#'
#' @export
safely_read_json <- function(json_url) {
  user_agent <- httr::user_agent("Mozilla/5.0")
  charset <- "utf-8"
  url <- httr::modify_url(json_url)
  api_response <- httr::GET(url, user_agent)

  if (httr::http_type(api_response) != "application/json") {
    stop("No JSON was returned from the server. ", call. = FALSE)
  }

  if ("content-type" %in% names(api_response$headers)) {
    media <- httr::parse_media(api_response$headers[["content-type"]])
    if ("params" %in% names(media) && "charset" %in% names(media$params)) {
      charset <- media$params$charset
    }
  }
  response_content <- httr::content(api_response, as = "text", encoding = charset)
  parsed <- jsonlite::fromJSON(response_content, flatten = TRUE)

  if (httr::status_code(api_response) != 200) {
    stop(sprintf("API request failed [%s]\n%s\n<%s>", httr::status_code(api_response),
      parsed$message, parsed$documentation_url), call. = FALSE)
  }
  return(parsed)
}