R/api_helpers.R

In scrobbler: Download 'Scrobbles' from 'Last.fm'

#' get_total_pages
#'
#' Returns the total number of pages that your song list spans across. Used for determining
#' how many pages to loop the api call over
#'
#' @param username Your `Last.fm` username, as a string
#' @param api_key Your `Last.fm` api_key, as a string
#'
#' @return A single number character string
#' @noRd
get_total_pages <- function(username, api_key, from = 0){
  print("Getting page numbers...")
  base_url <- paste0(
    "http://ws.audioscrobbler.com/2.0/?method=user.getRecentTracks&user=",
    username,
    "&limit=1000&api_key=",
    api_key,
    "&format=json&from=",
    from
  )

  repeat {
    response <- httr::GET(base_url)
    if (response$status_code == 200) break
  }
  text_response <- httr::content(response, "text", encoding = "UTF-8")
  parsed = jsonlite::fromJSON(text_response, flatten = TRUE)

  total_pages = as.integer(parsed[["recenttracks"]][["@attr"]][["totalPages"]])
  page_1 = parsed[["recenttracks"]][["track"]]

  return(list(total_pages,
              page_1))
}

#' construct_urls
#'
#' @param total_pages Total number of pages to build
#' @param username Your username
#' @param api_key Your api_key
#'
#' @return Vector of urls
#' @noRd
#'
construct_urls <- function(total_pages, username, api_key, from = 0){
  result <- vector("character")

  for (page in seq_along(1:total_pages)){
    urls <- paste0(
      "http://ws.audioscrobbler.com/2.0/?method=user.getRecentTracks&user=",
      username,
      "&limit=1000&api_key=",
      api_key,
      "&format=json&page=",
      page,
      "&from=",
      from
    )
    result[page] <- urls
  }
  return(stats::na.omit(result))
}


#' rename_api_response
#'
#' Takes the parsed response from the Last.fm API and renames the columns to make them user
#' friendly.
#'
#' @param api_data An api response that has been parsed by the `download_scrobbles` function.
#'
#' @return A renamed dataframe
#' @noRd
rename_api_response <- function(api_data){
  names(api_data)[names(api_data) == "name"] <- "song_title"
  names(api_data)[names(api_data) == "mbid"] <- "song_mbid"
  names(api_data)[names(api_data) == "artist.mbid"] <- "artist_mbid"
  names(api_data)[names(api_data) == "artist.#text"] <- "artist"
  names(api_data)[names(api_data) == "album.mbid"] <- "album_mbid"
  names(api_data)[names(api_data) == "album.#text"] <- "album"
  names(api_data)[names(api_data) == "date.#text"] <- "date"
  names(api_data)[names(api_data) == "date.uts"] <- "date_unix"
  return(api_data)
}


#' get_last_timestamp
#'
#' @param scrobbles_df A dataframe output of `download_scrobbles`
#' @param timestamp_column The column in `scrobbles_df` that corresponds to the `date_unix` column
#'
#' @return Numeric vector
#' @export
#'
#' @examples
#' \dontrun{
#' get_last_timestamp(mydata, 'date_unix')
#' }
get_last_timestamp <- function(scrobbles_df, timestamp_column){
  if (is.data.frame(scrobbles_df) == FALSE) {
    stop("`scrobbles_df`` must be a dataframe", call. = FALSE)
  }
  time_vec <- scrobbles_df[,timestamp_column]
  # if (!is.numeric(time_vec)){
  #   stop("timestamp_column column must be numeric", call. = FALSE)
  # }
  time_vec <- sort(time_vec, decreasing = TRUE)
  last_timestamp <- time_vec[1]

  return(last_timestamp)
}