##################################################################
##                           Function                           ##
##################################################################

fish <- function(l, keys, .dflt = NULL, missing.rm = FALSE) {
  if(!is.list(keys)) stop("The keys to search should be given as a list.")

  modified_names <- names(keys) %||% rep("", length(keys)) %>%
    str_replace("^$", as.character(NA))
  old_names <- map_chr(keys, get_very_last)
  new_names <- coalesce(modified_names, old_names)

  new_list <- keys %>%
    purrr::map(~purrr::pluck(l, ., .default = .dflt)) %>%
    set_names(new_names)

  if(missing.rm) return(compact(new_list))

  new_list
}

get_very_last <- function(l) {
  last_value <- l[[length(l)]]
  if(length(last_value) != 1) return(get_very_last(last_value))
  last_value
}


#################################################################
##                            Usage                            ##
#################################################################

# Define all the keys you want to keep as a list
# You can optionally define a new name, otherwise the deepest name is used

keys_to_keep <- list(
  "id",
  "amount_due",
  "amount_paid",
  "amount_remaining",
  "currency",
  "charge",
  "lines",
  "status",
  line_count = list("lines", "total_count"),
  plan_id = list("lines", "data", 1, "plan", "id"),
  plan_name = list("lines", "data", 1, "plan", "name"),
  period = list("lines", "data", 1, "period"),
  item_id = list("lines", "data", 1, "subscription_item"),
  "date",
  "due_date"
)

invoices <- invoice_raw_data %>%
  map(fish, keys_to_keep, missing.rm = TRUE)