gitlab_api.R

#' Request GitLab API
#'
#' This is 'gitlabr' core function to talk to GitLab's
#' server API via HTTP(S). Usually you will not
#' use this function directly too often, but either use 'gitlabr'
#'  convenience wrappers or write your
#' own. See the 'gitlabr' vignette for more information on this.
#'
#' @param req vector of characters that represents the call
#' (e.g. `c("projects", project_id, "events")`)
#' @param api_root URL where the GitLab API to request resides
#'  (e.g. `https://gitlab.myserver.com/api/v3/`)
#' @param verb http verb to use for request in form of one of the
#' `httr` functions
#' [httr::GET()], [httr::PUT()], [httr::POST()], [httr::DELETE()]
#' @param auto_format whether to format the returned object automatically
#'  to a flat data.frame
#' @param debug if TRUE API URL and query will be printed, defaults to FALSE
#' @param gitlab_con function to use for issuing API requests
#' (e.g. as returned by [get_gitlab_connection()]
#' @param page number of page of API response to get; if "all" (default),
#'  all pages (up to max_page parameter!) are queried successively and combined.
#' @param max_page maximum number of pages to retrieve.
#' Defaults to 10. This is an upper limit
#' to prevent 'gitlabr' getting stuck in retrieving
#' an unexpectedly high number of entries (e.g. of a
#' project list). It can be set to NA/Inf to retrieve
#' all available pages without limit, but this
#' is recommended only under controlled circumstances.
#' @param enforce_api_root if multiple pages are requested,
#' the API root URL is ensured
#' to be the same as in the original call for all calls
#' using the "next page" URL returned
#' by GitLab This makes sense for security and in cases
#' where GitLab is behind a reverse proxy
#' and ignorant about its URL from external.
#' @param argname_verb name of the argument of the verb
#' that fields and information are passed on to
#' @param ... named parameters to pass on to GitLab API
#' (technically: modifies query parameters of request URL),
#' may include private_token and all other parameters
#' as documented for the GitLab API
#'
#' @importFrom utils capture.output
#' @importFrom tibble tibble as_tibble
#' @importFrom magrittr %T>%
#' @importFrom dplyr bind_rows
#' @importFrom stringr str_replace_all str_replace
#' @export
#'
#' @return the response from the GitLab API,
#' usually as a `tibble` and including all pages
#'
#' @details
#' `gitlab()` function allows to use any request
#'  of the GitLab API <https://docs.gitlab.com/ce/api/>.
#'
#'  For instance, the API documentation shows how to create a new project in
#'  <https://docs.gitlab.com/ce/api/projects.html#create-project>:
#'
#'  - The verb is `POST`
#'  - The request is `projects`
#'  - Required attributes are `name` or `path` (if `name` not set)
#'  - `default_branch` is an attribute that can be set if wanted
#'
#'  The corresponding use of `gitlab()` is:
#'
#'  ```
#'  gitlab(
#'    req = "projects",
#'    verb = httr::POST,
#'    name = "toto",
#'    default_branch = "main"
#'  )
#'  ```
#'
#' Note: currently GitLab API v4 is supported.
#'  GitLab API v3 is no longer supported, but
#' you can give it a try.
#'
#' @examples \dontrun{
#' # Connect as a fixed user to a GitLab instance
#' set_gitlab_connection(
#'   gitlab_url = "https://gitlab.com",
#'   private_token = Sys.getenv("GITLAB_COM_TOKEN")
#' )
#'
#' # Use a simple request
#' gitlab(req = "projects")
#' # Use a combined request with extra parameters
#' gitlab(
#'   req = c("projects", 1234, "issues"),
#'   state = "closed"
#' )
#' }
gitlab <- function(req,
                   api_root,
                   verb = httr::GET,
                   auto_format = TRUE,
                   debug = FALSE,
                   gitlab_con = "default",
                   page = "all",
                   max_page = 10,
                   enforce_api_root = TRUE,
                   argname_verb =
                     if (
                       identical(verb, httr::GET) ||
                         identical(verb, httr::DELETE)
                     ) {
                       "query"
                     } else {
                       "body"
                     },
                   ...) {
  if (!is.function(gitlab_con) &&
    gitlab_con == "default" &&
    !is.null(get_gitlab_connection())) {
    gitlab_con <- get_gitlab_connection()
  }

  if (!is.function(gitlab_con)) {
    url <- req %>%
      paste(collapse = "/") %>%
      prefix(api_root, "/") %T>%
      iff(debug, function(x) {
        print(
          paste(c("URL:", x, " ",
            "query:",
            paste(
              utils::capture.output(print((list(...)))),
              collapse = " "
            ), " ",
            collapse = " "
          ))
        )
        x
      })

    # Extract private token to put it in header
    l <- list(...)
    private_token <- l$private_token
    l <- within(l, rm(private_token))
    private_token_header <- httr::add_headers("PRIVATE-TOKEN" = private_token)

    (if (page == "all") {
      flattenbody(l)
    } else {
      c(page = page, flattenbody(l))
    }) %>%
      pipe_into(argname_verb, verb, url = url, private_token_header) %>%
      http_error_or_content() -> resp

    resp$ct %>%
      ## better would be to check MIME type
      iff(auto_format, json_to_flat_df) %>%
      iff(debug, print) -> resp$ct

    if (page == "all") {
      pages_retrieved <- 1L # 1 already retrieved
      while (length(resp$nxt) > 0
      ) {
        if (
          !is.na(max_page) &&
            is.finite(max_page) &&
            pages_retrieved >= max_page
        ) {
          message("max_page reached, stop retrieving pages...")
          break
        }

        nxt_resp <- resp$nxt %>%
          as.character() %>%
          iff(
            enforce_api_root,
            stringr::str_replace, "^.*/api/v\\d/",
            api_root
          ) %>%
          httr::GET(private_token_header) %>%
          http_error_or_content()
        resp$nxt <- nxt_resp$nxt
        if (auto_format) {
          resp$ct <- bind_rows(
            resp$ct,
            nxt_resp$ct %>%
              json_to_flat_df()
          )
        } else {
          resp$ct <- c(resp$ct, nxt_resp$ct)
        }
        pages_retrieved <- pages_retrieved + 1
      }
    }

    return(resp$ct)
  } else {
    if (!missing(req)) {
      dot_args <- list(req = req)
    } else {
      dot_args <- list()
    }
    if (!missing(api_root)) {
      dot_args <- c(dot_args, api_root = api_root)
    }
    if (!missing(verb)) {
      dot_args <- c(dot_args, verb = verb)
    }
    if (!missing(auto_format)) {
      dot_args <- c(dot_args, auto_format = auto_format)
    }
    if (!missing(debug)) {
      dot_args <- c(dot_args, debug = debug)
    }
    if (!missing(page)) {
      dot_args <- c(dot_args, page = page)
    }
    if (!missing(max_page)) {
      dot_args <- c(dot_args, max_page = max_page)
    }
    do.call(gitlab_con, c(dot_args,
      gitlab_con = "self",
      list(...)
    )) %>%
      iff(debug, print)
  }
}

http_error_or_content <- function(response,
                                  handle = httr::stop_for_status,
                                  ...) {
  if (!identical(handle(response), FALSE)) {
    ct <- httr::content(response, ...)
    nxt <- get_next_link(httr::headers(response)$link)
    list(ct = ct, nxt = nxt)
  }
}

#' @importFrom stringr str_replace_all str_split
#' @noRd
get_rel <- function(links) {
  links %>%
    stringr::str_split(",\\s+") %>%
    getElement(1) -> strs
  tibble::tibble(
    link = strs %>%
      lapply(stringr::str_replace_all, "\\<(.+)\\>.*", "\\1") %>%
      unlist(),
    rel = strs %>%
      lapply(stringr::str_replace_all, ".+rel=.(\\w+).", "\\1") %>%
      unlist(),
    stringsAsFactors = FALSE
  )
}

#' @importFrom dplyr filter
#' @noRd
get_next_link <- function(links) {
  if (is.null(links)) {
    return(NULL)
  } else {
    links %>%
      get_rel() %>%
      filter(rel == "next") %>%
      getElement("link")
  }
}

is.nested.list <- function(l) {
  is.list(l) && any(unlist(lapply(l, is.list)))
  is.list(l[26]) && any(unlist(lapply(l[26], is.list)))
}

is_named <- function(v) {
  !is.null(names(v))
}


is_single_row <- function(l) {
  if (length(l) == 1 || !any(lapply(l, is.list) %>% unlist())) {
    return(TRUE)
  } else {
    # if (is.null(names(l)))
    # not named, then probably multiple rows
    # at least one name is the same shows multiple lines
    all_names <- lapply(l, names)
    if (any(
      lapply(all_names, function(x) any(x %in% all_names[[1]])) %>% unlist()
    )) {
      return(FALSE)
    } else {
      return(TRUE)
    }
  }
}

format_row <- function(row, ...) {
  row %>%
    lapply(unlist, use.names = FALSE, ...) %>%
    # tibble::as_tibble(stringsAsFactors = FALSE)
    tibble::as_tibble(.name_repair = "unique")
}

#' @importFrom dplyr bind_rows
#' @noRd
json_to_flat_df <- function(l) {
  l %>%
    iff(is_single_row, list) %>%
    lapply(unlist, recursive = TRUE) %>%
    lapply(format_row) %>%
    bind_rows()
}

call_filter_dots <- function(fun,
                             .dots = list(),
                             .dots_allowed = gitlab %>%
                               formals() %>%
                               names() %>%
                               setdiff("...") %>%
                               c("api_root", "private_token"),
                             ...) {
  do.call(fun, args = c(list(...), .dots[intersect(.dots_allowed, names(.dots))]))
}

#' Flatten a list as duplicate names list
#' for httr requests
#'
#' @param x a list
#' @return a list
#'
#' @noRd
flattenbody <- function(x) {
  # issued from https://stackoverflow.com/a/72532186
  # A form/query can only have one value per name, so take
  # any values that contain vectors length >1 and
  # split them up
  # list(x=1:2, y="a") becomes list(x=1, x=2, y="a")
  if (all(lengths(x) <= 1)) {
    return(x)
  }
  do.call("c", mapply(function(name, val) {
    if (length(val) == 1 || any(c("form_file", "form_data") %in% class(val))) {
      x <- list(val)
      names(x) <- name
      x
    } else {
      x <- as.list(val)
      names(x) <- rep(name, length(val))
      x
    }
  }, names(x), x, USE.NAMES = FALSE, SIMPLIFY = FALSE))
}