#' Create a lock file for the dependencies of a package tree

#'

#' The lock file can be used later, possibly in a new R session, to carry

#' out the installation of the dependencies, with

#' [local_install_lockfile()].

#'

#' Note, since the URLs of CRAN and most CRAN-like repositories change

#' over time, in practice you cannot use the lock file _much_ later.

#' For example, binary packages of older package version

#' might be deleted from the repository, breaking the URLs in the

#' lock file.

#'

#' Currently the intended use case of lock files in on CI systems, to

#' facilitate caching. The (hash of the) lock file provides a good key

#' for caching systems.

#'

#' @param lockfile Path to the lock file.

#' @param lib Library to base the lock file on. In most cases (e.g. on a

#'   CI system, or at deployment), this is an empty library. Supply

#'   `tempfile()` to make sure the lock file is based on an empty library.

#' @inheritParams local_install

#' @family lock files

#' @export

local_create_lockfile <- function(root = ".", lockfile = "pkg.lock",

                                  lib = .libPaths()[1], upgrade = TRUE,

                                  dependencies = TRUE) {

    },

  )

}

local_create_lockfile_internal <- function(root, lockfile, lib, upgrade,

                                           dependencies) {

  )

}

#' Install packages based on a lock file

#'

#' Install a lock file that was created with [local_create_lockfile()].

#'

#' @param lockfile Path to the lock file.

#' @param lib Library to carry out the installation on.

#' @family lock files

#' @export

local_install_lockfile <- function(lockfile = "pkg.lock",

                                   lib = .libPaths()[1]) {

    },

  )

}

local_install_lockfile_internal <- function(lockfile, lib, start) {

  ## Remove some largeish columns that we don't really need any more

  ## One line summary of the install

}