# http_save.ludic — Http.save_to / received / expected: a download streamed to a file.
#
#   let h = Http.open("GET", "https://example.com/big.nupkg")
#   Http.save_to(h, "big.nupkg.part")      # before send: the body goes to the file
#   Http.send(h)
#   handler Update {
#     if Http.poll(h) < 0 {                # pending: a progress bar
#       draw_bar(Http.received(h), Http.expected(h))   # expected is -1 until known
#     }
#   }
#
# Run as: http_save <source file> <destination file>. The source is read through a
# file:// URL (macOS reads those with the same streaming transport), so the check needs
# no network: it copies the file and prints the status, the byte counts and whether the
# body stayed out of memory. `cmp` the two files afterwards.
program HttpSave {
  function bi(b: bool) -> int { if b { return 1 };  return 0 }

  entry {
    let src = Os.arg(1)
    let dst = Os.arg(2)
    let h = Http.open("GET", `file://{src}`)
    Http.save_to(h, dst)
    let before = Http.received(h)
    let unknown = Http.expected(h)
    Http.send(h)
    var st = Http.poll(h)
    while st < 0 { st = Http.poll(h) }
    let n = Http.received(h)
    print(`{before} {unknown} {st} {bi(n > 0)} {bi(Http.expected(h) == n)} {bi(Http.body_len(h) == n)} {bi(Http.text(h) == null)}`)
    Http.free(h)
  }
}