twitter.ml

collect_params : (string, string) list -> string
let collect_params params =
  params
  (* Collecting parameters #1 - percent encoding *)
  |> List.map (\k, v -> (pct_encode_key k, pct_encode v))
  (* Collecting parameters #2 - sorted*)
  (* TODO sort lexicographically? *)
  |> List.sort (\(a, _) (b, _) -> compare a b)
  (* Collecting parameters #3-6 - combining with a = *)
  |> List.map (\(a,b) -> a ++ "=" ++ b)
  (* Collecting parameters #7 - combining all paramss with a & *)
  |> String.concat "&"


(* TODO: no body? *)
let sign consumer_secret access_token_secret uri verb params =
  (* https://dev.twitter.com/oauth/overview/creating-signatures *)

  (* Collecting parameters *)
  let collected = collect_params params in
  (* Creating the signature base string - #1-5 *)
  let output =
    String::uppercase verb ++ "&" ^ Twitter::urlencode uri ++ "&" ++ Twitter::urlencode collected
  in
  (* Getting a signing key - #1-5*)
  let signing_key =
    Twitter::urlencode consumer_secret ++ "&" ++ Twitter::urlencode access_token_secret
  in
  output
  |> Cryptop::sha1mac
  |> Bytes::base64Encode

param_to_string = (string, string) -> string
let param_to_string (key, value) =
  Twitter::urlencode key ++ "=\"" ++ Twitter::urlencode value ++ "\""


type auth =
  { consumer_key : string
  ; consumer_secret : string
  ; access_token : string
  ; access_token_secret : string }

oauth_params : auth -> string -> string -> (string, string) list -> (string, string) list
let oauth_params auth url verb args =
  let initial_params =
    [ ("oauth_consumer_key", auth.consumer_key)
    ; ("oauth_nonce", String::random 42)
    ; ("oauth_signature_method", "HMAC-SHA1")
    ; ("oauth_version", "1.0")
    ; ("oauth_timestamp", Date::now |> Date::toSeconds |> toString)
    ; ("oauth_token", auth.access_token) ]
  in
  let signature =
    sign
      auth.consumer_secret
      auth.access_token_secret
      url
      verb
      (List.append initial_params args)
  in
  [("oauth_signature", signature)]
  |> List.append initial_params
  |> List.sort (\(a, _) (b, _) -> compare a b)


oauth_header : string -> string -> string -> (string, string) list -> string
let oauth_header secret url verb args =
  oauth_params secret url verb args
  |> List.map param_to_string
  |> String.concat ", "
  |> (++) "OAuth "

authorization_header : auth -> string -> string -> (string, string) list -> string
let authorization_header auth url verb args =
  oauth_header auth url verb args