Twitter API Client in OCaml (Nocrypto, base64, OCurl, ocaml-uri)

otwitter.ml

#use "topfind";;
#require "nocrypto";;
#require "base64";;
#require "curl";;
#require "uri";;

let debug = true;;

let baseUrl = "https://api.twitter.com/1.1/";;

type request_method =
  | POST
  | GET;;

let rm_to_string = function
  | POST -> "POST"
  | GET  -> "GET";;

let url_encode x = Uri.pct_encode ~component:`Userinfo x;;
let getUnixtime = Unix.time () |> int_of_float |> string_of_int;;
let starts_with s1 s2 =
  let len1 = String.length s1
  and len2 = String.length s2 in
  if len1 < len2 then false else
    let sub = String.sub s1 0 len2 in
    (sub = s2);;

let buildParams consumerKey accessToken aparams = [
  ("oauth_consumer_key", consumerKey);
  ("oauth_nonce", "abcdef");
  ("oauth_signature_method", "HMAC-SHA1");
  ("oauth_timestamp", getUnixtime);
  ("oauth_token", accessToken);
  ("oauth_version", "1.0")
] @ aparams |> List.map (fun (x, y) -> (x, url_encode y));;

let signature _method url consumerSecret accessTokenSecret params =
  let query = params |> List.map (fun (x, y) -> x ^ "=" ^ y) |> String.concat "&" in
  (if debug then Printf.printf "query : %s\n" query);
  let key   = [consumerSecret; accessTokenSecret] |> List.map (fun x -> url_encode x) |> String.concat "&" in
  (if debug then Printf.printf "key : %s\n" key);
  let base  = [_method; url; query] |> List.map (fun x -> url_encode x) |> String.concat "&" in
  (if debug then Printf.printf "base : %s\n" base);
  let oauthSignature = Nocrypto.Hash.SHA1.hmac ~key:(Cstruct.of_string key) (Cstruct.of_string base)
                       |> Cstruct.to_string |> B64.encode |> url_encode in
  (if debug then Printf.printf "oauthSignature : %s\n" oauthSignature);
  oauthSignature;;

let writeFunc s =
  begin
    Printf.printf "RECIVED!!!\n";
    Printf.printf "[writeFunc] %s\n" s;
    flush stdout;
    String.length s
  end;;

(* REST API *)
let request _method endpoint consumerKey consumerSecret accessToken accessTokenSecret aparams =
  let method_str      = rm_to_string _method in
  let params          = buildParams consumerKey accessToken aparams in
  let url             = baseUrl ^ endpoint in
  let oauth_signature = signature method_str url consumerSecret accessTokenSecret params in
  let xparams         = [("oauth_signature", oauth_signature)] @ params in
  let authorizeKeys   = xparams |> List.filter (fun (x, _) -> starts_with x "oauth_") in
  let authorize       = "Authorization: OAuth " ^ (authorizeKeys |> List.map (fun (x, y) -> x ^ "=" ^ y) |> String.concat ",") in
  let path            = xparams |> List.map (fun (x, y) -> x ^ "=" ^ y) |> String.concat "&" in

  if debug then
    begin
      Printf.printf "method: %s\n" @@ rm_to_string _method;
      Printf.printf "path: %s\n" path;
      Printf.printf "authorize: %s\n" authorize;
    end;

  let connection = Curl.init () in
  if _method == POST then
    begin
      Curl.setopt connection (Curl.CURLOPT_POST true);
      Curl.setopt connection (Curl.CURLOPT_POSTFIELDS path);
      Curl.setopt connection (Curl.CURLOPT_POSTFIELDSIZE (String.length path));
      Curl.set_url connection url
    end
  else
    begin
      let reqURL = url ^ "?" ^ path in
      Curl.set_url connection reqURL
    end;

  Curl.set_writefunction connection writeFunc;
  Curl.set_httpheader connection [authorize];
  Curl.perform connection;
  Curl.cleanup connection;;

(* STREAMING API *)
let stream url consumerKey consumerSecret accessToken accessTokenSecret  aparams =
  let params          = buildParams consumerKey accessToken aparams in
  let oauth_signature = signature (rm_to_string GET) url consumerSecret accessTokenSecret params in
  let xparams         = [("oauth_signature", oauth_signature)] @ params in
  let authorizeKeys   = xparams |> List.filter (fun (x, _) -> starts_with x "oauth_") in
  let authorize       = "Authorization: OAuth " ^ (authorizeKeys |> List.map (fun (x, y) -> x ^ "=" ^ y) |> String.concat ",") in
  let path            = xparams |> List.map (fun (x, y) -> x ^ "=" ^ y) |> String.concat "&" in

  if debug then
    begin
      Printf.printf "path: %s\n" path;
      Printf.printf "authorize: %s\n" authorize;
    end;

  let connection = Curl.init () 
  and reqURL = url ^ "?" ^ path in

  Curl.set_url connection reqURL;
  Curl.set_writefunction connection writeFunc;
  Curl.set_httpheader connection [authorize];
  Curl.setopt connection (Curl.CURLOPT_SSLVERIFYPEER false);
  Curl.set_timeout connection 0;
  Curl.perform connection;
  Curl.cleanup connection;;

let () =
  Curl.global_init Curl.CURLINIT_GLOBALALL;
  begin
    let consumerKey       = "Your Consumer Key"
    and consumerSecret    = "Your Consumer Secret"
    and accessToken       = "Your Access Token"
    and accessTokenSecret = "Your Access Token Secret"
    and _method  = POST
    and endpoint = "statuses/update.json"
    and params   = [("status", "Tweeting via OCaml!!!")] in

    (* REST API *)
    request _method endpoint consumerKey consumerSecret accessToken accessTokenSecret params ;

    (* STREAMING API *)
    stream "https://userstream.twitter.com/1.1/user.json" consumerKey consumerSecret accessToken accessTokenSecret []
  end;
  Curl.global_cleanup ()
;;