open Lwt;

open Cohttp;

open Cohttp_lwt_unix;

type response = {

body: string,

status: int,

};

let body = response => response.body;

let status = response => response.status;

exception Not_found(response);

let throwOnKnownErrors =

fun

| {status: 404, _} as r => Lwt.fail(Not_found(r))

| r => Lwt.return(r);

let rec makeRequest = url =>

Uri.of_string(url)

|> Cohttp_lwt_unix.Client.get

>>= (

((resp, body)) => {

let status = resp |> Response.status;

let code_of_status = status |> Code.code_of_status;

let location = resp |> Response.headers |> Header.get_location;

switch (Code.is_redirection(code_of_status), location) {

| (true, Some(uri)) => makeRequest(Uri.to_string(uri))

| _ =>

let%lwt body = body |> Cohttp_lwt.Body.to_string;

throwOnKnownErrors({status: code_of_status, body});

};

}

);

let download = (url, ~into) => {

let%lwt _ =

makeRequest(url) >>= (({body, _}) => Fs.writeFile(into, body));

Lwt.return();

};