Source file server_service.ml

open Base
open Lwt.Syntax
module Sig = Server_service_sig

let run_forever () =
  let p, _ = Lwt.wait () in
  p

let registered_endpoints : Server_core.endpoint list ref = ref []

(* This is all the Opium & Cohttp specific stuff, it has to
   live in the service implementation, so swapping web server services
   is easy *)
let res_to_opium res =
  match Http.Res.opium_res res with
  | Some res -> Lwt.return res
  | None -> (
      let headers = res |> Http.Res.headers |> Cohttp.Header.of_list in
      let headers =
        Cohttp.Header.add headers "Content-Type"
          (Http.Core.show_content_type (Http.Res.content_type res))
      in
      let code = res |> Http.Res.status |> Cohttp.Code.status_of_code in
      let headers =
        match Http.Res.redirect_path res with
        | Some path -> Cohttp.Header.add headers "Location" path
        | None -> headers
      in
      let cookie_headers =
        res |> Http.Res.cookies
        |> List.map ~f:(fun cookie ->
               Cohttp.Cookie.Set_cookie_hdr.make ~secure:false ~path:"/" cookie)
        |> List.map ~f:Cohttp.Cookie.Set_cookie_hdr.serialize
      in
      let headers =
        List.fold_left cookie_headers ~init:headers ~f:(fun headers (k, v) ->
            Cohttp.Header.add headers k v)
      in
      match Http.Res.body res with
      | None -> Opium.Std.respond ~headers ~code (`String "") |> Lwt.return
      | Some (Http.Res.String body) ->
          Opium.Std.respond ~headers ~code (`String body) |> Lwt.return
      | Some (File_path fname) ->
          let* cohttp_response =
            Cohttp_lwt_unix.Server.respond_file ~headers ~fname ()
          in
          Opium_kernel.Rock.Response.of_response_body cohttp_response
          |> Lwt.return )

let handler_to_opium_handler handler opium_req =
  let* handler = Core.Ctx.empty |> Http.Req.add_to_ctx opium_req |> handler in
  handler |> res_to_opium

let to_opium_builder route =
  let meth = Http.Route.meth route in
  let path = Http.Route.path route in
  let handler = Http.Route.handler route in
  let handler = handler_to_opium_handler handler in
  match meth with
  | Get -> Opium.Std.get path handler
  | Post -> Opium.Std.post path handler
  | Put -> Opium.Std.put path handler
  | Delete -> Opium.Std.delete path handler
  | All -> Opium.Std.all path handler

let endpoints_to_opium_builders endpoints =
  endpoints
  |> List.map ~f:(fun (prefix, routes, middleware_stack) ->
         routes
         |> List.map ~f:(Http.Route.prefix prefix)
         |> List.map ~f:(Middleware.apply_stack middleware_stack)
         |> List.map ~f:to_opium_builder)
  |> List.concat

module MakeOpium
    (Log : Log.Service.Sig.SERVICE)
    (CmdService : Cmd.Service.Sig.SERVICE) : Sig.SERVICE = struct
  let start_server _ =
    Log.debug (fun m -> m "WEB: Starting HTTP server");
    let app = Opium.Std.App.(empty |> port 3000 |> cmd_name "Sihl App") in
    let builders = endpoints_to_opium_builders !registered_endpoints in
    let app =
      List.fold ~f:(fun app builder -> builder app) ~init:app builders
    in
    (* We don't want to block here, the returned Lwt.t will never resolve *)
    let _ = Opium.Std.App.start app in
    run_forever ()

  let start ctx = Lwt.return ctx

  let stop _ = Lwt.return ()

  let lifecycle =
    Core.Container.Lifecycle.make "web-server" ~start ~stop
      ~dependencies:[ Log.lifecycle; CmdService.lifecycle ]

  let register_endpoints routes = registered_endpoints := routes
end