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Source file service_endpoints_json.ml

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open! Core
open! Import

let to_request ~json_version ~target_prefix endpoints =
  let loc = !Ast_helper.default_loc in
  let unit_to_json = [%expr fun () -> `Assoc []] in
  let content_type =
    (match json_version with
     | "1.0" | "1.1" -> sprintf "application/x-amz-json-%s" json_version
     | _ -> failwithf "unexpected jsonVersion: %s" json_version ())
    |> Ast_convenience.str
  in
  let expr =
    Endpoint.cases endpoints ~f:(fun endpoint ->
      let to_json =
        Endpoint.in_request_module endpoint "to_json"
        |> Option.value ~default:unit_to_json
      in
      let name = Endpoint.name endpoint in
      let target = Printf.ksprintf Ast_convenience.str "%s.%s" target_prefix name in
      [%expr
        let json = [%e to_json] req in
        let body = Awsm.Json.to_string json in
        let headers =
          Awsm.Http.Headers.of_list
            [ "Content-Type", [%e content_type]; "X-Amz-Target", [%e target] ]
        in
        Awsm.Http.Request.make ~body ~headers (method_of_endpoint endp)])
    |> Ast_helper.Exp.match_ [%expr endp]
  in
  [%stri let to_request (type i o e) (endp : (i, o, e) t) (req : i) = [%e expr]]
;;

let%expect_test "to_request" =
  [ Endpoint.create_test "Name1" ~request_module:(Some "Module1")
  ; Endpoint.create_test "Name2" ~request_module:(Some "Module2")
  ; Endpoint.create_test "Name3" ~request_module:None
  ]
  |> to_request ~json_version:"1.1" ~target_prefix:"TARGET_PREFIX"
  |> List.return
  |> Util.structure_to_string
  |> printf "%s%!";
  [%expect
    {|
    let to_request (type i) (type o) (type e) (endp : (i, o, e) t) (req : i) =
      match endp with
      | Name1 ->
          let json = Module1.to_json req in
          let body = Awsm.Json.to_string json in
          let headers =
            Awsm.Http.Headers.of_list
              [("Content-Type", "application/x-amz-json-1.1");
              ("X-Amz-Target", "TARGET_PREFIX.Name1")] in
          Awsm.Http.Request.make ~body ~headers (method_of_endpoint endp)
      | Name2 ->
          let json = Module2.to_json req in
          let body = Awsm.Json.to_string json in
          let headers =
            Awsm.Http.Headers.of_list
              [("Content-Type", "application/x-amz-json-1.1");
              ("X-Amz-Target", "TARGET_PREFIX.Name2")] in
          Awsm.Http.Request.make ~body ~headers (method_of_endpoint endp)
      | Name3 ->
          let json = (fun () -> `Assoc []) req in
          let body = Awsm.Json.to_string json in
          let headers =
            Awsm.Http.Headers.of_list
              [("Content-Type", "application/x-amz-json-1.1");
              ("X-Amz-Target", "TARGET_PREFIX.Name3")] in
          Awsm.Http.Request.make ~body ~headers (method_of_endpoint endp) |}]
;;

let of_response endpoints =
  let loc = !Ast_helper.default_loc in
  let body =
    Endpoint.cases endpoints ~f:(fun endpoint ->
      let error_of_json =
        Service_endpoints_common.make_error_expression
          ~loc
          ~label:"error_of_json"
          endpoint
      in
      match Endpoint.in_result_module endpoint "of_json" with
      | None -> [%expr return (Ok ())]
      | Some of_json ->
        [%expr
          match resp with
          | Error err -> handle_error err [%e error_of_json]
          | Ok resp ->
            Awsm.Http.Response.body_to_string state resp
            >>= fun jsons ->
            let json = Awsm.Json.from_string jsons in
            return (Ok ([%e of_json] json))])
    |> Ast_helper.Exp.match_ [%expr endpoint]
  in
  [%stri
    let of_response
      (type s i o e)
      (state : s Awsm.Http.Monad.t)
      (endpoint : (i, o, e) t)
      resp
      : ( (o, [ `AWS of e | `Transport of Awsm.Http.Io.Error.call ]) result, s )
      Awsm.Http.Monad.app
      =
      let ( >>= ) = state.Awsm.Http.Monad.bind in
      let return = state.Awsm.Http.Monad.return in
      let handle_error err error_of_json =
        (* FIXME: this error handling pattern appears over and over again. factor out. *)
        let generic_error () = return (Error (`Transport err)) in
        match err with
        | `Too_many_redirects -> generic_error ()
        | `Bad_response { Awsm.Http.Io.Error.code; body; x_amzn_error_type = _ } -> (
          match error_of_json, code >= 400 && code <= 599 with
          | Some error_of_json, true -> (
            let json = Awsm.Json.from_string body in
            match json |> Awsm.Json.Util.member_or_null "__type" with
            | `String error_type -> return (Error (`AWS (error_of_json error_type json)))
            | `Null -> generic_error ()
            | _ -> failwith (sprintf "Error '__type' did not have string type: %s" body))
          | None, _ | _, false -> generic_error ())
      in
      [%e body]
    ;;]
;;

let%expect_test "of_response" =
  [ Endpoint.create_test "Name1" ~result_module:(Some "ResultModule1")
  ; Endpoint.create_test "Name2" ~result_module:(Some "ResultModule2")
  ; Endpoint.create_test "Name3" ~result_module:None
  ]
  |> of_response
  |> List.return
  |> Util.structure_to_string
  |> printf "%s%!";
  [%expect
    {|
    let of_response (type s) (type i) (type o) (type e)
      (state : s Awsm.Http.Monad.t) (endpoint : (i, o, e) t) resp =
      (let (>>=) = state.Awsm.Http.Monad.bind in
       let return = state.Awsm.Http.Monad.return in
       let handle_error err error_of_json =
         let generic_error () = return (Error (`Transport err)) in
         match err with
         | `Too_many_redirects -> generic_error ()
         | `Bad_response
             { Awsm.Http.Io.Error.code = code; body; x_amzn_error_type = _ } ->
             (match (error_of_json, ((code >= 400) && (code <= 599))) with
              | (Some error_of_json, true) ->
                  let json = Awsm.Json.from_string body in
                  (match json |> (Awsm.Json.Util.member_or_null "__type") with
                   | `String error_type ->
                       return (Error (`AWS (error_of_json error_type json)))
                   | `Null -> generic_error ()
                   | _ ->
                       failwith
                         (sprintf "Error '__type' did not have string type: %s"
                            body))
              | (None, _) | (_, false) -> generic_error ()) in
       match endpoint with
       | Name1 ->
           (match resp with
            | Error err -> handle_error err None
            | Ok resp ->
                (Awsm.Http.Response.body_to_string state resp) >>=
                  ((fun jsons ->
                      let json = Awsm.Json.from_string jsons in
                      return (Ok (ResultModule1.of_json json)))))
       | Name2 ->
           (match resp with
            | Error err -> handle_error err None
            | Ok resp ->
                (Awsm.Http.Response.body_to_string state resp) >>=
                  ((fun jsons ->
                      let json = Awsm.Json.from_string jsons in
                      return (Ok (ResultModule2.of_json json)))))
       | Name3 -> return (Ok ()) : ((o,
                                      [ `AWS of e
                                      | `Transport of Awsm.Http.Io.Error.call ])
                                      result,
                                     s) Awsm.Http.Monad.app) |}]
;;

let make_structure_for_protocol (metadata : Botodata.metadata) data =
  let target_prefix =
    metadata.targetPrefix
    |> Option.value_exn ~message:"make_structure_for_protocol: no target prefix"
    |> Uri.to_string
  in
  let json_version =
    Option.value_exn ~message:"No metadata.jsonVersion" metadata.jsonVersion
  in
  [ to_request ~json_version ~target_prefix data; of_response data ]
;;
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