(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
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(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

open Error_monad

class type ['pr] gen_simple =
  object
    method call_service :
      'm 'p 'q 'i 'o.
      (([< Resto.meth] as 'm), 'pr, 'p, 'q, 'i, 'o) RPC_service.t ->
      'p ->
      'q ->
      'i ->
      'o tzresult Lwt.t
  end

class type ['pr] gen_streamed =
  object
    method call_streamed_service :
      'm 'p 'q 'i 'o.
      (([< Resto.meth] as 'm), 'pr, 'p, 'q, 'i, 'o) RPC_service.t ->
      on_chunk:('o -> unit) ->
      on_close:(unit -> unit) ->
      'p ->
      'q ->
      'i ->
      (unit -> unit) tzresult Lwt.t
  end

class type ['pr] gen =
  object
    inherit ['pr] gen_simple

    inherit ['pr] gen_streamed
  end

class type simple =
  object
    inherit [unit] gen_simple
  end

class type streamed =
  object
    inherit [unit] gen_streamed
  end

class type t =
  object
    inherit simple

    inherit streamed
  end

type ('o, 'e) rest =
  [ `Ok of 'o
  | `Conflict of 'e
  | `Error of 'e
  | `Forbidden of 'e
  | `Not_found of 'e
  | `Gone of 'e
  | `Unauthorized of 'e ]

type ('o, 'e) rest_result = ('o, 'e) rest tzresult

type generic_call_result =
  [ `Json of (Data_encoding.json, Data_encoding.json option) rest
  | `Binary of (string, string option) rest
  | `Other of (string * string) option * (string, string option) rest ]

class type generic =
  object
    inherit t

    method generic_media_type_call :
      RPC_service.meth ->
      ?body:Data_encoding.json ->
      Uri.t ->
      generic_call_result tzresult Lwt.t

    method base : Uri.t
  end

type error +=
  | Not_found of {meth : RPC_service.meth; uri : Uri.t}
  | Gone of {meth : RPC_service.meth; uri : Uri.t}
  | Generic_error of {meth : RPC_service.meth; uri : Uri.t}

let base = Uri.make ~scheme:"ocaml" ()

let not_found s p q =
  let {RPC_service.meth; uri; _} =
    RPC_service.forge_partial_request s ~base p q
  in
  Lwt_result_syntax.tzfail (Not_found {meth; uri})

let gone s p q =
  let {RPC_service.meth; uri; _} =
    RPC_service.forge_partial_request s ~base p q
  in
  Lwt_result_syntax.tzfail (Gone {meth; uri})

let error_with s p q =
  let {RPC_service.meth; uri; _} =
    RPC_service.forge_partial_request s ~base p q
  in
  Lwt_result_syntax.tzfail (Generic_error {meth; uri})

class ['pr] of_directory (dir : 'pr RPC_directory.t) =
  object
    method call_service
        : 'm 'p 'q 'i 'o.
          (([< Resto.meth] as 'm), 'pr, 'p, 'q, 'i, 'o) RPC_service.t ->
          'p ->
          'q ->
          'i ->
          'o tzresult Lwt.t =
      fun s p q i ->
        let open Lwt_syntax in
        let* r = RPC_directory.transparent_lookup dir s p q i in
        match r with
        | `Ok v | `OkChunk v -> return_ok v
        | `OkStream {next; shutdown} -> (
            let* o = next () in
            match o with
            | Some v ->
                shutdown () ;
                return_ok v
            | None ->
                shutdown () ;
                not_found s p q)
        | `Gone None -> gone s p q
        | `Not_found None -> not_found s p q
        | `Unauthorized (Some err)
        | `Forbidden (Some err)
        | `Gone (Some err)
        | `Not_found (Some err)
        | `Conflict (Some err)
        | `Error (Some err) ->
            return_error err
        | `Unauthorized None
        | `Error None
        | `Forbidden None
        | `Created _
        | `Conflict None
        | `No_content ->
            error_with s p q

    method call_streamed_service
        : 'm 'p 'q 'i 'o.
          (([< Resto.meth] as 'm), 'pr, 'p, 'q, 'i, 'o) RPC_service.t ->
          on_chunk:('o -> unit) ->
          on_close:(unit -> unit) ->
          'p ->
          'q ->
          'i ->
          (unit -> unit) tzresult Lwt.t =
      fun s ~on_chunk ~on_close p q i ->
        let open Lwt_syntax in
        let* r = RPC_directory.transparent_lookup dir s p q i in
        match r with
        | `OkStream {next; shutdown} ->
            let rec loop () =
              let* o = next () in
              match o with
              | None ->
                  on_close () ;
                  return_unit
              | Some v ->
                  on_chunk v ;
                  loop ()
            in
            let _ = loop () in
            return_ok shutdown
        | `Ok v | `OkChunk v ->
            on_chunk v ;
            on_close () ;
            return_ok (fun () -> ())
        | `Gone None -> gone s p q
        | `Not_found None -> not_found s p q
        | `Unauthorized (Some err)
        | `Forbidden (Some err)
        | `Gone (Some err)
        | `Not_found (Some err)
        | `Conflict (Some err)
        | `Error (Some err) ->
            return_error err
        | `Unauthorized None
        | `Error None
        | `Forbidden None
        | `Created _
        | `Conflict None
        | `No_content ->
            error_with s p q
  end

let make_call s (ctxt : #simple) = ctxt#call_service s

let make_call1 s ctxt x = make_call s ctxt ((), x)

let make_call2 s ctxt x y = make_call s ctxt (((), x), y)

let make_call3 s ctxt x y z = make_call s ctxt ((((), x), y), z)

type stopper = unit -> unit

let make_streamed_call s (ctxt : #streamed) p q i =
  let open Lwt_result_syntax in
  let stream, push = Lwt_stream.create () in
  let on_chunk v = push (Some v) and on_close () = push None in
  let* spill_all = ctxt#call_streamed_service s ~on_chunk ~on_close p q i in
  let close () =
    spill_all () ;
    (* Resto returns a function which is essentially
       [Lwt_stream.junk_while (Fun.const true)], but the function doesn't
       actually close the stream, nor does it uninstalls handlers. Hence we
       need to call [on_close] here.
       Before we close, we check wether the stream has been closed (by one of
       the values being junked). *)
    if Lwt_stream.is_closed stream then () else on_close ()
  in
  return (stream, close)

let () =
  let open Data_encoding in
  register_error_kind
    `Branch
    ~id:"RPC_context.Not_found"
    ~title:"RPC lookup failed"
    ~description:
      "RPC lookup failed. No RPC exists at the URL or the RPC tried to access \
       non-existent data."
    (obj2
       (req "method" RPC_service.meth_encoding)
       (req "uri" RPC_encoding.uri_encoding))
    ~pp:(fun ppf (meth, uri) ->
      Format.fprintf
        ppf
        "Did not find service: %s %a"
        (RPC_service.string_of_meth meth)
        Uri.pp_hum
        uri)
    (function Not_found {meth; uri} -> Some (meth, uri) | _ -> None)
    (fun (meth, uri) -> Not_found {meth; uri})

let () =
  let open Data_encoding in
  register_error_kind
    `Branch
    ~id:"RPC_context.Gone"
    ~title:"RPC lookup failed because of deleted data"
    ~description:
      "RPC lookup failed. Block has been pruned and requested data deleted."
    (obj2
       (req "method" RPC_service.meth_encoding)
       (req "uri" RPC_encoding.uri_encoding))
    ~pp:(fun ppf (meth, uri) ->
      Format.fprintf
        ppf
        "RPC lookup failed. Block has been pruned and requested data deleted, \
         service: %s %a"
        (RPC_service.string_of_meth meth)
        Uri.pp_hum
        uri)
    (function Gone {meth; uri} -> Some (meth, uri) | _ -> None)
    (fun (meth, uri) -> Gone {meth; uri})