(** JMAP Invocation with Type-Safe Method Dispatch *)

(** Method witness type - encodes the relationship between
    method names and their argument/response types *)
type ('args, 'resp) method_witness =
  | Echo : (Ezjsonm.value, Ezjsonm.value) method_witness
  | Get : string -> ('a Jmap_standard_methods.Get.request, 'a Jmap_standard_methods.Get.response) method_witness
  | Changes : string -> (Jmap_standard_methods.Changes.request, Jmap_standard_methods.Changes.response) method_witness
  | Set : string -> ('a Jmap_standard_methods.Set.request, 'a Jmap_standard_methods.Set.response) method_witness
  | Copy : string -> ('a Jmap_standard_methods.Copy.request, 'a Jmap_standard_methods.Copy.response) method_witness
  | Query : string -> ('f Jmap_standard_methods.Query.request, Jmap_standard_methods.Query.response) method_witness
  | QueryChanges : string -> ('f Jmap_standard_methods.QueryChanges.request, Jmap_standard_methods.QueryChanges.response) method_witness

(** Type-safe invocation pairing method name with typed arguments *)
type _ invocation =
  | Invocation : {
      method_name : string;
      arguments : 'args;
      call_id : string;
      witness : ('args, 'resp) method_witness;
    } -> 'resp invocation

(** Existential wrapper for heterogeneous invocation lists *)
type packed_invocation =
  | Packed : 'resp invocation -> packed_invocation

(** Heterogeneous list of invocations (for Request.method_calls) *)
type invocation_list = packed_invocation list

(** Response invocation - pairs method name with typed response *)
type _ response_invocation =
  | ResponseInvocation : {
      method_name : string;
      response : 'resp;
      call_id : string;
      witness : ('args, 'resp) method_witness;
    } -> 'resp response_invocation

(** Packed response invocation *)
type packed_response =
  | PackedResponse : 'resp response_invocation -> packed_response

(** Heterogeneous list of responses (for Response.method_responses) *)
type response_list = packed_response list

(** Error response *)
type error_response = {
  error_type : Jmap_error.method_error;
  call_id : string;
}

(** Response can be either success or error *)
type method_response =
  | Success of packed_response
  | Error of error_response

(** Get method name from witness *)
val method_name_of_witness : ('a, 'r) method_witness -> string

(** Parse method name and return appropriate witness *)
val witness_of_method_name : string -> packed_invocation

(** Parse invocation from JSON array [method_name, arguments, call_id] *)
val of_json : Ezjsonm.value -> packed_invocation

(** Convert invocation to JSON *)
val to_json : 'resp invocation -> Ezjsonm.value

(** Extract response data as JSON from a packed response *)
val response_to_json : packed_response -> Ezjsonm.value