import {
  Either,
  type IEither,
  type ITraceable,
  LogLevel,
  Metric,
  PenguenoError,
  type PenguenoRequest,
  type RequestFilter,
  type ServerTrace,
  TraceUtil,
} from "@emprespresso/pengueno";

export interface JsonTransformer<R, ParsedJson = unknown> {
  (json: ITraceable<ParsedJson, ServerTrace>): IEither<PenguenoError, R>;
}

const ParseJsonMetric = Metric.fromName("JsonParse");
export const jsonModel =
  <MessageT>(
    jsonTransformer: JsonTransformer<MessageT>,
  ): RequestFilter<MessageT> =>
  (r: ITraceable<PenguenoRequest, ServerTrace>) =>
    r
        .bimap(TraceUtil.withFunctionTrace(jsonModel))
        .bimap(TraceUtil.withMetricTrace(ParseJsonMetric))
      .map((j) =>
        Either.fromFailableAsync<Error, MessageT>(() => j.get().json()).then(
          (either) =>
            either.mapLeft((errReason) => {
              j.trace.addTrace(LogLevel.WARN).trace(errReason);
              return new PenguenoError(
                "seems to be invalid JSON (>//<) can you fix?",
                400,
              );
            }),
        ),
      )
      .peek(
        TraceUtil.promiseify((traceableEither) =>
          traceableEither.get().fold(({ isLeft }) =>
              traceableEither.trace.trace(ParseJsonMetric[isLeft ? "failure" : "success"])
          ),
        ),
      )
      .map(
        TraceUtil.promiseify((traceableEitherJson) =>
          traceableEitherJson
            .get()
            .mapRight((j) => traceableEitherJson.move(j))
            .flatMap(jsonTransformer),
        ),
      )
      .get();