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.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().mapBoth(
          () => traceableEither.trace.trace(ParseJsonMetric.failure),
          () => traceableEither.trace.trace(ParseJsonMetric.success),
        )
      ),
    )
    .map(
      TraceUtil.promiseify((traceableEitherJson) =>
        traceableEitherJson.get()
          .mapRight(traceableEitherJson.move)
          .flatMap(jsonTransformer)
      ),
    )
    .get();