import * as TE from "fp-ts/lib/TaskEither";
import { pipe, identity } from "fp-ts/lib/function";
import type { Job, Schedule } from "../canary";
import * as RA from "fp-ts/lib/ReadonlyArray";
import * as T from "fp-ts/lib/Task";
import type { Separated } from "fp-ts/lib/Separated";

interface ScheduledJob {
  id: string;
  execute: () => TE.TaskEither<Error, boolean>;
  at: Date;
  schedule: Schedule;
}

type SchedulerState = ReadonlyArray<ScheduledJob>;

const executeAll = (
  jobs: ReadonlyArray<TE.TaskEither<Error, boolean>>,
): T.Task<Separated<ReadonlyArray<Error>, ReadonlyArray<boolean>>> =>
  pipe(jobs, RA.wilt(T.ApplicativePar)(identity));

export const schedulerLoop =
  (state: SchedulerState): TE.TaskEither<Error, void> =>
  () => {
    const loop = (
      currentState: SchedulerState,
      time: Date,
    ): TE.TaskEither<Error, void> =>
      pipe(
        currentState,
        RA.filter((job) => job.at <= time),
        RA.map(({ execute }) => execute()),
        executeAll,
        //T.delay(1000), // Delay for 1 second
        //        map((newState) => loop(newState)),
      );

    return loop(state)();
  };