import type { SyncSchedulerSettings } from "../lib/settings";
import {
  buildScheduleView,
  type ChannelEntry,
  type ChannelScheduleView,
} from "../jobs/syncScheduler";
import type {
  SchedulerRun,
  SchedulerState,
} from "../jobs/syncSchedulerState";
import type { ChannelPriority } from "../lib/channelPriority";

// THE READ-ONLY "SYNC SCHEDULE" VIEW.
//
// Shared by the SSR page and the /api/scheduler/status poll so the two can
// never drift. Everything it needs arrives as an argument: the settings, the
// scheduler state read off disk, the channel list, the clock and the effective
// heartbeat cadence. `buildScheduleView` is a pure projection in jobs/ and is
// the one definition of "when is this channel next due" — the console asks the
// scheduler rather than re-deriving it.

export type SchedulerStatusPayload = {
  now: number;
  scheduler: SyncSchedulerSettings;
  channels: ChannelScheduleView[];
  runs: SchedulerRun[];
  // Effective internal-heartbeat cadence in seconds (env override applied), so
  // the UI can show whether ticks are internally driven. 0 = no internal timer
  // (awaiting an external cron heartbeat).
  heartbeatSeconds: number;
};

export type SchedulerStatusInputs = {
  settings: {
    syncScheduler: SyncSchedulerSettings;
    channelPriority: ChannelPriority;
  };
  now: number;
  state: SchedulerState;
  channels: ReadonlyArray<ChannelEntry>;
  // Resolved by the shell: it reads the env override and imports the heartbeat
  // module, which owns a RUNNER. A view never names a runner.
  heartbeatSeconds: number;
};

export function buildSchedulerStatusPayload(
  inputs: SchedulerStatusInputs,
): SchedulerStatusPayload {
  const { settings, now, state, channels, heartbeatSeconds } = inputs;
  const view = buildScheduleView({
    channels,
    scheduler: settings.syncScheduler,
    state,
    now,
    priority: settings.channelPriority,
  });
  return {
    now,
    scheduler: settings.syncScheduler,
    channels: view,
    runs: state.runs,
    heartbeatSeconds,
  };
}