// What skipping an intro/credits marker does. An item can carry several credits blocks — mid- and
// post-credit scenes play between them — so only the block that ends the item moves on to the next
// one: the block Plex flags `final`, else the last one. Every other credits block is skipped like an
// intro, to its own end. And only an end Plex itself vouches for is left on its own (the credits
// auto-skip); an end inferred from the list waits for the viewer's Skip — the stretch after it may
// still be the show.
import type { PlexMarker } from "./api";

/** `leaves`: skipping it moves on to the next item (else: jumps to its end). `auto`: the auto-skip
 *  setting may act on it without the viewer. */
export interface MarkerSkip {
  leaves: boolean;
  auto: boolean;
}

function endCredits(markers: readonly PlexMarker[]): PlexMarker | undefined {
  const credits = markers.filter((m) => m.type === "credits");
  return (
    credits.find((m) => m.final) ??
    credits.reduce<PlexMarker | undefined>(
      (last, m) => (last && last.start_s > m.start_s ? last : m),
      undefined,
    )
  );
}

export function markerSkip(marker: PlexMarker, markers: readonly PlexMarker[]): MarkerSkip {
  if (marker.type === "intro") return { leaves: false, auto: true };
  // By offset, not identity: a refetched list hands back equal-but-new objects.
  const end = endCredits(markers);
  const leaves = end != null && end.start_s === marker.start_s && end.end_s === marker.end_s;
  return { leaves, auto: leaves && marker.final };
}