/**
 * Shot thumbnail resolution.
 *
 * A shot can carry two stills:
 *
 *   • `thumbnailUrl`          — the reference frame supplied with the brief
 *                               (client still, batch upload, ext API). Editorial
 *                               data: only ever written by a human.
 *   • `generatedThumbnailUrl` — a frame promoted from a render export, either
 *                               automatically (projects with
 *                               `pipelineConfig.autoShotThumbnail`) or by hand.
 *
 * The reference always wins. Shows that arrive with stills look exactly as they
 * do today; shows that arrive without any get their empty grids filled from the
 * renders instead. Because the two live in different columns, a promotion can
 * never destroy the reference — clearing the generated one always falls back to
 * the brief.
 */
export interface ShotThumbnailFields {
  thumbnailUrl?: string | null;
  generatedThumbnailUrl?: string | null;
}

/** The still to display for a shot, or null when it has neither. */
export function shotThumbnail(shot: ShotThumbnailFields | null | undefined): string | null {
  return shot?.thumbnailUrl || shot?.generatedThumbnailUrl || null;
}

/** True when the displayed still came from a render rather than the brief. */
export function isGeneratedThumbnail(shot: ShotThumbnailFields | null | undefined): boolean {
  return !shot?.thumbnailUrl && !!shot?.generatedThumbnailUrl;
}

/**
 * Prisma `select` fragment for the two columns. Spread it wherever a query
 * already selects `thumbnailUrl` so the fallback has something to fall back to.
 */
export const shotThumbnailSelect = {
  thumbnailUrl: true,
  generatedThumbnailUrl: true,
} as const;