/**
 * Review photo-strip lineup (REVIEW-5 / PUBLISH-45). Pure logic so keep/remove,
 * reorder, and the submission minimum are unit-testable without a browser.
 *
 * The owner taps photos to keep/remove and drags to reorder; the LEFTMOST kept
 * photo is the primary (Woo cover). Submission minimum: at least one clean
 * calibration photo AND its dimension-overlay copy (REVIEW-5). Batch photos
 * are optional.
 */

export type PhotoRole = 'calibration' | 'overlay' | 'batch';

export interface LineupItem {
  id: string;
  role: PhotoRole;
  isCalibration: boolean;
  /** True = the owner keeps this photo in the submission. */
  kept: boolean;
}

/**
 * The submission role of a photo: the calibration photo is `calibration`; a
 * photo carrying its dimension-overlay copy (`processedBlob`) is `overlay`;
 * everything else is `batch`. Single definition of the role rule — the review
 * strip (ReviewForm) and the server photo upload (photoUpload) both derive from
 * this so they can never disagree.
 */
export function photoRole(id: string, calibrationPhotoId: string, hasProcessed: boolean): PhotoRole {
  if (id === calibrationPhotoId) return 'calibration';
  if (hasProcessed) return 'overlay';
  return 'batch';
}

/** The kept photos in their current (left→right) order; the first is the primary. */
export function keptInOrder(items: LineupItem[]): LineupItem[] {
  return items.filter((it) => it.kept);
}

/** Move an item from one index to another (drag-reorder). Returns a new array. */
export function moveItem<T>(arr: T[], from: number, to: number): T[] {
  if (from === to || from < 0 || to < 0 || from >= arr.length || to >= arr.length) {
    return arr;
  }
  const next = arr.slice();
  const [item] = next.splice(from, 1);
  next.splice(to, 0, item);
  return next;
}

/**
 * Whether the kept lineup meets the submission minimum (REVIEW-5): at least one
 * clean calibration photo and one dimension-overlay copy. Returns the missing
 * role(s) so the UI can name them in a nudge.
 */
export function missingMinimums(items: LineupItem[]): PhotoRole[] {
  const kept = items.filter((it) => it.kept);
  const missing: PhotoRole[] = [];
  if (!kept.some((it) => it.role === 'calibration')) missing.push('calibration');
  if (!kept.some((it) => it.role === 'overlay')) missing.push('overlay');
  return missing;
}

/** True when the kept lineup is publishable from a photo standpoint. */
export function lineupValid(kept: LineupItem[]): boolean {
  return missingMinimums(kept).length === 0;
}

/** A short owner-facing label for a role (used in the minimum nudge). */
export function roleLabel(role: PhotoRole): string {
  if (role === 'calibration') return 'a clean photo';
  if (role === 'overlay') return 'its dimension-overlay copy';
  return 'a batch photo';
}

/**
 * Resolve the <img> src for a strip photo. A fresh in-memory blob must become
 * a `blob:` object URL — assigning a raw Blob renders a broken image. With no
 * usable blob, fall back to the stored endpoint.
 *
 * Pure + injectable: `createObjectUrl` defaults to `URL.createObjectURL` so it
 * is unit-testable without a real DOM/Blob.
 */
export function resolvePhotoUrl(
  blob: Blob | null,
  endpoint: string,
  createObjectUrl: (b: Blob) => string = (b) => URL.createObjectURL(b),
): string {
  if (blob && blob.size > 0) return createObjectUrl(blob);
  return endpoint;
}