export type ChangeAction = "baseline" | "created" | "updated" | "deleted";

/**
 * Maps the backend audit `operation` to the displayed {@link ChangeAction}.
 */
export const OPERATION_TO_ACTION: Record<string, ChangeAction> = {
  create: "created",
  update: "updated",
  delete: "deleted",
  baseline: "baseline",
};

/**
 * A single field's before/after, in raw database format (enum ids, ISO date
 * strings, entity-reference ids — hydrated for display via the schema, see
 * RecordDiffComponent).
 */
export interface FieldChange {
  field: string;
  /** previous raw value; empty/undefined for additions (created/baseline) */
  from: unknown;
  /** new raw value */
  to: unknown;
}

/**
 * One normalized change-history entry for an entity, derived from a raw audit
 * document.
 */
export interface ChangeEvent {
  /** the audit document `_id` */
  id: string;
  /** server-set time of the change */
  at: Date;
  /** authenticated author (user-entity id or name) recorded by the backend */
  by: string;
  action: ChangeAction;
  /** changed fields; empty for `deleted`, all-additions for `created`/`baseline` */
  changes: FieldChange[];
  /** optional contextual note (e.g. the baseline explanation) */
  note?: string;
}

/**
 * Explanation for the synthetic "initial snapshot" entry, shown both inline in
 * its diff and as the badge tooltip (single source of truth).
 */
export const BASELINE_NOTE = $localize`:Change history baseline note:Record state captured when change logging was enabled. Edits made before this point aren't recorded.`;