/** Reasons a credit transaction can be attributed to (drives icons/filters). */
export type CreditReason =
  | 'CONTENT_GEN'
  | 'PRODUCT_SCAN'
  | 'INLINE_FIX'
  | 'GAP_VERIFICATION'
  | 'KB_DOC'
  | 'ARTICLE_GEN'
  | 'ARTICLE_IMAGE'
  | 'VISIBILITY_SCAN';

/** A single ledger entry. `amount` is negative for consumption. */
export interface ICreditTransaction {
  id: string;
  user_id: string;
  amount: number;
  reason: CreditReason | string;
  ref_type: string | null;
  ref_id: string | null;
  balance_after: number;
  note: string | null;
  created_at: string;
}

/** Root-level response from GET /v2/credits/transactions. */
export interface ICreditTransactionsResponse {
  message: string;
  transactions: ICreditTransaction[];
  total: number;
  success: boolean;
  page: number;
  total_pages: number;
}

/** Current credits snapshot (from the user payload or GET /v2/credits/balance). */
export interface ICreditBalance {
  balance?: number;
  granted?: number;
  used?: number;
}

export const EMPTY_CREDIT_HISTORY: ICreditTransactionsResponse = {
  message: '',
  transactions: [],
  total: 0,
  success: true,
  page: 1,
  total_pages: 1,
};

/** Page-size bounds enforced by the API (1–100, default 25). */
export const CREDIT_HISTORY_PAGE_SIZE = 25;

/**
 * Validates a YYYY-MM-DD value for the transactions endpoints.
 * Returns the value when well-formed, undefined otherwise.
 */
export function creditDateParam(
  value: string | null | undefined
): string | undefined {
  return value && /^\d{4}-\d{2}-\d{2}$/.test(value) ? value : undefined;
}