import type { PaymentClientSdk } from 'brainerce';

/**
 * Render-mode negotiation: predict which mode a payment intent will come back
 * with, so the checkout can pass the matching return URL BEFORE the intent
 * exists. An iframe provider returns the shopper inside the frame, to a
 * same-origin transition page (`/payment-complete`) that posts to the parent;
 * a redirect provider returns them straight to `/order-confirmation`.
 *
 * This is the platform's own rule, verbatim:
 *  1. no preference                     -> the provider's default (`renderType`)
 *  2. preference listed in displayModes -> the preference
 *  3. preference not listed             -> the provider's default
 *  4. displayModes absent (legacy)      -> treated as `[renderType]`
 *
 * The SDK exports the same function as `resolveRenderType` from 'brainerce'.
 * This local copy exists because scaffolded stores pin an exact SDK version
 * that must be at least seven days old on npm (see cli-shared/versions.ts),
 * and the version carrying the export is younger than that. Replace this
 * file's body with `export { resolveRenderType } from 'brainerce'` once the
 * pin reaches it.
 */

export type PreferredRenderType = 'redirect' | 'iframe';

/**
 * The mode this storefront asks the platform for, or `undefined` to take each
 * provider's default. Set to `'iframe'` only if the payment step has a frame
 * to render into AND the provider's iframe has been verified on a real
 * checkout; set to `'redirect'` to keep every provider on a full-page
 * redirect. The platform only honours a mode the provider declares, and the
 * checkout always branches on the `renderType` that comes BACK, so a wrong
 * preference degrades to the provider default rather than breaking payment.
 */
export const PREFERRED_RENDER_MODE: PreferredRenderType | undefined = undefined;

type ProviderSdk = Pick<PaymentClientSdk, 'renderType'> & {
  /** Every mode the provider can serve. Sent by the platform; older SDK types omit it. */
  displayModes?: PaymentClientSdk['renderType'][];
};

export function resolveRenderType(
  sdk: ProviderSdk | null | undefined,
  preferred?: PreferredRenderType
): PaymentClientSdk['renderType'] {
  if (!sdk) return 'redirect';
  const declared = sdk.displayModes?.length ? sdk.displayModes : [sdk.renderType];
  return preferred && declared.includes(preferred) ? preferred : sdk.renderType;
}