import { Exchange, Operation } from '@urql/core';

/** Input parameters for the {@link requestPolicyExchange}. */
interface Options {
    /** Predicate allowing you to selectively not upgrade `Operation`s.
     *
     * @remarks
     * When `shouldUpgrade` is set, it may be used to selectively return a boolean
     * per `Operation`. This allows certain `Operation`s to not be upgraded to a
     * `cache-and-network` policy, when `false` is returned.
     *
     * By default, all `Operation`s are subject to be upgraded.
     * operation to "cache-and-network".
     */
    shouldUpgrade?: (op: Operation) => boolean;
    /** The time-to-live (TTL) for which a request policy won't be upgraded.
     *
     * @remarks
     * The `ttl` defines the time frame in which the `Operation` won't be updated
     * with a `cache-and-network` request policy. If an `Operation` is sent again
     * and the `ttl` time period has expired, the policy is upgraded.
     *
     * @defaultValue `300_000` - 5min
     */
    ttl?: number;
}
/** Exchange factory that upgrades request policies to `cache-and-network` for queries outside of a defined `ttl`.
 *
 * @param options - An {@link Options} configuration object.
 * @returns the created request-policy {@link Exchange}.
 *
 * @remarks
 * The `requestPolicyExchange` upgrades query operations based on {@link Options.ttl}.
 * The `ttl` defines a timeframe outside of which a query's request policy is set to
 * `cache-and-network` to refetch it in the background.
 *
 * You may define a {@link Options.shouldUpgrade} function to selectively ignore some
 * operations by returning `false` there.
 *
 * @example
 * ```ts
 * requestPolicyExchange({
 *   // Upgrade when we haven't seen this operation for 1 second
 *   ttl: 1000,
 *   // and only upgrade operations that query the `todos` field.
 *   shouldUpgrade: op => op.kind === 'query' && op.query.definitions[0].name?.value === 'todos'
 * });
 * ```
 */
declare const requestPolicyExchange: (options: Options) => Exchange;

export { requestPolicyExchange };