import { PolicyOptionVariants, Policy, ClientApi, ClientOptions, EnginePrototype, PolicyOptions } from '@hapi/catbox';

export type CachePolicyOptions<T> = PolicyOptionVariants<T> & {
    /**
     * @default '_default'
     */
    cache?: string | undefined;
    segment?: string | undefined;
};

/**
 * [See docs](https://github.com/hapijs/hapi/blob/master/API.md#-servercacheoptions)
 */
export interface ServerCache {
    /**
     * Provisions a cache segment within the server cache facility where:
     * @param options - [catbox policy](https://github.com/hapijs/catbox#policy) configuration where:
     * * expiresIn - relative expiration expressed in the number of milliseconds since the item was saved in the cache. Cannot be used together with expiresAt.
     * * expiresAt - time of day expressed in 24h notation using the 'HH:MM' format, at which point all cache records expire. Uses local time. Cannot be used together with expiresIn.
     * * generateFunc - a function used to generate a new cache item if one is not found in the cache when calling get(). The method's signature is async function(id, flags) where:
     * - `id` - the `id` string or object provided to the `get()` method.
     * - `flags` - an object used to pass back additional flags to the cache where:
     * - `ttl` - the cache ttl value in milliseconds. Set to `0` to skip storing in the cache. Defaults to the cache global policy.
     * * staleIn - number of milliseconds to mark an item stored in cache as stale and attempt to regenerate it when generateFunc is provided. Must be less than expiresIn.
     * * staleTimeout - number of milliseconds to wait before checking if an item is stale.
     * * generateTimeout - number of milliseconds to wait before returning a timeout error when the generateFunc function takes too long to return a value. When the value is eventually returned, it
     *     is stored in the cache for future requests. Required if generateFunc is present. Set to false to disable timeouts which may cause all get() requests to get stuck forever.
     * * generateOnReadError - if false, an upstream cache read error will stop the cache.get() method from calling the generate function and will instead pass back the cache error. Defaults to true.
     * * generateIgnoreWriteError - if false, an upstream cache write error when calling cache.get() will be passed back with the generated value when calling. Defaults to true.
     * * dropOnError - if true, an error or timeout in the generateFunc causes the stale value to be evicted from the cache. Defaults to true.
     * * pendingGenerateTimeout - number of milliseconds while generateFunc call is in progress for a given id, before a subsequent generateFunc call is allowed. Defaults to 0 (no blocking of
     *     concurrent generateFunc calls beyond staleTimeout).
     * * cache - the cache name configured in server.cache. Defaults to the default cache.
     * * segment - string segment name, used to isolate cached items within the cache partition. When called within a plugin, defaults to '!name' where 'name' is the plugin name. When called within a
     *     server method, defaults to '#name' where 'name' is the server method name. Required when called outside of a plugin.
     * * shared - if true, allows multiple cache provisions to share the same segment. Default to false.
     * @return Catbox Policy.
     * [See docs](https://github.com/hapijs/hapi/blob/master/API.md#-servercacheoptions)
     */
    <T, O extends CachePolicyOptions<T> = CachePolicyOptions<T>>(options: O): Policy<T, O>;

    /**
     * Provisions a server cache as described in server.cache where:
     * @param options - same as the server cache configuration options.
     * @return Return value: none.
     * Note that if the server has been initialized or started, the cache will be automatically started to match the state of any other provisioned server cache.
     * [See docs](https://github.com/hapijs/hapi/blob/master/API.md#-await-servercacheprovisionoptions)
     */
    provision(options: ServerOptionsCache): Promise<void>;
}

export type CacheProvider<T extends ClientOptions = ClientOptions> = EnginePrototype<any> | {
    constructor: EnginePrototype<any>;
    options?: T | undefined;
};

/**
 * hapi uses catbox for its cache implementation which includes support for common storage solutions (e.g. Redis,
 * MongoDB, Memcached, Riak, among others). Caching is only utilized if methods and plugins explicitly store their state in the cache.
 * [See docs](https://github.com/hapijs/hapi/blob/master/API.md#-cache)
 */
export interface ServerOptionsCache extends PolicyOptions<any> {
    /** catbox engine object. */
    engine?: ClientApi<any> | undefined;

    /**
     * a class or a prototype function
     */
    provider?: CacheProvider | undefined;

    /**
     * an identifier used later when provisioning or configuring caching for server methods or plugins. Each cache name must be unique. A single item may omit the name option which defines
     * the default cache. If every cache includes a name, a default memory cache is provisioned as well.
     */
    name?: string | undefined;

    /** if true, allows multiple cache users to share the same segment (e.g. multiple methods using the same cache storage container). Default to false. */
    shared?: boolean | undefined;

    /** (optional) string used to isolate cached data. Defaults to 'hapi-cache'. */
    partition?: string | undefined;

    /** other options passed to the catbox strategy used. Other options are only passed to catbox when engine above is a class or function and ignored if engine is a catbox engine object). */
    [s: string]: any;
}