import {EventEmitter} from 'events';

type WithRequiredProperties<T, K extends keyof T> = T & Required<Pick<T, K>>;

declare class Keyv<Value = any, Options extends Record<string, any> = Record<string, unknown>> extends EventEmitter {
    /**
     * `this.opts` is an object containing at least the properties listed
     * below. However, `Keyv.Options` allows arbitrary properties as well.
     * These properties can be specified as the second type parameter to `Keyv`.
     */
    opts: WithRequiredProperties<
    Keyv.Options<Value>,
    'deserialize' | 'namespace' | 'serialize' | 'store' | 'uri'
    > &
    Options;

    /**
     * @param opts The options object is also passed through to the storage adapter. Check your storage adapter docs for any extra options.
     */
    constructor(options?: Keyv.Options<Value> & Options);
    /**
     * @param uri The connection string URI.
     *
     * Merged into the options object as options.uri.
     * @param opts The options object is also passed through to the storage adapter. Check your storage adapter docs for any extra options.
     */
    constructor(uri?: string, options?: Keyv.Options<Value> & Options);

    /** Returns the value. */
    get(key: string, options?: {raw?: false}): Promise<Value | undefined>;
    /** Returns the raw value. */
    get(key: string, options: {raw: true}): Promise<Keyv.DeserializedData<Value> | undefined>;

    /** Returns an array of values. Uses `store.getMany` if it exists, otherwise uses parallel calls to `store.get`. */
    get(key: string[], options?: {raw?: false}): Promise<Array<Value | undefined>>;
    /** Returns an array of raw values. Uses `store.getMany` if it exists, otherwise uses parallel calls to `store.get`. */
    get(key: string[], options: {raw: true}): Promise<Array<Keyv.DeserializedData<Value> | undefined>>;

    /**
     * Set a value.
     *
     * By default keys are persistent. You can set an expiry TTL in milliseconds.
     */
    set(key: string, value: Value, ttl?: number): Promise<true>;
    /**
     * Deletes an entry.
     *
     * Returns `true` if the key existed, `false` if not.
     */
    delete(key: string | string[]): Promise<boolean>;
    /** Delete all entries in the current namespace. */
    clear(): Promise<void>;
    /** Check if key exists in current namespace. */
    has(key: string): Promise<boolean>;
    /** Iterator */
    iterator(namespace?: string): AsyncGenerator<any, void, any>;
    /**
     * Closes the connection.
     *
     * Returns `undefined` when the connection closes.
     */
    disconnect(): Promise<void>;
}

declare namespace Keyv {
    interface Options<Value> {
        [key: string]: any;

        /** Namespace for the current instance. */
        namespace?: string | undefined;
        /** A custom serialization function. */
        serialize?: ((data: DeserializedData<Value>) => string) | undefined;
        /** A custom deserialization function. */
        deserialize?: ((data: string) => DeserializedData<Value> | undefined) | undefined;
        /** The connection string URI. */
        uri?: string | undefined;
        /** The storage adapter instance to be used by Keyv. */
        store?: Store<string | undefined> | undefined;
        /** Default TTL. Can be overridden by specififying a TTL on `.set()`. */
        ttl?: number | undefined;
        /** Specify an adapter to use. e.g `'redis'` or `'mongodb'`. */
        adapter?: 'redis' | 'mongodb' | 'mongo' | 'sqlite' | 'postgresql' | 'postgres' | 'mysql' | undefined;
        /** Enable compression option **/
        compression?: CompressionAdapter | undefined;
    }

    interface CompressionAdapter {
        compress(value: any, options?: any): Promise<any>;
        decompress(value: any, options?: any): Promise<any>;
        serialize(value: any): Promise<any>;
        deserialize(value: any): Promise<any>;
    }

    interface DeserializedData<Value> {
        value: Value; expires: number | undefined;
    }

    type StoredData<Value> = DeserializedData<Value> | string | undefined;

    interface Store<Value> {
        get(key: string): Value | Promise<Value | undefined> | undefined;
        set(key: string, value: Value, ttl?: number): any;
        delete(key: string): boolean | Promise<boolean>;
        clear(): void | Promise<void>;
        has?(key: string): boolean | Promise<boolean>;
        getMany?(
            keys: string[]
        ): Array<StoredData<Value>> | Promise<Array<StoredData<Value>>> | undefined;
    }
}

export = Keyv;