import type { Integer, UnixTimestamp } from '@naturalcycles/js-lib/types'
import type { Pipeline } from '@naturalcycles/nodejs-lib/stream'
import type { CommonDBCreateOptions } from '../db.model.js'

/**
 * Common interface for Key-Value database implementations.
 *
 * @experimental
 */
export interface CommonKeyValueDB {
  /**
   * Manifest of supported features.
   */
  support: CommonKeyValueDBSupport

  /**
   * Check that DB connection is working properly.
   */
  ping: () => Promise<void>

  /**
   * Will do like `create table ...` for mysql.
   * Caution! dropIfExists defaults to false. If set to true - will actually DROP the table!
   */
  createTable: (table: string, opt?: CommonDBCreateOptions) => Promise<void>

  /**
   * Returns an array of tuples [key, value]. Not found values are not returned (no error is thrown).
   *
   * Currently it is NOT required to maintain the same order as input `ids`.
   */
  getByIds: (table: string, ids: string[]) => Promise<KeyValueDBTuple[]>

  deleteByIds: (table: string, ids: string[]) => Promise<void>

  saveBatch: (
    table: string,
    entries: KeyValueDBTuple[],
    opt?: CommonKeyValueDBSaveBatchOptions,
  ) => Promise<void>

  streamIds: (table: string, limit?: number) => Pipeline<string>
  streamValues: (table: string, limit?: number) => Pipeline<Buffer>
  streamEntries: (table: string, limit?: number) => Pipeline<KeyValueDBTuple>

  count: (table: string) => Promise<number>

  /**
   * Perform a batch of Increment operations.
   * Given entries array, increment each key of it (1st index of the tuple) by the given amount (2nd index of the tuple).
   *
   * Example:
   * [
   *   ['key1', 2],
   *   ['key2', 3],
   * ]
   * would increment `key1` by 2, and `key2` by 3.
   *
   * Returns the entries array with tuples of the same structure, with updated numbers.
   *
   * @experimental
   */
  incrementBatch: (table: string, entries: IncrementTuple[]) => Promise<IncrementTuple[]>
}

export type KeyValueDBTuple = [key: string, value: Buffer]

export type IncrementTuple = [key: string, value: Integer]

export interface CommonKeyValueDBSaveBatchOptions {
  /**
   * If set (and if it's implemented by the driver) - will set expiry TTL for each key of the batch.
   * E.g EXAT in Redis.
   */
  expireAt?: UnixTimestamp
}

/**
 * Manifest of supported features.
 */
export interface CommonKeyValueDBSupport {
  count?: boolean
  increment?: boolean
}

export const commonKeyValueDBFullSupport: CommonKeyValueDBSupport = {
  count: true,
  increment: true,
}