import minimist = require('minimist')
import ChainableConfig = require('webpack-chain')
import webpack = require('webpack')
import WebpackDevServer = require('webpack-dev-server')
import express = require('express') // @types/webpack-dev-server depends on @types/express
import { ProjectOptions, ConfigFunction } from './ProjectOptions'

type RegisterCommandFn = (args: minimist.ParsedArgs, rawArgv: string[]) => any

type RegisterCommandOpts = Partial<{
  description: string
  usage: string
  options: {
    [flags: string]: string
  }
  details: string
}>

type WebpackChainFn = (chainableConfig: ChainableConfig) => void

type webpackRawConfigFn = ((config: webpack.Configuration) => webpack.Configuration | void) | webpack.Configuration

type DevServerConfigFn = (app: express.Application, server: WebpackDevServer) => void

interface CacheConfig {
  cacheDirectory: string
  cacheIdentifier: string
}
declare class PluginAPI {
  id: string

  service: any

  readonly version: string

  assertVersion(range: number | string): void

  /**
   * Current working directory.
   */
  getCwd(): string

  /**
   * Resolve path for a project.
   *
   * @param  _path - Relative path from project root
   * @return The resolved absolute path.
   */
  resolve(_path: string): string

  /**
   * Check if the project has a given plugin.
   *
   * @param id - Plugin id, can omit the (@vue/|vue-|@scope/vue)-cli-plugin- prefix
   * @return `boolean`
   */
  hasPlugin(id: string): boolean

  /**
   * Register a command that will become available as `vue-cli-service [name]`.
   *
   * @param name
   * @param  [opts]
   * @param  fn
   */
  registerCommand(name: string, fn: RegisterCommandFn): void
  registerCommand(name: string, opts: RegisterCommandOpts, fn: RegisterCommandFn): void

  /**
   * Register a function that will receive a chainable webpack config
   * the function is lazy and won't be called until `resolveWebpackConfig` is
   * called
   *
   * @param fn
   */
  chainWebpack(fn: WebpackChainFn): void

  /**
   * Register
   * - a webpack configuration object that will be merged into the config
   * OR
   * - a function that will receive the raw webpack config.
   *   the function can either mutate the config directly or return an object
   *   that will be merged into the config.
   *
   * @param fn
   */
  configureWebpack(fn: webpackRawConfigFn): void

  /**
   * Register a dev serve config function. It will receive the express `app`
   * instance of the dev server.
   *
   * @param fn
   */
  configureDevServer(fn: DevServerConfigFn): void

  /**
   * Resolve the final raw webpack config, that will be passed to webpack.
   *
   * @param [chainableConfig]
   * @return Raw webpack config.
   */
  resolveWebpackConfig(chainableConfig?: ChainableConfig): webpack.Configuration

  /**
   * Resolve an intermediate chainable webpack config instance, which can be
   * further tweaked before generating the final raw webpack config.
   * You can call this multiple times to generate different branches of the
   * base webpack config.
   * See https://github.com/mozilla-neutrino/webpack-chain
   *
   * @return ChainableWebpackConfig
   */
  resolveChainableWebpackConfig(): ChainableConfig

  /**
   * Generate a cache identifier from a number of variables
   */
  genCacheConfig(id: string, partialIdentifier: any, configFiles?: string | string[]): CacheConfig
}

/**
 * Service plugin serves for modifying webpack config,
 * creating new vue-cli service commands or changing existing commands
 *
 * @param api - A PluginAPI instance
 * @param options - An object containing project local options specified in vue.config.js,
 *    or in the "vue" field in package.json.
 */
type ServicePlugin = (
  api: PluginAPI,
  options: ProjectOptions
) => any

export { ProjectOptions, ServicePlugin, PluginAPI }
type UserConfig = ProjectOptions | ConfigFunction
export function defineConfig(config: UserConfig): UserConfig