import deepmerge from 'deepmerge'

export interface PluginType {
  /** a unique identifier for your plugin */
  name: string
  /** extensions which should be resolved, including the leading period */
  extensions?: string[]
  /** fileName patterns which should be resolved, excluding the trailing extension */
  fileNames?: string[]
  /** Executed before require/import of config file */
  register?(filePath: string): Promise<void>
  /** Modify the config file before passing it along */
  transform?(module: any): Promise<any>
}

export interface Config<T = any> {
  /** An absolute path to a resolved configuration file */
  filePath: string
  /** The raw value of a resolved configuration file, before being merged with any `extends` configurations */
  raw: any
  /** The final, resolved value of a resolved configuration file */
  value: T
}

export interface LoadOptions<T = any> {
  /**
   * An exact filePath to a configuration file which should be loaded. If passed, this will keep proload from searching
   * for matching files.
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#filepath)
   */
  filePath?: string
  /**
   * The location from which to begin searching up the directory tree
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#cwd)
   */
  cwd?: string
  /**
   * If a configuration _must_ be resolved. If `true`, Proload will throw an error when a configuration is not found
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#mustExist)
   */
  mustExist?: boolean
  /**
   * If a resolved configuration file exports a factory function, this value will be passed as arguments to the function
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#context)
   */
  context?: any
  /**
   * A function to customize the `merge` behavior when a config with `extends` is encountered
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#merge)
   */
  // merge?(x: Partial<T>, y: Partial<T>): Partial<T>
  merge?: typeof deepmerge
  /**
   * A function to completely customize module resolution
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#accept)
   */
  accept?(fileName: string, context: { directory: string }): boolean | void
}

export interface ResolveOptions {
  /**
   * An exact filePath to a configuration file which should be loaded. If passed, this will keep proload from searching
   * for matching files.
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#filepath)
   */
  filePath?: string
  /**
   * The location from which to begin searching up the directory tree
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#cwd)
   */
  cwd?: string
  /**
   * If a configuration _must_ be resolved. If `true`, Proload will throw an error when a configuration is not found
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#mustExist)
   */
  mustExist?: boolean
  /**
   * A function to completely customize module resolution
   *
   * [Read the `@proload/core` docs](https://github.com/natemoo-re/proload/tree/main/packages/core#accept)
   */
  accept?(fileName: string, context: { directory: string }): boolean | void
}

export interface Load<T extends Record<any, any> = Record<any, any>> {
  /**
   * @param namespace The namespace which will be searched for the configuration file.
   *
   * For example, passing `"donut"` would resolve a files like `donut.config.js`, `donut.config.cjs`, and `donut.config.mjs` as well as a `package.json` with a `donut` property.
   *
   * @param opts Options to customize loader behavior
   */
  (namespace: string, opts?: LoadOptions<T>): Promise<Config<T> | undefined>
  use(plugins: Plugin[]): void
}