'use strict'

const ModuleError = require('module-error')
const formats = new Set(['buffer', 'view', 'utf8'])

/**
 * @template TIn, TFormat, TOut
 * @abstract
 */
class Encoding {
  /**
   * @param {IEncoding<TIn,TFormat,TOut>} options
   */
  constructor (options) {
    /** @type {(data: TIn) => TFormat} */
    this.encode = options.encode || this.encode

    /** @type {(data: TFormat) => TOut} */
    this.decode = options.decode || this.decode

    /** @type {string} */
    this.name = options.name || this.name

    /** @type {string} */
    this.format = options.format || this.format

    if (typeof this.encode !== 'function') {
      throw new TypeError("The 'encode' property must be a function")
    }

    if (typeof this.decode !== 'function') {
      throw new TypeError("The 'decode' property must be a function")
    }

    this.encode = this.encode.bind(this)
    this.decode = this.decode.bind(this)

    if (typeof this.name !== 'string' || this.name === '') {
      throw new TypeError("The 'name' property must be a string")
    }

    if (typeof this.format !== 'string' || !formats.has(this.format)) {
      throw new TypeError("The 'format' property must be one of 'buffer', 'view', 'utf8'")
    }

    if (options.createViewTranscoder) {
      this.createViewTranscoder = options.createViewTranscoder
    }

    if (options.createBufferTranscoder) {
      this.createBufferTranscoder = options.createBufferTranscoder
    }

    if (options.createUTF8Transcoder) {
      this.createUTF8Transcoder = options.createUTF8Transcoder
    }
  }

  get commonName () {
    return /** @type {string} */ (this.name.split('+')[0])
  }

  /** @return {BufferFormat<TIn,TOut>} */
  createBufferTranscoder () {
    throw new ModuleError(`Encoding '${this.name}' cannot be transcoded to 'buffer'`, {
      code: 'LEVEL_ENCODING_NOT_SUPPORTED'
    })
  }

  /** @return {ViewFormat<TIn,TOut>} */
  createViewTranscoder () {
    throw new ModuleError(`Encoding '${this.name}' cannot be transcoded to 'view'`, {
      code: 'LEVEL_ENCODING_NOT_SUPPORTED'
    })
  }

  /** @return {UTF8Format<TIn,TOut>} */
  createUTF8Transcoder () {
    throw new ModuleError(`Encoding '${this.name}' cannot be transcoded to 'utf8'`, {
      code: 'LEVEL_ENCODING_NOT_SUPPORTED'
    })
  }
}

exports.Encoding = Encoding

/**
 * @typedef {import('./encoding').IEncoding<TIn,TFormat,TOut>} IEncoding
 * @template TIn, TFormat, TOut
 */

/**
 * @typedef {import('./formats').BufferFormat<TIn,TOut>} BufferFormat
 * @template TIn, TOut
 */

/**
 * @typedef {import('./formats').ViewFormat<TIn,TOut>} ViewFormat
 * @template TIn, TOut
 */

/**
 * @typedef {import('./formats').UTF8Format<TIn,TOut>} UTF8Format
 * @template TIn, TOut
 */