import { generateRandomCharCodeArray, charCodeArrayToString } from './core'
import { noop } from './utils/noop'

type Options = {
  str: string
  speed?: number
  placeholderChar?: string
  frameOffset?: number
  charOffset?: number
  charStep?: number
  minCharCode?: number
  maxCharCode?: number
  onProgress?: (arg0: string) => void
  onComplete?: (arg0: string) => void
}

class RandomText {
  static defaults: Options = {
    str: '',
    speed: 2,
    placeholderChar: '_',
    frameOffset: 30,
    charOffset: 20,
    charStep: 10,
    minCharCode: 32,
    maxCharCode: 122,
    onProgress: noop,
    onComplete: noop,
  }
  str: string
  speed: number
  placeholderChar: string
  frameOffset: number
  charOffset: number
  charStep: number
  minCharCode: number
  maxCharCode: number
  onProgress: (...args: Array<string>) => string
  onComplete: (...args: Array<string>) => string
  rafId: number // TODO: should be #rafId for private

  constructor (options: Options) {
    Object.assign(this, { ...RandomText.defaults, ...options })
  }

  start = (): void => {
    const { frameOffset, charOffset, str, speed } = this
    const randoms = generateRandomCharCodeArray(frameOffset, charOffset)(str)
    this.stop()
    this.rafId = requestAnimationFrame(() => {
      this.step(randoms, speed, speed)
    })
  }

  stop (): void {
    cancelAnimationFrame(this.rafId)
  }

  step (randoms: number[], stepCount: number, speed: number): void {
    const {
      str,
      charStep,
      minCharCode,
      maxCharCode,
      placeholderChar,
      onProgress,
      onComplete,
    } = this
    const stepArray = randoms.slice(0, stepCount)
    const steppedArray = stepArray.map(item => {
      if (item > 0) return item - 1
      if (item < 0) return item + 1
      return 0
    })
    const output = charCodeArrayToString({
      str,
      minCharCode,
      maxCharCode,
      placeholderChar,
      charStep,
    })(steppedArray)
    const updatedRandoms = [...steppedArray, ...randoms.slice(stepCount)]
    onProgress(output)

    if (output !== str) {
      this.rafId = requestAnimationFrame(() => {
        this.step(updatedRandoms, stepCount + speed, speed)
      })
    } else {
      onComplete(output)
    }
  }
}

export default RandomText