import { toCanvas } from 'qrcode'
import type { QRCodeRenderersOptions } from 'qrcode'
import { RenderQrCodeParams, ContentType } from './types'

// 得到原QrCode的大小，以便缩放得到正确的QrCode大小
function getOriginWidth(content: ContentType, options: QRCodeRenderersOptions) {
  const _canvas = document.createElement('canvas')
  return toCanvas(_canvas, content, options).then(() => _canvas.width)
}

// 对于内容少的QrCode，增大容错率
function getErrorCorrectionLevel(content: ContentType) {
  if (content.length > 36) {
    return 'M'
  } else if (content.length > 16) {
    return 'Q'
  } else {
    return 'H'
  }
}

export const renderQrCode = ({ canvas, content, width = 0, options = {} }: RenderQrCodeParams) => {
  // 容错率，默认对内容少的二维码采用高容错率，内容多的二维码采用低容错率
  options.errorCorrectionLevel = options.errorCorrectionLevel || getErrorCorrectionLevel(content)

  return getOriginWidth(content, options).then((_width: number) => {
    options.scale = width === 0 ? undefined : (width / _width) * 4
    return toCanvas(canvas, content, options)
  })
}