import { Size } from '../types'
import { noContext } from './util'

export const testImageData = ( { width, height }: Size ) => {
  const imageData = new ImageData( width, height )

  for ( let y = 0; y < height; y++ ) {
    for ( let x = 0; x < width; x++ ) {
      const index = y * width + x
      const destIndex = index * 4

      const yValue = Math.floor( ( 255 / height ) * y )
      const xValue = Math.floor( ( 255 / width ) * x )

      imageData.data[ destIndex ] = xValue
      imageData.data[ destIndex + 1 ] = yValue
      imageData.data[ destIndex + 2 ] = yValue
      imageData.data[ destIndex + 3 ] = 255
    }
  }

  return imageData
}

export const testCanvas = ( size: Size ) => {
  const canvas = document.createElement( 'canvas' )
  const { width, height } = size

  canvas.width = width
  canvas.height = height

  const context = canvas.getContext( '2d' ) || noContext()

  context.putImageData( testImageData( size ), 0, 0 )

  return canvas
}