import { PNG } from 'pngjs'
import { BitmapData, RgbaToBit, BitToRgba } from './types'
import { createBitmap } from '.'

export const defaultRgbaToBit: RgbaToBit = ( r, g, b, _a ) => {
  const value = ( r + g + b ) / 3

  return value > 127 ? 1 : 0
}

export const defaultBitToRgba: BitToRgba = bit => {
  const r = bit ? 255 : 0
  const g = bit ? 255 : 0
  const b = bit ? 255 : 0
  const a = 255

  return [ r, g, b, a ]
}

export const fromPng = ( pngBuffer: Uint8Array, mapper = defaultRgbaToBit ) => {
  const png = PNG.sync.read( Buffer.from( pngBuffer ) )
  const { width, height, data } = png
  const pngData = new Uint8ClampedArray( data )

  const bitmap = createBitmap( width, height )

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

      const r = pngData[ sourceIndex ]
      const g = pngData[ sourceIndex + 1 ]
      const b = pngData[ sourceIndex + 2 ]
      const a = pngData[ sourceIndex + 3 ]

      bitmap.data[ index ] = mapper( r, g, b, a )
    }
  }

  return bitmap
}

export const toPng = ( imageData: BitmapData, mapper = defaultBitToRgba ) => {
  const { width, height, data } = imageData

  const options = { width, height }

  const png = new PNG( options )

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

      const [ r, g, b, a ] = mapper( data[ index ] )

      png.data[ destIndex ] = r
      png.data[ destIndex + 1 ] = g
      png.data[ destIndex + 2 ] = b
      png.data[ destIndex + 3 ] = a
    }
  }

  return new Uint8Array( PNG.sync.write( png ) )
}