;(function() {

	if(typeof Blob === 'undefined')
		return console.warn('Screw-FileReader is only meant to work in those' +
	'engine who already has some basic support for blob')

	var blob = Blob.prototype
	var fullStreamSupport = false
	var basicStreamSupport = false
	var fetchTransform = false
	var URL = window.URL || window.webkitURL

	function promisify(obj) {
		return new Promise(function(resolve, reject) {
			obj.onload =
			obj.onerror = function(evt) {
				obj.onload =
				obj.onerror = null

				evt.type === 'load'
					? resolve(obj.result || obj)
					: reject(obj.error)
			}
		})
	}

	function toImage(url) {
		var img = new Image
		img.src = url
		return promisify(img)
	}

	try {
		new ReadableStream({})
		basicStreamSupport = true
	} catch (e) {}

	try {
		new ReadableStream({type: 'bytes'})
		fullStreamSupport = true
	} catch (e) {}

	try {
		(new Response(new Blob)).getReader()
		fetchTransform = true
	} catch (e) {}

	if(!blob.arrayBuffer) {
		blob.arrayBuffer = function arrayBuffer() {
			var fr = new FileReader
			fr.readAsArrayBuffer(this)
			return promisify(fr)
		}
	}

	if(!blob.text) {
		blob.text = function text() {
			var fr = new FileReader
			fr.readAsText(this)
			return promisify(fr)
		}
	}

	if(!blob.dataURL) {
		blob.dataURL = function dataURL() {
			var fr = new FileReader
			fr.readAsDataURL(this)
			return promisify(fr)
		}
	}

	if(!blob.url) {
		blob.url = function url() {
			return URL ? URL.createObjectURL(this) : null
		}
	}

	if(!blob.json) {
		blob.json = function json() {
			return this.text().then(JSON.parse)
		}
	}

	if(!blob.image) {
		blob.image = function image() {
			return Promise.resolve(this.url() || this.dataURL()).then(toImage)
		}
	}

	if(!blob.stream) {
		blob.stream =

		fullStreamSupport ? function stream() {
			var position = 0
			var blob = this

			return new ReadableStream({
				type: 'bytes',
				autoAllocateChunkSize: 524288,

				pull: function (controller) {
					var v = controller.byobRequest.view
					var chunk = blob.slice(position, position + v.byteLength)
					return chunk.arrayBuffer()
					.then(function (buffer) {
						let uint8array = new Uint8Array(buffer)
						let bytesRead = uint8array.byteLength

						position += bytesRead
						v.set(uint8array)
							controller.byobRequest.respond(bytesRead)

						if(position >= blob.size)
							controller.close()
					})
				}
			})
		}:

		// basic stream support
		basicStreamSupport ? function stream(blob){
			var position = 0
			var blob = this

			return new ReadableStream({
				pull: function (controller) {
					var chunk = blob.slice(position, position + 524288)

					return chunk.arrayBuffer().then(function (buffer) {
						position += buffer.byteLength
						let uint8array = new Uint8Array(buffer)
						controller.enqueue(uint8array)

						if(position == blob.size)
							controller.close()
					})
				}
			})
		}:

		// fetchTransform
		fetchTransform ? function stream() {
			return (new Response(this)).body
		}:

		function stream() {
			throw new Error('Include https://github.com/creatorrr/web-streams-polyfill')
		}
	}

}());