import UIKit
import AVFoundation


class ZBSimleRecorder: NSObject {

	var audioEngine: AVAudioEngine?
	var file: ExtAudioFileRef?

	func start(fileURL:URL) {
		self.stop()

		func M4aFormat() -> AudioStreamBasicDescription {
			return AudioStreamBasicDescription(mSampleRate: 44100,
			                                   mFormatID: kAudioFormatMPEG4AAC,
			                                   mFormatFlags: AudioFormatFlags(MPEG4ObjectID.aac_Main.rawValue),
			                                   mBytesPerPacket: 0,
			                                   mFramesPerPacket: 1024,
			                                   mBytesPerFrame: 0,
			                                   mChannelsPerFrame: 2,
			                                   mBitsPerChannel: 0,
			                                   mReserved: 0)
		}

		audioEngine = AVAudioEngine()
		guard let audioEngine = audioEngine else {
			return
		}

		let audioSession = AVAudioSession.sharedInstance()
		try? audioSession.setCategory(AVAudioSessionCategoryRecord)
		try? audioSession.setMode(AVAudioSessionModeVoiceChat)
		try? audioSession.setActive(true, with: .notifyOthersOnDeactivation)

		guard let inputNode = audioEngine.inputNode else { fatalError("Audio engine has no input node") }
		let recordingFormat = inputNode.outputFormat(forBus: 0)

		var  outputFormat = M4aFormat()
		var status = noErr
		status = ExtAudioFileCreateWithURL(fileURL as CFURL, kAudioFileM4AType, &outputFormat, nil, AudioFileFlags.eraseFile.rawValue, &file)
		assert(status == noErr)
		var codecManufacturer = kAppleSoftwareAudioCodecManufacturer
		status =  ExtAudioFileSetProperty(file!, kExtAudioFileProperty_CodecManufacturer, UInt32(MemoryLayout<UInt32>.size), &codecManufacturer)
		assert(status == noErr)
		status =  ExtAudioFileSetProperty(file!, kExtAudioFileProperty_ClientDataFormat, UInt32(MemoryLayout<AudioStreamBasicDescription>.size), recordingFormat.streamDescription)
		assert(status == noErr)

		inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer: AVAudioPCMBuffer, when: AVAudioTime) in
			let numberOfFrames = buffer.frameLength
			let audioBufferList = buffer.audioBufferList
			let status = ExtAudioFileWrite(self.file!, numberOfFrames, audioBufferList)
			assert(status == noErr)
		}

		audioEngine.prepare()
		try? audioEngine.start()
	}

	func stop() {

		guard let audioEngine = audioEngine else {
			return
		}

		let audioSession = AVAudioSession.sharedInstance()
		try? audioSession.setActive(false, with: .notifyOthersOnDeactivation)

		if let file = file {
			ExtAudioFileDispose(file)
			self.file = nil
		}

		audioEngine.stop()

	}

}