//
//  TestingKaraokeVC.swift
//  WOKA
//
//  Created by MacBook Pro on 09/07/24.
//

import AVFAudio
import UIKit
import AVFoundation

class TestingKaraokeVC : UIViewController{
    
    var player: AVPlayer!
    var audioEngine: AVAudioEngine!
    var micInput: AVAudioInputNode!
    var playerNode: AVAudioPlayerNode!
    var audioFile: AVAudioFile!
    var fileURL: URL!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let videoURL = URL(string: "https://content.jwplatform.com/videos/DOhtETio-Ysj2G4DQ.mp4")!
        setupPlayer(with: videoURL)
        setupAudioEngine()
        setupAudioFile()
    }
    
    func setupPlayer(with url: URL) {
        player = AVPlayer(url: url)
        let playerLayer = AVPlayerLayer(player: player)
        playerLayer.frame = view.bounds
        view.layer.addSublayer(playerLayer)
        player.play()
    }
    
    func setupAudioEngine() {
        audioEngine = AVAudioEngine()
        micInput = audioEngine.inputNode
        playerNode = AVAudioPlayerNode()
        
        audioEngine.attach(playerNode)
        let format = micInput.inputFormat(forBus: 0)
        
        audioEngine.connect(micInput, to: audioEngine.mainMixerNode, format: format)
        audioEngine.connect(playerNode, to: audioEngine.mainMixerNode, format: format)
        
        try! audioEngine.start()
    }
    
    func setupAudioFile() {
        let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        fileURL = documentsDirectory.appendingPathComponent("output.m4a")
        let format = audioEngine.mainMixerNode.outputFormat(forBus: 0)
        
        do {
            audioFile = try AVAudioFile(forWriting: fileURL, settings: format.settings)
        } catch {
            print("Error creating audio file: \(error)")
        }
    }
    
    func startRecording() {
        let mixer = audioEngine.mainMixerNode
        let format = mixer.outputFormat(forBus: 0)
        
        mixer.installTap(onBus: 0, bufferSize: 1024, format: format) { (buffer, time) in
            do {
                try self.audioFile.write(from: buffer)
            } catch {
                print("Error writing audio buffer: \(error)")
            }
        }
    }
    
    func stopRecording() {
        let mixer = audioEngine.mainMixerNode
        mixer.removeTap(onBus: 0)
        
        // Save the file to Files app
        presentDocumentPicker()
    }
    
    func presentDocumentPicker() {
        //        let documentPicker = UIDocumentPickerViewController(forExporting: [fileURL])
        //        documentPicker.delegate = self
        //        present(documentPicker, animated: true, completion: nil)
        
        guard let mixedAudioURL = fileURL else { return }
        DispatchQueue.main.async {
            let documentPicker = UIDocumentPickerViewController(url: mixedAudioURL, in: .exportToService)
            documentPicker.delegate = self
            self.present(documentPicker, animated: true, completion: nil)
        }
    }
    
    @IBAction func startButtonPressed(_ sender: UIButton) {
        startRecording()
    }
    
    @IBAction func stopButtonPressed(_ sender: UIButton) {
        stopRecording()
    }
}

extension TestingKaraokeVC: UIDocumentPickerDelegate {
    func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
        guard let selectedURL = urls.first else { return }
        do {
            try FileManager.default.moveItem(at: fileURL, to: selectedURL)
        } catch {
            print("Error saving file to Files app: \(error)")
        }
    }
    
    func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
        print("Document picker was cancelled")
    }
}