//
//  ViewController.swift
//  TreeMeasure
//
//  Created by Basti SK on 13.04.24.
//

import UIKit
import AVFoundation
import CoreMotion

class ViewController: UIViewController {
    
    @IBOutlet weak var textView: UITextView!
    @IBOutlet weak var inputRefHeight: UITextField!
    @IBOutlet weak var statusText: UITextView!
    @IBOutlet weak var centerButton: UIButton!
    @IBOutlet weak var previewView: UIView!
    @IBOutlet var mainView: UIView!
    
    // Cam Variables
    var captureSession: AVCaptureSession!
    var videoPreviewLayer: AVCaptureVideoPreviewLayer!
    var globalQueue: OperationQueue!
    var backCamera: AVCaptureDevice!
    
    // VariablesForCalculations
    var globalDegrees: Double!
    var globalAttitude: Double!
    var globalGravityAngle: Double!
    var topPole: Double!
    var bottomPole: Double!
    var topTree: Double!
    
    // Motion Variables
    var motionManager: CMMotionManager!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // init motion manager
        motionManager = CMMotionManager();
        
        // init vars for calculations
        topPole = 0;
        bottomPole = 0;
        topTree = 0;
        
        statusText.text = "To start, please snapshot the top of the reference height."
        
        // enable tap out of edit for ref. heigth
        let tap = UITapGestureRecognizer(target: self, action: #selector(UIInputViewController.dismissKeyboard))
        tap.cancelsTouchesInView = false
        view.addGestureRecognizer(tap)
    }
    
    @objc func dismissKeyboard() {
        view.endEditing(true)
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        // start and prepare cam related things
        captureSession = AVCaptureSession()
        backCamera = AVCaptureDevice.default(for: AVMediaType.video)
        
        do {
            let input = try AVCaptureDeviceInput(device: backCamera)
            if(captureSession.canAddInput(input)) {
                captureSession.addInput(input)
                setupLivePreview()

            }
            
        }
        catch let error  {
            print("Error Unable to initialize back camera:  \(error.localizedDescription)")
        }
        
        // start monitoring the motion sensor
        startMotionMonitor();
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        self.captureSession.stopRunning()
        motionManager.stopDeviceMotionUpdates()
    }
    
    @IBAction func addMarker() {
        
        let l = Double(inputRefHeight.text ?? "1.0") ?? 1.0
        
        if(topPole == 0) {
            topPole = globalAttitude
            
            if globalGravityAngle < 0 {
                topPole = globalAttitude * -1
            }
            
            statusText.text = "Snaphost Angle: " + String(format: "%.2f", globalDegrees) + "°.\nNext, snapshot the bottom of the reference height."
            return;
        }
        
        if(bottomPole == 0) {
            bottomPole = globalAttitude
            
            if globalGravityAngle < 0 {
                bottomPole = bottomPole * -1
            }
            statusText.text = "Snapshot Angle: " + String(format: "%.2f", globalDegrees) + "°\nFinally, snapshot the top of the tree."
            return;
        }
        
        if(topTree == 0) {
            topTree = globalAttitude
            if globalGravityAngle < 0 {
                topTree = topTree * -1
            }
        }
        
        if((topPole != 0) && (bottomPole != 0) && (topTree != 0)) {
            let alpha3 = topPole - Double.pi / 2
            let alpha2 = bottomPole - Double.pi / 2
            let alpha1 = topTree - Double.pi / 2
            let e = abs(l / ( tan(alpha3) - tan(alpha2)))
            
            let h1 = e * tan(alpha1)
            let h2 = e * tan(alpha2)
        
            
            let h = abs(h1 - h2)
            statusText.text = "Height: " + String( format: "%.4f", h) + " m\nSnapshot top of the reference height to measure again."
            
            //reset
            topTree = 0
            bottomPole = 0
            topPole = 0
        }
        
    }
    
    @IBAction func changeZoom() {
        if(backCamera.videoZoomFactor > 1) {
            setZoomFactor(factor: backCamera.videoZoomFactor + 10)
        } else {
            setZoomFactor(factor: backCamera.maxAvailableVideoZoomFactor)
        }
    }
    
    @IBAction func zoomOut() {
        if(backCamera.videoZoomFactor > 1) {
            setZoomFactor(factor: backCamera.videoZoomFactor - 1)
        }
    }
    
    @IBAction func zoomIn() {
        if(backCamera.videoZoomFactor < backCamera.maxAvailableVideoZoomFactor) {
            setZoomFactor(factor: backCamera.videoZoomFactor + 1)
        }
    }
    
    func setZoomFactor(factor: CGFloat) {
        do {
            try backCamera.lockForConfiguration()
            if(factor <= backCamera.maxAvailableVideoZoomFactor) {
                backCamera.videoZoomFactor = factor
            }
 
            backCamera.unlockForConfiguration()
        } catch let error {
            print("Error Unable to set zoom for back camera:  \(error.localizedDescription)")
        }

    }
    
    func startMotionMonitor() {
        globalQueue = OperationQueue()
        if motionManager.isDeviceMotionAvailable == true {
            motionManager.deviceMotionUpdateInterval = 0.5
            motionManager.startDeviceMotionUpdates(using: .xMagneticNorthZVertical, to: self.globalQueue, withHandler: { (data, error) in
               
                if let attitude = data?.attitude {
                    // Get the pitch (in radians) and convert to degrees for display.
                    self.globalDegrees = (attitude.pitch * 180.0/Double.pi)
                    self.globalAttitude = attitude.pitch
                   
                    DispatchQueue.main.async {
                        self.textView.text = "Angle: " + String(format: "%.2f", self.globalDegrees) + "°";
                    }
                }
                
                if let gravity = data?.gravity {
                    
                    self.globalGravityAngle = gravity.z;
                }
                
                // we are looking up!
                if self.globalGravityAngle > 0 {
                    self.globalDegrees = 180 - self.globalDegrees;
                }
            })
            
            
        }
    }
    
    
    
    func setupLivePreview() {
        
        videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        
        videoPreviewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
        videoPreviewLayer.connection?.videoOrientation = .portrait
        previewView.layer.addSublayer(videoPreviewLayer)
               
        DispatchQueue.global(qos: .userInitiated).async { //[weak self] in
            self.captureSession.startRunning()
            DispatchQueue.main.async {
                self.videoPreviewLayer.frame = self.previewView.bounds
            }
        }
    }

}