ContentView.swift

//
//  ContentView.swift
//  playing2
//
//  Created by Scott O'Brien on 12/29/22.
//

import SwiftUI
import RealityKit
import ARKit

extension Array {
   func filteredByType<T> (_: T.Type) -> [T] {
       return compactMap({ (element) in
           return element as? T
       })
   }
}


let refImg = ReferenceImageDelegate()
var refBox: Experience.Box!

struct ContentView : View {
    var body: some View {
        ARViewContainer().edgesIgnoringSafeArea(.all)
    }
}

struct ARViewContainer: UIViewRepresentable {
    
    func makeUIView(context: Context) -> ARView {
        
        
        let arView = ARView(frame: .zero)
        
        // Load the "Box" scene from the "Experience" Reality File
        let boxAnchor = try! Experience.loadBox()
        refBox = boxAnchor
        
        // Add the box anchor to the scene
        arView.scene.anchors.append(boxAnchor)
        
        // Add the reference marker, assign the delegate
        refImg.set(arView: arView)
        arView.session.delegate = refImg

        return arView
        
    }
    
    func updateUIView(_ uiView: ARView, context: Context) {}
    
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}
#endif


// MARK: ReferenceMarker

final class ReferenceImageDelegate: NSObject, ARSessionDelegate {
    var arView: ARView!
    
    let markerA = AnchorEntity(world: [0, 0.5, 0])
    let markerB = AnchorEntity(world: [0, 0.5 ,0])
    var floorY: Float?

    // For showing the distance
    let distanceMarker = AnchorEntity(world: [0,0,0])
    var distanceMesh: ModelEntity!
    
    func set(arView: ARView) {
        self.arView = arView
        
        // Add in the markers
        let marker = ModelEntity(mesh: MeshResource.generateBox(width: 0.01, height: 1, depth: 0.01))
        let marker2 = ModelEntity(mesh: MeshResource.generateBox(width: 0.01, height: 1, depth: 0.01))
        markerA.addChild(marker)
        markerB.addChild(marker2)
        
        let positionDiff = markerB.position(relativeTo: markerA)
        let text = MeshResource.generateText(
            "\(abs(positionDiff.sum()))",
            extrusionDepth: 0.08,
            font: .systemFont(ofSize: 0.05, weight: .bold)
        )
        distanceMesh = ModelEntity(mesh: text)
        distanceMarker.addChild(distanceMesh)
        
        arView.scene.addAnchor(markerA)
        arView.scene.addAnchor(markerB)
        arView.scene.addAnchor(distanceMarker)
        
        // Add images to search for
        var imageAnchor = AnchorEntity(.image(group: "AR Resources", name: "a"))
        arView.scene.anchors.append(imageAnchor)
        imageAnchor = AnchorEntity(.image(group: "AR Resources", name: "b"))
        arView.scene.anchors.append(imageAnchor)
        
    }

    /*
     Used for when we find when a marker has a new position
     */
    func session(_ session: ARSession, didUpdate anchors: [ARAnchor]) {
        // Update the floor location if we can see a floor
        let planes = anchors.filteredByType(ARPlaneAnchor.self)
        let floor = planes.filter{$0.classification == ARPlaneAnchor.Classification.floor}.first
        if(floor != nil) {
            floorY = floor?.transform.columns.3.y
        }
        
        // Put the measurement text to one of the markers
        let positionDiff = markerB.position(relativeTo: markerA)
        let text = MeshResource.generateText(
            "\(abs(positionDiff.sum()))",
            extrusionDepth: 0.008,
            font: .systemFont(ofSize: 0.05, weight: .bold)
        )
        distanceMesh = ModelEntity(mesh: text)
        distanceMarker.children.removeAll()
        distanceMarker.addChild(distanceMesh)
        distanceMarker.transform = markerB.transform

        
        let imageMaps = anchors.filteredByType(ARImageAnchor.self)
        for image in imageMaps {
            var marker = markerB
            if image.name == "a" {
//                print(image.transform.columns.0)
//                print(image.transform.columns.1)
//                print(image.transform.columns.2)
//                print(image.transform.columns.3)
//                print("")

                marker = markerA
            }
                        
            // Magazines are 21.5cm wide, translate measuring to the edge
            let translation = simd_float4x4(
                SIMD4(1, 0, 0, 0),
                SIMD4(0, 1, 0, 0),
                SIMD4(0, 0, 1, 0),
                // float4(x, y, z, 1)
                SIMD4(0.1075, 0, 0, 1)
            )
            marker.transform = Transform(matrix: image.transform * translation)
            // Place the marker on the floor
            if(floorY != nil) {
                marker.position.y = floorY!
            }
            // Orient the marker straight up
            marker.orientation = simd_quatf(vector: [0,0,0,0])
        }
    }
    
    
    
}