JustScanIt/JustScanIt/View/MainView.swift

//
//  MainView.swift
//  JustScanIt
//
//  Created by Pradyun Setti on 03/07/2024.
//

import SwiftUI
import SwiftData
import AVKit

struct MainView: View {
    @Environment(\.modelContext) var ctx
    
    @State private var scannedImages: [UIImage] = []
    @State private var isShowingVNDocumentCameraView = false
    @State private var isShowingSettingsView = false
    
    @Query var scans: [Scan]
    
    @AppStorage(Prefs.autoLaunchCamera) var autolaunch = false
    
    var isAuthorized: Bool {
        get async {
            let status = AVCaptureDevice.authorizationStatus(for: .video)
            
            // Determine if the user previously authorized camera access.
            var isAuthorized = status == .authorized
            
            // If the system hasn't determined the user's authorization status,
            // explicitly prompt them for approval.
            if status == .notDetermined {
                isAuthorized = await AVCaptureDevice.requestAccess(for: .video)
            } else if status == .denied {
                // TODO: show alert when denied
            }
            
            return isAuthorized
        }
    }
    
    var body: some View {
        NavigationView {
            ScrollView {
                ForEach(scans, id: \.self) { scan in
                    ScanItemView(scan)
                }
            }
            .onAppear {
                if autolaunch {
                    isShowingVNDocumentCameraView = true
                }
            }
            .navigationTitle("Just Scan It!")
            .sheet(isPresented: $isShowingVNDocumentCameraView, onDismiss: saveImages) {
                VNDocumentCameraViewControllerRepresentable(scanResult: $scannedImages)
            }
            .sheet(isPresented: $isShowingSettingsView) {
                SettingsView()
            }
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    Button(action: { isShowingSettingsView.toggle() }) {
                        Image(systemName: "gear")
                    }
                }
                ToolbarItem {
                    Button(action: showVNDocumentCameraView) {
                        Image(systemName: "scanner.fill")
                    }
                }
            }
        }
    }
    
    private func showVNDocumentCameraView() {
        Task { guard await isAuthorized else { return } }
        
        isShowingVNDocumentCameraView = true
    }
    
    private func saveImages() {
        guard !scannedImages.isEmpty else { return }
        
        let newScan = Scan(images: scannedImages)
        
        withAnimation(.easeIn) {
            ctx.insert(newScan)
            try? ctx.save()
        }
        
        scannedImages = []
    }
}

#Preview {
    MainView()
}