OTP/OTP/Views/AddQRView.swift

//
//  AddQRView.swift
//  OTP
//
//  Created by Shadowfacts on 8/22/21.
//

import SwiftUI
import CodeScanner
import OTPKit

struct AddQRView: View {
    let dismiss: (DismissAction) -> Void
    @State private var isPresentingScanFailedAlert = false
    @State private var scanError: ScanError?
    @State private var scannedKey: TOTPKey?
    @State private var isShowingConfirmView = false
    
    var body: some View {
        NavigationView {
            CodeScannerView(codeTypes: [.qr], scanMode: .once) { (result) in
                switch result {
                case .success(let code):
                    if let components = URLComponents(string: code),
                       let key = TOTPKey(urlComponents: components) {
                        self.scannedKey = key
                        isShowingConfirmView = true
                    } else {
                        isPresentingScanFailedAlert = true
                        scanError = .invalidCode(code)
                    }
                case .failure(let error):
                    isPresentingScanFailedAlert = true
                    scanError = .scanner(error)
                }
            }
            .edgesIgnoringSafeArea(.bottom)
            .navigationBarTitle("Scan QR Code", displayMode: .inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Cancel") {
                        dismiss(.cancel)
                    }
                }
            }
            .overlay {
                NavigationLink(isActive: $isShowingConfirmView) {
                    EditKeyForm(editingKey: scannedKey, showCancelButton: false, dismiss: dismiss)
                        .navigationTitle("Add Key")
                } label: {
                    // EmptyView because this is only used to trigger programatic navigation
                    EmptyView()
                }

            }
        }
        .alert("Unable to get OTP key from QR code", isPresented: $isPresentingScanFailedAlert) {
            Button("Cancel", role: .cancel) {
                dismiss(.cancel)
            }
            Button("Try Again") {
                isPresentingScanFailedAlert = false
            }
        } message: {
            if let error = scanError {
                Text(error.localizedDescription)
            }
        }
    }
    
}

extension AddQRView {
    enum ScanError: LocalizedError {
        case scanner(CodeScannerView.ScanError)
        case invalidCode(String)
        
        var errorDescription: String? {
            switch self {
            case .invalidCode(let code):
                return "Invalid Code: '\(code)'"
            case .scanner(.badInput):
                return "Scanner: Bad Input"
            case .scanner(.badOutput):
                return "Scanner: Bad Output"
            }
        }
    }
}

struct AddQRView_Previews: PreviewProvider {
    static var previews: some View {
        AddQRView() { (_) in }
    }
}