sodalive-ios/SodaLive/Sources/User/Login/LoginViewModel.swift

//
//  LoginViewModel.swift
//  SodaLive
//
//  Created by klaus on 2023/08/09.
//

import Foundation
import Moya
import Combine
import AuthenticationServices
import CryptoKit
import Security
import UIKit

final class LoginViewModel: NSObject, ObservableObject {
    private let appViewModel = AppViewModel()
    private let repository = UserRepository()
    private var subscription = Set<AnyCancellable>()
    private var currentNonce: String?
    
    @Published var email = ""
    @Published var password = ""
    
    @Published var errorMessage = ""
    @Published var isShowPopup = false
    @Published var isLoading = false
    
    func login() {
        if email.isEmpty {
            self.errorMessage = "이메일을 입력해 주세요."
            self.isShowPopup = true
            return
        }
        
        if password.isEmpty {
            self.errorMessage = "비밀번호를 입력해 주세요."
            self.isShowPopup = true
            return
        }
        
        isLoading = true
        repository.login(request: LoginRequest(email: email, password: password))
            .sink { result in
                switch result {
                case .finished:
                    DEBUG_LOG("finish")
                case .failure(let error):
                    self.isLoading = false
                    ERROR_LOG(error.localizedDescription)
                }
            } receiveValue: { response in
                self.handleLoginResponse(response)
            }
            .store(in: &subscription)
    }
    
    func loginWithApple() {
        let nonce = randomNonceString()
        currentNonce = nonce
        
        let request = ASAuthorizationAppleIDProvider().createRequest()
        request.requestedScopes = [.email]
        request.nonce = hashNonce(nonce)
        
        let controller = ASAuthorizationController(authorizationRequests: [request])
        controller.delegate = self
        controller.presentationContextProvider = self
        controller.performRequests()
    }
    
    private func loginWithApple(identityToken: String, nonce: String) {
        let pushToken = UserDefaults.string(forKey: .pushToken)
        let marketingPid = UserDefaults.string(forKey: .marketingPid)
        let request = SocialLoginRequest(
            container: "ios",
            pushToken: pushToken.isEmpty ? nil : pushToken,
            marketingPid: marketingPid.isEmpty ? nil : marketingPid,
            identityToken: identityToken,
            nonce: nonce
        )
        
        isLoading = true
        repository.loginApple(request: request)
            .sink { result in
                switch result {
                case .finished:
                    DEBUG_LOG("finish")
                case .failure(let error):
                    self.isLoading = false
                    ERROR_LOG(error.localizedDescription)
                }
            } receiveValue: { response in
                self.handleLoginResponse(response)
            }
            .store(in: &subscription)
    }
    
    private func handleLoginResponse(_ response: Response) {
        self.isLoading = false
        let responseData = response.data
        do {
            let jsonDecoder = JSONDecoder()
            let decoded = try jsonDecoder.decode(ApiResponse<LoginResponse>.self, from: responseData)
            
            if let data = decoded.data, decoded.success {
                UserDefaults.set(data.profileImage, forKey: .profileImage)
                UserDefaults.set(data.nickname, forKey: .nickname)
                UserDefaults.set(data.userId, forKey: .userId)
                UserDefaults.set(data.email, forKey: .email)
                UserDefaults.set(data.token, forKey: .token)
                self.appViewModel.fetchAndUpdateIdfa()
                AppState.shared.isRestartApp = true
                AppState.shared.setAppStep(step: .splash)
            } else {
                if let message = decoded.message {
                    self.errorMessage = message
                } else {
                    self.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
                }
                
                self.isShowPopup = true
            }
        } catch {
            self.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
            self.isShowPopup = true
        }
    }
    
    private func randomNonceString(length: Int = 32) -> String {
        precondition(length > 0)
        let charset = Array("0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._")
        var result = ""
        var remainingLength = length
        
        while remainingLength > 0 {
            var randoms = [UInt8](repeating: 0, count: 16)
            let errorCode = SecRandomCopyBytes(kSecRandomDefault, randoms.count, &randoms)
            if errorCode != errSecSuccess {
                return UUID().uuidString
            }
            
            for random in randoms {
                if remainingLength == 0 {
                    break
                }
                
                if Int(random) < charset.count {
                    result.append(charset[Int(random)])
                    remainingLength -= 1
                }
            }
        }
        
        return result
    }
    
    private func hashNonce(_ input: String) -> String {
        let inputData = Data(input.utf8)
        let hashed = SHA256.hash(data: inputData)
        
        let hashData = Data(hashed)
        
        return hashData
            .base64EncodedString()
            .replacingOccurrences(of: "+", with: "-")
            .replacingOccurrences(of: "/", with: "_")
            .replacingOccurrences(of: "=", with: "")
    }
}

extension LoginViewModel: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        guard let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential else {
            self.errorMessage = "애플 로그인 정보를 가져오지 못했습니다."
            self.isShowPopup = true
            return
        }
        
        guard let identityTokenData = appleIDCredential.identityToken,
              let identityToken = String(data: identityTokenData, encoding: .utf8) else {
            self.errorMessage = "애플 인증 토큰을 가져오지 못했습니다."
            self.isShowPopup = true
            return
        }
        
        guard let nonce = currentNonce else {
            self.errorMessage = "다시 시도해 주세요."
            self.isShowPopup = true
            return
        }
        
        currentNonce = nil
        loginWithApple(identityToken: identityToken, nonce: nonce)
    }
    
    func authorizationController(controller: ASAuthorizationController, didCompleteWithError error: Error) {
        ERROR_LOG(error.localizedDescription)
        self.errorMessage = "애플 로그인에 실패했습니다.\n다시 시도해 주세요."
        self.isShowPopup = true
    }
}

extension LoginViewModel: ASAuthorizationControllerPresentationContextProviding {
    func presentationAnchor(for controller: ASAuthorizationController) -> ASPresentationAnchor {
        return UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
            .flatMap { $0.windows }
            .first { $0.isKeyWindow } ?? ASPresentationAnchor()
    }
}