import SwiftUI
import AuthenticationServices
import Alamofire
import CryptoKit
import Foundation

/// 主登录视图 - 处理苹果登录
struct LoginView: View {
    // MARK: - Properties
    
    @State private var isLoading = false
    @State private var showError = false
    @State private var errorMessage = ""
    @State private var currentNonce: String?
    @State private var isLoggedIn = false
    // MARK: - Body
    
    var body: some View {
        ZStack {
            // Background
            Color(red: 1.0, green: 0.67, blue: 0.15)
                .ignoresSafeArea()
            
            VStack(alignment: .leading, spacing: 4) {
                Text("Hi, I'm MeMo!")
                    .font(Typography.font(for: .largeTitle, family: .quicksandBold))
                    .foregroundColor(.black)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .padding(.horizontal, 24)
                    .padding(.top, 44)
                
                Text("Welcome~")
                    .font(Typography.font(for: .largeTitle, family: .quicksandBold))
                    .foregroundColor(.black)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .padding(.horizontal, 24)
                    .padding(.bottom, 20)
                
                Spacer()
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
            
            VStack(spacing: 16) {
                Spacer()
                signInButton()
                    .padding(.horizontal, 24)
                termsAndPrivacyView()
            }
            .frame(maxWidth: .infinity)
            .alert(isPresented: $showError) {
                Alert(
                    title: Text("Error"),
                    message: Text(errorMessage),
                    dismissButton: .default(Text("OK"))
                )
            }
            
            if isLoading {
                loadingView()
            }
        }
        .navigationBarBackButtonHidden(true)
        .navigationBarHidden(true)
    }
    
    // MARK: - Views
    
    private func signInButton() -> some View {
        print(" [1] 用户点击了登录按钮")
        return AppleSignInButton { request in
            print(" 开始创建登录请求")
            let nonce = String.randomURLSafeString(length: 32)
            self.currentNonce = nonce
            request.nonce = self.sha256(nonce)
            request.requestedScopes = [.fullName, .email]
            print(" 登录请求配置完成，nonce 已设置")
        } onCompletion: { result in
            print(" 收到 Apple 登录回调")
            switch result {
            case .success(let authResults):
                print(" Apple 登录授权成功，开始处理凭证")
                if let appleIDCredential = authResults.credential as? ASAuthorizationAppleIDCredential {
                    print(" 成功获取 Apple ID 凭证")
                    self.processAppleIDCredential(appleIDCredential)
                } else {
                    print(" 凭证类型转换失败")
                    print(" 凭证类型: \(type(of: authResults.credential))")
                    self.showError(message: "无法处理登录凭证")
                }
            case .failure(let error):
                print(" Apple 登录失败: \(error.localizedDescription)")
                print(" 错误详情: \(error as NSError)")
                self.handleSignInError(error)
            }
        }
    }
    
    private func termsAndPrivacyView() -> some View {
        VStack(spacing: 4) {
            HStack {
                Text("By continuing, you agree to our")
                    .font(.caption)
                    .foregroundColor(.themeTextMessage)
                
                Button("Terms of") {
                    openURL("https://yourwebsite.com/terms")
                }
                .font(.caption2)
                .foregroundColor(.themeTextMessageMain)
            }
            .multilineTextAlignment(.center)
            .padding(.horizontal, 24)
            
            HStack(spacing: 8) {
                Button("Service") {
                     if let url = URL(string: "https://memorywake.com/privacy-policy") {
                        UIApplication.shared.open(url)
                    }
                }
                .font(.caption2)
                .foregroundColor(.themeTextMessageMain)
                
                Text("and")
                    .foregroundColor(.themeTextMessage)
                    .font(.caption)
                
                Button("Privacy Policy") {
                    if let url = URL(string: "https://memorywake.com/privacy-policy") {
                        UIApplication.shared.open(url)
                    }
                }
                .font(.caption2)
                .foregroundColor(.themeTextMessageMain)
            }
            .padding(.top, 4)
        }
        .fixedSize(horizontal: false, vertical: true)
        .frame(maxWidth: .infinity)
        .padding(.horizontal, 24)
        .padding(.vertical, 12)
    }
    
    private func loadingView() -> some View {
        ZStack {
            Color.black.opacity(0.4)
                .edgesIgnoringSafeArea(.all)
            
            ProgressView()
                .scaleEffect(1.5)
                .progressViewStyle(CircularProgressViewStyle(tint: .white))
        }
    }
    
    // MARK: - Authentication
    
    private func handleAppleSignIn(result: Result<ASAuthorization, Error>) {
        print(" 开始处理登录结果...")
        switch result {
        case .success(let authResults):
            print(" 登录授权成功")
            processAppleIDCredential(authResults.credential)
        case .failure(let error):
            print(" 登录失败: \(error.localizedDescription)")
            handleSignInError(error)
        }
    }
    
    private func processAppleIDCredential(_ credential: ASAuthorizationCredential) {
        print(" 开始处理 Apple ID 凭证")
        guard let appleIDCredential = credential as? ASAuthorizationAppleIDCredential else {
            print(" 凭证类型不匹配")
            print(" 实际凭证类型: \(type(of: credential))")
            showError(message: "无法处理Apple ID凭证")
            return
        }
        
        let userId = appleIDCredential.user
        let email = appleIDCredential.email ?? ""
        let fullName = [
            appleIDCredential.fullName?.givenName,
            appleIDCredential.fullName?.familyName
        ]
        .compactMap { $0 }
        .joined(separator: " ")
        
        print(" 用户数据 - ID: \(userId), 邮箱: \(email.isEmpty ? "未提供" : email), 姓名: \(fullName.isEmpty ? "未提供" : fullName)")
        
        guard let identityTokenData = appleIDCredential.identityToken,
              let identityToken = String(data: identityTokenData, encoding: .utf8) else {
            print(" 无法获取身份令牌")
            showError(message: "无法获取身份令牌")
            return
        }
        
        print(" 成功获取 identityToken")
        
        var authCode: String? = nil
        if let authCodeData = appleIDCredential.authorizationCode {
            authCode = String(data: authCodeData, encoding: .utf8)
            print(" 获取到授权码")
        } else {
            print(" 未获取到授权码（可选）")
        }
        
        print(" 准备调用后端认证接口...")
        authenticateWithBackend(
            identityToken: identityToken,
            authCode: authCode
        )
    }
    
    // MARK: - Network
    
    private func authenticateWithBackend(
        identityToken: String,
        authCode: String?
    ) {
        print(" 开始后端认证流程...")
        isLoading = true
        
        var parameters: [String: Any] = [
            "token": identityToken,
            "provider": "Apple",
        ]
        
        if let authCode = authCode {
            parameters["authorization_code"] = authCode
            print(" 添加授权码到请求参数")
        }
        
        print(" 发送认证请求到服务器...")
        print(" 接口: /iam/login/oauth")
        print(" 请求参数: \(parameters.keys)")
        
        NetworkService.shared.post(
            path: "/iam/login/oauth", 
            parameters: parameters
        ) { (result: Result<AuthResponse, NetworkError>) -> Void in
            let handleResult: () -> Void = {
                self.isLoading = false
                
                switch result {
                case .success(let authResponse):
                    print("✅ [15] 后端认证成功")
                    
                    if let loginInfo = authResponse.data?.userLoginInfo {
                        print("🔑 [16] 保存认证信息")
                        print("   - 用户ID: \(loginInfo.userId)")
                        print("   - 昵称: \(loginInfo.nickname)")
                        
                        KeychainHelper.saveAccessToken(loginInfo.accessToken)
                        KeychainHelper.saveRefreshToken(loginInfo.refreshToken)
                        
                        print("🔄 [17] 准备跳转到用户信息页面...")
                        print("🔍 isLoggedIn 当前值: \(self.isLoggedIn)")
                        
                        self.isLoggedIn = true
                        
                        print("✅ [18] isLoggedIn 已设置为 true")
                        print("🎉 登录流程完成，即将跳转")
                    } else {
                        print("⚠️ [16] 认证成功但返回的用户信息不完整")
                        self.errorMessage = "登录信息不完整，请重试"
                        self.showError = true
                    }
                    // 跳转到userinfo
                    Router.shared.navigate(to: .userInfo)
                    
                case .failure(let error):
                    print("❌ [15] 后端认证失败")
                    print("⚠️ 错误类型: \(type(of: error))")
                    print("📝 错误信息: \(error.localizedDescription)")
                    
                    var errorMessage = "登录失败，请重试"
                    
                    switch error {
                    case .invalidURL:
                        print("   → 无效的URL")
                        errorMessage = "服务器地址无效"
                    case .noData:
                        print("   → 服务器未返回数据")
                        errorMessage = "服务器未响应，请检查网络"
                    case .decodingError(let error):
                        print("   → 数据解析失败: \(error.localizedDescription)")
                        errorMessage = "服务器响应格式错误"
                    case .serverError(let message):
                        print("   → 服务器错误: \(message)")
                        errorMessage = "服务器错误: \(message)"
                    case .unauthorized:
                        print("   → 认证失败: 未授权")
                        errorMessage = "登录信息已过期，请重新登录"
                    case .networkError(let error):
                        print("   → 网络错误: \(error.localizedDescription)")
                        errorMessage = "网络连接失败，请检查网络"
                    case .other(let error):
                        print("   → 其他错误: \(error.localizedDescription)")
                        errorMessage = "发生未知错误"
                    case .unknownError(let error):
                        print("   → 未知错误: \(error.localizedDescription)")
                        errorMessage = "发生未知错误"
                    case .invalidParameters:
                        print("   → 无效的参数")
                        errorMessage = "请求参数错误，请重试"
                    }
                    
                    self.errorMessage = errorMessage
                    self.showError = true
                    print("❌ 登录失败: \(errorMessage)")
                }
            }
            
            // Execute on main thread
            if Thread.isMainThread {
                handleResult()
            } else {
                DispatchQueue.main.async(execute: handleResult)
            }
        }
    }
    
    // MARK: - Helpers
    
    private func handleSuccessfulAuthentication() {
        print(" 登录成功，准备跳转到用户信息页面...")
        print(" isLoggedIn before update: \(isLoggedIn)")
        DispatchQueue.main.async {
            print(" Setting isLoggedIn to true")
            self.isLoggedIn = true
            print(" isLoggedIn after update: \(self.isLoggedIn)")
        }
    }
    
    private func handleSignInError(_ error: Error) {
        let errorMessage = (error as NSError).localizedDescription
        print(" 登录错误: \(errorMessage)")
        showError(message: "登录失败: \(error.localizedDescription)")
    }
    
    private func handleAuthenticationError(_ error: Error) {
        let errorMessage = error.localizedDescription
        print(" 认证错误: \(errorMessage)")
        DispatchQueue.main.async {
            self.isLoggedIn = false
            self.showError(message: "登录失败: \(errorMessage)")
        }
    }
    
    private func showError(message: String) {
        DispatchQueue.main.async {
            self.errorMessage = message
            self.showError = true
        }
    }
    
    private func openURL(_ string: String) {
        guard let url = URL(string: string) else { return }
        UIApplication.shared.open(url)
    }
    
    private func sha256(_ input: String) -> String {
        let inputData = Data(input.utf8)
        let hashedData = SHA256.hash(data: inputData)
        return hashedData.compactMap { String(format: "%02x", $0) }.joined()
    }
}

// MARK: - Extensions

extension String {
    static func randomURLSafeString(length: Int) -> String {
        let characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~"
        var randomString = ""
        
        for _ in 0..<length {
            let randomIndex = Int.random(in: 0..<characters.count)
            let character = characters[characters.index(characters.startIndex, offsetBy: randomIndex)]
            randomString.append(character)
        }
        
        return randomString
    }
}

// MARK: - Preview

struct LoginView_Previews: PreviewProvider {
    static var previews: some View {
        LoginView()
    }
}