//
//  LoginView.swift
//  VolnahubApp
//
//  Created by cheykrym on 09/06/2025.
//

import SwiftUI

struct LoginView: View {
    @ObservedObject var viewModel: LoginViewModel
    @EnvironmentObject private var themeManager: ThemeManager
    @Environment(\.colorScheme) private var colorScheme
    
    @State private var isShowingRegistration = false
    @FocusState private var focusedField: Field?

    private enum Field: Hashable {
        case username
        case password
    }

    private var isUsernameValid: Bool {
        let pattern = "^[A-Za-z0-9_]{3,32}$"
        return viewModel.username.range(of: pattern, options: .regularExpression) != nil
    }

    private var isPasswordValid: Bool {
        return viewModel.password.count >= 8 && viewModel.password.count <= 128
    }
    
    var body: some View {

        ZStack {
            Color.clear // чтобы поймать тап
                .contentShape(Rectangle())
                .onTapGesture {
                    focusedField = nil
                }

            VStack {
                HStack {

                    Button(action: openLanguageSettings) {
                        Text("🌍")
                            .padding()
                    }
                    Spacer()
                    Button(action: toggleTheme) {
                        Image(systemName: themeIconName)
                            .padding()
                    }
                }
                .onTapGesture {
                    focusedField = nil
                }

                Spacer()

                TextField(NSLocalizedString("Логин", comment: ""), text: $viewModel.username)
                    .padding()
                    .background(Color(.secondarySystemBackground))
                    .cornerRadius(8)
                    .autocapitalization(.none)
                    .disableAutocorrection(true)
                    .focused($focusedField, equals: .username)
                    .onChange(of: viewModel.username) { newValue in
                        if newValue.count > 32 {
                            viewModel.username = String(newValue.prefix(32))
                        }
                    }

                // Показываем ошибку для логина
                if !isUsernameValid && !viewModel.username.isEmpty {
                    Text(NSLocalizedString("Неверный логин", comment: "Неверный логин"))
                        .foregroundColor(.red)
                        .font(.caption)
                }

                // Показываем поле пароля
                SecureField(NSLocalizedString("Пароль", comment: ""), text: $viewModel.password)
                    .padding()
                    .background(Color(.secondarySystemBackground))
                    .cornerRadius(8)
                    .autocapitalization(.none)
                    .focused($focusedField, equals: .password)
                    .onChange(of: viewModel.password) { newValue in
                        if newValue.count > 32 {
                            viewModel.password = String(newValue.prefix(32))
                        }
                    }

                // Показываем ошибку для пароля
                if !isPasswordValid && !viewModel.password.isEmpty {
                    Text(NSLocalizedString("Неверный пароль", comment: "Неверный пароль"))
                        .foregroundColor(.red)
                        .font(.caption)
                }

                var isButtonEnabled: Bool {
                    !viewModel.isLoading && isUsernameValid && isPasswordValid
                }
                
                Button(action: {
                    viewModel.login()
                }) {
                    if viewModel.isLoading {
                        ProgressView()
                            .progressViewStyle(CircularProgressViewStyle())
                            .padding()
                            .frame(maxWidth: .infinity)
                            .background(Color.gray.opacity(0.6))
                            .cornerRadius(8)
                    } else {
                        Text(NSLocalizedString("Войти", comment: ""))
                            .foregroundColor(.white)
                            .padding()
                            .frame(maxWidth: .infinity)
                            .background(isButtonEnabled ? Color.blue : Color.gray)
                            .cornerRadius(8)
                    }
                }
                .disabled(!isButtonEnabled)

//                Spacer()
                
                // Кнопка регистрации
                Button(action: {
                    isShowingRegistration = true
                }) {
                    Text(NSLocalizedString("Нет аккаунта? Регистрация", comment: "Регистрация"))
                        .foregroundColor(.blue)
                }
                .padding(.top, 10)
                .sheet(isPresented: $isShowingRegistration) {
                    RegistrationView(viewModel: viewModel, isPresented: $isShowingRegistration)
                }
                
                Spacer()
                
            }
            .padding()
            .alert(isPresented: $viewModel.showError) {
                Alert(
                    title: Text(NSLocalizedString("Ошибка авторизации", comment: "")),
                    message: Text(viewModel.errorMessage),
                    dismissButton: .default(Text(NSLocalizedString("OK", comment: "")))
                )
            }
            .onTapGesture {
                focusedField = nil
            }
        }
    }
    
    


    
    private var themeIconName: String {
        switch themeManager.theme {
        case .system:
            return colorScheme == .dark ? "moon.fill" : "sun.max.fill"
        case .light:
            return "sun.max.fill"
        case .dark:
            return "moon.fill"
        }
    }

    private func toggleTheme() {
        themeManager.toggleTheme(from: colorScheme)
    }
    
    private func openLanguageSettings() {
        guard let url = URL(string: UIApplication.openSettingsURLString) else { return }
        UIApplication.shared.open(url)
    }
    
}

struct LoginView_Previews: PreviewProvider {
    static var previews: some View {
        let viewModel = LoginViewModel()
        viewModel.isLoading = false // чтобы убрать спиннер
        return LoginView(viewModel: viewModel)
    }
}
