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

import SwiftUI

struct RegistrationView: View {
    @ObservedObject var viewModel: LoginViewModel
    @Binding var isPresented: Bool
    @Environment(\.presentationMode) private var presentationMode

    @State private var username: String = ""
    @State private var password: String = ""
    @State private var confirmPassword: String = ""
    @State private var inviteCode: String = ""

    @State private var isLoading: Bool = false
    @State private var showError: Bool = false
    @State private var errorMessage: String = ""
    @State private var isShowingTerms: Bool = false

    @FocusState private var focusedField: Field?

    private enum Field: Hashable {
        case username
        case password
        case confirmPassword
        case invite
    }

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

    private var isPasswordValid: Bool {
        password.count >= 8 && password.count <= 128
    }

    private var isConfirmPasswordValid: Bool {
        confirmPassword == password && !confirmPassword.isEmpty
    }

    private var isFormValid: Bool {
        isUsernameValid && isPasswordValid && isConfirmPasswordValid && viewModel.hasAcceptedTerms
    }

    var body: some View {
        NavigationView {
            ScrollView {
                ZStack(alignment: .top) {
                    Color.clear
                        .contentShape(Rectangle())
                        .onTapGesture { focusedField = nil }

                    VStack(alignment: .leading, spacing: 16) {
                        Group {
                            HStack {
                                TextField(NSLocalizedString("Логин", comment: "Логин"), text: $username)
                                    .autocapitalization(.none)
                                    .disableAutocorrection(true)
                                    .focused($focusedField, equals: .username)
                                Spacer()
                                if !username.isEmpty {
                                    Image(systemName: isUsernameValid ? "checkmark.circle" : "xmark.circle")
                                        .foregroundColor(isUsernameValid ? .green : .red)
                                }
                            }
                            .padding()
                            .background(Color(.secondarySystemBackground))
                            .cornerRadius(8)
                            .autocapitalization(.none)
                            .disableAutocorrection(true)
                            .onChange(of: username) { newValue in
                                if newValue.count > 32 {
                                    username = String(newValue.prefix(32))
                                }
                            }

                            if !isUsernameValid && !username.isEmpty {
                                Text(NSLocalizedString("Логин должен быть от 3 до 32 символов (английские буквы, цифры, _)", comment: "Логин должен быть от 3 до 32 символов (английские буквы, цифры, _)"))
                                    .foregroundColor(.red)
                                    .font(.caption)
                            }

                            HStack {
                                SecureField(NSLocalizedString("Пароль", comment: "Пароль"), text: $password)
                                    .autocapitalization(.none)
                                    .focused($focusedField, equals: .password)
                                Spacer()
                                if !password.isEmpty {
                                    Image(systemName: isPasswordValid ? "checkmark.circle" : "xmark.circle")
                                        .foregroundColor(isPasswordValid ? .green : .red)
                                }
                            }
                            .padding()
                            .background(Color(.secondarySystemBackground))
                            .cornerRadius(8)
                            .autocapitalization(.none)
                            .onChange(of: password) { newValue in
                                if newValue.count > 128 {
                                    password = String(newValue.prefix(128))
                                }
                            }

                            if !isPasswordValid && !password.isEmpty {
                                Text(NSLocalizedString("Пароль должен быть от 8 до 128 символов", comment: "Пароль должен быть от 6 до 32 символов"))
                                    .foregroundColor(.red)
                                    .font(.caption)
                            }

                            HStack {
                                SecureField(NSLocalizedString("Подтверждение пароля", comment: "Подтверждение пароля"), text: $confirmPassword)
                                    .autocapitalization(.none)
                                    .focused($focusedField, equals: .confirmPassword)
                                Spacer()
                                if !confirmPassword.isEmpty {
                                    Image(systemName: isConfirmPasswordValid ? "checkmark.circle" : "xmark.circle")
                                        .foregroundColor(isConfirmPasswordValid ? .green : .red)
                                }
                            }
                            .padding()
                            .background(Color(.secondarySystemBackground))
                            .cornerRadius(8)
                            .autocapitalization(.none)
                            .onChange(of: confirmPassword) { newValue in
                                if newValue.count > 32 {
                                    confirmPassword = String(newValue.prefix(32))
                                }
                            }

                            if !isConfirmPasswordValid && !confirmPassword.isEmpty {
                                Text(NSLocalizedString("Пароли не совпадают", comment: "Пароли не совпадают"))
                                    .foregroundColor(.red)
                                    .font(.caption)
                            }

                            TextField(NSLocalizedString("Инвайт-код (необязательно)", comment: "Инвайт-код"), text: $inviteCode)
                                .padding()
                                .background(Color(.secondarySystemBackground))
                                .cornerRadius(8)
                                .autocapitalization(.none)
                                .disableAutocorrection(true)
                                .focused($focusedField, equals: .invite)
                        }

                        TermsAgreementCard(
                            isAccepted: $viewModel.hasAcceptedTerms,
                            openTerms: {
                                viewModel.loadTermsIfNeeded()
                                isShowingTerms = true
                            }
                        )

                        Button(action: registerUser) {
                            if isLoading {
                                ProgressView()
                                    .padding()
                                    .frame(maxWidth: .infinity)
                                    .background(Color.gray.opacity(0.6))
                                    .cornerRadius(8)
                            } else {
                                Text(NSLocalizedString("Зарегистрироваться", comment: "Зарегистрироваться"))
                                    .foregroundColor(.white)
                                    .padding()
                                    .frame(maxWidth: .infinity)
                                    .background(isFormValid ? Color.blue : Color.gray.opacity(0.6))
                                    .cornerRadius(8)
                            }
                        }
                        .disabled(!isFormValid)
                        .padding(.bottom)
                    }
                    .padding()
                }
            }
            .navigationTitle(Text(NSLocalizedString("Регистрация", comment: "Регистрация")))
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button(action: dismissSheet) {
                        Text(NSLocalizedString("Закрыть", comment: "Закрыть"))
                    }
                }
            }
            .alert(isPresented: $showError) {
                Alert(
                    title: Text(NSLocalizedString("Ошибка регистрация", comment: "Ошибка")),
                    message: Text(errorMessage),
                    dismissButton: .default(Text(NSLocalizedString("OK", comment: "")))
                )
            }
        }
        .fullScreenCover(isPresented: $isShowingTerms) {
            TermsFullScreenView(
                isPresented: $isShowingTerms,
                title: NSLocalizedString("Правила сервиса", comment: ""),
                content: viewModel.termsContent,
                isLoading: viewModel.isLoadingTerms,
                errorMessage: viewModel.termsErrorMessage,
                onRetry: {
                    viewModel.reloadTerms()
                }
            )
            .onAppear {
                if viewModel.termsContent.isEmpty {
                    viewModel.loadTermsIfNeeded()
                }
            }
        }
    }

    private func registerUser() {
        isLoading = true
        errorMessage = ""
        viewModel.registerUser(username: username, password: password, invite: inviteCode.isEmpty ? nil : inviteCode) { success, message in
            isLoading = false
            if success {
                dismissSheet()
            } else {
                errorMessage = message ?? NSLocalizedString("Неизвестная ошибка.", comment: "")
                showError = true
            }
        }
    }

    private func dismissSheet() {
        focusedField = nil
        viewModel.hasAcceptedTerms = false
        isPresented = false
        presentationMode.wrappedValue.dismiss()
    }
}


struct RegistrationView_Previews: PreviewProvider {
    static var previews: some View {
        let viewModel = LoginViewModel()
        viewModel.isLoading = false // чтобы убрать спиннер
        return RegistrationView(viewModel: viewModel, isPresented: .constant(true))
    }
}