package com.mailserver.service;

import com.mailserver.domain.Folder;
import com.mailserver.domain.User;
import com.mailserver.repository.FolderRepository;
import com.mailserver.repository.UserRepository;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.stereotype.Service;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.time.Instant;

@Service
public class UserService {

    private final UserRepository userRepository;
    private final FolderRepository folderRepository;
    private final BCryptPasswordEncoder passwordEncoder;

    public UserService(UserRepository userRepository, FolderRepository folderRepository) {
        this.userRepository = userRepository;
        this.folderRepository = folderRepository;
        this.passwordEncoder = new BCryptPasswordEncoder();
    }

    public Mono<User> register(String email, String password, String displayName) {
        return userRepository.existsByEmail(email)
                .flatMap(exists -> {
                    if (exists) {
                        return Mono.error(new IllegalArgumentException("Email already registered: " + email));
                    }

                    User user = new User();
                    user.setEmail(email);
                    user.setPassword(passwordEncoder.encode(password));
                    user.setDisplayName(displayName == null || displayName.isBlank() ? email.substring(0, email.indexOf('@')) : displayName.trim());
                    user.setCreatedAt(Instant.now());
                    return userRepository.save(user);
                })
                .flatMap(user -> {
                    // Создаём стандартные папки
                    return Flux.fromIterable(MailService.SYSTEM_FOLDERS)
                            .concatMap(name -> {
                                Folder folder = new Folder();
                                folder.setUserId(user.getId());
                                folder.setName(name);
                                folder.setSystem(true);
                                folder.setCreatedAt(Instant.now());
                                return folderRepository.save(folder);
                            })
                            .then(Mono.just(user));
                });
    }

    public Mono<User> findByEmail(String email) {
        return userRepository.findByEmail(email)
                .switchIfEmpty(Mono.error(new IllegalArgumentException("User not found: " + email)));
    }

    /**
     * Проверяет, совпадает ли пароль с хэшем, хранящимся у пользователя.
     */
    public boolean checkPassword(User user, String rawPassword) {
        return passwordEncoder.matches(rawPassword, user.getPassword());
    }

    /** New password, only with the current one. */
    public Mono<Void> changePassword(User user, String currentPassword, String newPassword) {
        if (!checkPassword(user, currentPassword)) {
            return Mono.error(MailService.badRequest("Current password is wrong"));
        }
        user.setPassword(passwordEncoder.encode(newPassword));
        return userRepository.save(user).then();
    }

    /** The mailbox, or empty (no error). */
    public Mono<User> findOptional(String email) {
        return userRepository.findByEmail(email.toLowerCase(java.util.Locale.ROOT));
    }

    public Flux<User> all() {
        return userRepository.findAll();
    }

    public Mono<User> byId(Long id) {
        return userRepository.findById(id);
    }

    /** Administrator sets a new password (Settings → Mailboxes): no current password needed. */
    public Mono<User> setPassword(User user, String newPassword) {
        user.setPassword(passwordEncoder.encode(newPassword));
        return userRepository.save(user);
    }

    public Mono<User> setActive(User user, boolean active) {
        user.setActive(active);
        return userRepository.save(user);
    }

    public Mono<User> setTrap(User user, boolean trap) {
        user.setTrap(trap);
        return userRepository.save(user);
    }

    public Mono<User> updateDisplayName(User user, String displayName) {
        user.setDisplayName(displayName.trim());
        return userRepository.save(user);
    }
}