package com.mailserver.controller;

import com.mailserver.config.MailAdmins;
import com.mailserver.config.MailDomains;
import com.mailserver.domain.User;
import com.mailserver.dto.LoginResponse;
import com.mailserver.service.MailDirectory;
import com.mailserver.service.MailLists;
import com.mailserver.service.MailService;
import com.mailserver.service.UserService;
import com.mailserver.util.JwtUtils;
import jakarta.validation.constraints.NotBlank;
import jakarta.validation.constraints.Size;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.security.core.Authentication;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.server.ResponseStatusException;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.time.Instant;
import java.util.Comparator;
import java.util.List;

/**
 * Mailboxes of this server for its administrators ({@link MailAdmins}): list, create (no-reply@, monitor@,
 * support@ — registration stays closed), new password, switch off. A generated password is returned once, in the
 * answer — it is not logged.
 */
@RestController
@RequestMapping("/api/admin/mailboxes")
public class MailboxAdminController {

    private static final Logger log = LoggerFactory.getLogger(MailboxAdminController.class);
    private static final int MIN_PASSWORD = MailDirectory.MIN_PASSWORD;

    public record MailboxView(Long id, String email, String displayName, boolean active, boolean admin, boolean trap,
                              long usedBytes, long quotaBytes, Instant createdAt) {
    }

    /** @param password empty — the server generates one and returns it once */
    public record CreateRequest(@NotBlank @Size(max = 254) String email, @Size(max = 100) String displayName,
                                @Size(max = 200) String password) {
    }

    public record PasswordRequest(@Size(max = 200) String password) {
    }

    public record ActiveRequest(boolean active) {
    }

    public record TrapRequest(boolean trap) {
    }

    /** @param password the generated password, or null when the administrator chose it */
    public record Created(MailboxView mailbox, String password) {
    }

    private final UserService users;
    private final MailService mail;
    private final MailDomains domains;
    private final MailAdmins admins;
    private final JwtUtils jwt;
    private final MailDirectory directory;
    private final MailLists lists;

    public MailboxAdminController(UserService users, MailService mail, MailDomains domains, MailAdmins admins, JwtUtils jwt,
                                  MailDirectory directory, MailLists lists) {
        this.jwt = jwt;
        this.directory = directory;
        this.lists = lists;
        this.users = users;
        this.mail = mail;
        this.domains = domains;
        this.admins = admins;
    }

    @GetMapping
    public Flux<MailboxView> list(Mono<Authentication> auth) {
        return admin(auth).thenMany(users.all())
                .concatMap(this::view)
                .sort(Comparator.comparing(MailboxView::email));
    }

    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    public Mono<Created> create(Mono<Authentication> auth, @RequestBody Mono<CreateRequest> body) {
        return admin(auth).then(body).flatMap(request -> {
            String chosen = request.password() == null ? "" : request.password();
            if (!chosen.isEmpty() && chosen.length() < MIN_PASSWORD) {
                return Mono.error(bad("Password: at least " + MIN_PASSWORD + " characters, or leave it empty to generate one"));
            }
            String password = chosen.isEmpty() ? randomPassword() : chosen;
            return directory.createMailbox(request.email(), request.displayName(), password)
                    .doOnNext(user -> log.info("Mailbox created by administrator: {}", user.getEmail()))
                    .flatMap(this::view)
                    .map(view -> new Created(view, chosen.isEmpty() ? password : null));
        });
    }

    /** New password: the given one, or a generated one returned once. */
    @PostMapping("/{id}/password")
    public Mono<Created> password(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<PasswordRequest> body) {
        return admin(auth).then(body.defaultIfEmpty(new PasswordRequest(null))).flatMap(request -> {
            String chosen = request.password() == null ? "" : request.password();
            if (!chosen.isEmpty() && chosen.length() < MIN_PASSWORD) {
                return Mono.error(bad("Password: at least " + MIN_PASSWORD + " characters, or leave it empty to generate one"));
            }
            String password = chosen.isEmpty() ? randomPassword() : chosen;
            return mailbox(id)
                    .flatMap(user -> users.setPassword(user, password))
                    .doOnNext(user -> log.info("Password of {} set by administrator", user.getEmail()))
                    .flatMap(this::view)
                    .map(view -> new Created(view, chosen.isEmpty() ? password : null));
        });
    }

    /**
     * Administrator opens a mailbox without its password (Settings → MAILBOXES → Open): a session of that mailbox.
     * Every opening is logged — who opened which mailbox.
     */
    @PostMapping("/{id}/open")
    public Mono<LoginResponse> open(Mono<Authentication> auth, @PathVariable Long id) {
        return admin(auth).flatMap(me -> mailbox(id).map(user -> {
            log.warn("Administrator {} opened mailbox {}", me, user.getEmail());
            LoginResponse response = new LoginResponse();
            response.setToken(jwt.generateToken(user.getEmail()));
            response.setEmail(user.getEmail());
            return response;
        }));
    }

    /** Switched off: no login (web, SMTP, IMAP); mail to it is still received. */
    @PutMapping("/{id}/active")
    public Mono<MailboxView> active(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<ActiveRequest> body) {
        return admin(auth).flatMap(me -> body.flatMap(request -> mailbox(id).flatMap(user -> {
            if (!request.active() && user.getEmail().equalsIgnoreCase(me)) {
                return Mono.error(bad("You can not switch off your own mailbox"));
            }
            log.info("Mailbox {} {} by administrator", user.getEmail(), request.active() ? "switched on" : "switched off");
            return users.setActive(user, request.active());
        }))).flatMap(this::view);
    }

    /** Trap: what the mailbox sends is stored in its own INBOX, nothing leaves the server (staging@). */
    @PutMapping("/{id}/trap")
    public Mono<MailboxView> trap(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<TrapRequest> body) {
        return admin(auth).flatMap(me -> body.flatMap(request -> mailbox(id).flatMap(user -> {
            log.info("Mailbox {} trap {} by administrator {}", user.getEmail(), request.trap() ? "ON" : "OFF", me);
            return users.setTrap(user, request.trap());
        }))).flatMap(this::view);
    }

    // --- Mailing lists (Settings → LISTS) ---

    public record ListRequest(@Size(max = 50) String folder, @Size(max = 255) String description, boolean openToOutside,
                              List<String> members) {
    }

    @GetMapping("/lists")
    public Flux<MailLists.MailList> lists(Mono<Authentication> auth) {
        return admin(auth).thenMany(lists.all());
    }

    /** Creates or replaces the list {@code address} (settings + the exact member set). */
    @PutMapping("/lists/{address}")
    public Mono<MailLists.MailList> saveList(Mono<Authentication> auth, @PathVariable String address,
                                             @RequestBody Mono<ListRequest> body) {
        return admin(auth).flatMap(me -> body.flatMap(request ->
                directory.saveList(address, request.folder(), request.description(), request.openToOutside(), request.members())
                        .doOnNext(list -> log.info("List {} saved by administrator {}: {} members", list.address(), me, list.members().size()))));
    }

    @DeleteMapping("/lists/{address}")
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public Mono<Void> deleteList(Mono<Authentication> auth, @PathVariable String address) {
        return admin(auth).flatMap(me -> lists.delete(address)
                .flatMap(deleted -> deleted ? Mono.<Void>empty()
                        : Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "List not found")))
                .doOnSuccess(v -> log.info("List {} deleted by administrator {}", address, me)));
    }

    private Mono<String> admin(Mono<Authentication> auth) {
        return auth.switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.UNAUTHORIZED)))
                .map(Authentication::getName)
                .filter(admins::isAdmin)
                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.FORBIDDEN, "Only for mail administrators")));
    }

    private Mono<User> mailbox(Long id) {
        return users.byId(id).switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "Mailbox not found")));
    }

    private Mono<MailboxView> view(User user) {
        return mail.usedBytes(user.getId()).defaultIfEmpty(0L)
                .map(used -> new MailboxView(user.getId(), user.getEmail(), user.getDisplayName(), user.isActive(),
                        admins.isAdmin(user.getEmail()), user.isTrap(), used, user.getQuotaBytes() == null ? 0 : user.getQuotaBytes(),
                        user.getCreatedAt()));
    }

    private static ResponseStatusException bad(String message) {
        return new ResponseStatusException(HttpStatus.BAD_REQUEST, message);
    }

    static String randomPassword() {
        return MailDirectory.randomPassword();
    }
}