package de.oaa.xxx.dating;

import de.oaa.xxx.social.SystemMessageService;
import de.oaa.xxx.social.entity.MessageCause;
import de.oaa.xxx.social.repository.BlockRepository;
import de.oaa.xxx.subscription.SubscriptionLimitService;
import de.oaa.xxx.user.Geschlecht;
import de.oaa.xxx.user.Neigung;
import de.oaa.xxx.user.UserEntity;
import de.oaa.xxx.user.UserRepository;
import de.oaa.xxx.user.UserService;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.server.ResponseStatusException;

import java.security.Principal;
import java.time.LocalDateTime;
import java.util.*;
import java.util.stream.Collectors;

@RestController
@RequestMapping("/dating/dates")
public class DatingDateController {

    private static final int MAX_DATES_STANDARD = 1;
    private static final int MAX_DATES_PRO      = 5;

    private final DatingDateRepository dateRepository;
    private final DatingDateInterestRepository interestRepository;
    private final DatingService datingService;
    private final UserService userService;
    private final UserRepository userRepository;
    private final BlockRepository blockRepository;
    private final SubscriptionLimitService subscriptionLimitService;
    private final SystemMessageService systemMessageService;

    public DatingDateController(DatingDateRepository dateRepository,
                                DatingDateInterestRepository interestRepository,
                                DatingService datingService,
                                UserService userService,
                                UserRepository userRepository,
                                BlockRepository blockRepository,
                                SubscriptionLimitService subscriptionLimitService,
                                SystemMessageService systemMessageService) {
        this.dateRepository          = dateRepository;
        this.interestRepository      = interestRepository;
        this.datingService           = datingService;
        this.userService             = userService;
        this.userRepository          = userRepository;
        this.blockRepository         = blockRepository;
        this.subscriptionLimitService = subscriptionLimitService;
        this.systemMessageService    = systemMessageService;
    }

    // ── DTOs ──────────────────────────────────────────────────────────────────

    record DatingDateDto(
            UUID dateId,
            UUID creatorId,
            String creatorName,
            String creatorProfilePicture,
            String title,
            String description,
            String imageData,
            LocalDateTime scheduledAt,
            LocalDateTime createdAt,
            int interestCount,
            boolean myInterest
    ) {}

    record DatesResult(List<DatingDateDto> mine, List<DatingDateDto> available) {}

    record CreateDateRequest(String title, String description, String imageData, LocalDateTime scheduledAt) {}

    record InterestResult(boolean myInterest, int interestCount) {}

    record DateInterestDto(UUID userId, String name, String profilePicture, LocalDateTime interestedAt, boolean blocked) {}

    // ── Dates abrufen ─────────────────────────────────────────────────────────

    /**
     * Gibt eigene Dates (ungefiltert) + verfügbare Dates (gefiltert nach Suchkriterien) zurück.
     * Erfordert Dating aktiv + Standort (gleiche Voraussetzung wie Entdecken-Tab).
     */
    @GetMapping
    public ResponseEntity<DatesResult> getDates(
            @RequestParam(name = "maxDistanceKm", defaultValue = "50")    int maxDistanceKm,
            @RequestParam(name = "minAge",         defaultValue = "18")    int minAge,
            @RequestParam(name = "maxAge",         defaultValue = "99")    int maxAge,
            @RequestParam(name = "geschlechter",   required = false)       List<String> geschlechter,
            @RequestParam(name = "neigungen",      required = false)       List<String> neigungen,
            @RequestParam(name = "vorliebenIds",   required = false)       List<UUID> vorliebenIds,
            @RequestParam(name = "vorliebenUnd",   defaultValue = "false") boolean vorliebenUnd,
            Principal principal) {

        UserEntity me = requireDatingUser(principal);
        UUID myId = me.getUserId();

        LocalDateTime now = LocalDateTime.now();

        // Meine eigenen Dates (aktive)
        List<DatingDateEntity> myDates = dateRepository.findByCreatorIdOrderByCreatedAtDesc(myId).stream()
                .filter(d -> d.getExpiresAt().isAfter(now))
                .toList();

        // Alle fremden, noch nicht abgelaufenen Dates
        List<DatingDateEntity> candidates = dateRepository.findAvailableExcluding(myId, now);

        // Ersteller-IDs filtern (gleiche Kriterien wie Entdecken-Tab)
        Set<UUID> creatorIds = candidates.stream().map(DatingDateEntity::getCreatorId).collect(Collectors.toSet());
        DatingService.DatingFilter filter = new DatingService.DatingFilter(
                Math.max(maxDistanceKm, 1),
                Math.max(minAge, 0),
                Math.min(maxAge, 120),
                parseEnumList(geschlechter, Geschlecht.class),
                parseEnumList(neigungen, Neigung.class),
                vorliebenIds != null ? vorliebenIds : List.of(),
                vorliebenUnd
        );
        Set<UUID> matchingCreators = datingService.filterUserIds(creatorIds, filter,
                me.getDatingLat(), me.getDatingLon());

        List<DatingDateEntity> available = candidates.stream()
                .filter(d -> matchingCreators.contains(d.getCreatorId()))
                .toList();

        // Creator-User-Daten laden
        Set<UUID> allCreatorIds = new HashSet<>(creatorIds);
        myDates.forEach(d -> allCreatorIds.add(d.getCreatorId()));
        Map<UUID, UserEntity> creators = userRepository.findAllById(allCreatorIds).stream()
                .collect(Collectors.toMap(UserEntity::getUserId, u -> u));

        // Alle relevanten Date-IDs
        Set<UUID> allDateIds = new HashSet<>();
        myDates.forEach(d -> allDateIds.add(d.getDateId()));
        available.forEach(d -> allDateIds.add(d.getDateId()));

        // Meine Interessen und Interest-Counts
        Set<UUID> myInterests = new HashSet<>();
        Map<UUID, Long> interestCounts = new HashMap<>();
        for (UUID dateId : allDateIds) {
            if (interestRepository.existsByDateIdAndUserId(dateId, myId)) myInterests.add(dateId);
            interestCounts.put(dateId, interestRepository.countByDateId(dateId));
        }

        List<DatingDateDto> mineDtos = myDates.stream()
                .map(d -> toDto(d, creators, myInterests, interestCounts))
                .toList();

        List<DatingDateDto> availableDtos = available.stream()
                .map(d -> toDto(d, creators, myInterests, interestCounts))
                .toList();

        return ResponseEntity.ok(new DatesResult(mineDtos, availableDtos));
    }

    // ── Dates eines bestimmten Users abrufen (Profilansicht) ─────────────────

    /**
     * Gibt die aktiven Dates eines bestimmten Users zurück.
     * Nur abrufbar, wenn der anfragende User selbst Dating aktiviert hat.
     */
    @GetMapping("/by-user/{userId}")
    public ResponseEntity<List<DatingDateDto>> getDatesByUser(
            @PathVariable("userId") UUID userId,
            Principal principal) {

        UserEntity me = requireDatingUser(principal);
        LocalDateTime now = LocalDateTime.now();

        List<DatingDateEntity> dates = dateRepository.findByCreatorIdOrderByCreatedAtDesc(userId).stream()
                .filter(d -> d.getExpiresAt().isAfter(now))
                .toList();

        if (dates.isEmpty()) return ResponseEntity.ok(List.of());

        UserEntity creator = userRepository.findById(userId).orElse(null);
        Map<UUID, UserEntity> creators = creator != null ? Map.of(userId, creator) : Map.of();

        Set<UUID> myInterests = new HashSet<>();
        Map<UUID, Long> interestCounts = new HashMap<>();
        for (DatingDateEntity d : dates) {
            if (interestRepository.existsByDateIdAndUserId(d.getDateId(), me.getUserId()))
                myInterests.add(d.getDateId());
            interestCounts.put(d.getDateId(), interestRepository.countByDateId(d.getDateId()));
        }

        return ResponseEntity.ok(dates.stream()
                .map(d -> toDto(d, creators, myInterests, interestCounts))
                .toList());
    }

    // ── Date erstellen ────────────────────────────────────────────────────────

    @PostMapping
    public ResponseEntity<DatingDateDto> createDate(@RequestBody CreateDateRequest req, Principal principal) {
        UserEntity me = requireDatingUser(principal);

        if (req.title() == null || req.title().isBlank())
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Titel fehlt");
        if (req.description() == null || req.description().isBlank())
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Beschreibung fehlt");
        if (req.title().length() > 200)
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Titel zu lang");

        boolean pro = subscriptionLimitService.hasActivePaidSubscription(me.getUserId());
        int maxDates = pro ? MAX_DATES_PRO : MAX_DATES_STANDARD;
        long existing = dateRepository.countByCreatorId(me.getUserId());
        if (existing >= maxDates) {
            throw new ResponseStatusException(HttpStatus.UNPROCESSABLE_ENTITY,
                    pro ? "Maximal 5 Dates erlaubt (Pro)" : "Als Standardmitglied ist nur 1 Date erlaubt");
        }

        LocalDateTime now = LocalDateTime.now();
        LocalDateTime expiresAt = req.scheduledAt() != null ? req.scheduledAt() : now.plusDays(30);

        DatingDateEntity entity = new DatingDateEntity();
        entity.setDateId(UUID.randomUUID());
        entity.setCreatorId(me.getUserId());
        entity.setTitle(req.title().strip());
        entity.setDescription(req.description().strip());
        entity.setImageData(req.imageData());
        entity.setScheduledAt(req.scheduledAt());
        entity.setCreatedAt(now);
        entity.setExpiresAt(expiresAt);
        dateRepository.save(entity);

        Map<UUID, UserEntity> creators = Map.of(me.getUserId(), me);
        return ResponseEntity.status(HttpStatus.CREATED)
                .body(toDto(entity, creators, Set.of(), Map.of(entity.getDateId(), 0L)));
    }

    // ── Date bearbeiten ───────────────────────────────────────────────────────

    @PutMapping("/{dateId}")
    public ResponseEntity<DatingDateDto> updateDate(@PathVariable("dateId") UUID dateId,
                                                    @RequestBody CreateDateRequest req,
                                                    Principal principal) {
        UserEntity me = requireDatingUser(principal);
        DatingDateEntity entity = requireMyDate(dateId, me.getUserId());

        if (req.title() == null || req.title().isBlank())
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Titel fehlt");
        if (req.description() == null || req.description().isBlank())
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Beschreibung fehlt");
        if (req.title().length() > 200)
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Titel zu lang");

        entity.setTitle(req.title().strip());
        entity.setDescription(req.description().strip());
        if (req.imageData() != null) entity.setImageData(req.imageData().isBlank() ? null : req.imageData());
        entity.setScheduledAt(req.scheduledAt());
        entity.setExpiresAt(req.scheduledAt() != null ? req.scheduledAt() : entity.getCreatedAt().plusDays(30));
        dateRepository.save(entity);

        long count = interestRepository.countByDateId(dateId);
        boolean myInterest = interestRepository.existsByDateIdAndUserId(dateId, me.getUserId());
        Map<UUID, UserEntity> creators = Map.of(me.getUserId(), me);
        return ResponseEntity.ok(toDto(entity, creators, myInterest ? Set.of(dateId) : Set.of(),
                Map.of(dateId, count)));
    }

    // ── Date löschen ──────────────────────────────────────────────────────────

    @DeleteMapping("/{dateId}")
    @Transactional
    public ResponseEntity<Void> deleteDate(@PathVariable("dateId") UUID dateId, Principal principal) {
        UserEntity me = requireDatingUser(principal);
        requireMyDate(dateId, me.getUserId());
        interestRepository.deleteByDateId(dateId);
        dateRepository.deleteById(dateId);
        return ResponseEntity.noContent().build();
    }

    // ── Interesse bekunden / zurückziehen ──────────────────────────────────────

    @PostMapping("/{dateId}/interest")
    @Transactional
    public ResponseEntity<InterestResult> toggleInterest(@PathVariable("dateId") UUID dateId,
                                                         Principal principal) {
        UserEntity me = userService.requireUser(principal);
        DatingDateEntity date = dateRepository.findById(dateId)
                .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Date nicht gefunden"));

        if (date.getCreatorId().equals(me.getUserId()))
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Eigenes Date");
        if (date.getExpiresAt().isBefore(LocalDateTime.now()))
            throw new ResponseStatusException(HttpStatus.GONE, "Date abgelaufen");

        Optional<DatingDateInterestEntity> existing =
                interestRepository.findByDateIdAndUserId(dateId, me.getUserId());

        boolean myInterest;
        if (existing.isPresent()) {
            interestRepository.delete(existing.get());
            myInterest = false;
        } else {
            DatingDateInterestEntity interest = new DatingDateInterestEntity();
            interest.setInterestId(UUID.randomUUID());
            interest.setDateId(dateId);
            interest.setUserId(me.getUserId());
            interest.setInterestedAt(LocalDateTime.now());
            interestRepository.save(interest);
            myInterest = true;

            // Benachrichtigung an Ersteller
            String text = me.getName() + " hat Interesse an deinem Date \"" + date.getTitle() + "\" bekundet.";
            systemMessageService.send(me.getUserId(), date.getCreatorId(), text,
                    "/dating.html?tab=dates", MessageCause.DATE_INTEREST);
        }

        long count = interestRepository.countByDateId(dateId);
        return ResponseEntity.ok(new InterestResult(myInterest, (int) count));
    }

    // ── Interessenten abrufen (nur Ersteller) ─────────────────────────────────

    @GetMapping("/{dateId}/interests")
    public ResponseEntity<List<DateInterestDto>> getInterests(@PathVariable("dateId") UUID dateId,
                                                              Principal principal) {
        UserEntity me = userService.requireUser(principal);
        DatingDateEntity date = dateRepository.findById(dateId)
                .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Date nicht gefunden"));

        if (!date.getCreatorId().equals(me.getUserId()))
            throw new ResponseStatusException(HttpStatus.FORBIDDEN, "Kein Zugriff");

        List<DatingDateInterestEntity> interests = interestRepository.findByDateIdOrderByInterestedAtDesc(dateId);
        Set<UUID> userIds = interests.stream().map(DatingDateInterestEntity::getUserId).collect(Collectors.toSet());
        Map<UUID, UserEntity> users = userRepository.findAllById(userIds).stream()
                .collect(Collectors.toMap(UserEntity::getUserId, u -> u));

        List<DateInterestDto> dtos = interests.stream()
                .map(i -> {
                    UserEntity u = users.get(i.getUserId());
                    if (u == null) return null;
                    boolean blocked = blockRepository.existsBlock(me.getUserId(), u.getUserId());
                    return new DateInterestDto(u.getUserId(), u.getName(),
                            u.getProfilePicture(), i.getInterestedAt(), blocked);
                })
                .filter(Objects::nonNull)
                .toList();

        return ResponseEntity.ok(dtos);
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    private UserEntity requireDatingUser(Principal principal) {
        UserEntity me = userService.requireUser(principal);
        if (!me.isDatingAktiv())
            throw new ResponseStatusException(HttpStatus.FORBIDDEN, "Dating nicht aktiviert");
        if (me.getDatingLat() == null || me.getDatingLon() == null)
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Standort nicht gesetzt");
        return me;
    }

    private DatingDateEntity requireMyDate(UUID dateId, UUID userId) {
        DatingDateEntity entity = dateRepository.findById(dateId)
                .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Date nicht gefunden"));
        if (!entity.getCreatorId().equals(userId))
            throw new ResponseStatusException(HttpStatus.FORBIDDEN, "Kein Zugriff");
        return entity;
    }

    private DatingDateDto toDto(DatingDateEntity d, Map<UUID, UserEntity> creators,
                                 Set<UUID> myInterests, Map<UUID, Long> interestCounts) {
        UserEntity creator = creators.get(d.getCreatorId());
        return new DatingDateDto(
                d.getDateId(),
                d.getCreatorId(),
                creator != null ? creator.getName() : null,
                creator != null ? creator.getProfilePicture() : null,
                d.getTitle(),
                d.getDescription(),
                d.getImageData(),
                d.getScheduledAt(),
                d.getCreatedAt(),
                interestCounts.getOrDefault(d.getDateId(), 0L).intValue(),
                myInterests.contains(d.getDateId())
        );
    }

    private <E extends Enum<E>> List<E> parseEnumList(List<String> values, Class<E> enumClass) {
        if (values == null || values.isEmpty()) return List.of();
        return values.stream()
                .map(s -> {
                    try { return Enum.valueOf(enumClass, s); }
                    catch (IllegalArgumentException e) { return null; }
                })
                .filter(Objects::nonNull)
                .toList();
    }
}