import { Prisma } from "@/app/generated/prisma/client";
import type { ActivityCategory } from "@/app/generated/prisma/enums";
import { prisma } from "@/lib/prisma";
import { tripRepo, type TripFilters } from "@/server/repositories/trip.repo";
import { participantRepo } from "@/server/repositories/participant.repo";
import { LIMITS } from "@/lib/limits";
import { utcStartOfDay, isTripDepartureDayPast } from "@/lib/trip-dates";

const SERIAL_TX_ATTEMPTS = 6;

function isSerializationConflict(err: unknown): boolean {
  return (
    typeof err === "object" &&
    err !== null &&
    "code" in err &&
    (err as { code: string }).code === "P2034"
  );
}

interface CreateTripInput {
  category: ActivityCategory;
  title: string;
  description?: string;
  destination: string;
  location: string;
  meetingPoint?: string;
  itinerary?: string;
  whatsIncluded?: string;
  whatsExcluded?: string;
  date: Date;
  endDate?: Date;
  maxParticipants: number;
  price: number;
  organizerId: string;
  imageUrls?: string[];
}

export const tripService = {
  async getOpenTrips(filters?: TripFilters) {
    return tripRepo.findOpen(filters);
  },

  async getAllTrips() {
    return tripRepo.findAll();
  },

  async getTripById(id: string) {
    const trip = await tripRepo.findById(id);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }
    return trip;
  },

  async createTrip(input: CreateTripInput) {
    if (isTripDepartureDayPast(input.date)) {
      throw new Error("Tanggal berangkat tidak boleh di masa lalu");
    }

    if (input.endDate && input.endDate.getTime() < input.date.getTime()) {
      throw new Error("Tanggal pulang tidak boleh sebelum tanggal berangkat");
    }

    const since = utcStartOfDay(new Date());
    const images = input.imageUrls?.length
      ? {
          create: input.imageUrls.map((url, i) => ({ url, order: i })),
        }
      : undefined;

    const tripData = {
      category: input.category,
      title: input.title,
      description: input.description,
      destination: input.destination,
      location: input.location,
      meetingPoint: input.meetingPoint,
      itinerary: input.itinerary,
      whatsIncluded: input.whatsIncluded,
      whatsExcluded: input.whatsExcluded,
      date: input.date,
      endDate: input.endDate,
      maxParticipants: input.maxParticipants,
      price: input.price,
      organizer: { connect: { id: input.organizerId } },
      images,
    } satisfies Prisma.TripCreateInput;

    let lastErr: unknown;
    for (let attempt = 0; attempt < SERIAL_TX_ATTEMPTS; attempt++) {
      try {
        return await prisma.$transaction(
          async (tx) => {
            const todayCount = await tx.trip.count({
              where: {
                organizerId: input.organizerId,
                createdAt: { gte: since },
              },
            });
            if (todayCount >= LIMITS.MAX_TRIPS_PER_ORGANIZER_PER_DAY) {
              throw new Error(
                `Batas harian: maksimal ${LIMITS.MAX_TRIPS_PER_ORGANIZER_PER_DAY} trip per hari. Coba lagi besok.`
              );
            }
            return tx.trip.create({ data: tripData });
          },
          {
            isolationLevel: Prisma.TransactionIsolationLevel.Serializable,
            maxWait: 5000,
            timeout: 15000,
          }
        );
      } catch (e) {
        lastErr = e;
        if (isSerializationConflict(e) && attempt < SERIAL_TX_ATTEMPTS - 1) {
          continue;
        }
        throw e;
      }
    }
    throw lastErr instanceof Error
      ? lastErr
      : new Error("Gagal membuat trip. Coba lagi sebentar.");
  },

  async joinTrip(tripId: string, userId: string) {
    let lastErr: unknown;
    for (let attempt = 0; attempt < SERIAL_TX_ATTEMPTS; attempt++) {
      try {
        return await prisma.$transaction(
          async (tx) => {
            const trip = await tx.trip.findUnique({
              where: { id: tripId },
              select: {
                id: true,
                status: true,
                date: true,
                organizerId: true,
                maxParticipants: true,
              },
            });

            if (!trip) {
              throw new Error("Trip tidak ditemukan");
            }
            if (trip.status !== "OPEN") {
              throw new Error("Trip tidak tersedia untuk pendaftaran");
            }
            if (isTripDepartureDayPast(trip.date)) {
              throw new Error(
                "Trip sudah melewati tanggal berangkat, tidak bisa mendaftar"
              );
            }
            if (trip.organizerId === userId) {
              throw new Error("Organizer tidak bisa join trip sendiri");
            }

            const existing = await tx.tripParticipant.findUnique({
              where: { tripId_userId: { tripId, userId } },
            });
            if (existing && existing.status !== "CANCELLED") {
              throw new Error("Kamu sudah terdaftar di trip ini");
            }

            const participantCount = await tx.tripParticipant.count({
              where: { tripId, status: { not: "CANCELLED" } },
            });
            if (participantCount >= trip.maxParticipants) {
              throw new Error("Trip sudah penuh");
            }

            const participant =
              existing?.status === "CANCELLED"
                ? await tx.tripParticipant.update({
                    where: { tripId_userId: { tripId, userId } },
                    data: {
                      status: "PENDING",
                      markedPaidAt: null,
                      paymentConfirmedAt: null,
                    },
                  })
                : await tx.tripParticipant.create({
                    data: { tripId, userId, status: "PENDING" },
                  });

            const newCount = await tx.tripParticipant.count({
              where: { tripId, status: { not: "CANCELLED" } },
            });
            if (newCount >= trip.maxParticipants) {
              await tx.trip.update({
                where: { id: tripId },
                data: { status: "FULL" },
              });
            }

            return participant;
          },
          {
            isolationLevel: Prisma.TransactionIsolationLevel.Serializable,
            maxWait: 5000,
            timeout: 15000,
          }
        );
      } catch (e) {
        lastErr = e;
        if (isSerializationConflict(e) && attempt < SERIAL_TX_ATTEMPTS - 1) {
          continue;
        }
        throw e;
      }
    }
    throw lastErr instanceof Error
      ? lastErr
      : new Error("Pendaftaran sedang ramai. Coba lagi sebentar.");
  },

  async cancelJoin(tripId: string, userId: string) {
    const trip = await tripRepo.findById(tripId);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }

    if (isTripDepartureDayPast(trip.date)) {
      throw new Error(
        "Tanggal berangkat trip sudah lewat — pendaftaran tidak bisa dibatalkan. Jika trip sudah selesai, gunakan bagian ulasan."
      );
    }

    const existing = await participantRepo.findByTripAndUser(tripId, userId);
    if (!existing || existing.status === "CANCELLED") {
      throw new Error("Kamu tidak terdaftar di trip ini");
    }

    const result = await participantRepo.cancel(tripId, userId);

    if (trip.status === "FULL") {
      const count = await participantRepo.countByTrip(tripId);
      if (count < trip.maxParticipants) {
        await tripRepo.updateStatus(tripId, "OPEN");
      }
    }

    return result;
  },

  async confirmParticipant(
    tripId: string,
    participantId: string,
    organizerId: string
  ) {
    const trip = await tripRepo.findById(tripId);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }
    if (trip.organizerId !== organizerId) {
      throw new Error("Hanya organizer trip ini yang bisa mengonfirmasi peserta");
    }

    const participant = await participantRepo.findById(participantId);
    if (!participant || participant.tripId !== tripId) {
      throw new Error("Peserta tidak ditemukan");
    }
    if (participant.status !== "PENDING") {
      throw new Error("Peserta ini tidak dalam status menunggu persetujuan");
    }

    return participantRepo.setStatus(participantId, "CONFIRMED");
  },

  async rejectParticipant(
    tripId: string,
    participantId: string,
    organizerId: string
  ) {
    const trip = await tripRepo.findById(tripId);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }
    if (trip.organizerId !== organizerId) {
      throw new Error("Hanya organizer trip ini yang bisa menolak permintaan bergabung");
    }

    const participant = await participantRepo.findById(participantId);
    if (!participant || participant.tripId !== tripId) {
      throw new Error("Peserta tidak ditemukan");
    }
    if (participant.status !== "PENDING") {
      throw new Error("Hanya permintaan yang masih menunggu yang bisa ditolak");
    }

    await participantRepo.setStatusAndClearPayment(
      participantId,
      "CANCELLED"
    );

    if (trip.status === "FULL") {
      const count = await participantRepo.countByTrip(tripId);
      if (count < trip.maxParticipants) {
        await tripRepo.updateStatus(tripId, "OPEN");
      }
    }

    return { ok: true as const };
  },

  async markParticipantPayment(tripId: string, userId: string) {
    const trip = await tripRepo.findById(tripId);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }

    if (isTripDepartureDayPast(trip.date)) {
      throw new Error("Trip sudah lewat — pembayaran tidak perlu ditandai");
    }

    const p = await participantRepo.findByTripAndUser(tripId, userId);
    if (!p || p.status === "CANCELLED") {
      throw new Error("Kamu tidak terdaftar di trip ini");
    }

    if (p.paymentConfirmedAt) {
      throw new Error("Pembayaran kamu sudah dikonfirmasi organizer");
    }
    if (p.markedPaidAt) {
      throw new Error("Kamu sudah menandai sudah bayar — tunggu konfirmasi organizer");
    }

    const updated = await participantRepo.tryMarkPaidByUser(tripId, userId);
    if (updated.count === 0) {
      const again = await participantRepo.findByTripAndUser(tripId, userId);
      if (!again || again.status === "CANCELLED") {
        throw new Error("Kamu tidak terdaftar di trip ini");
      }
      if (again.paymentConfirmedAt) {
        throw new Error("Pembayaran kamu sudah dikonfirmasi organizer");
      }
      if (again.markedPaidAt) {
        throw new Error(
          "Kamu sudah menandai sudah bayar — tunggu konfirmasi organizer"
        );
      }
      throw new Error("Tidak bisa menandai pembayaran. Coba lagi sebentar.");
    }

    const row = await participantRepo.findByTripAndUser(tripId, userId);
    if (!row) {
      throw new Error("Data peserta tidak ditemukan setelah update");
    }
    return row;
  },

  async confirmParticipantPayment(
    tripId: string,
    participantId: string,
    organizerId: string
  ) {
    const trip = await tripRepo.findById(tripId);
    if (!trip) {
      throw new Error("Trip tidak ditemukan");
    }
    if (trip.organizerId !== organizerId) {
      throw new Error("Hanya organizer yang bisa mengonfirmasi pembayaran");
    }

    const participant = await participantRepo.findById(participantId);
    if (!participant || participant.tripId !== tripId) {
      throw new Error("Peserta tidak ditemukan");
    }
    if (participant.status === "CANCELLED") {
      throw new Error("Peserta sudah tidak aktif");
    }
    if (!participant.markedPaidAt) {
      throw new Error("Peserta belum menandai sudah membayar");
    }
    if (participant.paymentConfirmedAt) {
      throw new Error("Pembayaran peserta ini sudah dikonfirmasi");
    }

    const updated = await participantRepo.tryConfirmPaymentByOrganizer(
      participantId
    );
    if (updated.count === 0) {
      throw new Error(
        "Konfirmasi tidak diproses — mungkin sudah dikonfirmasi atau pembayaran belum ditandai peserta."
      );
    }

    return participantRepo.findById(participantId);
  },
};