import type { PrismaClient } from '@generated/prisma/client';
import type { CreateAttendee, CreateAttendeeResult, ProblemDetails, Result } from '@gruperly/shared';
import { err, ok } from '@gruperly/shared';
import {
  alreadyWaitlistedProblem,
  capacityReachedProblem,
  conflictProblem,
  noGroupAccessProblem,
  notFoundResourceProblem,
} from '@/http/problem-builders';
import prisma from '@/lib/prisma';
import { type AttendeeRecord, normalizePhone, toAttendeeDto } from '../../lib/helpers';

type CreateAttendeeDeps = {
  db?: Pick<PrismaClient, 'group' | 'attendee' | 'groupWaitlistEntry'>;
};

type CreateAttendeeOptions = {
  allowOverflow?: boolean;
};

export class CreateAttendeeUseCase {
  constructor(private readonly deps: CreateAttendeeDeps = {}) {}

  async execute(
    groupId: string,
    userId: string,
    payload: CreateAttendee,
    options: CreateAttendeeOptions = {},
  ): Promise<Result<CreateAttendeeResult, ProblemDetails>> {
    const db = this.deps.db ?? prisma;

    const group = await db.group.findUnique({
      where: { id: groupId },
      include: {
        members: { where: { userId } },
      },
    });

    if (!group) {
      return err(notFoundResourceProblem('Group', groupId));
    }

    const isOwner = group.createdById === userId;
    const isMember = group.members.length > 0;
    if (!isOwner && !isMember) {
      return err(noGroupAccessProblem());
    }

    const phone = normalizePhone(payload.phone);
    const existing = await db.attendee.findFirst({
      where: {
        groupId,
        OR: [
          { phone },
          { phone: payload.phone.trim() },
        ],
      },
    });

    if (existing) {
      return err(
        conflictProblem({
          detail: 'Ya existe un alumno registrado con este número de teléfono en este grupo.',
          code: 'attendee_already_registered',
        }),
      );
    }

    const fullName = `${payload.firstName.trim()} ${payload.lastName.trim()}`.trim();

    if (group.capacity !== null) {
      const currentCount = await db.attendee.count({ where: { groupId } });

      if (currentCount >= group.capacity) {
        if (isOwner && !options.allowOverflow) {
          return err(capacityReachedProblem(group.capacity));
        }

        if (!isOwner) {
          const existingWaitlistEntry = await db.groupWaitlistEntry.findFirst({
            where: { groupId, phone },
          });

          if (existingWaitlistEntry) {
            return err(alreadyWaitlistedProblem());
          }

          await db.groupWaitlistEntry.create({
            data: {
              groupId,
              fullName,
              phone,
              email: payload.email?.trim() || null,
              notes: payload.notes?.trim() || null,
            },
          });

          return ok({
            outcome: 'waitlisted',
            message: `${fullName} fue agregado a la lista de espera del grupo.`,
          });
        }
      }
    }

    const attendee = await db.attendee.create({
      data: {
        groupId,
        fullName,
        phone,
        email: payload.email?.trim() || null,
        notes: payload.notes?.trim() || null,
      },
    });

    return ok({
      outcome: 'created',
      attendee: toAttendeeDto(attendee as unknown as AttendeeRecord),
    });
  }
}