import {
  BadRequestException,
  ForbiddenException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { PrismaService } from '../../../prisma/prisma.service';
import {
  appointmentWithinWorkingHours,
  blocksForDay,
  localDayOfWeekMondayZero,
} from '../../common/working-hours';
import { StaffWorkingHoursService } from '../staff/staff-working-hours.service';
import { CreateAppointmentDto } from './dto/create-appointment.dto';
import { ListAppointmentsDto } from './dto/list-appointments.dto';
import { UpdateAppointmentDto } from './dto/update-appointment.dto';

const MS_PER_DAY = 86_400_000;

@Injectable()
export class AppointmentsService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly staffWorkingHoursService: StaffWorkingHoursService,
  ) {}

  getOrganizationIdFromUser(user: { organizationId?: string }) {
    if (!user?.organizationId) {
      throw new BadRequestException('Organization is not selected');
    }
    return user.organizationId;
  }

  async listColumnProviders(organizationId: string, actorUserId: string, date?: string) {
    await this.assertCanViewAppointments(actorUserId, organizationId);

    const members = await this.prisma.membership.findMany({
      where: {
        organizationId,
        isOwner: false,
        isActive: true,
        permissions: {
          some: {
            permission: {
              name: 'TAB_TREATMENT_EDIT',
            },
          },
        },
      },
      include: {
        user: { select: { id: true, name: true } },
      },
      orderBy: [{ createdAt: 'asc' }],
    });

    const scheduleBlocksByMembership =
      await this.staffWorkingHoursService.loadScheduleBlocksByMembershipIds(
        members.map((m) => m.id),
      );

    const dayOfWeek = this.resolveDayOfWeekMondayZero(date);

    const data = members.map((m) => {
      const allBlocks = scheduleBlocksByMembership.get(m.id) ?? [];
      const dayBlocks = blocksForDay(allBlocks, dayOfWeek);
      return {
        userId: m.user.id,
        name: m.user.name,
        hasWorkingHours: allBlocks.length > 0,
        dayBlocks,
      };
    });

    return { success: true, data };
  }

  async list(query: ListAppointmentsDto, organizationId: string, actorUserId: string) {
    await this.assertCanViewAppointments(actorUserId, organizationId);

    const from = new Date(query.from);
    const to = new Date(query.to);

    if (Number.isNaN(from.getTime()) || Number.isNaN(to.getTime())) {
      throw new BadRequestException('Invalid date range');
    }

    if (to <= from) {
      throw new BadRequestException('Range "to" must be after "from"');
    }

    const items = await this.prisma.appointment.findMany({
      where: {
        organizationId,
        startAt: { lt: to },
        endAt: { gt: from },
      },
      include: {
        patient: {
          select: { id: true, firstName: true, lastName: true, phone: true },
        },
      },
      orderBy: [{ startAt: 'asc' }],
    });

    return { success: true, data: items };
  }

  async create(
    dto: CreateAppointmentDto,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanEditAppointments(actorUserId, organizationId);

    const startAt = new Date(dto.startAt);
    const endAt = new Date(dto.endAt);

    if (Number.isNaN(startAt.getTime()) || Number.isNaN(endAt.getTime())) {
      throw new BadRequestException('Invalid start or end time');
    }

    if (endAt <= startAt) {
      throw new BadRequestException('End time must be after start time');
    }

    if (endAt.getTime() - startAt.getTime() > MS_PER_DAY) {
      throw new BadRequestException('Appointment cannot span more than 24 hours');
    }

    const now = Date.now();
    if (startAt.getTime() < now) {
      throw new BadRequestException('Cannot schedule appointments in the past');
    }

    await this.ensurePatientInOrg(dto.patientId, organizationId);
    await this.ensureProviderIsTreatmentEditor(dto.providerUserId, organizationId);
    await this.ensureAppointmentWithinProviderWorkingHours(
      dto.providerUserId,
      organizationId,
      startAt,
      endAt,
    );

    const appointment = await this.prisma.appointment.create({
      data: {
        organizationId,
        patientId: dto.patientId,
        providerUserId: dto.providerUserId,
        startAt,
        endAt,
        purpose: dto.purpose,
      },
      include: {
        patient: {
          select: { id: true, firstName: true, lastName: true, phone: true },
        },
      },
    });

    return { success: true, data: appointment };
  }

  async update(
    id: string,
    dto: UpdateAppointmentDto,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanEditAppointments(actorUserId, organizationId);

    const existing = await this.prisma.appointment.findFirst({
      where: { id, organizationId },
    });

    if (!existing) {
      throw new NotFoundException('Appointment not found');
    }

    const startAt = dto.startAt ? new Date(dto.startAt) : existing.startAt;
    const endAt = dto.endAt ? new Date(dto.endAt) : existing.endAt;

    if (Number.isNaN(startAt.getTime()) || Number.isNaN(endAt.getTime())) {
      throw new BadRequestException('Invalid start or end time');
    }

    if (endAt <= startAt) {
      throw new BadRequestException('End time must be after start time');
    }

    if (endAt.getTime() - startAt.getTime() > MS_PER_DAY) {
      throw new BadRequestException('Appointment cannot span more than 24 hours');
    }

    const patientId = dto.patientId ?? existing.patientId;
    const providerUserId = dto.providerUserId ?? existing.providerUserId;
    const purpose = dto.purpose ?? existing.purpose;

    await this.ensurePatientInOrg(patientId, organizationId);
    await this.ensureProviderIsTreatmentEditor(providerUserId, organizationId);
    await this.ensureAppointmentWithinProviderWorkingHours(
      providerUserId,
      organizationId,
      startAt,
      endAt,
    );

    const appointment = await this.prisma.appointment.update({
      where: { id },
      data: {
        patientId,
        providerUserId,
        startAt,
        endAt,
        purpose,
      },
      include: {
        patient: {
          select: { id: true, firstName: true, lastName: true, phone: true },
        },
      },
    });

    return { success: true, data: appointment };
  }

  async remove(id: string, organizationId: string, actorUserId: string) {
    await this.assertCanEditAppointments(actorUserId, organizationId);

    const existing = await this.prisma.appointment.findFirst({
      where: { id, organizationId },
      select: { id: true },
    });

    if (!existing) {
      throw new NotFoundException('Appointment not found');
    }

    await this.prisma.appointment.delete({
      where: { id },
    });

    return { success: true };
  }

  private async assertCanViewAppointments(userId: string, organizationId: string) {
    const m = await this.getMembership(userId, organizationId);
    if (!m) {
      throw new ForbiddenException('You are not a member of this organization');
    }
    if (m.isOwner) {
      return;
    }
    const names = m.permissions.map((p) => p.permission.name);
    if (names.includes('TAB_APPOINTMENTS_READ')) {
      return;
    }
    if (names.includes('TAB_TREATMENT_EDIT')) {
      return;
    }
    if (names.includes('TAB_TREATMENT_READ')) {
      return;
    }
    throw new ForbiddenException('You do not have access to appointments');
  }

  private async assertCanEditAppointments(userId: string, organizationId: string) {
    const m = await this.getMembership(userId, organizationId);
    if (!m) {
      throw new ForbiddenException('You are not a member of this organization');
    }
    if (m.isOwner) {
      return;
    }
    const names = m.permissions.map((p) => p.permission.name);
    if (names.includes('TAB_APPOINTMENTS_EDIT')) {
      return;
    }
    if (names.includes('TAB_TREATMENT_EDIT')) {
      return;
    }
    throw new ForbiddenException('You cannot create or modify appointments');
  }

  private async ensureProviderIsTreatmentEditor(providerUserId: string, organizationId: string) {
    const m = await this.getMembership(providerUserId, organizationId);
    if (!m) {
      throw new BadRequestException('Provider is not a member of this organization');
    }
    if (m.isOwner) {
      throw new BadRequestException(
        'Appointments must be assigned to staff with treatment access, not the organization owner',
      );
    }
    if (!m.isActive) {
      throw new BadRequestException('Provider is not an active staff member');
    }
    const names = m.permissions.map((p) => p.permission.name);
    if (!names.includes('TAB_TREATMENT_EDIT')) {
      throw new BadRequestException('Provider does not have treatment edit access');
    }
  }

  private async ensurePatientInOrg(patientId: string, organizationId: string) {
    const patient = await this.prisma.patient.findFirst({
      where: { id: patientId, organizationId },
      select: { id: true },
    });
    if (!patient) {
      throw new NotFoundException('Patient not found');
    }
  }

  private resolveDayOfWeekMondayZero(date?: string): number {
    if (!date) {
      return localDayOfWeekMondayZero(new Date().getDay());
    }
    const [y, m, d] = date.split('-').map(Number);
    const parsed = new Date(y, m - 1, d, 12, 0, 0, 0);
    if (Number.isNaN(parsed.getTime())) {
      throw new BadRequestException('Invalid date query parameter');
    }
    return localDayOfWeekMondayZero(parsed.getDay());
  }

  private async ensureAppointmentWithinProviderWorkingHours(
    providerUserId: string,
    organizationId: string,
    startAt: Date,
    endAt: Date,
  ) {
    const membership = await this.getMembership(providerUserId, organizationId);
    if (!membership) {
      throw new BadRequestException('Provider is not a member of this organization');
    }

    const scheduleBlocksByMembership =
      await this.staffWorkingHoursService.loadScheduleBlocksByMembershipIds([membership.id]);
    const allBlocks = scheduleBlocksByMembership.get(membership.id) ?? [];
    if (allBlocks.length === 0) {
      throw new BadRequestException('Provider has no working hours configured');
    }

    const dayOfWeek = localDayOfWeekMondayZero(startAt.getDay());
    const dayBlocks = blocksForDay(allBlocks, dayOfWeek);
    if (dayBlocks.length === 0) {
      throw new BadRequestException('Provider is not working on this day');
    }

    if (!appointmentWithinWorkingHours(startAt, endAt, dayBlocks)) {
      throw new BadRequestException('Appointment must fall within the provider working hours');
    }
  }

  private async getMembership(userId: string, organizationId: string) {
    return this.prisma.membership.findFirst({
      where: { userId, organizationId },
      include: { permissions: { include: { permission: true } } },
    });
  }
}