import {
  BadRequestException,
  ForbiddenException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { LinkStatus, TreatmentStatus } from '@prisma/client';
import { createReadStream, existsSync, mkdirSync } from 'fs';
import { join } from 'path';
import { randomUUID } from 'crypto';
import { PrismaService } from '../../../prisma/prisma.service';
import { SaveTreatmentDraftDto, SendTreatmentCaseDto } from './dto/treatment.dto';
import {
  generateTreatmentTitle,
  isTreatmentType,
  mapTreatmentStatusForApi,
  normalizeTeeth,
} from './treatment.utils';

const treatmentInclude = {
  cases: {
    orderBy: [{ sortOrder: 'asc' as const }],
    include: {
      attachments: { orderBy: [{ createdAt: 'asc' as const }] },
      sends: {
        orderBy: [{ sentAt: 'asc' as const }],
        include: { organization: { select: { id: true, name: true } } },
      },
    },
  },
};

@Injectable()
export class TreatmentsService {
  private readonly uploadRoot = join(process.cwd(), 'uploads', 'treatments');

  constructor(private readonly prisma: PrismaService) {}

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

  async listLinkedOrganizations(userId: string, organizationId: string) {
    await this.assertCanReadTreatment(userId, organizationId);

    const [linksA, linksB] = await Promise.all([
      this.prisma.organizationLink.findMany({
        where: { organizationAId: organizationId, status: LinkStatus.ACTIVE },
        include: { organizationB: { select: { id: true, name: true } } },
      }),
      this.prisma.organizationLink.findMany({
        where: { organizationBId: organizationId, status: LinkStatus.ACTIVE },
        include: { organizationA: { select: { id: true, name: true } } },
      }),
    ]);

    const data = [
      ...linksA.map((l) => ({
        id: l.organizationB.id,
        name: l.organizationB.name,
        active: true,
      })),
      ...linksB.map((l) => ({
        id: l.organizationA.id,
        name: l.organizationA.name,
        active: true,
      })),
    ].sort((a, b) => a.name.localeCompare(b.name));

    return { success: true, data };
  }

  async listPatientHistory(
    patientId: string,
    organizationId: string,
    actorUserId: string,
    limit = 20,
  ) {
    await this.assertCanReadTreatment(actorUserId, organizationId);
    await this.ensurePatientInOrg(patientId, organizationId);

    const items = await this.prisma.treatment.findMany({
      where: {
        patientId,
        organizationId,
        status: TreatmentStatus.COMPLETED,
      },
      include: treatmentInclude,
      orderBy: [{ treatmentAt: 'desc' }],
      take: Math.min(Math.max(limit, 1), 100),
    });

    return { success: true, data: items.map((t) => this.mapTreatment(t)) };
  }

  async getDraftForAppointment(
    appointmentId: string,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanReadTreatment(actorUserId, organizationId);
    const appointment = await this.ensureAppointmentProvider(
      appointmentId,
      organizationId,
      actorUserId,
      false,
    );

    const treatment = await this.prisma.treatment.findFirst({
      where: {
        appointmentId: appointment.id,
        organizationId,
        status: TreatmentStatus.DRAFT,
      },
      include: treatmentInclude,
    });

    return { success: true, data: treatment ? this.mapTreatment(treatment) : null };
  }

  async saveDraftForAppointment(
    appointmentId: string,
    dto: SaveTreatmentDraftDto,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanEditTreatment(actorUserId, organizationId);
    const appointment = await this.ensureAppointmentProvider(
      appointmentId,
      organizationId,
      actorUserId,
      true,
    );

    for (const c of dto.cases) {
      if (!isTreatmentType(c.treatmentType)) {
        throw new BadRequestException(`Invalid treatment type: ${c.treatmentType}`);
      }
    }

    const normalizedCases = dto.cases.map((c, index) => ({
      ...c,
      sortOrder: index,
      teeth: normalizeTeeth(c.teeth),
      comment: c.comment?.trim() || null,
      attachmentIds: c.attachmentIds ?? [],
    }));

    const title = generateTreatmentTitle(
      normalizedCases.map((c) => ({ treatmentType: c.treatmentType, teeth: c.teeth })),
    );

    const treatment = await this.prisma.$transaction(async (tx) => {
      const existing = await tx.treatment.findFirst({
        where: { appointmentId: appointment.id, organizationId },
        select: { id: true },
      });

      const saved = existing
        ? await tx.treatment.update({
            where: { id: existing.id },
            data: {
              title,
              treatmentAt: appointment.startAt,
              patientId: appointment.patientId,
              providerUserId: appointment.providerUserId,
              status: TreatmentStatus.DRAFT,
            },
          })
        : await tx.treatment.create({
            data: {
              organizationId,
              patientId: appointment.patientId,
              appointmentId: appointment.id,
              providerUserId: appointment.providerUserId,
              title,
              status: TreatmentStatus.DRAFT,
              treatmentAt: appointment.startAt,
            },
          });

      const keepCaseIds = normalizedCases.map((c) => c.id).filter(Boolean) as string[];
      const existingCases = existing
        ? await tx.treatmentCase.findMany({
            where: { treatmentId: saved.id },
            select: { id: true, sentAt: true },
          })
        : [];

      const sentCaseIds = new Set(
        existingCases.filter((c) => c.sentAt).map((c) => c.id),
      );

      const removableCaseIds = existingCases
        .filter((c) => !keepCaseIds.includes(c.id) && !c.sentAt)
        .map((c) => c.id);

      if (removableCaseIds.length > 0) {
        await tx.treatmentCase.deleteMany({
          where: { id: { in: removableCaseIds }, treatmentId: saved.id },
        });
      }

      for (const c of normalizedCases) {
        if (c.id && sentCaseIds.has(c.id)) {
          continue;
        }

        const row = c.id
          ? await tx.treatmentCase.update({
              where: { id: c.id },
              data: {
                clientKey: c.clientId,
                sortOrder: c.sortOrder,
                treatmentType: c.treatmentType,
                teeth: c.teeth,
                comment: c.comment,
              },
            })
          : await tx.treatmentCase.create({
              data: {
                treatmentId: saved.id,
                clientKey: c.clientId,
                sortOrder: c.sortOrder,
                treatmentType: c.treatmentType,
                teeth: c.teeth,
                comment: c.comment,
              },
            });

        const allowedAttachmentIds = new Set(c.attachmentIds);
        const pendingAttachments = await tx.treatmentCaseAttachment.findMany({
          where: {
            appointmentId: appointment.id,
            caseClientKey: c.clientId,
          },
        });

        for (const attachment of pendingAttachments) {
          if (!allowedAttachmentIds.has(attachment.id)) {
            await tx.treatmentCaseAttachment.delete({ where: { id: attachment.id } });
          } else {
            await tx.treatmentCaseAttachment.update({
              where: { id: attachment.id },
              data: { caseId: row.id, appointmentId: null, caseClientKey: null },
            });
          }
        }

        await tx.treatmentCaseAttachment.deleteMany({
          where: {
            caseId: row.id,
            id: { notIn: [...allowedAttachmentIds] },
          },
        });
      }

      return tx.treatment.findUniqueOrThrow({
        where: { id: saved.id },
        include: treatmentInclude,
      });
    });

    return { success: true, data: this.mapTreatment(treatment) };
  }

  async sendCase(
    caseId: string,
    dto: SendTreatmentCaseDto,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanEditTreatment(actorUserId, organizationId);

    const treatmentCase = await this.prisma.treatmentCase.findFirst({
      where: {
        id: caseId,
        treatment: { organizationId },
      },
      include: {
        treatment: { select: { providerUserId: true, appointmentId: true } },
        sends: { select: { organizationId: true } },
      },
    });

    if (!treatmentCase) {
      throw new NotFoundException('Treatment case not found');
    }

    if (treatmentCase.treatment.providerUserId !== actorUserId) {
      const membership = await this.getMembership(actorUserId, organizationId);
      if (!membership?.isOwner) {
        throw new ForbiddenException('Only the appointment provider can send this case');
      }
    }

    const linkedOrgIds = await this.getActiveLinkedOrganizationIds(organizationId);
    const uniqueTargets = [...new Set(dto.organizationIds)];

    for (const orgId of uniqueTargets) {
      if (!linkedOrgIds.has(orgId)) {
        throw new BadRequestException('One or more organizations are not active linked counterparts');
      }
    }

    const alreadySent = new Set(treatmentCase.sends.map((s) => s.organizationId));
    const newTargets = uniqueTargets.filter((id) => !alreadySent.has(id));

    if (newTargets.length === 0) {
      throw new BadRequestException('Case was already sent to all selected organizations');
    }

    const now = new Date();

    await this.prisma.$transaction(async (tx) => {
      await tx.treatmentCaseSend.createMany({
        data: newTargets.map((organizationId) => ({
          caseId,
          organizationId,
        })),
      });

      if (!treatmentCase.sentAt) {
        await tx.treatmentCase.update({
          where: { id: caseId },
          data: { sentAt: now },
        });
      }
    });

    const refreshed = await this.prisma.treatmentCase.findUniqueOrThrow({
      where: { id: caseId },
      include: {
        attachments: { orderBy: [{ createdAt: 'asc' }] },
        sends: {
          orderBy: [{ sentAt: 'asc' }],
          include: { organization: { select: { id: true, name: true } } },
        },
      },
    });

    return { success: true, data: this.mapCase(refreshed) };
  }

  async uploadCaseAttachments(
    appointmentId: string,
    caseClientKey: string,
    files: Express.Multer.File[],
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanEditTreatment(actorUserId, organizationId);
    await this.ensureAppointmentProvider(appointmentId, organizationId, actorUserId, true);

    if (!caseClientKey?.trim()) {
      throw new BadRequestException('caseClientKey is required');
    }

    if (!files?.length) {
      throw new BadRequestException('At least one file is required');
    }

    const orgDir = join(this.uploadRoot, organizationId);
    mkdirSync(orgDir, { recursive: true });

    const created: {
      id: string;
      fileName: string;
      mimeType: string;
      sizeBytes: number;
    }[] = [];

    for (const file of files) {
      const storageName = `${randomUUID()}-${file.originalname.replace(/[^\w.\-()+]/g, '_')}`;
      const storagePath = join(orgDir, storageName);
      const { writeFileSync } = await import('fs');
      writeFileSync(storagePath, file.buffer);

      const attachment = await this.prisma.treatmentCaseAttachment.create({
        data: {
          appointmentId,
          caseClientKey,
          fileName: file.originalname,
          mimeType: file.mimetype || 'application/octet-stream',
          sizeBytes: file.size,
          storagePath,
        },
      });

      created.push(this.mapAttachment(attachment));
    }

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

  async streamAttachmentFile(
    attachmentId: string,
    organizationId: string,
    actorUserId: string,
  ) {
    await this.assertCanReadTreatment(actorUserId, organizationId);

    const attachment = await this.prisma.treatmentCaseAttachment.findFirst({
      where: {
        id: attachmentId,
        OR: [
          { case: { treatment: { organizationId } } },
          { appointmentId: { not: null } },
        ],
      },
      include: {
        case: { select: { treatment: { select: { organizationId: true } } } },
      },
    });

    if (!attachment) {
      throw new NotFoundException('Attachment not found');
    }

    if (attachment.case && attachment.case.treatment.organizationId !== organizationId) {
      throw new NotFoundException('Attachment not found');
    }

    if (!attachment.case && attachment.appointmentId) {
      const appointment = await this.prisma.appointment.findFirst({
        where: { id: attachment.appointmentId, organizationId },
        select: { id: true },
      });
      if (!appointment) {
        throw new NotFoundException('Attachment not found');
      }
    }

    if (!existsSync(attachment.storagePath)) {
      throw new NotFoundException('File is no longer available');
    }

    return {
      stream: createReadStream(attachment.storagePath),
      fileName: attachment.fileName,
      mimeType: attachment.mimeType,
    };
  }

  private mapTreatment(treatment: {
    id: string;
    patientId: string;
    appointmentId: string | null;
    title: string;
    status: TreatmentStatus;
    treatmentAt: Date;
    cases: Array<{
      id: string;
      clientKey: string | null;
      treatmentType: string;
      teeth: unknown;
      comment: string | null;
      sentAt: Date | null;
      attachments: Array<{
        id: string;
        fileName: string;
        mimeType: string;
        sizeBytes: number;
      }>;
      sends: Array<{ organizationId: string; sentAt: Date; organization: { id: string; name: string } }>;
    }>;
  }) {
    const documents = treatment.cases.flatMap((c) =>
      c.attachments.map((a) => this.mapAttachment(a)),
    );

    return {
      id: treatment.id,
      patientId: treatment.patientId,
      appointmentId: treatment.appointmentId,
      title: treatment.title,
      treatmentAt: treatment.treatmentAt.toISOString(),
      status: mapTreatmentStatusForApi(treatment.status),
      cases: treatment.cases.map((c) => this.mapCase(c)),
      documents,
    };
  }

  private mapCase(c: {
    id: string;
    clientKey?: string | null;
    treatmentType: string;
    teeth: unknown;
    comment?: string | null;
    sentAt?: Date | null;
    attachments?: Array<{
      id: string;
      fileName: string;
      mimeType: string;
      sizeBytes: number;
    }>;
    sends?: Array<{ organizationId: string; sentAt: Date; organization?: { id: string; name: string } }>;
  }) {
    return {
      id: c.id,
      clientId: c.clientKey ?? c.id,
      treatmentType: c.treatmentType,
      teeth: normalizeTeeth(c.teeth),
      notes: c.comment ?? null,
      sentAt: c.sentAt?.toISOString() ?? null,
      sendToOrganizationIds: c.sends?.map((s) => s.organizationId) ?? [],
      sends:
        c.sends?.map((s) => ({
          organizationId: s.organizationId,
          organizationName: s.organization?.name ?? 'Unknown organization',
          sentAt: s.sentAt.toISOString(),
        })) ?? [],
      attachmentMetas: (c.attachments ?? []).map((a) => this.mapAttachment(a)),
    };
  }

  private mapAttachment(a: {
    id: string;
    fileName: string;
    mimeType: string;
    sizeBytes: number;
  }) {
    return {
      id: a.id,
      fileName: a.fileName,
      mimeType: a.mimeType,
      sizeBytes: a.sizeBytes,
    };
  }

  private async getActiveLinkedOrganizationIds(organizationId: string) {
    const [linksA, linksB] = await Promise.all([
      this.prisma.organizationLink.findMany({
        where: { organizationAId: organizationId, status: LinkStatus.ACTIVE },
        select: { organizationBId: true },
      }),
      this.prisma.organizationLink.findMany({
        where: { organizationBId: organizationId, status: LinkStatus.ACTIVE },
        select: { organizationAId: true },
      }),
    ]);

    return new Set([
      ...linksA.map((l) => l.organizationBId),
      ...linksB.map((l) => l.organizationAId),
    ]);
  }

  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 async ensureAppointmentProvider(
    appointmentId: string,
    organizationId: string,
    actorUserId: string,
    requireProviderMatch: boolean,
  ) {
    const appointment = await this.prisma.appointment.findFirst({
      where: { id: appointmentId, organizationId },
      select: {
        id: true,
        patientId: true,
        providerUserId: true,
        startAt: true,
      },
    });

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

    if (requireProviderMatch) {
      const membership = await this.getMembership(actorUserId, organizationId);
      const isOwner = membership?.isOwner ?? false;
      if (!isOwner && appointment.providerUserId !== actorUserId) {
        throw new ForbiddenException('You are not the provider for this appointment');
      }
    }

    return appointment;
  }

  private async assertCanReadTreatment(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_TREATMENT_READ') || names.includes('TAB_TREATMENT_EDIT')) {
      return;
    }
    throw new ForbiddenException('You do not have access to treatments');
  }

  private async assertCanEditTreatment(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_TREATMENT_EDIT')) {
      return;
    }
    throw new ForbiddenException('You cannot edit treatments');
  }

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