import { ConflictException, Injectable } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { forTenant } from '../prisma/prisma-tenant.extension';
import { prismaErrorCode } from '../prisma/prisma-error';

/**
 * Partial triage update accepted by setTriage(). Both fields are optional
 * so a caller can flip just isRead or just isFavorite without clobbering
 * the other (see the "partial update" spec case).
 */
export interface SetTriageInput {
  isRead?: boolean;
  isFavorite?: boolean;
}

/**
 * Service for managing per-user Tender triage state (gelesen/ungelesen,
 * Favorit — UI-03/04, D-09/D-10/D-11).
 *
 * Access control (T-11-10 / V4 — IDOR): every query is ADDITIONALLY scoped
 * by userId, exactly the `FavoritesService` convention (T-08-06). This
 * stays deliberate belt-and-suspenders after binding to `forTenant()`
 * (260909-laa): the delivered `tenant_isolation_policy` on TenderTriage
 * has no user dimension — a foreign user of the SAME tenant is not
 * excluded by the database alone (Befund E, measured for the sibling
 * TenderSavedSearch policy in Aufgabe 1; all five policies of this area
 * share the identical `"tenantId" = current_tenant_id()` text).
 *
 * Nachtrag (260911-nke, Etappe 3b): seit Migration 20260911120000 traegt
 * die Regel auf TenderTriage die Benutzerdimension (`current_user_id() IS
 * NULL OR "userId" = current_user_id()`) — alle drei `forTenant()`-Aufrufe
 * unten reichen `userId` als drittes Argument durch. Die anwendungsseitige
 * userId-Filterung bleibt zweites Netz, kein Ersatz.
 *
 * Cascade (Pitfall 6): the schema's `Tender @relation(..., onDelete:
 * Cascade)` removes a tender's triage rows automatically when Phase 10's
 * retention job deletes the tender — no manual cleanup needed here.
 */
@Injectable()
export class TenderTriageService {
  constructor(private readonly prisma: PrismaService) {}

  /**
   * Upserts the triage row for (userId, tenderId) on the
   * `@@unique([userId, tenderId])` target — idempotent: calling this twice
   * with the same params never creates a second row. Only the fields
   * present in `dto` are touched; the other flag (and its timestamp) is
   * left as-is on both the update and create branches.
   *
   * Gegenrichtung der Bindung (Befund F, 260909-laa): der Eindeutigkeits-
   * schluessel `@@unique([userId, tenderId])` traegt KEINE Mandanten-
   * dimension. Ist die vorhandene Zeile unter dem gebundenen Kontext
   * unsichtbar (veralteter Mandant in der Sitzung), findet das `upsert`
   * sie nicht, versucht anzulegen und laeuft in die Eindeutigkeits-
   * verletzung — aus stillem Ueberschreiben wird ein harter Fehler. Der
   * `P2002`-Zweig uebersetzt das in eine verstaendliche deutsche Meldung
   * statt in einen 500, wie in `tender-saved-search.service.ts`. Gemessen
   * in `rls-scratch-check.mjs`, Pruefung
   * `tendertriage-einfuegen-auf-unsichtbare-zeile-verletzt-eindeutigkeit`.
   */
  async setTriage(
    userId: string,
    tenantId: string,
    tenderId: string,
    dto: SetTriageInput,
  ) {
    const now = new Date();
    const update: Record<string, unknown> = {};

    if (dto.isRead !== undefined) {
      update.isRead = dto.isRead;
      update.readAt = dto.isRead ? now : null;
    }
    if (dto.isFavorite !== undefined) {
      update.isFavorite = dto.isFavorite;
      update.favoritedAt = dto.isFavorite ? now : null;
    }

    const tenantPrisma = forTenant(this.prisma, tenantId, userId);
    try {
      return await tenantPrisma.tenderTriage.upsert({
        where: { userId_tenderId: { userId, tenderId } },
        update,
        create: {
          userId,
          tenantId,
          tenderId,
          isRead: dto.isRead ?? false,
          isFavorite: dto.isFavorite ?? false,
          readAt: dto.isRead ? now : null,
          favoritedAt: dto.isFavorite ? now : null,
        },
      });
    } catch (error: unknown) {
      if (prismaErrorCode(error) === 'P2002') {
        throw new ConflictException(
          'Der Bearbeitungsstand zu dieser Ausschreibung konnte nicht gespeichert werden. Bitte die Seite neu laden und es erneut versuchen.',
        );
      }
      throw error;
    }
  }

  /**
   * Batch-fetch this user's triage rows for a set of tenderIds (used by
   * the Trefferliste to merge read/favorite state into the visible page).
   * Scoped by userId (V4/IDOR) — a foreign userId never sees another
   * user's rows, even for the same tenderId. Returns [] without querying
   * prisma when tenderIds is empty (avoids an unbounded `in: []` no-op
   * round-trip) — deliberately BEFORE forTenant() is created, so an empty
   * batch never even opens a bound client.
   */
  async listForUser(userId: string, tenantId: string, tenderIds: string[]) {
    if (!tenderIds.length) return [];
    const tenantPrisma = forTenant(this.prisma, tenantId, userId);
    return tenantPrisma.tenderTriage.findMany({
      where: { userId, tenderId: { in: tenderIds } },
    });
  }

  /**
   * Returns the tenderIds this user has marked as favorite (UI-04
   * Merklisten-Filter). Scoped by userId — feeds the favOnly branch of
   * tender-query.builder.ts's buildTenderWhere.
   */
  async favoriteIds(userId: string, tenantId: string): Promise<string[]> {
    const tenantPrisma = forTenant(this.prisma, tenantId, userId);
    const rows = await tenantPrisma.tenderTriage.findMany({
      where: { userId, isFavorite: true },
      select: { tenderId: true },
    });
    return rows.map((r: { tenderId: string }) => r.tenderId);
  }
}