import { Prisma } from '@prisma/client';
import type { TenderQueryDto } from './dto/tender-query.dto';

/**
 * Pure functions building the Prisma `where`/`orderBy` for the global
 * `Tender` catalog read path (listTenders). Kept out of the controller so
 * both are independently unit-testable without a live DB (RESEARCH
 * Pattern 1/2/4/5, Don't Hand-Roll: "Filter-where-Zusammenbau").
 *
 * Security (T-11-01/T-11-03): every branch is a parametrized Prisma
 * filter — no raw SQL, no string concatenation. `sort` is resolved via a
 * fixed SORT_MAP whitelist (buildOrderBy), never a dynamic user-supplied
 * orderBy key.
 */

/**
 * T-11-11 (DoS): bounds the favOnly `id: { in: [...] }` list — a user's
 * own favorites are already implicitly bounded by their behavior, but a
 * hard cap keeps the generated query's IN-list size predictable
 * regardless of how many rows accumulate over time.
 */
const MAX_FAV_IDS = 500;

/**
 * buildTenderWhere — conditional AND-composition. Empty DTO fields never
 * add a constraint; every non-empty field is a correctness/security
 * requirement documented inline (D-01/04/05).
 *
 * `favIds` (UI-04, T-11-10): the current user's favorited tenderIds,
 * resolved by the CALLER (TendersController, via
 * `TenderTriageService.favoriteIds(userId)`) from the auth context —
 * never accepted here as user input. Only consulted when `dto.favOnly` is
 * true.
 */
export function buildTenderWhere(
  dto: TenderQueryDto,
  favIds?: string[],
): Prisma.TenderWhereInput {
  const where: Prisma.TenderWhereInput = {};
  const AND: Prisma.TenderWhereInput[] = [];

  // D-04 / FILTER-04: status defaults to 'active'; explicit status wins.
  where.status = dto.status ?? 'active';

  // D-04 / FILTER-04: "nur noch offene" default view. NULL deadlines are
  // NEVER hidden by this branch (17% of live rows have deadlineAt=null) —
  // hiding them would silently drop legitimate open-ended tenders.
  if (dto.openOnly ?? true) {
    AND.push({
      OR: [{ deadlineAt: { gte: new Date() } }, { deadlineAt: null }],
    });
  }

  // FILTER-04: explicit deadline date-range, combinable with openOnly above.
  if (dto.deadlineFrom != null || dto.deadlineTo != null) {
    const range: Prisma.DateTimeFilter = {};
    if (dto.deadlineFrom != null) range.gte = dto.deadlineFrom;
    if (dto.deadlineTo != null) range.lte = dto.deadlineTo;
    AND.push({ deadlineAt: range });
  }

  // FILTER-01 / D-01: case-insensitive keyword over title + buyerName.
  if (dto.q) {
    AND.push({
      OR: [
        { title: { contains: dto.q, mode: 'insensitive' } },
        { buyerName: { contains: dto.q, mode: 'insensitive' } },
      ],
    });
  }

  // FILTER-05 / D-05 (Pflichtkriterium): an active value filter must NEVER
  // silently eliminate estimatedValue=null rows (91.6% of live data).
  // includeNullValue defaults to true — the OR-with-null branch is the
  // Kern-Test for this task.
  if (dto.valueMin != null || dto.valueMax != null) {
    const range: Prisma.DecimalNullableFilter = {};
    if (dto.valueMin != null) range.gte = dto.valueMin;
    if (dto.valueMax != null) range.lte = dto.valueMax;

    AND.push(
      (dto.includeNullValue ?? true)
        ? { OR: [{ estimatedValue: range }, { estimatedValue: null }] }
        : { estimatedValue: range },
    );
  }

  // FILTER-02 / D-02: PLZ prefix match — plz is a 5-digit German postal
  // code column; startsWith allows shorter prefixes to broaden the match.
  if (dto.plz) {
    AND.push({ plz: { startsWith: dto.plz } });
  }

  // FILTER-02 / D-02: Bundesland exact match against the backfilled/
  // normalizer-derived `bundesland` column (indexed, Pitfall 1) — real
  // hits only after the 20260721140000_tender_bundesland_backfill
  // migration has run. Preferred over region-prefix matching once
  // bundesland is populated.
  if (dto.bundesland) {
    AND.push({ bundesland: dto.bundesland });
  }

  // FILTER-02 / D-02: raw NUTS-region prefix match, independent of the
  // bundesland column — usable even for rows whose bundesland derivation
  // hasn't run yet, and for finer-grained region-level filtering.
  if (dto.region) {
    AND.push({ region: { startsWith: dto.region } });
  }

  // FILTER-03 / D-03 (Pitfall 2): CPV-Division-Filter — matched via
  // `hasSome` against the normalizer/backfill-derived `cpvDivisions`
  // column (typesafe, GIN-indexable), never an exact-equality match
  // against the inconsistently-formatted raw `cpvCodes` array.
  if (dto.cpv?.length) {
    AND.push({ cpvDivisions: { hasSome: dto.cpv } });
  }

  // UI-04 / D-10 (Merklisten-Filter, Pflichtkriterium): favOnly restricts
  // the result to the current user's favorited tenders. Empty favIds (no
  // favorites yet, or favIds not supplied) MUST yield ZERO matches, never
  // "all tenders" — `'__none__'` is a sentinel that can never equal a real
  // Tender.id (uuid), so `{ in: ['__none__'] }` is a guaranteed-empty
  // match rather than an accidentally-unconstrained query.
  if (dto.favOnly) {
    const ids = (favIds ?? []).slice(0, MAX_FAV_IDS);
    AND.push({ id: { in: ids.length ? ids : ['__none__'] } });
  }

  if (AND.length) where.AND = AND;
  return where;
}

/**
 * Sort-Whitelist (UI-01, D-06, T-11-01). Only these three keys are ever
 * translated into a Prisma orderBy — an unrecognized/missing key falls
 * back to the pre-existing default (publishedAt desc), never a
 * dynamically-constructed field from user input.
 */
const SORT_MAP: Record<string, Prisma.TenderOrderByWithRelationInput> = {
  deadline: { deadlineAt: 'asc' },
  value: { estimatedValue: 'desc' },
  published: { publishedAt: 'desc' },
};

export function buildOrderBy(
  sort: string | undefined,
): Prisma.TenderOrderByWithRelationInput {
  return SORT_MAP[sort ?? 'published'] ?? SORT_MAP.published;
}