/**
 * In-memory EvidenceLink repository.
 *
 * Implements the storage layer for `src/binder/services/bindings.ts`. The
 * repo is deliberately the same shape as the engine's MVP repos so the
 * future durable-store ADR (see ADR-0005) replaces it with the same
 * interface.
 *
 * Indexed by `(targetType, targetId)` and by `evidenceItemId` for the
 * two query directions the binder needs: "all evidence for this field"
 * and "all targets this evidence is linked to".
 */

import type { EvidenceLink, EvidenceTarget } from "@shared/evidence-link";
import type { EvidenceItemId, EvidenceLinkId } from "@shared/ids";

export interface EvidenceLinkRepository {
  create(link: EvidenceLink): EvidenceLink;
  get(id: EvidenceLinkId): EvidenceLink | null;
  update(link: EvidenceLink): EvidenceLink;
  delete(id: EvidenceLinkId): boolean;
  listForTarget(target: EvidenceTarget): readonly EvidenceLink[];
  listForEvidenceItem(id: EvidenceItemId): readonly EvidenceLink[];
  list(): readonly EvidenceLink[];
}

function targetKey(target: EvidenceTarget): string {
  return `${target.targetType} ${target.targetId}`;
}

export function createInMemoryLinkRepo(): EvidenceLinkRepository {
  const byId = new Map<EvidenceLinkId, EvidenceLink>();

  return {
    create(link) {
      if (byId.has(link.id)) {
        throw new Error(`EvidenceLinkRepository.create: duplicate id ${link.id}`);
      }
      byId.set(link.id, link);
      return link;
    },
    get(id) {
      return byId.get(id) ?? null;
    },
    update(link) {
      if (!byId.has(link.id)) {
        throw new Error(`EvidenceLinkRepository.update: unknown id ${link.id}`);
      }
      byId.set(link.id, link);
      return link;
    },
    delete(id) {
      return byId.delete(id);
    },
    listForTarget(target) {
      const key = targetKey(target);
      const out: EvidenceLink[] = [];
      for (const link of byId.values()) {
        if (targetKey({ targetType: link.targetType, targetId: link.targetId }) === key) {
          out.push(link);
        }
      }
      return out;
    },
    listForEvidenceItem(id) {
      const out: EvidenceLink[] = [];
      for (const link of byId.values()) {
        if (link.evidenceItemId === id) out.push(link);
      }
      return out;
    },
    list() {
      return [...byId.values()];
    },
  };
}