import { createHash } from "node:crypto";
import {
  canonicalEvidence,
  safeParseReportDocument,
  ReportDocumentValidationError,
  type EvidenceAppendix,
  type ReportDocumentParseResult,
  type ReportDocumentV1,
} from "./personal-report-contract.ts";

/**
 * Server hash core for ReportDocument v1.
 *
 * Pure Node implementation (node:crypto) without the server-only marker so
 * tests can import it directly; the production entry
 * personal-report-contract.server.ts adds `import "server-only"` and
 * re-exports this module. Client bundles must never import this file: besides
 * the marker on the production entry, node:crypto fails Next.js client builds.
 *
 * Flow per the architecture ruling: canonical isomorphic parse first, then
 * verify provenance.evidenceHash against the recomputed hash. The hash is
 * never trusted as a model self-report. The Python validator
 * (scripts/personal_report_contract.py) performs the same recomputation.
 */

export function computeEvidenceHash(appendix: EvidenceAppendix): string {
  const canonical = canonicalEvidence(appendix);
  return createHash("sha256").update(JSON.stringify(canonical), "utf8").digest("hex");
}

export function safeParseServerReportDocument(input: unknown): ReportDocumentParseResult {
  const parsed = safeParseReportDocument(input);
  if (!parsed.ok) return parsed;
  const recomputed = computeEvidenceHash(parsed.document.evidenceAppendix);
  if (parsed.document.provenance.evidenceHash !== recomputed) {
    return {
      ok: false,
      errors: [{
        path: "provenance.evidenceHash",
        message: `does not match recomputed evidence hash ${recomputed}`,
      }],
    };
  }
  return parsed;
}

export function parseServerReportDocument(input: unknown): ReportDocumentV1 {
  const result = safeParseServerReportDocument(input);
  if (!result.ok) throw new ReportDocumentValidationError(result.errors);
  return result.document;
}