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

/**
 * Server hash core for ReportDocument v1/v2.
 *
 * 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.
 *
 * The canonical isomorphic parse runs first, then provenance.evidenceHash is
 * recomputed over the evidence appendix. Stored documents are never trusted to
 * self-report their evidence hash. The Python validator performs the same
 * recomputation for both schema versions.
 */

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): ReportDocument {
  const result = safeParseServerReportDocument(input);
  if (!result.ok) throw new ReportDocumentValidationError(result.errors);
  return result.document;
}