#!/usr/bin/env node
import { mkdir, open, readFile } from "node:fs/promises";
import { join } from "node:path";
import { pathToFileURL } from "node:url";

import {
  canonicalJsonDigest,
  canonicalValueBytes,
  isSha256Hex,
  parseCanonicalJson,
} from "../../src/security/canonical-digest.ts";

const workerFields = [
  "schema",
  "workerId",
  "imageDigest",
  "toolchain",
  "inputDigest",
  "checkId",
  "normalizedOutputDigest",
  "normalizedMembers",
  "verdict",
  "findingsDigest",
];
const matcherFields = [
  "schema",
  "inputDigest",
  "checkId",
  "normalizedOutputDigest",
  "normalizedMembers",
  "ruleSetDigest",
  "appliedRuleIds",
  "verdict",
  "workerImageDigests",
];
const safeToken = /^[A-Za-z0-9][A-Za-z0-9._/-]{0,127}$/u;

function object(value, label) {
  if (value === null || typeof value !== "object" || Array.isArray(value))
    throw new Error(`${label} must be an object.`);
  return value;
}
function exact(value, fields, label) {
  if (
    JSON.stringify(Object.keys(value).sort()) !==
    JSON.stringify([...fields].sort())
  )
    throw new Error(`${label} contains missing or extra fields.`);
}
function stringsEqual(left, right) {
  return JSON.stringify(left) === JSON.stringify(right);
}
function validateMembers(value) {
  if (
    !Array.isArray(value) ||
    value.some(
      (member) =>
        typeof member !== "string" ||
        member !== member.normalize("NFC") ||
        !/^[a-z][a-z0-9-]*:[a-f0-9]{64}$/u.test(member),
    )
  )
    throw new Error("Normalized members must contain typed digests only.");
  const sorted = [...value].sort((a, b) =>
    Buffer.from(a).compare(Buffer.from(b)),
  );
  if (!stringsEqual(value, sorted) || new Set(value).size !== value.length)
    throw new Error("Normalized members must be unique and byte sorted.");
}
function validateWorker(value, expectedWorker) {
  const report = object(value, "worker report");
  exact(report, workerFields, "worker report");
  if (
    report.schema !== "portfolio-privacy-worker-report/v1" ||
    report.workerId !== expectedWorker ||
    !isSha256Hex(report.imageDigest) ||
    !safeToken.test(report.toolchain) ||
    !isSha256Hex(report.inputDigest) ||
    !safeToken.test(report.checkId) ||
    !isSha256Hex(report.normalizedOutputDigest) ||
    !isSha256Hex(report.findingsDigest) ||
    !["pass", "fail", "unsupported"].includes(report.verdict)
  )
    throw new Error("Worker report is invalid.");
  validateMembers(report.normalizedMembers);
  return report;
}
function validateMatcher(value) {
  const result = object(value, "matcher result");
  exact(result, matcherFields, "matcher result");
  if (
    result.schema !== "portfolio-privacy-matcher-result/v1" ||
    !isSha256Hex(result.inputDigest) ||
    !safeToken.test(result.checkId) ||
    !isSha256Hex(result.normalizedOutputDigest) ||
    !isSha256Hex(result.ruleSetDigest) ||
    !["pass", "fail"].includes(result.verdict) ||
    !Array.isArray(result.workerImageDigests) ||
    result.workerImageDigests.length !== 2 ||
    result.workerImageDigests.some((v) => !isSha256Hex(v))
  )
    throw new Error("Matcher result is invalid.");
  validateMembers(result.normalizedMembers);
  if (
    !Array.isArray(result.appliedRuleIds) ||
    result.appliedRuleIds.length === 0 ||
    result.appliedRuleIds.some((value) => !safeToken.test(value)) ||
    new Set(result.appliedRuleIds).size !== result.appliedRuleIds.length ||
    !stringsEqual(
      result.appliedRuleIds,
      [...result.appliedRuleIds].sort((a, b) =>
        Buffer.from(a).compare(Buffer.from(b)),
      ),
    )
  )
    throw new Error("Matcher rule IDs must be unique and byte sorted.");
  return result;
}
async function writeOnce(root, digest, bytes) {
  await mkdir(root, { recursive: true });
  const path = join(root, digest);
  try {
    const handle = await open(path, "wx", 0o400);
    try {
      await handle.writeFile(bytes);
      await handle.sync();
    } finally {
      await handle.close();
    }
  } catch (error) {
    if (error && error.code === "EEXIST") {
      const existing = await readFile(path);
      if (Buffer.compare(existing, Buffer.from(bytes)) !== 0)
        throw new Error(
          "Content-addressed object is immutable and differs from existing bytes.",
        );
      return;
    }
    throw error;
  }
}

export function reconcileScan({
  expectedChecks,
  reports,
  matcherResults,
  candidate,
}) {
  if (
    !Array.isArray(expectedChecks) ||
    !Array.isArray(reports) ||
    !Array.isArray(matcherResults) ||
    expectedChecks.length === 0
  )
    throw new Error("Reconciliation input is invalid.");
  const ordered = [...expectedChecks].sort((a, b) =>
    Buffer.from(`${a.inputDigest}\0${a.checkId}`).compare(
      Buffer.from(`${b.inputDigest}\0${b.checkId}`),
    ),
  );
  if (
    !stringsEqual(expectedChecks, ordered) ||
    new Set(expectedChecks.map((v) => `${v.inputDigest}\0${v.checkId}`))
      .size !== expectedChecks.length
  )
    throw new Error("Expected check closure must be unique and byte sorted.");
  if (
    reports.length !== expectedChecks.length * 2 ||
    matcherResults.length !== expectedChecks.length
  )
    throw new Error("Missing or extra privacy evidence.");
  const checks = [];
  expectedChecks.forEach((expected, index) => {
    if (!isSha256Hex(expected.inputDigest) || !safeToken.test(expected.checkId))
      throw new Error("Expected check is invalid.");
    const a = validateWorker(reports[index * 2], "worker-a");
    const b = validateWorker(reports[index * 2 + 1], "worker-b");
    const match = validateMatcher(matcherResults[index]);
    for (const item of [a, b, match])
      if (
        item.inputDigest !== expected.inputDigest ||
        item.checkId !== expected.checkId
      )
        throw new Error(
          "Privacy evidence is missing, reordered, or bound to another check.",
        );
    if (a.imageDigest === b.imageDigest || a.toolchain === b.toolchain)
      throw new Error("Privacy workers are not heterogeneous.");
    if (
      a.verdict !== "pass" ||
      b.verdict !== "pass" ||
      match.verdict !== "pass"
    )
      throw new Error("Every worker and matcher must independently pass.");
    if (
      a.normalizedOutputDigest !== b.normalizedOutputDigest ||
      a.normalizedOutputDigest !== match.normalizedOutputDigest ||
      !stringsEqual(a.normalizedMembers, b.normalizedMembers) ||
      !stringsEqual(a.normalizedMembers, match.normalizedMembers) ||
      !stringsEqual(match.workerImageDigests, [a.imageDigest, b.imageDigest])
    )
      throw new Error("Independent normalized evidence disagrees.");
    checks.push({
      inputDigest: expected.inputDigest,
      checkId: expected.checkId,
      normalizedOutputDigest: a.normalizedOutputDigest,
      normalizedMembers: a.normalizedMembers,
      workerReports: [
        canonicalJsonDigest("portfolio-privacy-worker-report/v1", a),
        canonicalJsonDigest("portfolio-privacy-worker-report/v1", b),
      ],
      matcherResult: canonicalJsonDigest(
        "portfolio-privacy-matcher-result/v1",
        match,
      ),
      ruleSetDigest: match.ruleSetDigest,
      appliedRuleIds: match.appliedRuleIds,
    });
  });
  const evidence = {
    schema: "portfolio-scan-evidence/v1",
    coverageCount: checks.length,
    passedCount: checks.length,
    checks,
  };
  const evidenceBytes = canonicalValueBytes(evidence);
  const evidenceDigest = canonicalJsonDigest(
    "portfolio-scan-evidence/v1",
    evidence,
  );
  const candidateRecord = object(candidate, "candidate");
  if (candidateRecord.schema !== "portfolio-candidate-release-manifest/v1")
    throw new Error("Candidate schema is invalid.");
  const candidateBytes = canonicalValueBytes(candidateRecord);
  const candidateDigest = canonicalJsonDigest(
    "portfolio-candidate-release-manifest/v1",
    candidateRecord,
  );
  return {
    evidence,
    evidenceBytes,
    evidenceDigest,
    candidate: candidateRecord,
    candidateBytes,
    candidateDigest,
    async writeContentAddressed(root) {
      await writeOnce(root, evidenceDigest, evidenceBytes);
      await writeOnce(root, candidateDigest, candidateBytes);
    },
  };
}

async function main() {
  if (process.argv.length !== 4 || process.argv[2] !== "--request")
    throw new Error(
      "Usage: reconcile-scan.mjs --request <canonical-request.json>",
    );
  const request = parseCanonicalJson(await readFile(process.argv[3]));
  const result = reconcileScan(request);
  process.stdout.write(
    Buffer.from(
      canonicalValueBytes({
        schema: "portfolio-reconciliation-result/v1",
        evidenceDigest: result.evidenceDigest,
        candidateDigest: result.candidateDigest,
      }),
    ),
  );
  process.stdout.write("\n");
}

if (
  process.argv[1] &&
  import.meta.url === pathToFileURL(process.argv[1]).href
) {
  main().catch((error) => {
    process.stderr.write(
      `Privacy reconciliation failed: ${error instanceof Error ? error.message : "unknown error"}\n`,
    );
    process.exitCode = 1;
  });
}