import { createHash } from 'node:crypto';
import { chmod, lstat, mkdir, open, readFile, readdir, realpath, rename, rm, stat, writeFile } from 'node:fs/promises';
import { dirname, isAbsolute, join, relative, resolve, sep } from 'node:path';
import { pathToFileURL } from 'node:url';

import { byteDigest, canonicalJsonDigest, canonicalValueBytes, isSha256Hex, parseCanonicalJson } from '../../../src/security/canonical-digest.ts';
import { validatePublicPath } from '../../../src/security/production-input-root.ts';
import { validateReleaseManifest } from '../../../src/security/release-manifest.ts';

const encoder = new TextEncoder();
const reservedPrefix = '.release/';
const safeToken = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/u;
const timestamp = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d{1,3})?Z$/u;

export function exactObject(value, fields, label) {
  if (value === null || typeof value !== 'object' || Array.isArray(value)) throw new Error(`${label} must be an object.`);
  const actual = Object.keys(value).sort();
  const expected = [...fields].sort();
  if (actual.length !== expected.length || actual.some((field, index) => field !== expected[index])) {
    throw new Error(`${label} contains missing or unknown fields.`);
  }
  return value;
}

export function assertToken(value, label) {
  if (typeof value !== 'string' || !safeToken.test(value)) throw new Error(`${label} is invalid.`);
  return value;
}

export function assertTimestamp(value, label) {
  if (typeof value !== 'string' || !timestamp.test(value) || Number.isNaN(Date.parse(value))) throw new Error(`${label} is invalid.`);
  return value;
}

export function assertDigest(value, label) {
  if (!isSha256Hex(value)) throw new Error(`${label} is invalid.`);
  return value;
}

export async function readCanonicalFile(path, label) {
  const info = await lstat(path);
  if (!info.isFile() || info.isSymbolicLink()) throw new Error(`${label} must be a regular file.`);
  return parseCanonicalJson(await readFile(path));
}

export async function loadVerifier(modulePath) {
  if (!isAbsolute(modulePath)) throw new Error('Verifier module path must be absolute.');
  const info = await lstat(modulePath);
  if (!info.isFile() || info.isSymbolicLink()) throw new Error('Verifier module must be a regular file.');
  const module = await import(/* @vite-ignore */ pathToFileURL(await realpath(modulePath)).href);
  if (typeof module.verifySignedReleaseEnvelope !== 'function') throw new Error('Verifier module does not expose verifySignedReleaseEnvelope.');
  return module.verifySignedReleaseEnvelope;
}

export function validateProtectedState(value) {
  const state = exactObject(value, ['latestLedgerHeadHash', 'latestLedgerRevision', 'currentManifestDigest', 'publisherFence'], 'protected state');
  assertDigest(state.latestLedgerHeadHash, 'protected ledger head');
  if (!Number.isSafeInteger(state.latestLedgerRevision) || state.latestLedgerRevision < 0 ||
      !Number.isSafeInteger(state.publisherFence) || state.publisherFence < 0 ||
      (state.currentManifestDigest !== null && !isSha256Hex(state.currentManifestDigest))) throw new Error('Protected state is invalid.');
  return state;
}

export function validateAdmission(value, protectedState, now) {
  const admission = exactObject(value, [
    'schema', 'manifestDigest', 'manifestPayload', 'expiresAt', 'predecessorManifestDigest', 'latestLedgerHeadHash',
    'latestLedgerRevision', 'expectedFence', 'signatureVerified',
  ], 'verified release admission');
  if (admission.schema !== 'portfolio-verified-release-admission/v1' || admission.signatureVerified !== true) {
    throw new Error('Release signature was not verified.');
  }
  assertDigest(admission.manifestDigest, 'manifest digest');
  assertTimestamp(now, 'trusted time');
  assertTimestamp(admission.expiresAt, 'admission expiry');
  if (Date.parse(now) >= Date.parse(admission.expiresAt)) throw new Error('Release admission is expired.');
  if (admission.predecessorManifestDigest !== null) assertDigest(admission.predecessorManifestDigest, 'predecessor manifest digest');
  const state = validateProtectedState(protectedState);
  if (admission.latestLedgerHeadHash !== state.latestLedgerHeadHash || admission.latestLedgerRevision !== state.latestLedgerRevision) {
    throw new Error('Release admission is stale relative to the protected ledger.');
  }
  if (admission.predecessorManifestDigest !== state.currentManifestDigest || admission.expectedFence !== state.publisherFence + 1) {
    throw new Error('Release admission predecessor or fence is stale.');
  }
  const manifest = validateReleaseManifest(admission.manifestPayload, { now });
  if (manifest.expiresAt !== admission.expiresAt || manifest.currentManifestDigest !== admission.predecessorManifestDigest ||
      manifest.predecessorManifestDigest !== admission.predecessorManifestDigest) throw new Error('Admission does not bind the embedded release manifest.');
  return { admission, manifest };
}

export async function verifySignedRelease({ signedManifestPath, trustPolicyPath, verifierModulePath, verifySignedReleaseEnvelope, protectedState, now }) {
  const [signedRelease, trustPolicy] = await Promise.all([
    readCanonicalFile(signedManifestPath, 'signed release'), readCanonicalFile(trustPolicyPath, 'trust policy'),
  ]);
  const verifier = verifySignedReleaseEnvelope ?? await loadVerifier(verifierModulePath);
  if (typeof verifier !== 'function') throw new Error('A release signature verifier is required.');
  const result = await verifier({ signedRelease, trustPolicy, now, protectedState });
  const verified = validateAdmission(result, protectedState, now);
  return { ...verified, signedRelease, signedReleaseBytes: canonicalValueBytes(signedRelease) };
}

export async function enumerateRegularFiles(root) {
  const rootPath = await realpath(root);
  const output = [];
  async function visit(directory, prefix = '') {
    const entries = await readdir(directory, { withFileTypes: true });
    entries.sort((left, right) => Buffer.compare(Buffer.from(left.name), Buffer.from(right.name)));
    for (const entry of entries) {
      const path = join(directory, entry.name);
      const publicPath = prefix === '' ? entry.name : `${prefix}/${entry.name}`;
      if (entry.isSymbolicLink()) throw new Error(`Symlink is forbidden in release closure: ${publicPath}`);
      if (entry.isDirectory()) await visit(path, publicPath);
      else if (entry.isFile()) output.push({ path, publicPath });
      else throw new Error(`Non-regular release input is forbidden: ${publicPath}`);
    }
  }
  await visit(rootPath);
  return output;
}

function splitTarPath(path) {
  const bytes = encoder.encode(path);
  if (bytes.length <= 100) return { name: path, prefix: '' };
  const segments = path.split('/');
  for (let index = segments.length - 1; index > 0; index -= 1) {
    const prefix = segments.slice(0, index).join('/');
    const name = segments.slice(index).join('/');
    if (encoder.encode(prefix).length <= 155 && encoder.encode(name).length <= 100) return { name, prefix };
  }
  throw new Error(`Release path is too long for deterministic ustar: ${path}`);
}

function writeString(target, offset, length, value) {
  const bytes = encoder.encode(value);
  if (bytes.length > length) throw new Error('Tar header value exceeds its field.');
  target.set(bytes, offset);
}

function writeOctal(target, offset, length, value) {
  const text = value.toString(8).padStart(length - 1, '0');
  if (text.length !== length - 1) throw new Error('Tar numeric field overflow.');
  writeString(target, offset, length, `${text}\0`);
}

function tarHeader(path, size) {
  const header = new Uint8Array(512);
  const { name, prefix } = splitTarPath(path);
  writeString(header, 0, 100, name);
  writeOctal(header, 100, 8, 0o444);
  writeOctal(header, 108, 8, 0);
  writeOctal(header, 116, 8, 0);
  writeOctal(header, 124, 12, size);
  writeOctal(header, 136, 12, 0);
  header.fill(0x20, 148, 156);
  writeString(header, 156, 1, '0');
  writeString(header, 257, 6, 'ustar\0');
  writeString(header, 263, 2, '00');
  writeString(header, 345, 155, prefix);
  const checksum = header.reduce((sum, byte) => sum + byte, 0);
  const checksumText = checksum.toString(8).padStart(6, '0');
  writeString(header, 148, 8, `${checksumText}\0 `);
  return header;
}

export function createDeterministicTar(files) {
  const ordered = [...files].sort((left, right) => Buffer.compare(Buffer.from(left.path), Buffer.from(right.path)));
  const seen = new Set();
  const chunks = [];
  for (const file of ordered) {
    validatePublicPath(file.path);
    if (seen.has(file.path)) throw new Error(`Duplicate release archive path: ${file.path}`);
    seen.add(file.path);
    const bytes = new Uint8Array(file.bytes);
    chunks.push(tarHeader(file.path, bytes.length), bytes);
    const remainder = bytes.length % 512;
    if (remainder !== 0) chunks.push(new Uint8Array(512 - remainder));
  }
  chunks.push(new Uint8Array(1024));
  return Buffer.concat(chunks.map((chunk) => Buffer.from(chunk)));
}

function readString(bytes, start, length) {
  const end = bytes.indexOf(0, start);
  return new TextDecoder('utf-8', { fatal: true }).decode(bytes.subarray(start, end === -1 || end > start + length ? start + length : end));
}

function readOctal(bytes, start, length, label) {
  const text = readString(bytes, start, length).trim();
  if (!/^[0-7]+$/u.test(text)) throw new Error(`Invalid tar ${label}.`);
  const value = Number.parseInt(text, 8);
  if (!Number.isSafeInteger(value) || value < 0) throw new Error(`Invalid tar ${label}.`);
  return value;
}

export function parseDeterministicTar(source) {
  const bytes = new Uint8Array(source);
  const files = [];
  const seen = new Set();
  let offset = 0;
  let zeroBlocks = 0;
  while (offset + 512 <= bytes.length) {
    const header = bytes.subarray(offset, offset + 512);
    offset += 512;
    if (header.every((byte) => byte === 0)) {
      zeroBlocks += 1;
      if (zeroBlocks === 2) break;
      continue;
    }
    if (zeroBlocks !== 0) throw new Error('Malformed tar end marker.');
    const expectedChecksum = readOctal(header, 148, 8, 'checksum');
    const checksumHeader = new Uint8Array(header);
    checksumHeader.fill(0x20, 148, 156);
    if (checksumHeader.reduce((sum, byte) => sum + byte, 0) !== expectedChecksum) throw new Error('Tar checksum mismatch.');
    if (readString(header, 257, 6) !== 'ustar' || String.fromCharCode(header[156] ?? 0) !== '0') throw new Error('Only deterministic regular ustar entries are accepted.');
    const name = readString(header, 0, 100);
    const prefix = readString(header, 345, 155);
    const path = prefix === '' ? name : `${prefix}/${name}`;
    validatePublicPath(path);
    if (seen.has(path)) throw new Error(`Duplicate archive entry: ${path}`);
    seen.add(path);
    const size = readOctal(header, 124, 12, 'size');
    if (offset + size > bytes.length) throw new Error('Truncated tar entry.');
    files.push({ path, bytes: bytes.slice(offset, offset + size) });
    offset += Math.ceil(size / 512) * 512;
  }
  if (zeroBlocks !== 2 || offset !== bytes.length) throw new Error('Tar archive has trailing or missing data.');
  return files;
}

export function packageIndexFor({ admission, manifest, signedBytes, sbomBytes }) {
  const artifacts = [...manifest.artifacts].sort((left, right) => Buffer.compare(Buffer.from(left.path), Buffer.from(right.path)));
  return {
    schema: 'portfolio-release-package/v1',
    buildId: manifest.buildId,
    releaseId: `${manifest.buildId}-${admission.manifestDigest}`,
    manifestDigest: admission.manifestDigest,
    predecessorManifestDigest: admission.predecessorManifestDigest,
    expiresAt: admission.expiresAt,
    expectedFence: admission.expectedFence,
    latestLedgerHeadHash: admission.latestLedgerHeadHash,
    latestLedgerRevision: admission.latestLedgerRevision,
    signedManifest: { path: '.release/signed-release-manifest.json', sha256: byteDigest(signedBytes), bytes: signedBytes.length },
    sbom: { path: '.release/sbom.cdx.json', sha256: byteDigest(sbomBytes), bytes: sbomBytes.length },
    artifacts,
  };
}

export function validatePackageFiles(files) {
  const byPath = new Map(files.map((file) => [file.path, file]));
  const indexFile = byPath.get('.release/package-index.json');
  if (indexFile === undefined) throw new Error('Release package index is missing.');
  const index = exactObject(parseCanonicalJson(indexFile.bytes), [
    'schema', 'buildId', 'releaseId', 'manifestDigest', 'predecessorManifestDigest', 'expiresAt', 'expectedFence',
    'latestLedgerHeadHash', 'latestLedgerRevision', 'signedManifest', 'sbom', 'artifacts',
  ], 'release package index');
  if (index.schema !== 'portfolio-release-package/v1') throw new Error('Release package schema is invalid.');
  assertToken(index.buildId, 'package buildId');
  assertToken(index.releaseId, 'package releaseId');
  assertDigest(index.manifestDigest, 'package manifest digest');
  assertTimestamp(index.expiresAt, 'package expiry');
  if (!Number.isSafeInteger(index.expectedFence) || index.expectedFence < 1) throw new Error('Package fence is invalid.');
  const metadata = [index.signedManifest, index.sbom];
  for (const record of metadata) {
    exactObject(record, ['path', 'sha256', 'bytes'], 'package metadata record');
    const file = byPath.get(record.path);
    if (file === undefined || byteDigest(file.bytes) !== record.sha256 || file.bytes.length !== record.bytes) throw new Error('Package metadata hash or size mismatch.');
  }
  if (!Array.isArray(index.artifacts) || index.artifacts.length === 0) throw new Error('Package artifact closure is empty.');
  const expectedPaths = new Set(['.release/package-index.json', '.release/signed-release-manifest.json', '.release/sbom.cdx.json']);
  for (const artifact of index.artifacts) {
    exactObject(artifact, ['path', 'sha256', 'bytes', 'encoding'], 'package artifact');
    if (typeof artifact.path !== 'string' || artifact.path.startsWith(reservedPrefix)) throw new Error('Package artifact uses a reserved path.');
    const file = byPath.get(artifact.path);
    if (file === undefined || byteDigest(file.bytes) !== artifact.sha256 || file.bytes.length !== artifact.bytes) throw new Error(`Artifact hash or size mismatch: ${artifact.path}`);
    expectedPaths.add(artifact.path);
  }
  if (expectedPaths.size !== byPath.size || [...byPath.keys()].some((path) => !expectedPaths.has(path))) throw new Error('Release package files do not exactly match the signed closure.');
  return { index, byPath };
}

export async function writeArchiveFiles(files, targetRoot) {
  await mkdir(targetRoot, { recursive: false, mode: 0o700 });
  const root = resolve(targetRoot);
  for (const file of files) {
    const destination = resolve(root, file.path);
    if (relative(root, destination).startsWith(`..${sep}`) || destination === root) throw new Error('Archive entry escapes staging root.');
    await mkdir(dirname(destination), { recursive: true, mode: 0o700 });
    await writeFile(destination, file.bytes, { flag: 'wx', mode: 0o600 });
  }
}

export async function makeImmutable(root, uid, gid) {
  if (!Number.isSafeInteger(uid) || uid < 0 || !Number.isSafeInteger(gid) || gid < 0) throw new Error('Release owner UID/GID is invalid.');
  async function visit(path) {
    const info = await lstat(path);
    if (info.isSymbolicLink()) throw new Error('Symlink found in immutable release.');
    if (info.uid !== uid || info.gid !== gid) throw new Error(`Release ownership mismatch at ${path}.`);
    if (info.isDirectory()) {
      for (const entry of await readdir(path)) await visit(join(path, entry));
      await chmod(path, 0o555);
    } else if (info.isFile()) await chmod(path, 0o444);
    else throw new Error('Immutable release contains a non-file entry.');
  }
  await visit(root);
}

export async function assertReleaseRoot(rootPath) {
  if (typeof rootPath !== 'string' || !isAbsolute(rootPath)) throw new Error('Release root must be an explicit absolute path.');
  const normalized = resolve(rootPath);
  if (normalized === '/' || normalized.split('/').filter(Boolean).length < 2) throw new Error('Broad release root is forbidden.');
  const info = await lstat(normalized);
  if (!info.isDirectory() || info.isSymbolicLink()) throw new Error('Release root must be a real dedicated directory.');
  const marker = await readFile(join(normalized, '.portfolio-release-root'), 'utf8').catch((error) => {
    if (error?.code === 'ENOENT') throw new Error('Release root sentinel is missing or invalid.');
    throw error;
  });
  if (marker !== 'portfolio-release-root/v1\n') throw new Error('Release root sentinel is missing or invalid.');
  return normalized;
}

export async function atomicCanonicalWrite(path, value, mode = 0o600) {
  const temporary = `${path}.next-${process.pid}`;
  const handle = await open(temporary, 'wx', mode);
  try {
    await handle.writeFile(canonicalValueBytes(value));
    await handle.sync();
  } finally {
    await handle.close();
  }
  await rename(temporary, path);
}

export async function safeRemoveStage(root, stageName) {
  assertToken(stageName, 'stage name');
  const staging = join(root, 'staging');
  const target = join(staging, stageName);
  const rel = relative(staging, target);
  if (rel.startsWith('..') || isAbsolute(rel)) throw new Error('Stage cleanup escaped its root.');
  await rm(target, { recursive: true, force: true });
}

export function digestBytes(bytes) {
  return createHash('sha256').update(bytes).digest('hex');
}