'use strict';

// Starts an already-built, frozen directory. There is intentionally no build,
// codegen, Git checkout, publish, or fallback-to-RC operation in this entrypoint.
const { createHash } = require('node:crypto');
const { readdirSync, lstatSync, readFileSync } = require('node:fs');
const path = require('node:path');
const { spawnSync } = require('node:child_process');

const SHA256 = /^[a-f0-9]{64}$/;
const COMMIT = /^(?:[a-f0-9]{40}|[a-f0-9]{64})$/;
const STABLE = /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)$/;

function ensure(condition, message) {
  if (!condition) throw new Error(`Stable startup refused: ${message}`);
}

function canonicalJson(value) {
  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(',')}]`;
  if (value && typeof value === 'object') return `{${Object.keys(value).sort().map(key => `${JSON.stringify(key)}:${canonicalJson(value[key])}`).join(',')}}`;
  return JSON.stringify(value);
}

function candidateLockChecksum(lock) {
  ensure(Object.keys(lock || {}).sort().join(',') === 'branchName,buildChecksum,buildRevision,candidateVersion,moduleCode,schemaInputChecksum', 'invalid Candidate lock fields');
  return createHash('sha256').update(canonicalJson(lock), 'utf8').digest('hex');
}

function calculateCompiledArtifactDigest(projectDir) {
  const root = path.resolve(projectDir, 'dist');
  ensure(lstatSync(root, { throwIfNoEntry: false })?.isDirectory(), 'dist does not exist; deploy the frozen build, do not rebuild during startup');
  const files = [];
  function visit(directory) {
    for (const name of readdirSync(directory)) {
      const file = path.join(directory, name);
      const stat = lstatSync(file);
      ensure(!stat.isSymbolicLink(), 'compiled artifact must not contain symbolic links');
      if (stat.isDirectory()) visit(file);
      else {
        ensure(stat.isFile(), 'compiled artifact contains a non-file entry');
        files.push([path.relative(root, file).replace(/\\/g, '/'), file]);
      }
    }
  }
  visit(root);
  ensure(files.length > 0, 'compiled artifact is empty');
  // Exact algorithm used by cool saas-model finalize with artifactDir: dist.
  const hash = createHash('sha256').update('COOL_SAAS_ARTIFACT_DIRECTORY_V1\0', 'utf8');
  for (const [name, file] of files.sort(([left], [right]) => left.localeCompare(right))) {
    const content = readFileSync(file);
    hash.update(`${Buffer.byteLength(name, 'utf8')}:`, 'utf8');
    hash.update(name, 'utf8');
    hash.update(`:${content.length}:`, 'utf8');
    hash.update(content);
  }
  return `sha256:${hash.digest('hex')}`;
}

function sourceCommit(projectDir, environment) {
  const gitOptions = { cwd: projectDir, encoding: 'utf8', windowsHide: true, timeout: 30_000 };
  const root = spawnSync('git', ['rev-parse', '--show-toplevel'], gitOptions);
  if (root.status === 0) {
    ensure(path.resolve(root.stdout.trim()) === path.resolve(projectDir), 'project must be its own exact Git checkout');
    const status = spawnSync('git', ['status', '--porcelain=v1', '--untracked-files=all'], gitOptions);
    ensure(status.status === 0 && !status.stdout.trim(), 'Git checkout is dirty');
    const commit = spawnSync('git', ['rev-parse', 'HEAD'], gitOptions);
    ensure(commit.status === 0 && COMMIT.test(commit.stdout.trim()), 'Git HEAD is unavailable');
    ensure(!environment.BUILD_SHA || environment.BUILD_SHA === commit.stdout.trim(), 'BUILD_SHA differs from Git HEAD');
    return commit.stdout.trim();
  }
  ensure(!lstatSync(path.join(projectDir, '.git'), { throwIfNoEntry: false }), 'Git metadata exists but could not be verified');
  // Git-free deployment archives must carry the trusted orchestrator's commit.
  // This is cross-checked against both the authoritative Frozen Artifact and
  // its actual compiled bytes, never accepted as a digest substitute.
  ensure(COMMIT.test(environment.BUILD_SHA || ''), 'Git-free deployments require an exact BUILD_SHA');
  return environment.BUILD_SHA;
}

async function fetchReleaseEvidence(environment, fetcher = fetch) {
  const releaseId = Number(environment.RPC_RELEASE_ID);
  ensure(Number.isSafeInteger(releaseId) && releaseId > 0, 'RPC_RELEASE_ID must select a Stable release');
  const base = new URL(environment.SAAS_CONTROL_PLANE_URL || environment.COOL_SAAS_CONTROL_PLANE_URL || 'http://127.0.0.1:8080');
  const local = ['local', 'test'].includes(environment.NODE_ENV);
  ensure(base.protocol === 'https:' || (local && base.protocol === 'http:' && ['127.0.0.1', 'localhost', '[::1]'].includes(base.hostname)), 'use HTTPS (loopback HTTP is local/test only)');
  ensure(!base.username && !base.password, 'control-plane URL must not contain credentials');
  ensure(String(environment.COOL_SAAS_TOKEN || '').trim(), 'a short-lived CLI/CI Bearer credential is required to verify immutable release evidence');
  const url = new URL('/admin/saas/module_release/info', base);
  url.searchParams.set('id', String(releaseId));
  const response = await fetcher(url, {
    method: 'GET', headers: { Authorization: `Bearer ${environment.COOL_SAAS_TOKEN}` },
    redirect: 'error', signal: AbortSignal.timeout(10_000)
  });
  ensure(response.ok, `control plane rejected release evidence (${response.status})`);
  const body = await response.json();
  ensure(body?.code === 1000 && body.data, 'control plane did not return release evidence');
  return body.data;
}

function verifyStableEvidence({ release, lock, generated, digest, commit, releaseId }) {
  const build = release?.build;
  const artifact = release?.frozenArtifact;
  ensure(release?.id === Number(releaseId) && release.releaseType === 'stable' && release.status === 'published' && release.lifecycleVersion === 1, 'target is not a published lifecycle Stable release');
  ensure(STABLE.test(release.version || '') && release.serviceVersion === release.version, 'Stable version identity is invalid');
  ensure(build && artifact && Number(release.promotedFromReleaseId) === Number(artifact.rcReleaseId) && Number(release.frozenArtifactId) === Number(artifact.id), 'Stable does not reference its source RC frozen artifact');
  ensure(Number(build.id) === Number(release.buildSnapshotId) && Number(build.moduleId) === Number(release.moduleId) && Number(artifact.moduleId) === Number(release.moduleId), 'Build/module/artifact association differs');
  ensure(Number(build.revision) === Number(lock.buildRevision) && Number(release.buildRevision) === Number(lock.buildRevision) && Number(artifact.buildRevision) === Number(lock.buildRevision), 'Build Revision differs from the Candidate lock');
  ensure(SHA256.test(build.buildChecksum || '') && build.buildChecksum === lock.buildChecksum && build.schemaInputChecksum === lock.schemaInputChecksum, 'Build checksums differ from the Candidate lock');
  ensure(lock.candidateVersion === `${release.version}-rc.${lock.buildRevision}` && lock.branchName === `release/${lock.candidateVersion}` && artifact.sourceBranch === lock.branchName && artifact.tagName === `v${lock.candidateVersion}`, 'source Candidate branch/version/tag differs');
  ensure(candidateLockChecksum(lock) === artifact.generatedLockChecksum, 'generated Candidate lock checksum differs');
  ensure(COMMIT.test(artifact.sourceCommit || '') && artifact.sourceCommit === commit, 'source commit differs from the Frozen Artifact');
  ensure(/^sha256:[a-f0-9]{64}$/.test(artifact.artifactDigest || ''), 'Frozen Artifact has no compiled digest; old Git-only evidence cannot be upgraded or forged here');
  ensure(artifact.artifactDigest === digest, 'compiled artifact digest differs from the Frozen Artifact');
  ensure(SHA256.test(artifact.artifactIdentityChecksum || '') && SHA256.test(artifact.implementationManifestChecksum || ''), 'frozen implementation identity is incomplete');
  ensure(generated.moduleCode === lock.moduleCode && generated.revision === lock.buildRevision && generated.schemaInputChecksum === lock.schemaInputChecksum, 'compiled generated identity differs from the immutable Build');
  ensure(!generated.releaseVersion || generated.releaseVersion === release.version, 'generated runtime embeds a different Release version');
  ensure(!generated.implementationManifestChecksum || generated.implementationManifestChecksum === artifact.implementationManifestChecksum, 'compiled implementation checksum differs');
  const manifest = release.schemaSnapshot?.actionManifest;
  const contracts = release.schemaSnapshot?.runtimeContracts;
  ensure(manifest && contracts?.implementationManifestChecksum === artifact.implementationManifestChecksum && manifest.artifactDigest === artifact.artifactDigest, 'Stable release envelope differs from the frozen implementation/artifact');
  ensure(generated.runtimeContractChecksum === contracts.runtimeContractChecksum && SHA256.test(contracts.runtimeContractChecksum || ''), 'compiled Runtime contract checksum differs');
  ensure(generated.schemaVersion === release.schemaVersion && build.schemaVersion === release.schemaVersion, 'compiled Schema version differs');
  return {
    SAAS_RUNTIME_MODE: 'production', RPC_REQUIRE_EXACT_RELEASE: 'true',
    RPC_MODULE_CODE: lock.moduleCode, RPC_RELEASE_ID: String(release.id),
    RPC_RELEASE_VERSION: release.version, RPC_SERVICE_VERSION: release.serviceVersion,
    SAAS_BUILD_REVISION: String(build.revision), SAAS_BUILD_CHECKSUM: build.buildChecksum,
    SAAS_SCHEMA_INPUT_CHECKSUM: build.schemaInputChecksum,
    RPC_MIN_SCHEMA_VERSION: String(release.schemaVersion), RPC_MAX_SCHEMA_VERSION: String(release.schemaVersion),
    RPC_SCHEMA_CHECKSUM: release.schemaChecksum,
    RPC_ACTION_MANIFEST_CHECKSUM: release.schemaSnapshot.actionManifestChecksum,
    RPC_RUNTIME_CONTRACT_CHECKSUM: contracts.runtimeContractChecksum,
    RPC_IMPLEMENTATION_MANIFEST_CHECKSUM: artifact.implementationManifestChecksum,
    RPC_ARTIFACT_DIGEST: artifact.artifactDigest,
    RPC_ARTIFACT_IDENTITY_CHECKSUM: artifact.artifactIdentityChecksum,
    BUILD_SHA: artifact.sourceCommit
  };
}

function applyExactEnvironment(environment, exact) {
  for (const [key, value] of Object.entries(exact)) {
    ensure(value != null && String(value).length > 0, `authoritative field ${key} is missing`);
    ensure(!environment[key] || environment[key] === String(value), `${key} conflicts with authoritative Stable evidence`);
    environment[key] = String(value);
  }
}

function verifyBootstrapSession(session, exact) {
  ensure(session?.moduleCode === exact.RPC_MODULE_CODE && session.revision === Number(exact.SAAS_BUILD_REVISION), 'bootstrap module/Revision differs');
  const mapping = {
    releaseId: 'RPC_RELEASE_ID', releaseVersion: 'RPC_RELEASE_VERSION', serviceVersion: 'RPC_SERVICE_VERSION',
    runtimeMode: 'SAAS_RUNTIME_MODE', buildRevision: 'SAAS_BUILD_REVISION', buildChecksum: 'SAAS_BUILD_CHECKSUM',
    schemaInputChecksum: 'SAAS_SCHEMA_INPUT_CHECKSUM', implementationManifestChecksum: 'RPC_IMPLEMENTATION_MANIFEST_CHECKSUM',
    artifactDigest: 'RPC_ARTIFACT_DIGEST', artifactIdentityChecksum: 'RPC_ARTIFACT_IDENTITY_CHECKSUM'
  };
  for (const [field, key] of Object.entries(mapping)) ensure(String(session.release?.[field]) === exact[key], `authenticated bootstrap ${field} differs from Stable evidence`);
}

async function startStable(options = {}) {
  const projectDir = path.resolve(options.projectDir || __dirname);
  const environment = options.environment || process.env;
  const release = await fetchReleaseEvidence(environment, options.fetch);
  const lock = JSON.parse(readFileSync(path.join(projectDir, '.cool-saas-candidate.json'), 'utf8'));
  const digest = calculateCompiledArtifactDigest(projectDir);
  const commit = sourceCommit(projectDir, environment);
  // Do not execute generated JavaScript before its compiled digest is verified.
  ensure(digest === release.frozenArtifact?.artifactDigest, 'compiled artifact digest differs from the Frozen Artifact');
  const generated = (options.loadGenerated || (() => require(path.join(projectDir, 'dist/saas/generated')).GeneratedSaasModule))();
  const exact = verifyStableEvidence({ release, lock, generated, digest, commit, releaseId: environment.RPC_RELEASE_ID });
  applyExactEnvironment(environment, exact);
  environment.SAAS_CONTROL_PLANE_URL ||= environment.COOL_SAAS_CONTROL_PLANE_URL || 'http://127.0.0.1:8080';
  delete environment.COOL_SAAS_TOKEN;
  delete environment.NODE_AUTH_TOKEN;
  delete environment.npm_config__authToken;
  const start = options.start || require(path.join(projectDir, 'bootstrap.js')).start;
  return start({ verifySession: session => {
    verifyBootstrapSession(session, exact);
    ensure(calculateCompiledArtifactDigest(projectDir) === digest, 'compiled bytes changed during bootstrap');
  } });
}

if (require.main === module) startStable().catch(error => {
  process.stderr.write(`${error?.message || error}\n`);
  process.exitCode = 1;
});

module.exports = { startStable, verifyStableEvidence, verifyBootstrapSession, applyExactEnvironment, calculateCompiledArtifactDigest, candidateLockChecksum, fetchReleaseEvidence, sourceCommit };