#!/usr/bin/env node

import assert from "node:assert/strict";
import { execFile } from "node:child_process";
import { constants } from "node:fs";
import { access, lstat, mkdtemp, readFile, realpath, rm } from "node:fs/promises";
import { tmpdir } from "node:os";
import { isAbsolute, join, relative } from "node:path";
import { promisify } from "node:util";

const execFileAsync = promisify(execFile);
const PACKAGE_NAME = "@bodicsek/codex-app-server-bridge";
const BIN_NAME = "codex-app-server-bridge";
const DEFAULT_CACHE = "/private/tmp/codex-app-server-bridge-npm-cache";
const USAGE = "usage: npm run verify:git-package -- <git+https|git+ssh|git+file URL>#<vX.Y.Z|40-character-commit>";

function selectedGitPackage(argv) {
  if (argv.length !== 1) throw new Error(USAGE);
  const packageSpec = argv[0];
  const fragmentAt = packageSpec.lastIndexOf("#");
  const repository = packageSpec.slice(0, fragmentAt);
  const revision = packageSpec.slice(fragmentAt + 1);
  const supportedRepository = /^(?:git\+https|git\+ssh|git\+file):\/\/.+\.git$/.test(repository);
  const immutableRevision = /^(?:[0-9a-fA-F]{40}|v\d+\.\d+\.\d+(?:-[0-9A-Za-z.-]+)?)$/.test(revision);
  if (fragmentAt <= 0 || !supportedRepository || !immutableRevision) {
    throw new Error("Git package must use a supported URL pinned to a full commit or release tag");
  }
  return { packageSpec, revision };
}

function isWithin(parent, child) {
  const pathFromParent = relative(parent, child);
  return pathFromParent === "" || (!pathFromParent.startsWith("..") && !isAbsolute(pathFromParent));
}

function commandExit(error) {
  return typeof error === "object" && error !== null && "code" in error
    ? String(error.code)
    : "unknown";
}

async function installPackage(prefix, cache, packageSpec) {
  try {
    await execFileAsync("npm", [
      "install",
      "--global",
      "--prefix",
      prefix,
      "--ignore-scripts",
      "--cache",
      cache,
      packageSpec,
    ], { maxBuffer: 10 * 1024 * 1024 });
  } catch (error) {
    throw new Error(`isolated npm installation failed with exit code ${commandExit(error)}`);
  }
}

async function installedPackage(prefix, cache) {
  const packageRoot = join(prefix, "lib", "node_modules", PACKAGE_NAME);
  const executable = join(prefix, "bin", BIN_NAME);
  await Promise.all([
    access(executable, constants.X_OK),
    access(join(packageRoot, "dist", "cli.js"), constants.R_OK),
    access(join(packageRoot, "dist", "config.js"), constants.R_OK),
  ]);

  const packageMetadata = await lstat(packageRoot);
  if (packageMetadata.isSymbolicLink()) {
    throw new Error("installed package must not be a temporary link");
  }

  const [realPrefix, realCache, realPackage, realExecutable] = await Promise.all([
    realpath(prefix),
    realpath(cache),
    realpath(packageRoot),
    realpath(executable),
  ]);
  if (!isWithin(realPrefix, realPackage) || isWithin(realCache, realPackage)) {
    throw new Error("installed package resolved outside the isolated prefix");
  }
  if (!isWithin(realPackage, realExecutable) || isWithin(realCache, realExecutable)) {
    throw new Error("installed executable resolved outside the installed package");
  }

  const manifest = JSON.parse(await readFile(join(realPackage, "package.json"), "utf8"));
  assert.equal(manifest.name, PACKAGE_NAME);
  assert.deepEqual(manifest.bin, { [BIN_NAME]: `bin/${BIN_NAME}.js` });
  return { executable, version: String(manifest.version) };
}

async function verifyExecutable(executable) {
  try {
    await execFileAsync(executable, ["--unsupported"], {
      env: process.env,
      maxBuffer: 1024 * 1024,
    });
    throw new Error("installed executable unexpectedly accepted an unsupported invocation");
  } catch (error) {
    if (typeof error !== "object" || error === null || !("code" in error) || error.code !== 1) {
      throw error;
    }
    const stdout = "stdout" in error ? String(error.stdout) : "";
    const stderr = "stderr" in error ? String(error.stderr) : "";
    assert.equal(stdout, "");
    assert.match(stderr, /Usage: codex-app-server-bridge app-server/);
  }
}

async function verify() {
  const { packageSpec, revision } = selectedGitPackage(process.argv.slice(2));
  const prefix = await mkdtemp(join(tmpdir(), "codex-app-server-bridge-git-package-"));
  const cache = process.env.CODEX_APP_SERVER_BRIDGE_NPM_CACHE ?? DEFAULT_CACHE;

  try {
    await installPackage(prefix, cache, packageSpec);
    const installed = await installedPackage(prefix, cache);
    await verifyExecutable(installed.executable);
    process.stdout.write(`${JSON.stringify({
      ok: true,
      package: `${PACKAGE_NAME}@${installed.version}`,
      revision,
      executable: `bin/${BIN_NAME}`,
      storage: "isolated-prefix",
      invocation: "verified",
    })}\n`);
  } finally {
    await rm(prefix, { recursive: true, force: true });
  }
}

verify().catch((error) => {
  const message = error instanceof Error ? error.message : String(error);
  process.stderr.write(`Git-package verification failed: ${message}\n`);
  process.exitCode = 1;
});