/**
 * Installer utilities — safe execFile wrapper for npm operations.
 *
 * Hard rule #13: never string-interpolate runtime values into shell commands.
 * All npm invocations use execFile() with an explicit args array, never exec().
 */

import { execFile } from "node:child_process";
import { sanitizeErrorMessage } from "@omniroute/open-sse/utils/error";

const DEFAULT_TIMEOUT_MS = 300_000; // 5 min — npm install can be slow

export interface NpmRunResult {
  stdout: string;
  stderr: string;
}

export class InstallError extends Error {
  constructor(
    message: string,
    public readonly friendly: string,
    public readonly httpStatus: number = 500
  ) {
    super(message);
    this.name = "InstallError";
  }
}

/** Classify raw npm/OS errors into user-friendly messages. */
function classifyError(
  // execFile's callback error is an ExecFileException — it carries `signal`/`killed`
  // (a timed-out/terminated child) on top of ErrnoException, which @types/node's
  // ErrnoException itself does not declare. Widen the param so both are typed.
  err: NodeJS.ErrnoException & {
    stdout?: string;
    stderr?: string;
    signal?: NodeJS.Signals | null;
    killed?: boolean;
  }
): InstallError {
  const raw = sanitizeErrorMessage(err.message);
  const stderr = err.stderr ?? "";

  if (err.code === "EACCES") {
    return new InstallError(
      raw,
      "Sem permissão para instalar. Verifique as permissões da pasta de dados.",
      403
    );
  }
  if (err.code === "ENOENT" && err.message.includes("npm")) {
    return new InstallError(
      raw,
      "Node.js/npm não está disponível no PATH. Instale Node ≥22.22.2.",
      500
    );
  }
  if (err.code === "ENOSPC" || stderr.includes("ENOSPC")) {
    return new InstallError(raw, "Espaço em disco insuficiente.", 507);
  }
  if (err.signal === "SIGTERM" || err.code === "ETIMEDOUT" || err.killed) {
    return new InstallError(raw, "Instalação demorou demais. Tente novamente.", 504);
  }
  if (
    stderr.includes("ENOTFOUND") ||
    stderr.includes("network") ||
    stderr.includes("ECONNREFUSED") ||
    stderr.includes("ERR_INVALID_URL")
  ) {
    return new InstallError(
      raw,
      "Falha de rede ao instalar. Verifique a conexão e tente novamente.",
      503
    );
  }

  return new InstallError(raw, `Falha na instalação: ${raw}`, 500);
}

/**
 * Validates a user-supplied service version (npm dist-tag or semver). Constrained
 * to letters, digits and `. _ + -`, with a leading alphanumeric, so the value can
 * never carry shell metacharacters once `runNpm` runs under a shell on Windows
 * (see `buildNpmExecOptions`). Accepts `latest`, `next`, `1.2.3`, `1.2.3-beta.1`,
 * `1.2.3+build.5`; rejects `latest && calc`, `$(id)`, spaces, leading `-`, etc.
 */
export const SERVICE_VERSION_PATTERN = /^[A-Za-z0-9][A-Za-z0-9._+-]*$/;

export interface NpmExecOptions {
  cwd?: string;
  timeout: number;
  env: NodeJS.ProcessEnv;
  maxBuffer: number;
  shell?: boolean;
  windowsHide: boolean;
}

/**
 * Builds the `execFile` options for {@link runNpm}.
 *
 * On Windows, npm is `npm.cmd` (a batch wrapper). Node 24 refuses to `execFile`
 * a `.cmd` without a shell (nodejs/node#52554 — manifests as `spawn EINVAL`, see
 * issue #5379), so we enable `shell` on win32 only.
 *
 * Enabling the shell means the shell — not `execFile` — splits the command line,
 * so NO runtime value may be interpolated into argv (Hard Rule #13). The install
 * prefix (a DATA_DIR path that can legitimately contain spaces, e.g.
 * `C:\Users\John Doe\.omniroute\…`) is therefore exported as the
 * `npm_config_prefix` environment variable — npm's documented env form of
 * `--prefix` — never as an argv entry. With the prefix moved to the environment
 * and the version constrained by {@link SERVICE_VERSION_PATTERN}, every remaining
 * argv entry is a static, metacharacter-free flag.
 */
export function buildNpmExecOptions(
  platform: NodeJS.Platform,
  options: { cwd?: string; timeoutMs: number; prefix?: string }
): NpmExecOptions {
  const env: NodeJS.ProcessEnv = { ...process.env };
  if (options.prefix) {
    env.npm_config_prefix = options.prefix;
  }
  const execOptions: NpmExecOptions = {
    cwd: options.cwd,
    timeout: options.timeoutMs,
    env,
    maxBuffer: 10 * 1024 * 1024, // 10 MB for npm output
    // Suppress the transient conhost.exe/cmd console window Windows briefly
    // flashes open for spawned child processes (see #8131).
    windowsHide: true,
  };
  if (platform === "win32") {
    execOptions.shell = true;
  }
  return execOptions;
}

/**
 * Runs npm with the given args array. Never uses shell interpolation: argv holds
 * only static flags, and any install prefix is passed via `options.prefix`
 * (exported as `npm_config_prefix`), not as an argv path. See
 * {@link buildNpmExecOptions} for the Windows/Node-24 shell handling.
 */
export function runNpm(
  args: string[],
  options: { cwd?: string; timeoutMs?: number; prefix?: string } = {}
): Promise<NpmRunResult> {
  const timeoutMs = options.timeoutMs ?? DEFAULT_TIMEOUT_MS;
  // On Windows, npm is npm.cmd; on Unix it's npm.
  const npmBin = process.platform === "win32" ? "npm.cmd" : "npm";

  return new Promise((resolve, reject) => {
    execFile(
      npmBin,
      args,
      buildNpmExecOptions(process.platform, {
        cwd: options.cwd,
        timeoutMs,
        prefix: options.prefix,
      }),
      (err, stdout, stderr) => {
        if (err) {
          const classified = classifyError(
            Object.assign(err, { stdout, stderr }) as NodeJS.ErrnoException & {
              stdout: string;
              stderr: string;
            }
          );
          reject(classified);
        } else {
          resolve({ stdout, stderr });
        }
      }
    );
  });
}