import { promises as fs } from "fs";
import * as path from "path";

export const MAX_FILE_BYTES = 5 * 1024 * 1024;

/**
 * Heuristic: a NUL byte, or >30% control characters, means binary. Bytes >= 128
 * are not counted so UTF-8 text in any script is not misflagged.
 */
export function looksBinary(sample: Buffer): boolean {
  if (sample.includes(0)) return true;
  if (sample.length === 0) return false;
  let control = 0;
  for (const b of sample) {
    const isText = b >= 128 || (b >= 32 && b < 127) || b === 8 || b === 9 || b === 10 || b === 12 || b === 13;
    if (!isText) control++;
  }
  return control / sample.length > 0.3;
}

/** Map a Node fs error to a plain message that never leaks the real path. */
export function fsError(e: unknown, userPath: string): string {
  const code = (e as NodeJS.ErrnoException).code;
  switch (code) {
    case "ENOENT":
      return `Error: no such file: ${userPath}`;
    case "EACCES":
    case "EPERM":
      return `Error: permission denied: ${userPath}`;
    case "EISDIR":
      return `Error: is a directory, not a file: ${userPath}`;
    case "ENOTDIR":
      return `Error: not a directory in path: ${userPath}`;
    default:
      return `Error: cannot access ${userPath} (${code ?? "unknown"})`;
  }
}

/** Write via temp file in the same directory + rename, so a crash never leaves a partial file. */
export async function atomicWrite(abs: string, data: string): Promise<void> {
  const tmp = path.join(path.dirname(abs), `.${path.basename(abs)}.${process.pid}.${Date.now()}.tmp`);
  try {
    await fs.writeFile(tmp, data, "utf8");
    const existing = await fs.stat(abs).catch(() => null);
    if (existing) await fs.chmod(tmp, existing.mode & 0o777);
    await fs.rename(tmp, abs);
  } catch (e) {
    await fs.rm(tmp, { force: true });
    throw e;
  }
}

import { promises as fs } from "fs";
import * as path from "path";

export const MAX_FILE_BYTES = 5 * 1024 * 1024;

/**
 * Heuristic: a NUL byte, or >30% control characters, means binary. Bytes >= 128
 * are not counted so UTF-8 text in any script is not misflagged.
 */
export function looksBinary(sample: Buffer): boolean {
  if (sample.includes(0)) return true;
  if (sample.length === 0) return false;
  let control = 0;
  for (const b of sample) {
    const isText = b >= 128 || (b >= 32 && b < 127) || b === 8 || b === 9 || b === 10 || b === 12 || b === 13;
    if (!isText) control++;
  }
  return control / sample.length > 0.3;
}

/** Map a Node fs error to a plain message that never leaks the real path. */
export function fsError(e: unknown, userPath: string): string {
  const code = (e as NodeJS.ErrnoException).code;
  switch (code) {
    case "ENOENT":
      return `Error: no such file: ${userPath}`;
    case "EACCES":
    case "EPERM":
      return `Error: permission denied: ${userPath}`;
    case "EISDIR":
      return `Error: is a directory, not a file: ${userPath}`;
    case "ENOTDIR":
      return `Error: not a directory in path: ${userPath}`;
    default:
      return `Error: cannot access ${userPath} (${code ?? "unknown"})`;
  }
}

/** Write via temp file in the same directory + rename, so a crash never leaves a partial file. */
export async function atomicWrite(abs: string, data: string): Promise<void> {
  const tmp = path.join(path.dirname(abs), `.${path.basename(abs)}.${process.pid}.${Date.now()}.tmp`);
  try {
    await fs.writeFile(tmp, data, "utf8");
    const existing = await fs.stat(abs).catch(() => null);
    if (existing) await fs.chmod(tmp, existing.mode & 0o777);
    await fs.rename(tmp, abs);
  } catch (e) {
    await fs.rm(tmp, { force: true });
    throw e;
  }
}