import path from "node:path";
import fs from "node:fs";

/**
 * Get the real path of a file or directory, even if it doesn't exist.
 * For non-existent paths, it resolves the real path of the nearest existing parent.
 */
function getSafeRealPath(p: string): string {
  try {
    return fs.realpathSync(p);
  } catch {
    const parent = path.dirname(p);
    if (parent === p) return p; // Root reached
    return path.join(getSafeRealPath(parent), path.basename(p));
  }
}

/**
 * Check if a target path is inside a parent directory.
 * Resolves symlinks and handles absolute paths.
 * Returns true if target is the same as parent or is a subdirectory of parent.
 * @param target The path to check
 * @param parent The parent directory path
 * @returns boolean
 */
export function isPathInside(target: string, parent: string): boolean {
  try {
    const absoluteTarget = path.resolve(target);
    const absoluteParent = path.resolve(parent);

    const realTarget = getSafeRealPath(absoluteTarget);
    const realParent = getSafeRealPath(absoluteParent);

    const relative = path.relative(realParent, realTarget);

    return !relative.startsWith("..") && !path.isAbsolute(relative);
  } catch {
    return false;
  }
}