excel-tools

import * as path from "path";
import * as fs from "fs";

/**
 * Resolve a file path:
 * - Absolute paths are used as-is
 * - Relative paths are resolved against the LM Studio working directory
 */
export function resolvePath(filePath: string, workingDir: string): string {
  return path.isAbsolute(filePath) ? filePath : path.resolve(workingDir, filePath);
}

/** Create a .bak copy before destructive operations */
export function backupFile(filePath: string): string {
  const backupPath = filePath + ".bak";
  fs.copyFileSync(filePath, backupPath);
  return backupPath;
}

/** Ensure the directory for a file path exists */
export function ensureDir(filePath: string): void {
  const dir = path.dirname(filePath);
  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
}

/** Supported formats for reading */
export const READABLE_EXTS = [".xlsx", ".xlsm", ".xls", ".xlsb", ".ods", ".csv", ".tsv"];

export function checkReadable(filePath: string): string | null {
  if (!fs.existsSync(filePath)) return `File not found: "${filePath}"`;
  const ext = path.extname(filePath).toLowerCase();
  if (!READABLE_EXTS.includes(ext)) return `Unsupported format "${ext}". Supported: ${READABLE_EXTS.join(", ")}`;
  return null;
}