/**
 * Check whether a binary is available on PATH.
 *
 * Pure module: no I/O side effects beyond `spawnSync`. No Pi runtime imports,
 * no `src/` imports — kept self-contained so it can be unit-tested without
 * jiti and reused in any future tooling.
 *
 * Why this exists (v0.14.0): when the user has a formatter configured but
 * the binary is not installed, we degrade gracefully to the built-in autofix
 * path (default mode) instead of leaving the file with raw `newText` drift.
 * Detection happens at `session_start` time so the rest of the cascade —
 * `tool_call` / `tool_result` — sees a `ResolvedFormatter[]` that already
 * excludes the missing binaries.
 */

import { spawnSync } from 'node:child_process';

const PROBE = process.platform === 'win32' ? 'where' : 'which';

/**
 * Return true when `bin` resolves to an executable on PATH.
 *
 * Implementation notes:
 *   - Uses `which` on POSIX and `where` on Windows. Both are standard on
 *     every supported platform (Linux, macOS, Windows 10+).
 *   - `spawnSync` with an argv array does NOT invoke a shell, so command
 *     injection through bin names is not possible.
 *   - Any error (probe missing, sandbox blocking, etc.) returns false
 *     (conservative — we treat "can't tell" as "not available").
 *   - Empty string returns false (no probe is meaningful).
 *
 * Cost: one `fork`+`execve` per unique binary per `session_start`. With the
 * default config (a handful of binaries) and only the ones matched against
 * the current project's filetypes being probed, this is well under 50ms in
 * total. Negligible.
 *
 * @param bin - The executable name to probe (e.g. `"prettier"`, `"biome"`).
 * @returns `true` if the binary resolves on PATH, `false` otherwise (including
 *   empty input and error cases).
 */
export function binaryAvailable(bin: string): boolean {
  if (!bin) return false;
  try {
    const result = spawnSync(PROBE, [bin], {
      stdio: 'ignore',
      windowsHide: true,
    });
    return result.status === 0;
  } catch {
    return false;
  }
}