import { existsSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";
import { execFileSync } from "node:child_process";

/** Candidate locations for the HSP release binary. */
export function hspCandidates(): string[] {
  const home = homedir();
  const env = process.env.HSP_BIN?.trim();
  const out: string[] = [];
  if (env) out.push(env);
  out.push(
    join(home, ".local", "bin", "hsp"),
    "/usr/local/bin/hsp",
    join(home, "github-clone", "HSP", "hsp-rs", "target", "release", "hsp"),
    join(home, "Projects", "HSP", "hsp-rs", "target", "release", "hsp"),
  );
  return out;
}

export function resolveHspBin(): string | null {
  for (const p of hspCandidates()) {
    if (p && existsSync(p)) return p;
  }
  try {
    const which = execFileSync("which", ["hsp"], { encoding: "utf8" }).trim();
    if (which && existsSync(which)) return which;
  } catch {
    /* not on PATH */
  }
  return null;
}

export function hspStateDir(): string {
  return join(homedir(), ".local", "state", "hsp-pi");
}

export function hspPidPath(): string {
  return join(hspStateDir(), "hsp-run.pid");
}

export function hspLogPath(): string {
  return join(hspStateDir(), "hsp-run.log");
}