import path from "node:path";
import { execFileSync } from "node:child_process";

export type GitWorkspaceInfo = {
  root: string;
  commonDir: string;
  gitDir: string;
  hooksPath: string;
};

/**
 * Resolve the repository metadata Git exposes for both primary checkouts and
 * linked worktrees. Returns null outside a Git working tree.
 */
export function detectGitWorkspaceInfo(cwd: string): GitWorkspaceInfo | null {
  try {
    const root = execFileSync("git", ["rev-parse", "--show-toplevel"], {
      cwd,
      encoding: "utf8",
      stdio: ["ignore", "pipe", "ignore"],
    }).trim();
    const commonDirRaw = execFileSync("git", ["rev-parse", "--git-common-dir"], {
      cwd: root,
      encoding: "utf8",
      stdio: ["ignore", "pipe", "ignore"],
    }).trim();
    const gitDirRaw = execFileSync("git", ["rev-parse", "--git-dir"], {
      cwd: root,
      encoding: "utf8",
      stdio: ["ignore", "pipe", "ignore"],
    }).trim();
    const hooksPathRaw = execFileSync("git", ["rev-parse", "--git-path", "hooks"], {
      cwd: root,
      encoding: "utf8",
      stdio: ["ignore", "pipe", "ignore"],
    }).trim();
    return {
      root: path.resolve(root),
      commonDir: path.resolve(root, commonDirRaw),
      gitDir: path.resolve(root, gitDirRaw),
      hooksPath: path.resolve(root, hooksPathRaw),
    };
  } catch {
    return null;
  }
}

export function isLinkedGitWorktree(cwd: string): boolean {
  const workspace = detectGitWorkspaceInfo(cwd);
  return Boolean(workspace && workspace.gitDir !== workspace.commonDir);
}