import * as fs from "node:fs/promises";
import * as path from "node:path";

const SAFE_NAME = /^[a-zA-Z0-9][a-zA-Z0-9._-]{0,254}$/;

export const assertSafeRepoName = (name: string): string => {
  const trimmed = name.trim();
  if (!SAFE_NAME.test(trimmed)) {
    throw new Error("Invalid repo name: use letters, digits, . _ - only; no path segments.");
  }
  if (trimmed.includes("..")) {
    throw new Error("Invalid repo name: path traversal rejected.");
  }
  return trimmed;
};

export const getCodeRoot = (): string => {
  const raw = process.env.REPOS_DEVTOOLS_ROOT ?? "/home/ncantu/code";
  return path.resolve(raw);
};

export const repoDirForName = (codeRoot: string, name: string): string => {
  const safe = assertSafeRepoName(name);
  return path.join(codeRoot, safe);
};

export const isGitRepo = async (dir: string): Promise<boolean> => {
  try {
    const stat = await fs.stat(path.join(dir, ".git"));
    return stat.isDirectory() || stat.isFile();
  } catch {
    return false;
  }
};

export const repoNameFromGitUrl = (rawUrl: string): string => {
  const trimmed = rawUrl.trim();
  const noQuery = trimmed.split("?")[0] ?? trimmed;
  const base = noQuery.replace(/[/]+$/, "");
  const segment = base.split("/").filter((s) => s.length > 0).pop() ?? "";
  const withoutGit = segment.replace(/\.git$/i, "");
  if (withoutGit.length === 0) {
    throw new Error("Could not derive repository name from URL.");
  }
  return assertSafeRepoName(withoutGit);
};