import type { GitHubRepoData } from "@/types";

export function parseGitHubUrl(url: string): { owner: string; repo: string } | null {
  const trimmed = url.trim();
  const patterns = [
    /github\.com\/([^/\s]+)\/([^/\s#?]+)/i,
    /^([^/\s]+)\/([^/\s]+)$/,
  ];

  for (const pattern of patterns) {
    const match = trimmed.match(pattern);
    if (match) {
      return {
        owner: match[1].replace(/\.git$/, ""),
        repo: match[2].replace(/\.git$/, ""),
      };
    }
  }
  return null;
}

async function githubFetch(path: string): Promise<Response> {
  const headers: Record<string, string> = {
    Accept: "application/vnd.github+json",
    "User-Agent": "caption-studio",
  };
  // ponytail: a placeholder token 401s every request — treat it as absent
  const token = process.env.GITHUB_TOKEN?.trim();
  if (token && token.length > 20) {
    headers.Authorization = `Bearer ${token}`;
  }
  return fetch(`https://api.github.com${path}`, { headers });
}

export async function fetchRepoData(url: string): Promise<GitHubRepoData> {
  const parsed = parseGitHubUrl(url);
  if (!parsed) throw new Error("Invalid GitHub repo URL");

  const { owner, repo } = parsed;
  const repoRes = await githubFetch(`/repos/${owner}/${repo}`);
  if (!repoRes.ok) {
    throw new Error(
      `GitHub repo fetch failed (${repoRes.status}): ${owner}/${repo}`,
    );
  }
  const repoData = await repoRes.json();

  let readme = "";
  const readmeRes = await githubFetch(`/repos/${owner}/${repo}/readme`);
  if (readmeRes.ok) {
    readme = await readmeRes.text();
    if (readme.length > 4000) readme = readme.slice(0, 4000) + "...";
  }

  return {
    owner,
    repo,
    fullName: repoData.full_name as string,
    htmlUrl: repoData.html_url as string,
    description: (repoData.description as string) || "",
    stars: (repoData.stargazers_count as number) || 0,
    language: (repoData.language as string) || "Unknown",
    topics: (repoData.topics as string[]) || [],
    readme,
  };
}