import { execFile } from 'node:child_process';

// Read-only GitHub REST client. Anonymous access works for public repos but
// is rate-limited to 60 requests/hour; a token (GITHUB_TOKEN or GH_TOKEN env,
// or the gh CLI's stored token) raises that to 5000.

const API = 'https://api.github.com';

// GitHub reaction names → the exact emoji set of org.tangled.feed.reaction.
export const REACTION_EMOJI = {
  '+1': '👍',
  '-1': '👎',
  laugh: '😆',
  hooray: '🎉',
  confused: '🫤',
  heart: '❤️',
  rocket: '🚀',
  eyes: '👀',
};

// Accepts "owner/repo", github.com URLs (with or without extra path bits),
// and git@github.com:owner/repo.git remotes.
export function parseGitHubRepo(input) {
  const m =
    input.match(
      /^(?:https?:\/\/(?:www\.)?github\.com\/|git@github\.com:)([^/\s]+)\/([^/\s#?]+?)(?:\.git)?(?:[/#?].*)?$/,
    ) || input.match(/^([A-Za-z0-9][A-Za-z0-9-]*)\/([A-Za-z0-9._-]+?)(?:\.git)?$/);
  if (!m) {
    throw new Error(
      `Cannot parse "${input}" as a GitHub repo. Use owner/name or a github.com URL.`,
    );
  }
  return { owner: m[1], repo: m[2] };
}

export async function githubToken() {
  if (process.env.GITHUB_TOKEN) return process.env.GITHUB_TOKEN;
  if (process.env.GH_TOKEN) return process.env.GH_TOKEN;
  // Borrow the gh CLI's token when it's installed and logged in.
  return new Promise((resolve) => {
    execFile('gh', ['auth', 'token'], (err, stdout) =>
      resolve(err ? null : stdout.trim() || null),
    );
  });
}

async function ghFetch(path, { token, accept = 'application/vnd.github+json', text = false } = {}) {
  const headers = {
    accept,
    'user-agent': 'tangy-cli',
    'x-github-api-version': '2022-11-28',
  };
  if (token) headers.authorization = `Bearer ${token}`;
  const res = await fetch(API + path, { headers });
  if (!res.ok) {
    if ((res.status === 403 || res.status === 429) && res.headers.get('x-ratelimit-remaining') === '0') {
      throw new Error(
        'GitHub API rate limit exceeded. Set GITHUB_TOKEN (or log in with `gh auth login`) and retry.',
      );
    }
    if (res.status === 404) {
      throw new Error(`GitHub returned 404 for ${path} — is the repo public and the name right?`);
    }
    const body = await res.text().catch(() => '');
    throw new Error(`GitHub API error ${res.status} on ${path}: ${body.slice(0, 200)}`);
  }
  return text ? res.text() : res.json();
}

async function ghPaged(path, opts) {
  const sep = path.includes('?') ? '&' : '?';
  const all = [];
  for (let page = 1; ; page++) {
    const batch = await ghFetch(`${path}${sep}per_page=100&page=${page}`, opts);
    all.push(...batch);
    if (batch.length < 100) return all;
  }
}

// Open issues, oldest first, with pull requests filtered out (GitHub's issues
// endpoint returns both).
export async function fetchOpenIssues(owner, repo, token) {
  const items = await ghPaged(
    `/repos/${owner}/${repo}/issues?state=open&sort=created&direction=asc`,
    { token },
  );
  return items.filter((i) => !i.pull_request);
}

export function fetchOpenPulls(owner, repo, token) {
  return ghPaged(`/repos/${owner}/${repo}/pulls?state=open&sort=created&direction=asc`, {
    token,
  });
}

// Conversation comments; works for both issues and pull requests.
export function fetchComments(owner, repo, number, token) {
  return ghPaged(`/repos/${owner}/${repo}/issues/${number}/comments`, { token });
}

// Individual reactions ({ content, user, created_at }); works for both kinds.
export function fetchIssueReactions(owner, repo, number, token) {
  return ghPaged(`/repos/${owner}/${repo}/issues/${number}/reactions`, { token });
}

export function fetchCommentReactions(owner, repo, commentId, token) {
  return ghPaged(`/repos/${owner}/${repo}/issues/comments/${commentId}/reactions`, { token });
}