/**
 * ─────────────────────────────────────────────
 *  SPB Git — Personal Git Platform
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : cli/lib/git.mjs
 *  Purpose : Local git helpers — workspace scan, authed push, status
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { execFile } from 'node:child_process';
import { promisify } from 'node:util';
import { readdirSync, existsSync, chmodSync } from 'node:fs';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';

const execFileAsync = promisify(execFile);
const ASKPASS = join(dirname(fileURLToPath(import.meta.url)), 'askpass.sh');

/**
 * Run git in a directory.
 * @param {string} cwd
 * @param {string[]} args
 * @param {{token?: string}} [opts] token → authenticated via GIT_ASKPASS (never argv)
 * @returns {Promise<{ok: boolean, stdout: string, stderr: string}>}
 */
export async function git(cwd, args, opts = {}) {
  const env = { ...process.env, GIT_TERMINAL_PROMPT: '0' };
  if (opts.token) {
    try {
      chmodSync(ASKPASS, 0o755);
    } catch {
      /* read-only install — askpass already executable from packaging */
    }
    env.GIT_ASKPASS = ASKPASS;
    env.SPBGIT_TOKEN = opts.token;
    env.SPBGIT_USERNAME = 'spb';
  }
  try {
    const { stdout, stderr } = await execFileAsync('git', args, { cwd, env, maxBuffer: 32 * 1024 * 1024 });
    return { ok: true, stdout, stderr };
  } catch (err) {
    return { ok: false, stdout: err.stdout ?? '', stderr: err.stderr ?? err.message };
  }
}

/**
 * List workspace repositories (immediate subdirectories containing .git).
 * @param {string} workspace
 * @returns {string[]} absolute paths
 */
export function workspaceRepos(workspace) {
  if (!existsSync(workspace)) return [];
  return readdirSync(workspace)
    .filter((entry) => !entry.startsWith('.'))
    .map((entry) => join(workspace, entry))
    .filter((dir) => existsSync(join(dir, '.git')))
    .sort();
}

/**
 * Status snapshot of one repo.
 * @param {string} dir
 * @returns {Promise<{branch: string, ahead: number, behind: number, dirty: number, hasUpstream: boolean}>}
 */
export async function repoStatus(dir) {
  const branchRes = await git(dir, ['rev-parse', '--abbrev-ref', 'HEAD']);
  const branch = branchRes.ok ? branchRes.stdout.trim() : '?';
  const dirtyRes = await git(dir, ['status', '--porcelain']);
  const dirty = dirtyRes.ok ? dirtyRes.stdout.split('\n').filter(Boolean).length : 0;
  let ahead = 0;
  let behind = 0;
  let hasUpstream = false;
  const upstream = await git(dir, ['rev-parse', '--abbrev-ref', '--symbolic-full-name', '@{u}']);
  if (upstream.ok) {
    hasUpstream = true;
    const counts = await git(dir, ['rev-list', '--left-right', '--count', '@{u}...HEAD']);
    if (counts.ok) {
      const [b, a] = counts.stdout.trim().split('\t').map(Number);
      behind = b || 0;
      ahead = a || 0;
    }
  }
  return { branch, ahead, behind, dirty, hasUpstream };
}