/**
 * ─────────────────────────────────────────────
 *  SPB Git — Personal Git Platform
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : src/git/hooks.mjs
 *  Purpose : post-receive hook installer + localhost-only hook endpoint
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { writeFileSync, chmodSync, mkdirSync } from 'node:fs';
import { join } from 'node:path';

const LOCALHOST = new Set(['127.0.0.1', '::1', '::ffff:127.0.0.1']);
const ZERO_SHA = /^0+$/;

/**
 * Render the post-receive hook script for a given server port.
 * @param {number} port
 * @returns {string}
 */
export function hookScript(port) {
  return `#!/bin/sh
# ─────────────────────────────────────────────
#  SPB Git — Personal Git Platform
# ─────────────────────────────────────────────
#  Author  : Simon-Pierre Boucher
#  Contact : contact@spboucher.ai
#  File    : hooks/post-receive (installed by SPB Git)
#  Purpose : Notify the server of pushes (cache bust + activity feed)
#  License : MIT © Simon-Pierre Boucher
# ─────────────────────────────────────────────
input="$(cat)"
repo="$(basename "$PWD" .git)"
printf '%s' "$input" | curl -s -m 15 -X POST \\
  -H 'Content-Type: text/plain' \\
  --data-binary @- \\
  "http://127.0.0.1:${port}/internal/hooks/post-receive?repo=$repo" \\
  >/dev/null 2>&1 || true
exit 0
`;
}

/**
 * Install (or refresh) the post-receive hook in one bare repo. Idempotent.
 * @param {string} repoDir absolute bare repo path
 * @param {number} port server port the hook reports to
 */
export function installHooks(repoDir, port) {
  const hooksDir = join(repoDir, 'hooks');
  mkdirSync(hooksDir, { recursive: true });
  const path = join(hooksDir, 'post-receive');
  writeFileSync(path, hookScript(port));
  chmodSync(path, 0o755);
}

/**
 * Refresh hooks in every existing repo (run at boot so port changes stick).
 * @param {{repos: object, config: object}} ctx
 */
export function ensureHooksInstalled(ctx) {
  for (const name of ctx.repos.list()) {
    installHooks(ctx.repos.dir(name), ctx.config.port);
  }
}

/**
 * Register the localhost-only internal hook endpoint.
 * @param {import('fastify').FastifyInstance} app
 * @param {{config, repos, cache, meta, activity, warmers}} ctx
 *   `warmers` is an async fn (repo) => void that re-primes caches after a push.
 */
export function registerHookRoutes(app, ctx) {
  app.post('/internal/hooks/post-receive', async (request, reply) => {
    if (!LOCALHOST.has(request.socket.remoteAddress)) {
      return reply.code(403).send({ error: { code: 'forbidden', message: 'internal endpoint' } });
    }
    const repo = String(request.query.repo ?? '');
    if (!ctx.repos.exists(repo)) {
      return reply.code(404).send({ error: { code: 'not_found', message: 'unknown repository' } });
    }

    const body = typeof request.body === 'string' ? request.body : '';
    const updates = body
      .split('\n')
      .map((l) => l.trim())
      .filter(Boolean)
      .map((line) => {
        const [oldSha, newSha, ref] = line.split(/\s+/);
        return { oldSha, newSha, ref };
      })
      .filter((u) => u.oldSha && u.newSha && u.ref);

    ctx.cache.bustRepo(repo);

    for (const update of updates) {
      let commits = 0;
      if (ZERO_SHA.test(update.newSha)) {
        // branch deletion — record nothing countable
      } else if (ZERO_SHA.test(update.oldSha)) {
        const out = await ctx.repos.tryGit(repo, ['rev-list', '--count', update.newSha]);
        commits = out ? Number(out.trim()) : 0;
      } else {
        const out = await ctx.repos.tryGit(repo, ['rev-list', '--count', `${update.oldSha}..${update.newSha}`]);
        commits = out ? Number(out.trim()) : 0;
      }
      ctx.activity.append({
        repo,
        ref: update.ref.replace(/^refs\/(heads|tags)\//, ''),
        refType: update.ref.startsWith('refs/tags/') ? 'tag' : 'branch',
        deleted: ZERO_SHA.test(update.newSha),
        commits,
        sha: ZERO_SHA.test(update.newSha) ? null : update.newSha,
      });
    }

    // Warm caches in the background — the pushing client should not wait.
    queueMicrotask(() => {
      Promise.resolve(ctx.warmers?.(repo)).catch((err) => {
        request.log.warn({ err, repo }, 'cache warm failed');
      });
    });

    return { ok: true, updates: updates.length };
  });
}