/**
 * ─────────────────────────────────────────────
 *  SPB Git — Personal Git Platform
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : src/lib/overview.mjs
 *  Purpose : Aggregated per-repo overview (meta + git facts), cached
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { readFileSync, existsSync } from 'node:fs';
import { join } from 'node:path';
import { computeLanguages } from '../stats/languages.mjs';
import { mapLimit } from './util.mjs';

/** @returns {Record<string, number>} clone counts by repo */
function cloneCounts(ctx) {
  const path = join(ctx.config.dataDir, 'clones.json');
  try {
    if (existsSync(path)) return JSON.parse(readFileSync(path, 'utf8'));
  } catch {
    /* ignore */
  }
  return {};
}

/**
 * Build (or read from cache) the full overview of one repository.
 * @param {{config, repos, meta, cache}} ctx
 * @param {string} name
 * @returns {Promise<object|null>}
 */
export async function repoOverview(ctx, name) {
  if (!ctx.repos.exists(name)) return null;
  const cachePath = ctx.cache.path('repos', name, '_repo', 'overview.json');
  const cached = ctx.cache.getJSON(cachePath);
  const clones = cloneCounts(ctx)[name] ?? 0;
  if (cached) return { ...cached, cloneCount: clones };

  const meta = ctx.meta.get(name) ?? {};
  const head = await ctx.repos.head(name);
  const defaultBranch = await ctx.repos.defaultBranch(name);
  const branches = await ctx.repos.branches(name);
  const tags = await ctx.repos.tags(name);
  let commitCount = 0;
  let languages = { languages: [], totalBytes: 0 };
  let license = null;
  if (head) {
    commitCount = await ctx.repos.commitCount(name, head);
    languages = computeLanguages(await ctx.repos.allFiles(name, head));
    license = await ctx.repos.license(name, head);
  }
  const overview = {
    name,
    description: meta.description ?? '',
    topics: meta.topics ?? [],
    homepage: meta.homepage ?? '',
    pinned: Boolean(meta.pinned),
    created: meta.created ?? null,
    defaultBranch,
    head,
    empty: head === null,
    lastPush: await ctx.repos.lastPushDate(name),
    commitCount,
    branchCount: branches.length,
    tagCount: tags.length,
    sizeBytes: await ctx.repos.sizeBytes(name),
    languages: languages.languages,
    languageBytes: languages.totalBytes,
    topLanguage: languages.languages[0]?.name ?? null,
    license: license?.name ?? null,
    licensePath: license?.path ?? null,
    cloneUrl: `${ctx.config.publicUrl}/${name}.git`,
    url: `${ctx.config.publicUrl}/${name}`,
  };
  ctx.cache.setJSON(cachePath, overview);
  return { ...overview, cloneCount: clones };
}

/**
 * Overviews for every repo, most recently pushed first.
 * @param {{config, repos, meta, cache}} ctx
 * @returns {Promise<object[]>}
 */
export async function allOverviews(ctx) {
  const names = ctx.repos.list();
  const overviews = await mapLimit(names, 8, (name) => repoOverview(ctx, name));
  return overviews
    .filter(Boolean)
    .sort((a, b) => String(b.lastPush ?? '').localeCompare(String(a.lastPush ?? '')));
}

/**
 * Site-wide stats for the home hero + /api/v1/stats.
 * @param {{config, repos, meta, cache}} ctx
 */
export async function siteStats(ctx) {
  const overviews = await allOverviews(ctx);
  const languages = new Set();
  let commits = 0;
  for (const o of overviews) {
    commits += o.commitCount;
    for (const lang of o.languages) languages.add(lang.name);
  }
  return {
    repos: overviews.length,
    commits,
    languages: languages.size,
    languageNames: [...languages].sort(),
  };
}