export type SavedProject = { project_id: string; title: string; updated: string; versions: number };

/** Groups builds (newest first) into one project per session; the title is the first prompt. */
export function groupProjects(rows: { session_id: string; prompt: string; created_at: string }[]): SavedProject[] {
  const map = new Map<string, SavedProject>();
  for (const r of rows) {
    const p = map.get(r.session_id);
    if (p) { p.versions++; p.title = r.prompt.slice(0, 80); }
    else map.set(r.session_id, { project_id: r.session_id, title: r.prompt.slice(0, 80), updated: r.created_at, versions: 1 });
  }
  return [...map.values()];
}

/** Picks a project by exact id, "latest"/"last", list number ("2"), or the most matching title words. */
export function matchProject(projects: SavedProject[], query: string): SavedProject | null {
  const q = query.trim().toLowerCase();
  if (!projects.length || !q) return null;
  const byId = projects.find((p) => p.project_id === q);
  if (byId) return byId;
  if (/^(latest|last|newest|recent|most recent)( project| one)?$/.test(q)) return projects[0]!;
  const n = Number(q.replace(/^(number|#|project)\s*/, ""));
  if (Number.isInteger(n) && n >= 1 && n <= projects.length) return projects[n - 1]!;
  const words = q.split(/\W+/).filter((w) => w.length > 2 && !["the", "project", "website", "site", "app", "one", "my"].includes(w));
  let best: SavedProject | null = null, score = 0;
  for (const p of projects) {
    const t = p.title.toLowerCase();
    const s = words.filter((w) => t.includes(w)).length;
    if (s > score) { best = p; score = s; }
  }
  return best;
}