import type { MemoryEntry } from './entries.js';
import { scanProjectMemory } from './scan.js';

function extractKeywords(query: string): string[] {
  return query
    .toLowerCase()
    .replace(/[^a-z0-9\s]/g, '')
    .split(/\s+/)
    .filter((w) => w.length > 2);
}

export function rankByRelevance(query: string, entries: MemoryEntry[]): MemoryEntry[] {
  const keywords = extractKeywords(query);
  if (keywords.length === 0) return entries.slice(0, 5);

  const scored = entries.map((entry) => {
    let score = 0;
    const searchText = `${entry.title} ${entry.content} ${entry.tags.join(' ')}`.toLowerCase();
    for (const kw of keywords) {
      if (entry.title.toLowerCase().includes(kw)) score += 3;
      if (entry.tags.some((t) => t.toLowerCase().includes(kw))) score += 2;
      if (entry.content.toLowerCase().includes(kw)) score += 1;
    }
    return { entry, score };
  });

  return scored
    .filter((s) => s.score > 0)
    .sort((a, b) => b.score - a.score)
    .slice(0, 10)
    .map((s) => s.entry);
}

export async function loadMemoryForSession(
  projectRoot: string,
  _sessionId?: string,
  query?: string,
): Promise<string[]> {
  const entries = await scanProjectMemory(projectRoot);
  if (entries.length === 0) return [];

  const relevant = query ? rankByRelevance(query, entries) : entries.slice(0, 5);
  return relevant.map((e) => `[${e.topic}] ${e.title}: ${e.content}`);
}