'use strict';

const path = require('path');
const fs = require('fs');
const os = require('os');
const { randomUUID } = require('crypto');
const { LocalIndex } = require('vectra');

const STORE_DIR = path.join(os.homedir(), '.memory-bridge', 'index');

let index = null;

async function init() {
  fs.mkdirSync(STORE_DIR, { recursive: true });
  index = new LocalIndex(STORE_DIR);
  if (!(await index.isIndexCreated())) {
    await index.createIndex();
    console.log(`Vector index    : created at ${STORE_DIR}`);
  } else {
    console.log(`Vector index    : loaded from ${STORE_DIR}`);
  }
}

async function add({ text, tags = [], source = '', vector }) {
  const id = randomUUID();
  const createdAt = new Date().toISOString();
  await index.insertItem({ id, vector, metadata: { id, text, tags, source, createdAt } });
  return { id, createdAt };
}

async function query({ vector, limit = 10, tags = [] }) {
  const topK = tags.length ? Math.min(limit * 3, 300) : limit;
  const results = await index.queryItems(vector, topK);
  let items = results;
  if (tags.length) {
    items = results.filter((r) =>
      tags.some((t) => (r.item.metadata.tags || []).includes(t))
    );
  }
  return items.slice(0, limit).map((r) => ({
    ...r.item.metadata,
    score: r.score,
  }));
}

async function remove(id) {
  await index.deleteItem(id);
}

async function list({ page = 1, pageSize = 50 } = {}) {
  const all = await index.listItems();
  const total = all.length;
  const start = (page - 1) * pageSize;
  const data = all.slice(start, start + pageSize).map((item) => item.metadata);
  return { data, total, page, pageSize, pages: Math.ceil(total / pageSize) };
}

async function count() {
  const all = await index.listItems();
  return all.length;
}

module.exports = { init, add, query, remove, list, count };