query.ts

import { readFileSync } from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { z } from "zod";
import { tool } from "@langchain/core/tools";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

function parseCsv(raw: string): Record<string, string>[] {
  const lines = raw.trim().split(/\r?\n/);
  if (lines.length === 0) return [];
  const headers = lines[0].split(",");
  const rows: Record<string, string>[] = [];
  for (let i = 1; i < lines.length; i++) {
    const cells = splitCsvLine(lines[i]);
    const row: Record<string, string> = {};
    headers.forEach((h, idx) => {
      row[h] = cells[idx] ?? "";
    });
    rows.push(row);
  }
  return rows;
}

function splitCsvLine(line: string): string[] {
  const out: string[] = [];
  let cur = "";
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const ch = line[i];
    if (inQuotes) {
      if (ch === '"' && line[i + 1] === '"') {
        cur += '"';
        i++;
      } else if (ch === '"') {
        inQuotes = false;
      } else {
        cur += ch;
      }
    } else if (ch === '"') {
      inQuotes = true;
    } else if (ch === ",") {
      out.push(cur);
      cur = "";
    } else {
      cur += ch;
    }
  }
  out.push(cur);
  return out;
}

const _cached_data = parseCsv(
  readFileSync(path.join(__dirname, "db.csv"), "utf8"),
);

export const query_data = tool(
  (_input: { query: string }) => {
    return JSON.stringify(_cached_data);
  },
  {
    name: "query_data",
    description:
      "Query the database, takes natural language. Always call before showing a chart or graph.",
    schema: z.object({ query: z.string() }),
  },
);