#!/usr/bin/env bun

/**
 * Get DE Bundeshaushalt Data
 *
 * Fetches federal budget data from the Bundeshaushalt Digital API and produces:
 *   - Data/DE-Federal-Budget/haushalt-expenses-2024.csv
 *   - Data/DE-Federal-Budget/haushalt-income-2024.csv
 *
 * API: https://bundeshaushalt.de/internalapi/budgetData
 * Source: https://www.bundeshaushalt.de/DE/Bundeshaushalt-digital/bundeshaushalt-digital.html
 */

// Bun on macOS may lack the Bundeshaushalt CA in its bundled cert store.
// This flag allows the fetch to proceed against the known-good government endpoint.
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

import { writeFileSync, mkdirSync } from "fs";
import { join } from "path";

const BASE_URL = "https://bundeshaushalt.de/internalapi/budgetData";
const OUT_DIR = join(__dirname, "Data/DE-Federal-Budget");
const YEAR = 2024;

interface BudgetMeta {
  year: number;
  unit: string;
  quota: string;
  account: string;
  timestamp: number;
  modifyDate: string;
  entity: string;
  levelCur: number;
  levelMax: number;
}

interface BudgetDetail {
  label: string;
  value: number;
  relativeToParentValue: number;
  relativeValue: number;
}

interface BudgetChild {
  id: string;
  budgetNumber: string;
  label: string;
  value: number;
  relativeToParentValue: number;
  relativeValue: number;
}

interface BudgetResponse {
  meta: BudgetMeta;
  detail: BudgetDetail;
  children: BudgetChild[];
}

function csvEscape(value: string | number | undefined | null): string {
  if (value === null || value === undefined) return "";
  const s = String(value);
  if (s.includes(",") || s.includes('"') || s.includes("\n")) {
    return `"${s.replace(/"/g, '""')}"`;
  }
  return s;
}

async function fetchBudget(account: "expenses" | "income"): Promise<BudgetResponse> {
  const url = `${BASE_URL}?year=${YEAR}&account=${account}&quota=actual`;
  console.log(`Fetching ${account} data from ${url}…`);
  const res = await fetch(url);
  if (!res.ok) throw new Error(`HTTP ${res.status}: ${res.statusText} (${url})`);
  return (await res.json()) as BudgetResponse;
}

function writeCsv(data: BudgetResponse, filename: string): void {
  const sorted = [...data.children].sort((a, b) => b.value - a.value);

  const header = "rank,id,label,value_eur,share_pct";
  const rows = sorted.map((child, i) =>
    [
      i + 1,
      csvEscape(child.id),
      csvEscape(child.label),
      child.value.toFixed(2),
      child.relativeToParentValue.toFixed(2),
    ].join(",")
  );

  const path = join(OUT_DIR, filename);
  writeFileSync(path, [header, ...rows].join("\n") + "\n");
  console.log(`Wrote ${path} (${rows.length} Einzelpläne)`);
}

async function main() {
  mkdirSync(OUT_DIR, { recursive: true });

  const [expenses, income] = await Promise.all([
    fetchBudget("expenses"),
    fetchBudget("income"),
  ]);

  writeCsv(expenses, `haushalt-expenses-${YEAR}.csv`);
  writeCsv(income, `haushalt-income-${YEAR}.csv`);

  const totalExpenses = expenses.detail.value;
  const totalIncome = income.detail.value;
  const balance = totalIncome - totalExpenses;

  const sortedExpenses = [...expenses.children].sort((a, b) => b.value - a.value);
  const top5 = sortedExpenses.slice(0, 5);

  console.log(`\n── Bundeshaushalt ${YEAR} Summary (Ist-Werte) ────────────────────`);
  console.log(`Total Ausgaben:  €${(totalExpenses / 1e9).toFixed(2)}B`);
  console.log(`Total Einnahmen: €${(totalIncome / 1e9).toFixed(2)}B`);
  console.log(`Balance:         €${(balance / 1e9).toFixed(2)}B (${balance >= 0 ? "Überschuss" : "Defizit"})`);
  console.log(`\nTop 5 Ausgaben-Einzelpläne:`);
  for (const [i, ep] of top5.entries()) {
    console.log(
      `  ${i + 1}. ${ep.label} — €${(ep.value / 1e9).toFixed(2)}B (${ep.relativeToParentValue.toFixed(1)}%)`
    );
  }
  console.log(`\nModify date (expenses): ${expenses.meta.modifyDate}`);
}

main().catch((err) => {
  console.error("Error:", err.message);
  process.exit(1);
});