import type { CategoryBreakdown, FinanceAnalysis, SimpleFINAccount } from '../types';

export class PersonalFinanceAnalyzer {
  analyze(accounts: SimpleFINAccount[]): FinanceAnalysis {
    const assets = accounts.filter((a) => !['CREDIT', 'LOAN'].includes(a.type));
    const liabilities = accounts.filter((a) => ['CREDIT', 'LOAN'].includes(a.type));

    const totalAssets = assets.reduce((s, a) => s + Math.max(0, a.balance), 0);
    const totalLiabilities = liabilities.reduce((s, a) => s + Math.abs(Math.min(0, a.balance)), 0);
    const netWorth = totalAssets - totalLiabilities;

    const cash = accounts.filter((a) => ['CHECKING', 'SAVINGS'].includes(a.type));
    const investments = accounts.filter((a) => a.type === 'INVESTMENT');
    const totalCash = cash.reduce((s, a) => s + Math.max(0, a.balance), 0);
    const totalInvest = investments.reduce((s, a) => s + Math.max(0, a.balance), 0);

    const allTx = accounts.flatMap((a) => a.transactions);
    const spending = allTx.filter((tx) => tx.amount < 0 && tx.category !== 'Transfer');
    const income = allTx.filter((tx) => tx.amount > 0 && tx.category === 'Income');

    const totalSpend = spending.reduce((s, tx) => s + Math.abs(tx.amount), 0);
    const totalIncome = income.reduce((s, tx) => s + tx.amount, 0);

    const byCategory: Record<string, number> = {};
    for (const tx of spending) {
      byCategory[tx.category] = (byCategory[tx.category] ?? 0) + Math.abs(tx.amount);
    }

    const categoryBreakdown: CategoryBreakdown[] = Object.entries(byCategory)
      .sort((a, b) => b[1] - a[1])
      .map(([category, amount]) => ({
        category,
        amount,
        pct: totalSpend > 0 ? ((amount / totalSpend) * 100).toFixed(1) : '0',
      }));

    return {
      netWorth,
      totalAssets,
      totalLiabilities,
      totalCash,
      totalInvestments: totalInvest,
      cashPct: totalAssets > 0 ? ((totalCash / totalAssets) * 100).toFixed(1) : '0',
      investPct: totalAssets > 0 ? ((totalInvest / totalAssets) * 100).toFixed(1) : '0',
      totalIncome,
      totalSpend,
      savingsRate:
        totalIncome > 0 ? (((totalIncome - totalSpend) / totalIncome) * 100).toFixed(1) : null,
      categoryBreakdown,
      accounts,
    };
  }
}