import { useState, useEffect } from 'react';
import { Transaction, Category, TransactionSummary } from '../types';
import { apiClient } from '../utils/api';
import { API_ENDPOINTS } from '../config/api';

export const useTransactions = () => {
  const [transactions, setTransactions] = useState<Transaction[]>([]);
  const [categories, setCategories] = useState<Category[]>([]);
  const [loading, setLoading] = useState(false);
  const [summary, setSummary] = useState<TransactionSummary>({
    totalIncome: 0,
    totalExpenses: 0,
    balance: 0,
    categoryBreakdown: [],
  });

  const fetchTransactions = async () => {
    setLoading(true);
    try {
      const data = await apiClient.get<Transaction[]>(API_ENDPOINTS.transactions.list);
      setTransactions(data);
      calculateSummary(data);
    } catch (error) {
      console.error('Failed to fetch transactions:', error);
    } finally {
      setLoading(false);
    }
  };

  const fetchCategories = async () => {
    try {
      const data = await apiClient.get<Category[]>(API_ENDPOINTS.categories.list);
      setCategories(data);
    } catch (error) {
      console.error('Failed to fetch categories:', error);
    }
  };

  const createTransaction = async (transaction: Omit<Transaction, 'id' | 'user_id' | 'created_at' | 'updated_at'>) => {
    try {
      const newTransaction = await apiClient.post<Transaction>(
        API_ENDPOINTS.transactions.create,
        transaction
      );
      setTransactions(prev => [newTransaction, ...prev]);
      calculateSummary([newTransaction, ...transactions]);
      return newTransaction;
    } catch (error) {
      throw new Error('Failed to create transaction');
    }
  };

  const updateTransaction = async (id: string, updates: Partial<Transaction>) => {
    try {
      const updatedTransaction = await apiClient.put<Transaction>(
        API_ENDPOINTS.transactions.update(id),
        updates
      );
      setTransactions(prev =>
        prev.map(t => (t.id === id ? updatedTransaction : t))
      );
      const newTransactions = transactions.map(t => (t.id === id ? updatedTransaction : t));
      calculateSummary(newTransactions);
      return updatedTransaction;
    } catch (error) {
      throw new Error('Failed to update transaction');
    }
  };

  const deleteTransaction = async (id: string) => {
    try {
      await apiClient.delete(API_ENDPOINTS.transactions.delete(id));
      setTransactions(prev => prev.filter(t => t.id !== id));
      const newTransactions = transactions.filter(t => t.id !== id);
      calculateSummary(newTransactions);
    } catch (error) {
      throw new Error('Failed to delete transaction');
    }
  };

  const calculateSummary = (transactionList: Transaction[]) => {
    const totalIncome = transactionList
      .filter(t => t.type === 'income')
      .reduce((sum, t) => sum + t.amount, 0);

    const totalExpenses = transactionList
      .filter(t => t.type === 'expense')
      .reduce((sum, t) => sum + t.amount, 0);

    const balance = totalIncome - totalExpenses;

    const categoryTotals = transactionList.reduce((acc, transaction) => {
      const categoryName = transaction.category?.name || 'Uncategorized';
      acc[categoryName] = (acc[categoryName] || 0) + Math.abs(transaction.amount);
      return acc;
    }, {} as Record<string, number>);

    const totalAmount = Object.values(categoryTotals).reduce((sum, amount) => sum + amount, 0);
    const categoryBreakdown = Object.entries(categoryTotals)
      .map(([category, amount]) => ({
        category,
        amount,
        percentage: totalAmount > 0 ? (amount / totalAmount) * 100 : 0,
      }))
      .sort((a, b) => b.amount - a.amount);

    setSummary({
      totalIncome,
      totalExpenses,
      balance,
      categoryBreakdown,
    });
  };

  useEffect(() => {
    fetchTransactions();
    fetchCategories();
  }, []);

  return {
    transactions,
    categories,
    loading,
    summary,
    createTransaction,
    updateTransaction,
    deleteTransaction,
    refreshTransactions: fetchTransactions,
    refreshCategories: fetchCategories,
  };
};