using Duempelkas.App.Services;
using Duempelkas.App.Services.Models;
using Duempelkas.Domain.Enums;
using Duempelkas.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace Duempelkas.Infrastructure.Services;

public class BalanceQueryService : IBalanceQueryService
{
    private readonly IDbContextFactory<FinanceDbContext> _dbFactory;

    public BalanceQueryService(IDbContextFactory<FinanceDbContext> dbFactory) => _dbFactory = dbFactory;

    public async Task<AccountBalanceDto> GetAccountBalanceAsync(int accountId, int? year = null)
    {
        await using var db = await _dbFactory.CreateDbContextAsync();

        var account = await db.Accounts
            .Include(a => a.Entries)
            .FirstOrDefaultAsync(a => a.Id == accountId)
            ?? throw new InvalidOperationException($"Konto {accountId} nicht gefunden.");

        var selectedYear = year ?? DateTime.Now.Year;

        var activeEntries = account.Entries.Where(e => !e.IsDeleted).ToList();
        var totalIncome = activeEntries.Where(e => e.Type == EntryType.Income).Sum(e => e.Amount);
        var totalExpense = activeEntries.Where(e => e.Type == EntryType.Expense).Sum(e => e.Amount);

        var selectedYearIncome = activeEntries
            .Where(e => e.Type == EntryType.Income && e.Date.Year == selectedYear)
            .Sum(e => e.Amount);
        var selectedYearExpense = activeEntries
            .Where(e => e.Type == EntryType.Expense && e.Date.Year == selectedYear)
            .Sum(e => e.Amount);

        var selectedYearCarryover = account.CarryoverBalance + activeEntries
            .Where(e => e.Date.Year < selectedYear)
            .Sum(e => e.Type == EntryType.Income ? e.Amount : -e.Amount);

        var totalBalance = year.HasValue
            ? selectedYearCarryover + selectedYearIncome - selectedYearExpense
            : account.CarryoverBalance + totalIncome - totalExpense;

        return new AccountBalanceDto(
            year.HasValue ? selectedYearCarryover : account.CarryoverBalance,
            totalIncome,
            totalExpense,
            selectedYearIncome,
            selectedYearExpense,
            totalBalance);
    }
}