budget/src/Budget.Api/Controllers/SummaryController.cs

using Budget.Api.Services;
using Budget.Core.DTOs;
using Budget.Core.Models;
using Budget.Core.Services;
using Budget.Infrastructure.Data;
using Budget.Infrastructure.Services;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace Budget.Api.Controllers;

[ApiController]
[Route("api/budgets/{budgetId:guid}/summary")]
[Authorize(Roles = "admin,user")]
public class SummaryController(AppDbContext db, BudgetAuthorizationService authz) : ControllerBase
{
    private IActionResult? TryGetUserId(out string userId)
    {
        var id = User.GetUserId();
        if (id is null) { userId = string.Empty; return Unauthorized(); }
        userId = id;
        return null;
    }

    [HttpGet]
    public async Task<IActionResult> Get(Guid budgetId)
    {
        if (TryGetUserId(out var userId) is { } err) return err;
        if (!await authz.CanReadAsync(budgetId, userId)) return Forbid();

        var budget = await db.Budgets.FindAsync(budgetId);
        if (budget is null) return NotFound();

        var incomes = await db.Incomes.Where(i => i.BudgetId == budgetId).ToListAsync();
        var outgos  = await db.Outgos.Where(o => o.BudgetId == budgetId).ToListAsync();

        var monthlyIncome = incomes.Sum(i => FrequencyCalculator.ToMonthly(i.Amount, i.Frequency));
        var annualIncome  = monthlyIncome * 12m;

        var typeTargets = new Dictionary<OutgoType, int>
        {
            [OutgoType.Need] = 50,
            [OutgoType.Want] = 30,
            [OutgoType.Save] = 20,
        };

        var breakdown = new List<SummaryBreakdownItem>();
        decimal totalMonthlyOutgo = 0m;

        foreach (var (type, target) in typeTargets)
        {
            var typeOutgos    = outgos.Where(o => o.Type == type).ToList();
            var monthlyTotal  = typeOutgos.Sum(o => FrequencyCalculator.ToMonthly(o.Amount, o.Frequency));
            var annualTotal   = monthlyTotal * 12m;
            totalMonthlyOutgo += monthlyTotal;
            var percent    = monthlyIncome > 0 ? Math.Round(monthlyTotal / monthlyIncome * 100, 2) : 0m;
            var maxAmount  = monthlyIncome * target / 100m;
            var remaining  = maxAmount - monthlyTotal;
            breakdown.Add(new SummaryBreakdownItem(type.ToString(), target, monthlyTotal, annualTotal, percent, maxAmount, remaining));
        }

        var unspent        = monthlyIncome - totalMonthlyOutgo;
        var unspentPercent = monthlyIncome > 0 ? Math.Round(unspent / monthlyIncome * 100, 2) : 0m;
        breakdown.Add(new SummaryBreakdownItem("Unspent", null, unspent, unspent * 12m, unspentPercent, null, null));

        return Ok(new SummaryDto(monthlyIncome, annualIncome, breakdown));
    }
}