vegasco/src/Vegasco.Server.Api/Consumptions/GetConsumptions.cs

using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Vegasco.Server.Api.Cars;
using Vegasco.Server.Api.Persistence;

namespace Vegasco.Server.Api.Consumptions;

public static class GetConsumptions
{
	public class ApiResponse
	{
		public IEnumerable<ResponseDto> Consumptions { get; set; } = [];
	}

	public record ResponseDto(
		Guid Id,
		DateTimeOffset DateTime,
		double Distance,
		double Amount,
		CarDto Car,
		double? LiterPer100Km);

	public record CarDto(
		Guid Id,
		string Name)
	{
		public static CarDto FromCar(Car car)
		{
			return new CarDto(car.Id.Value, car.Name);
		}
	}

	public class Request
	{
		[FromQuery(Name = "page")] public int? Page { get; set; }
		[FromQuery(Name = "pageSize")] public int? PageSize { get; set; }
	}

	public static RouteHandlerBuilder MapEndpoint(IEndpointRouteBuilder builder)
	{
		return builder
			.MapGet("consumptions", Endpoint)
			.WithDescription("Returns all consumption entries")
			.WithTags("Consumptions")
			.Produces<ApiResponse>();
	}

	private static async Task<Ok<ApiResponse>> Endpoint(
		[AsParameters] Request request,
		ApplicationDbContext dbContext,
		CancellationToken cancellationToken)
	{
		Dictionary<CarId, List<Consumption>> consumptionsByCar = await dbContext.Consumptions
			.OrderByDescending(x => x.DateTime)
			.Include(x => x.Car)
			.GroupBy(x => x.CarId)
			.ToDictionaryAsync(x => x.Key, x => x.ToList(), cancellationToken);

		List<ResponseDto> responses = [];

		foreach (var consumptions in consumptionsByCar.Select(x => x.Value))
		{
			for (int i = 0; i < consumptions.Count; i++)
			{
				Consumption consumption = consumptions[i];

				double? literPer100Km = null;

				bool isLast = i == consumptions.Count - 1;
				if (!isLast)
				{
					Consumption previousConsumption = consumptions[i + 1];
					double distanceDiff = consumption.Distance - previousConsumption.Distance;
					literPer100Km = consumption.Amount / (distanceDiff / 100);
				}

				responses.Add(new ResponseDto(
					consumption.Id.Value,
					consumption.DateTime,
					consumption.Distance,
					consumption.Amount,
					CarDto.FromCar(consumption.Car),
					literPer100Km));
			}
		}

		ApiResponse apiResponse = new() { Consumptions = responses };
		return TypedResults.Ok(apiResponse);
	}
}