using System;
using System.Linq;
using System.Threading.Tasks;

using Microsoft.Data.Sqlite;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using Microsoft.EntityFrameworkCore.Storage.ValueConversion;

using NUnit.Framework;

namespace EnumCast;

public class Entity
{
    public int Id { get; set; }
    public DateTimeKind DateTimeKind { get; set; }
}

public class EnumProjectionDbContext : DbContext
{
    public DbSet<Entity> Entities => Set<Entity>();

    public EnumProjectionDbContext(
        DbContextOptions<EnumProjectionDbContext> options) :
        base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        EntityTypeBuilder<Entity> entityTypeBuilder = modelBuilder.Entity<Entity>();

        entityTypeBuilder.Property(e => e.DateTimeKind)
            .HasConversion<EnumToStringConverter<DateTimeKind>>();
    }
}

public class EnumCastTests
{
    [Test]
    public async Task Retrieve_projected_nullable_enum()
    {
        await using SqliteConnection dbConnection = new("DataSource=:memory:");

        await dbConnection.OpenAsync();

        DbContextOptionsBuilder<EnumProjectionDbContext> dbOptionsBuilder =
            new DbContextOptionsBuilder<EnumProjectionDbContext>()
                .UseSqlite(dbConnection);
        await using EnumProjectionDbContext dbContext = new(dbOptionsBuilder.Options);
        DateTimeKind expected = DateTimeKind.Utc;
        Entity entity = new()
        {
            DateTimeKind = expected,
        };

        await dbContext.Database.EnsureCreatedAsync();
        dbContext.Entities.Add(entity);
        await dbContext.SaveChangesAsync();

        int actual = await dbContext.Entities
            .Select(e => (int)e.DateTimeKind)
            .FirstOrDefaultAsync();

        Assert.AreEqual(
            expected: (int)expected,
            actual: actual);
        // Expected: 1
        //   But was:  0
    }
}