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using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using MySql.EntityFrameworkCore.Basic.Tests.DbContextClasses;
using MySql.EntityFrameworkCore.Extensions;
using NUnit.Framework;
using System;
using System.Linq;

namespace MySql.EntityFrameworkCore.Basic.Tests
{
  public class ConcurrencyTests
  {
    [Test]
    public void CanHandleConcurrencyConflicts()
    {
      var serviceCollection = new ServiceCollection();
      serviceCollection.AddEntityFrameworkMySQL()
        .AddDbContext<ConcurrencyTestsContext>();

      var serviceProvider = serviceCollection.BuildServiceProvider();

      using (var context = serviceProvider.GetRequiredService<ConcurrencyTestsContext>())
      {
        context.Database.EnsureDeleted();
        context.Database.EnsureCreated();

        context.People.Add(new Person { Name = "Mike Redman", SocialSecurityNumber = "SSS1229932", PhoneNumber = "565665656" });
        context.SaveChanges();

        var person = context.People.Single(p => p.PersonId == 1);
        person.SocialSecurityNumber = "SS15555";

        context.Database.ExecuteSqlInterpolated($"UPDATE People SET Name = 'Jane' WHERE PersonId = 1");

        try
        {
          context.SaveChanges();
        }
        catch (DbUpdateConcurrencyException ex)
        {
          foreach (var entry in ex.Entries)
          {
            if (entry.Entity is Person)
            {
              // Using a NoTracking query means we get the entity but it is not tracked by the context
              // and will not be merged with existing entities in the context.
              var databaseEntity = context.People.AsNoTracking().Single(p => p.PersonId == ((Person)entry.Entity).PersonId);
              var databaseEntry = context.Entry(databaseEntity);

              foreach (var property in entry.Metadata.GetProperties())
              {
                if (property.Name.Equals("Name"))
                {
                  var proposedValue = entry.Property(property.Name).CurrentValue;
                  var originalValue = entry.Property(property.Name).OriginalValue;
                  var databaseValue = databaseEntry.Property(property.Name).CurrentValue;
                  entry.Property(property.Name).OriginalValue = databaseEntry.Property(property.Name).CurrentValue;
                  Assert.AreEqual("Jane", databaseValue);
                }
              }
            }
            else
            {
              throw new NotSupportedException("Don't know how to handle concurrency conflicts for " + entry.Metadata.Name);
            }
          }

          // Retry the save operation
          context.SaveChanges();
        }
        finally
        {
          context.Database.EnsureDeleted();
        }
      }
    }
  }
}
