// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using JetBrains.Annotations;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;
using EntityFrameworkCore.Jet.Utilities;
using Microsoft.EntityFrameworkCore.ValueGeneration;
using Microsoft.Extensions.DependencyInjection;

namespace EntityFrameworkCore.Jet.ValueGeneration.Internal
{
    /// <summary>
    ///     <para>
    ///         This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///         the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///         any release. You should only use it directly in your code with extreme caution and knowing that
    ///         doing so can result in application failures when updating to a new Entity Framework Core release.
    ///     </para>
    ///     <para>
    ///         The service lifetime is <see cref="ServiceLifetime.Scoped" />. This means that each
    ///         <see cref="DbContext" /> instance will use its own instance of this service.
    ///         The implementation may depend on other services registered with any lifetime.
    ///         The implementation does not need to be thread-safe.
    ///     </para>
    /// </summary>
    public class JetValueGeneratorSelector : RelationalValueGeneratorSelector
    {
        /// <summary>
        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
        ///     any release. You should only use it directly in your code with extreme caution and knowing that
        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
        /// </summary>
        public JetValueGeneratorSelector(
            [NotNull] ValueGeneratorSelectorDependencies dependencies)
            : base(dependencies)
        {
        }

        /// <summary>
        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
        ///     any release. You should only use it directly in your code with extreme caution and knowing that
        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
        /// </summary>
        public override ValueGenerator Create(IProperty property, IEntityType entityType)
        {
            Check.NotNull(property, nameof(property));
            Check.NotNull(entityType, nameof(entityType));

            return property.ClrType.UnwrapNullableType() == typeof(Guid)
                ? property.ValueGenerated == ValueGenerated.Never || property.GetDefaultValueSql() != null
                    ? (ValueGenerator) new TemporaryGuidValueGenerator()
                    : new SequentialGuidValueGenerator()
                : base.Create(property, entityType);
        }
    }
}