using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using Microsoft.EntityFrameworkCore.Query.Expressions;
using Microsoft.EntityFrameworkCore.Query.ExpressionTranslators;

namespace Luticate2.Utils.DataAccess.Npgsql
{
    public class NpgsqlIntToStringTranslator : IMethodCallTranslator
    {
        private readonly Type[] _declaringTypes = {typeof(int), typeof(int?)};

        private readonly string _clrMethodName = nameof(ToString);

        public Expression Translate(MethodCallExpression methodCallExpression)
        {
            foreach (var declaringType in _declaringTypes)
            {
                var methodInfo = declaringType.GetTypeInfo()
                    .GetDeclaredMethods(_clrMethodName).SingleOrDefault(m => !m.GetParameters().Any());
                if (methodInfo != null && methodCallExpression.Method.Name == _clrMethodName
                    && declaringType.IsAssignableFrom(methodCallExpression.Object.Type))
                {
                    return new ExplicitCastExpression(methodCallExpression.Object, typeof(string));
                }
            }

            return null;
        }
    }
}