using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using Luticate2.Utils.Dbo.Result;
using Microsoft.EntityFrameworkCore;

namespace Luticate2.Utils.DataAccess
{
    public abstract class LuEfDataAccess<TModel, TDbContext> : LuDataAccess
        where TModel : class
        where TDbContext : DbContext
    {
        private readonly IServiceProvider _serviceProvider;

        protected LuEfDataAccess(IServiceProvider serviceProvider)
        {
            _serviceProvider = serviceProvider;
        }

        protected abstract DbSet<TModel> GetTable(TDbContext db);

        public LuResult<T> Execute<T>(Func<TDbContext, DbSet<TModel>, LuResult<T>> func)
        {
            try
            {
                using (var db = (TDbContext)_serviceProvider.GetService(typeof(TDbContext)))
                {
                    var table = GetTable(db);
                    return func(db, table);
                }
            }
            catch (Exception e)
            {
                return LuResult<T>.Error(LuStatus.DbError, e);
            }
        }

        public static Expression<Func<TModel, bool>> GetExpression(params KeyValuePair<string, object>[] keys)
        {
            var param = Expression.Parameter(typeof(TModel), "x");
            Expression totalExp = null;
            foreach (var pair in keys)
            {
                var equalExp = Expression.Equal(Expression.Property(param, pair.Key), Expression.Constant(pair.Value));
                totalExp = totalExp == null ? equalExp : Expression.And(equalExp, totalExp);
            }
            return Expression.Lambda<Func<TModel, bool>>(totalExp, param);
        }

    }
}