using System;
using System.Collections.Generic;
using System.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace Luticate2.Utils.DataAccess
{
    public class LuEfTransactionScope
    {
        protected IDictionary<Type, DbContext> Contexts;

        private readonly IServiceProvider _serviceProvider;

        public LuEfTransactionScope(IServiceProvider serviceProvider)
        {
            _serviceProvider = serviceProvider;
            Contexts = new Dictionary<Type, DbContext>();
        }

        public TDbContext GetTransactedDbContext<TDbContext>()
            where TDbContext : DbContext
        {
            if (Contexts.ContainsKey(typeof(TDbContext)))
            {
                return (TDbContext) Contexts[typeof(TDbContext)];
            }
            return null;
        }

        public bool BeginTransaction<TDbContext>(TDbContext dbContext, IsolationLevel? level = null)
            where TDbContext : DbContext
        {
            if (dbContext == null)
            {
                dbContext = GetTransactedDbContext<TDbContext>();
                if (dbContext == null)
                {
                    dbContext = _serviceProvider.GetService<TDbContext>();
                }
            }
            if (!Contexts.Contains(new KeyValuePair<Type, DbContext>(typeof(TDbContext), dbContext)))
            {
                Contexts.Add(typeof(TDbContext), dbContext);
            }

            if (dbContext.Database.CurrentTransaction != null)
            {
                return false;
            }

            if (level == null)
            {
                dbContext.Database.BeginTransaction();
            }
            else
            {
                dbContext.Database.BeginTransaction(level.Value);
            }
            return true;
        }

        public void CommitTransaction<TDbContext>()
            where TDbContext : DbContext
        {
            try
            {
                GetTransactedDbContext<TDbContext>().Database.CommitTransaction();
            }
            finally
            {
                Contexts.Remove(typeof(TDbContext));
            }
        }

        public void RollbackTransaction<TDbContext>()
            where TDbContext : DbContext
        {
            try
            {
                GetTransactedDbContext<TDbContext>().Database.RollbackTransaction();
            }
            finally
            {
                Contexts.Remove(typeof(TDbContext));
            }
        }
    }
}