using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using gehGassiApp.Core.Data;

namespace gehGassiApp.Data
{
    /// <summary>
    /// Service welcher Operationen in einem Repository gruppiert und bestätigt (speichert).
    /// Weiters werden die einzelnen Repositories nur über diesen Service abgerufen
    /// </summary>
    public class UnitOfWork : IUnitOfWork
    {
        private readonly LocalDbContext _context;
        private bool _disposed = false;
        private readonly Dictionary<object, object> _repositories = new Dictionary<object, object>();
        private readonly AsyncLock _asyncLock;

        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        /// <param name="context">Datenbank-Kontext</param>
        public UnitOfWork(LocalDbContext context)
        {
            _asyncLock = new AsyncLock();
            _context = context;
        }

        /// <summary>
        /// Gibt ein Repository im Kontext der UnitOfWork zurück
        /// </summary>
        /// <typeparam name="T">Typ (Klasse)</typeparam>
        /// <returns>IRepository oder null, wenn nicht verfügbar</returns>
        public IRepository<T> GetRepository<T>() where T : class
        {
            if (!_repositories.ContainsKey(typeof(T)))
            {
                _repositories.Add(typeof(T), new Repository<T>(_context as DbContext, _asyncLock));
            }
            return (IRepository<T>)_repositories[typeof(T)];
        }

        /// <summary>
        /// Schließt Daten-Änderungen ab und speichert die selben
        /// </summary>
        public int Commit()
        {
            using (_asyncLock.Lock())
            {
                try
                {
                    return _context.SaveChanges();
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.Message);
                    return 0;
                }
            }
        }

        /// <summary>
        /// Schließt Daten-Änderungen ab und speichert die selben
        /// </summary>
        public async Task<int> CommitAsync()
        {
            using (await _asyncLock.LockAsync())
            {
                try
                {
                    return await _context.SaveChangesAsync();
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.Message);
                    return 0;
                }
            }
        }

        /// <summary>
        /// Dispose
        /// </summary>
        /// <param name="disposing"></param>
        protected virtual void Dispose(bool disposing)
        {
            if (!this._disposed)
            {
                if (disposing)
                {
                    _context.Dispose();
                }
            }
            this._disposed = true;
        }

        /// <summary>
        /// Dispose
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
    }
}