using API.Authentication.Interfaces;
using API.DTO;
using API.Services.Interfaces;
using DAL.Contexts;
using DAL.Models;
using DAL.Models.Audits;
using System.Linq.Expressions;

namespace API.Services
{
	public class ServiceBase<TLoggerCategory, TDTO, TModel, TAudit, TAuthentication> : IGenericService<TDTO, TModel, TAudit>
		where TAuthentication : IGenericAuthentication<TDTO, TModel>
		where TModel : Model<TModel, TAudit>
		where TAudit : AuditModel<TModel>
		where TDTO : IAdaptable<TModel>
	{
		private readonly TAuthentication _auth;
		private readonly SASGContext _context;
		private readonly ILogger<TLoggerCategory> _logger;

		public ServiceBase(ILogger<TLoggerCategory> logger, SASGContext context, TAuthentication auth)
		{
			_logger = logger;
			_context = context;
			_auth = auth;
		}

		public TModel? get(ulong id, User user)
		{
			TModel? result = _context.Set<TModel>().Find(id);
			if (result == null)
				return null;

			return _auth.canGet(result, user) ? result : null;
		}

		public IEnumerable<TModel>? get(User user, Expression<Func<TModel, bool>>? whereClause = null)
		{
			if (!_auth.canGetAll(user))
				return null;

			return whereClause != null ? _context.Set<TModel>().Where(whereClause) : _context.Set<TModel>();
		}

		public TModel? getNoAuthentication(ulong id)
		{
			return _context.Set<TModel>().Find(id);
		}

		public IEnumerable<TModel> getNoAuthentication(Expression<Func<TModel, bool>>? whereClause = null)
		{
			return whereClause != null ? _context.Set<TModel>().Where(whereClause) : _context.Set<TModel>();
		}

		public TModel? add(TDTO item, User user)
		{
			if (!_auth.canAdd(item, user))
				return null;

			TModel model = item.adaptToModel();

			model.updater = user.id;
			model.updated = DateTime.Now;
			_context.Add(model);
			_context.SaveChanges();

			return model;
		}

		public TModel? update(TModel model, User user)
		{
			if (!_auth.canUpdate(model, user))
				return null;

			TModel? origModel = _context.Set<TModel>().Find(model.id);
			if (origModel == null)
				return null;

			copyToAudit(origModel);

			model.updateModel(ref origModel);

			origModel.updated = DateTime.Now;
			origModel.updater = user.id;

			_context.SaveChanges();

			return origModel;
		}

		public TAudit? delete(TModel model, User user)
		{
			if (!_auth.canDelete(model, user))
				return null;

			TModel? origModel = _context.Set<TModel>().Find(model.id);
			if (origModel == null)
				return null;

			copyToAudit(origModel);

			origModel.updated = DateTime.Now;
			origModel.updater = user.id;

			copyToAudit(origModel);

			_context.Remove(origModel);
			_context.SaveChanges();

			return origModel.adaptToAudit();
		}

		private void copyToAudit(TModel model)
		{
			_context.Set<TAudit>().Add(model.adaptToAudit());
		}
	}
}