using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WorkFlowCheck.Common.RequestContext;
using WorkFlowCheck.DL.Configurations;
using WorkFlowCheck.DL.Extensions;
using WorkFlowCheck.DL.Interfaces;

namespace WorkFlowCheck.DL
{
    public class AppDbContext : DbContext
    {
        private readonly IRequestContext _requestContext;

#if !DEBUG
        public AppDbContext(DbContextOptions<AppDbContext> options, IRequestContext requestContext)
            : base(options)
        {
            _requestContext = requestContext;
        }
#endif
#if DEBUG
        public AppDbContext(DbContextOptions<AppDbContext> options)
            : base(options)
        {
            var _requestContext = new { CurrentUserEmail = "", CurrentUsername = "", TraceId = 0 };
        }
#endif
        #region Entities DbSet
        public DbSet<Entities.CheckListHeader> CheckListHeaders { get; set; } = null!;
        public DbSet<Entities.CheckListTemplateHeader> CheckListTemplateHeaders { get; set; } = null!;
        public DbSet<Entities.CheckListTemplateRow> CheckListTemplateRows { get; set; } = null!;
        public DbSet<Entities.CheckPoint> CheckPoints { get; set; } = null!;
        public DbSet<Entities.Equipment> Equipments { get; set; } = null!;
        public DbSet<Entities.Location> Locations { get; set; } = null!;
        public DbSet<Entities.Role> Roles { get; set; } = null!;
        public DbSet<Entities.User> Users { get; set; } = null!;
        public DbSet<Entities.UsersCheckListTemplateHeader> UsersCheckListTemplateHeaders { get; set; } = null!;
        #endregion



        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.ApplyConfiguration(new EquipmentTypeConfiguration());
            modelBuilder.ApplyConfiguration(new LocationTypeConfiguration());
            modelBuilder.ApplyConfiguration(new UserTypeConfiguration());
            
            modelBuilder.RegisterSoftDeleteQueryFilters();
        }
        public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
        {
            SaveChangesCore();
            return await base.SaveChangesAsync(cancellationToken);
        }
        protected virtual void SaveChangesCore()
        {
            var utcNow = DateTime.UtcNow;

            var deletedEntries = ChangeTracker
                  .Entries()
                  .Where(e => e.Entity is ISoftDeletableEntity && e.State == EntityState.Deleted);

            UpdateDeletedEntries(deletedEntries);

            var modifiedEntries = ChangeTracker
                .Entries()
                .Where(e => e.Entity is IAuditableEntity && e.State == EntityState.Modified);

            UpdateModifiedEntires(modifiedEntries, utcNow);

            var addedEntries = ChangeTracker
                   .Entries()
                   .Where(e => e.Entity is IAuditableEntity && e.State == EntityState.Added);

            UpdateAddedEntries(addedEntries, utcNow);
        }
        private void UpdateAddedEntries(IEnumerable<EntityEntry> addedEntries, DateTime utcNow)
        {
            foreach (var entry in addedEntries)
            {
                ((IAuditableEntity)entry.Entity).CreatedAt = utcNow;
                ((IAuditableEntity)entry.Entity).LastModAt = utcNow;
                ((IAuditableEntity)entry.Entity).CreatedBy = _requestContext.CurrentUsername;
                ((IAuditableEntity)entry.Entity).LastModBy = _requestContext.CurrentUsername;
            }
        }
        private void UpdateModifiedEntires(IEnumerable<EntityEntry> modifiedEntries, DateTime utcNow)
        {
            foreach (var entry in modifiedEntries)
            {
                ((IAuditableEntity)entry.Entity).LastModAt = utcNow;
                ((IAuditableEntity)entry.Entity).LastModBy = _requestContext.CurrentUsername;
            }
        }
        private void UpdateDeletedEntries(IEnumerable<EntityEntry> deletedEntries)
        {
            foreach (var entry in deletedEntries)
            {
                ((ISoftDeletableEntity)entry.Entity).IsDeleted = true;
                entry.State = EntityState.Modified;
            }
        }
    }
}