using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading;
using System.Threading.Tasks;
using LinqToDB;
using UserService.DatabaseLayer.DataModels;
using UserService.Infrastructure.DataModels;

namespace UserService.DatabaseLayer.Repositories
{
    public class OrganizationUnitsRepository : BaseRepository, IOrganizationUnitsRepository
    {
        public async Task<IReadOnlyList<OrganizationUnit>> GetAllAsync(Expression<Func<NodeModel, bool>>? predicate = null, CancellationToken token = default)
        {
            await using var db = new UserService2DB();
            var organizationUnits = await db.NodeModels
                .Where(x => x.Discriminator == nameof(OrganizationUnit))
                .WhereOrDefault(predicate)
                .Select(x => new OrganizationUnit
                {
                    Id = x.Id,
                    CommonName = x.CommonName,
                    Description = x.Description,
                    ParentId = x.ParentId,
                })
                .ToListAsync(token).ConfigureAwait(false);
            return organizationUnits;
        }

        public async Task<OrganizationUnit?> GetAsync(Expression<Func<NodeModel, bool>> predicate, CancellationToken token = default)
        {
            await using var db = new UserService2DB();
            var result = await db.NodeModels
                .Where(predicate)
                .Select(x => new OrganizationUnit
                {
                    Id = x.Id,
                    CommonName = x.CommonName,
                    Description = x.Description,
                    ParentId = x.ParentId,
                    ManagerId = x.ManagerId,
                }).FirstOrDefaultAsync(token).ConfigureAwait(false);
            return result;
        }

        public async Task<int> AddAsync(OrganizationUnit entity, CancellationToken token = default)
        {
            if (entity == null) throw new ArgumentNullException(nameof(entity));
            await using var db = new UserService2DB();

            var managerId = entity.Manager?.Id;
            return await db.NodeModels.InsertWithInt32IdentityAsync(() => new NodeModel
            {
                CommonName = entity.CommonName,
                Description = entity.Description,
                Discriminator = nameof(OrganizationUnit),
                ParentId = entity.ParentId,
                ManagerId = managerId,
            }, token).ConfigureAwait(false);
        }

        public async Task<bool> UpdateAsync(OrganizationUnit entity, CancellationToken token = default)
        {
            if (entity == null) throw new ArgumentNullException(nameof(entity));
            await using var db = new UserService2DB();
            var managerId = entity.Manager?.Id;
            var changedRows = await db.NodeModels.UpdateAsync(x => new NodeModel
            {
                Id = entity.Id,
                CommonName = entity.CommonName,
                Description = entity.Description,
                Discriminator = nameof(OrganizationUnit),
                ParentId = entity.ParentId,
                ManagerId = managerId,
            }, token).ConfigureAwait(false);
            return changedRows > 0;
        }

        public async Task DeleteAsync(OrganizationUnit entity, CancellationToken token = default)
        {
            await using var db = new UserService2DB();
            await db.NodeModels.DeleteAsync(x => x.Id == entity.Id, token).ConfigureAwait(false);
        }
    }
}