using System.Threading.Tasks;
using xCommons.Extensions;
using xIdentityModels.Extensions;
using xIdentityModels.Models;
using xIdentityModels.Navigations;

namespace xIds.Providers
{
    public partial class XIdentityManager
    {
        //
        #region Verification Code Actions ...
        /// <summary>
        /// Check a Device Requeste for Verification Code before or not
        /// </summary>
        /// <param name="device">an instance of <see>XDevice</see></param>
        /// <returns>a boolean value</returns>
        private async Task<bool> IsDeviceRequestedForVerificationCodeBefor(
            XDevice device
        )
        {
            //
            var result = false;
            var enumerator = DbContext.VerificationRequests
                .AsAsyncEnumerable();
            await
            foreach (var entity in enumerator)
            {
                //
                if (entity.Device.IsSameAs(device))
                {
                    //
                    result = true;
                    break;
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Check a Verification Code Requested before or not
        /// </summary>
        /// <param name="verificationCode">Confirm Verification Code</param>
        /// <returns>a boolean value</returns>
        private async Task<bool> IsVerificationCodeRequested(
            string verificationCode
        )
        {
            //
            // Validate Args ...
            if (verificationCode.IsNullOrEmpty())
            {
                return false;
            }

            //
            var result = false;
            var enumerator = DbContext.VerificationRequests
                .AsAsyncEnumerable();
            await
            foreach (var entity in enumerator)
            {
                //
                if (entity.VerificationCode == verificationCode)
                {
                    //
                    result = true;
                    break;
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Retrieve Verification Request
        /// </summary>
        /// <param name="device">an instance of <see>XDevice</see></param>
        /// <returns>an instance of <see>XVerificationRequest</see></returns>
        private async Task<XVerificationRequest> GetVerificationRequest(
            XDevice device
        )
        {
            //
            XVerificationRequest result = null;
            var enumerator = DbContext.VerificationRequests
                .AsAsyncEnumerable();
            await
            foreach (var entity in enumerator)
            {
                //
                if (entity.Device.IsSameAs(device))
                {
                    //
                    result = entity;
                    break;
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Retrieve Verification Request
        /// </summary>
        /// <param name="verificationCode">Confirm Verification Code</param>
        /// <returns>an instance of <see>XVerificationRequest</see></returns>
        private async Task<XVerificationRequest> GetVerificationRequest(
            string verificationCode
        )
        {
            //
            XVerificationRequest result = null;
            var enumerator = DbContext.VerificationRequests
                .AsAsyncEnumerable();
            await
            foreach (var entity in enumerator)
            {
                //
                if (entity.VerificationCode == verificationCode)
                {
                    //
                    result = entity;
                    break;
                }
            }

            //
            return result;
        }

        /// <summary>
        /// Remove Exists Verification Code Request
        /// </summary>
        /// <param name="device">an instance of <see>XDevice</see></param>
        /// <param name="saveChanges">save changes on DbContext, default is true</param>
        /// <returns></returns>
        private async Task RemoveVerificationCodeRequestByDevice(
            XDevice device,
            bool saveChanges = true
        )
        {
            //
            if (!await IsDeviceRequestedForVerificationCodeBefor(device))
            {
                return;
            }

            //
            var xvr = await GetVerificationRequest(device);
            DbContext.VerificationRequests.Remove(xvr);

            //
            if (saveChanges)
            {
                await DbContext.SaveChangesAsync();
            }
        }

        /// <summary>
        /// Remove Exists Verification Code Request
        /// </summary>
        /// <param name="verificationCode">Confirm Verification Code</param>
        /// <param name="saveChanges">save changes on DbContext, default is true</param>
        /// <returns></returns>
        private async Task RemoveVerificationRequest(
            string verificationCode,
            bool saveChanges = true
        )
        {
            //
            ValidationProvider.NotEmpty(verificationCode);

            //
            var request = await GetVerificationRequest(verificationCode);
            DbContext.VerificationRequests.Remove(request);

            //
            if (saveChanges)
            {
                await DbContext.SaveChangesAsync();
            }
        }

        /// <summary>
        /// Add Verification Code Request
        /// </summary>
        /// <param name="request">an instance of <see>XVerificationRequest</see></param>
        /// <param name="saveChanges">save changes on DbContext, default is true</param>
        /// <returns>an instance of <see>XVerificationRequest</see></returns>
        private async Task<XVerificationRequest> AddVerificationRequest(
            XVerificationRequest request,
            bool saveChanges = true
        )
        {
            //
            if (await IsDeviceRequestedForVerificationCodeBefor(request.Device))
            {
                await RemoveVerificationCodeRequestByDevice(request.Device);
            }

            //
            var entry = await DbContext.VerificationRequests.AddAsync(request);

            //
            if (saveChanges)
            {
                await DbContext.SaveChangesAsync();
            }

            //
            return entry.Entity;
        }
        #endregion        
    }
}