using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity;
using xCommons.Extensions;
using xExceptions.Constants;
using xIdentityModels;

namespace xIds.Providers
{
    public partial class XIdentityManager
    {
        //
        #region Role Actions ...
        /// <summary>
        /// Check a Role exists or not
        /// </summary>
        /// <param name="roleName">role name</param>
        /// <returns>a boolean value</returns>
        public async Task<bool> IsRoleExistsAsync(
            string roleName
        )
        {
            //
            if (roleName.IsNullOrEmpty())
            {
                XException.InvalidArgs.Throw();
            }

            //
            return await RoleManager.RoleExistsAsync(roleName);
        }

        /// <summary>
        /// Create a new Role 
        /// </summary>
        /// <param name="roleName">role name</param>
        /// <returns>an instance of <see>IdentityResult</see></returns>
        public async Task<IdentityResult> CreateRoleAsync(
            string roleName
        )
        {
            //
            var isExists = await RoleManager
                .RoleExistsAsync(roleName);
            if (isExists)
            {
                XException.Duplicate.Throw();
            }

            //
            var result = await RoleManager
                .CreateAsync(new IdentityRole(roleName));

            //
            return result;
        }

        /// <summary>
        /// Get a Role
        /// </summary>
        /// <param name="roleName">role name</param>
        /// <returns>an instance of <see>IdentityRole</see></returns>
        public async Task<IdentityRole> GetRoleAsync(
            string roleName
        )
        {
            //
            var isExists = await IsRoleExistsAsync(roleName);
            if (!isExists)
            {
                XException.NotFound.Throw();
            }

            //
            var result = await RoleManager
                .FindByNameAsync(roleName);

            //
            return result;
        }

        /// <summary>
        /// Remove a User From Role 
        /// </summary>
        /// <param name="user">an instance of <see>XUser</see></param>
        /// <param name="roleName">role name</param>
        /// <returns>an instance of <see>IdentityResult</see></returns>
        public async Task<IdentityResult> RemoveFromRoleAsync(
            XUser user,
            string roleName
        )
        {
            return await UserManager.RemoveFromRoleAsync(user, roleName);
        }

        /// <summary>
        /// Remove a User From Roles
        /// </summary>
        /// <param name="user">an instance of <see>XUser</see></param>
        /// <param name="roleNames">a collection of role names</param>
        /// <returns>an instance of <see>IdentityResult</see></returns>
        public async Task<IdentityResult> RemoveFromRolesAsync(
            XUser user,
            IEnumerable<string> roleNames
        )
        {
            return await UserManager.RemoveFromRolesAsync(user, roleNames);
        }

        /// <summary>
        /// Assign a User to Specific Role
        /// </summary>
        /// <param name="user">an instance of <see>XUser</see></param>
        /// <param name="roleName">role name</param>
        /// <returns>an instance of <see>IdentityResult</see></returns>
        public async Task<IdentityResult> AddUserToRoleAsync(
            XUser user,
            string roleName
        )
        {
            //
            if (user == null ||
                roleName.IsNullOrEmpty())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var userSelectByParam = GetUserSelectByParam(user);
            var isExistsUser = await IsUserExistsAsync(userSelectByParam);
            var isExistsRole = await IsRoleExistsAsync(roleName);
            if (!isExistsUser || !isExistsRole)
            {
                XException.NotFound.Throw();
            }

            //
            var result = await UserManager
                .AddToRoleAsync(user, roleName);

            //
            return result;
        }

        /// <summary>
        /// Retrieve Role Name by it's ID
        /// </summary>
        /// <param name="roleId">role id</param>
        /// <returns>role name as string</returns>
        public async Task<string> GetRoleNameAsync(
            string roleId
        )
        {
            //
            // Validate Args ...
            if (roleId.IsNullOrEmpty())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var role = await RoleManager
                .FindByIdAsync(roleId);

            //
            return role.Name.ToNormalString();
        }

        /// <summary>
        /// Get a List Of User Roles 
        /// </summary>
        /// <param name="userSelectByParam">user identifier</param>
        /// <param name="checkCanLoginPolicies"></param>
        /// <param name="checkIsBanned"></param>
        /// <returns>a collection of role names</returns>
        public async Task<IEnumerable<string>> GetRoleNamesAsync(
            string userSelectByParam,
            bool checkCanLoginPolicies = true,
            bool checkIsBanned = true
        )
        {
            //
            // Validate Args ...
            if (userSelectByParam.IsNullOrEmpty())
            {
                XException.InvalidArgs.Throw();
            }

            //
            var user = await ValidateUserExistsAndRetrieve(
                userSelectByParam,
                containDetails: true,
                checkCanLoginPolicies: checkCanLoginPolicies,
                checkIsBanned: checkIsBanned
            );

            //
            var result = new List<string>();
            foreach (var role in user.Roles)
            {
                //
                var roleName = await GetRoleNameAsync(role.RoleId);
                roleName = roleName.ToNormalString();

                //
                result.Add(roleName);
            }

            //
            return result;
        }

        /// <summary>
        /// Check a User is Adminr not
        /// </summary>
        /// <param name="userSelectByParam">user identifier</param>
        /// <returns>a boolean value</returns>
        public async Task<bool> IsAdmin(
            string userSelectByParam
        )
        {
            //
            // Validate Args ...
            ValidationProvider.NotEmpty(userSelectByParam);

            //
            var user = await ValidateUserExistsAndRetrieve(
                userSelectByParam,
                containDetails: true,
                checkCanLoginPolicies: true);

            //
            var result = await IsAdmin(user);

            //
            return result;
        }

        /// <summary>
        /// Check a User is Adminr not
        /// </summary>
        /// <param name="user">an instance of <see>XUser</see></param>
        /// <returns>a boolean value</returns>
        public async Task<bool> IsAdmin(
            XUser user
        )
        {
            //
            // Validate Args ...
            ValidationProvider.NotNull(user);
            ValidationProvider.NotEmpty(user.Id);

            //
            // Retrieve Admin Role ...
            // TODO: Fix this ...
            var adminRole = "admin";
            // XUserRole.Admin
            //     .GetStringValue ()
            //     .ToNormalString ();

            //
            // Check Admin Role Exists in User Roles or not ...
            var userRoleNames = await GetRoleNamesAsync(user.Id);
            var isContainsAdminRole = userRoleNames.Contains(adminRole);

            //
            // Return Result ...
            return isContainsAdminRole;
        }
        #endregion        
    }
}