using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using SiteManagementSystem_SoftwareEngineering_.Entity;
using SiteManagementSystem_SoftwareEngineering_.Interface;
using System.Security.Cryptography;
using System.Text;

namespace SiteManagementSystem_SoftwareEngineering_.Service
{
    public enum IdentityPolicyNames
    {
        NotSupport,
        CommonUser,
        Administrator
    }
    public class UserManagerService
    {
        public class UserManageService(
        SQLService storageService,
        ILogger<UserManageService> logger,
        string secretSalt
    ) : IUserManageService
        {
            private readonly SQLService _storageService = storageService;
            private readonly ILogger<UserManageService> _logger = logger;
            private readonly string _salt = secretSalt;
            private static readonly object _lock = new();
            public void AddUser(User user)
            {
                if (user.Name is null)
                    throw new ArgumentException("Miss Name!");
                if (user.RoleName is null)
                    throw new ArgumentException("Miss PolicyName!");
                if (user.Role is IdentityPolicyNames.NotSupport)
                    throw new ArgumentException("PolicyName not support");
                if (user.Secret is null)
                    throw new ArgumentException("Miss Secret!");
                user.HashSecret = ComputeHash(user.Secret);
                if (_storageService.Users.Where(x => x.Name==user.Name).Any())
                    throw new InvalidOperationException($"已存在名字为{user.Name}的用户");
                lock (_lock)
                {
                    _storageService.Users.Add(user);
                    _storageService.SaveChanges();
                }
            }

            public (bool, string) IsUserExist(ref User user)
            {
                string name = user.Name;
                var result = _storageService.Users.Where(x => x.Name == name);
                if (!result.Any())
                    return (false, "账号不存在");
                if (result.First().HashSecret != ComputeHash(user.Secret))
                    return (false, "密码不匹配");
                user = (User)result.First().Clone();
                return (true, "");
            }

            private string ComputeHash(string key)
            {
                if (key.IsNullOrEmpty())
                    throw new ArgumentException("ComputeHash: Key is null or empty.");
                return Convert.ToBase64String(
                    SHA256.HashData(Encoding.UTF8.GetBytes(_salt + key + _salt))
                );
            }
        }
    }
}