using MailKit.Net.Smtp;

using Microsoft.Extensions.Localization;

using MimeKit;

using MongoDB.Driver;
using MongoDB.Entities;

using PasswordGenerator;

using PrivaPub.ClientModels;
using PrivaPub.ClientModels.User;
using PrivaPub.Models;
using PrivaPub.Models.User;
using PrivaPub.Resources;
using PrivaPub.StaticServices;

using System.Globalization;

#pragma warning disable 8603
#pragma warning disable 8625

namespace PrivaPub.Services
{
	public class RootUsersService : IRootUsersService
	{
		readonly DbEntities DbEntities;
		readonly IPasswordHasher PasswordHasher;
		readonly IStringLocalizer Localizer;
		readonly ILogger<RootUsersService> Logger;
		readonly AppConfigurationService AppConfigurationService;
		readonly AuthTokenManager AuthTokenManager;

		public RootUsersService(
			IStringLocalizer<GenericRes> localizer,
			ILogger<RootUsersService> logger,
			IPasswordHasher passwordHasher,
			DbEntities dbEntities,
			AppConfigurationService appConfigurationService,
			AuthTokenManager authTokenManager)
		{
			DbEntities = dbEntities;
			AuthTokenManager = authTokenManager;
			PasswordHasher = passwordHasher;
			Localizer = localizer;
			Logger = logger;
			AppConfigurationService = appConfigurationService;
		}

		public async Task<WebResult> SignUpAsync(LoginForm signUpForm, string invitationCode = default,
			bool isPasswordRequired = false)
		{
			var result = new WebResult();
			try
			{
				signUpForm.UserName = signUpForm.UserName.ToLower();
				if (await DbEntities.RootUsers.Match(u => u.UserName == signUpForm.UserName).ExecuteAnyAsync())
					return result.Invalidate(Localizer["Username '{0}' already taken.", signUpForm.UserName]);

				var signUpPasswordHashed = PasswordHasher.Hash(signUpForm.Password);
				var newUser = new RootUser
				{
					UserName = signUpForm.UserName,
					HashedPassword = signUpPasswordHashed
				};
				if (signUpForm.UserName == "admin")
				{
					newUser.Policies.Clear();
					newUser.Policies.Add(Policies.IsAdmin);
					newUser.Policies.Add(Policies.IsUser);
					newUser.Policies.Add(Policies.IsModerator);
				}

				await newUser.SaveAsync();
				var cultureLanguage = CultureInfo.CurrentCulture.TwoLetterISOLanguageName;
				var language = await DbEntities.Languages.Match(l => l.International2Code == cultureLanguage).ExecuteFirstAsync();
				var newRootUserSettings = new RootUserSettings
				{
					RootUserId = newUser.ID,
					LanguageCode = language?.International2Code ?? "en",
					LightThemeIndexColour = signUpForm.LightThemeIndexColour,
					DarkThemeIndexColour = signUpForm.DarkThemeIndexColour,
					IconsThemeIndexColour = signUpForm.IconsThemeIndexColour,
					ThemeIsDarkGray = signUpForm.ThemeIsDarkGray,
					ThemeIsLightGray = signUpForm.ThemeIsLightGray,
					PreferSystemTheming = signUpForm.PreferSystemTheming,
					ThemeIsDarkMode = signUpForm.ThemeIsDarkMode
				};
				await newRootUserSettings.SaveAsync();

				//if (!string.IsNullOrEmpty(invitationCode))
				//{
				//	if (isPasswordRequired)
				//		result = await DiscussionService.InviteUserToDiscussion(new PwDiscussionPreviewForm
				//		{
				//			InvitationCode = invitationCode,
				//			Password = signUpForm.InvitationPassword
				//		}, newUser.ID);
				//	else
				//		result = await DiscussionService.InviteUserToDiscussion(new NoPwDiscussionPreviewForm
				//		{
				//			InvitationCode = invitationCode,
				//		}, newUser.ID);
				//	if (!result.IsValid)
				//		return result;
				//}

				result.Data = (newUser, new ViewAvatarServer
				{
					LanguageCode = newRootUserSettings.LanguageCode,
					LightThemeIndexColour = newRootUserSettings.LightThemeIndexColour,
					ThemeIsDarkMode = newRootUserSettings.ThemeIsDarkMode,
					IconsThemeIndexColour = newRootUserSettings.IconsThemeIndexColour,
					ThemeIsDarkGray = newRootUserSettings.ThemeIsDarkGray,
					ThemeIsLightGray = newRootUserSettings.ThemeIsLightGray,
					DarkThemeIndexColour = newRootUserSettings.DarkThemeIndexColour,
					PreferSystemTheming = newRootUserSettings.PreferSystemTheming
				});

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(SignUpAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> LoginAsync(LoginForm loginForm, string invitationCode = default,
			bool isPasswordRequired = false)
		{
			var result = new WebResult();
			try
			{
				loginForm.UserName = loginForm.UserName.ToLower();
				if (!await DbEntities.RootUsers.Match(u => u.UserName == loginForm.UserName && u.DeletionDate == null)
							.ExecuteAnyAsync())
					return result.Invalidate(Localizer["Username '{0}' not found.", loginForm.UserName]);

				var user = await DbEntities.RootUsers.Match(u => u.UserName == loginForm.UserName).ExecuteFirstAsync();
				if (user.IsBanned)
					return result.Invalidate(Localizer["User '{0}' banned.", user.UserName]);

				var (verified, needsUpgrade) = PasswordHasher.Check(user.HashedPassword, loginForm.Password);

				if (!verified)
					return result.Invalidate(Localizer["Wrong password."]);

				if (needsUpgrade)
					result.ErrorMessage = Localizer["Needs upgrade!"];

				var userSettingsResult = await GetUserSettingsAsync(user.ID, loginForm);
				var userSettings = (ViewAvatarServer)userSettingsResult.Data;

				//if (!string.IsNullOrEmpty(invitationCode))
				//{
				//	if (isPasswordRequired)
				//		result = await DiscussionService.InviteUserToDiscussion(new PwDiscussionPreviewForm
				//		{
				//			InvitationCode = invitationCode,
				//			Password = loginForm.InvitationPassword
				//		}, user.ID);
				//	else
				//		result = await DiscussionService.InviteUserToDiscussion(new NoPwDiscussionPreviewForm
				//		{
				//			InvitationCode = invitationCode,
				//		}, user.ID);
				//	if (!result.IsValid)
				//		return result;
				//}

				result.Data = (user, userSettings);

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(LoginAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> UpdateUserAsync(UserForm userForm, string userId)
		{
			var result = new WebResult();
			try
			{
				var currentUser = await DbEntities.RootUsers.Match(u => u.ID == userId).ExecuteFirstAsync();
				if (!string.IsNullOrEmpty(userForm.Email) && currentUser.Email != userForm.Email)
				{
					var emailAlreadyUsed = await DbEntities.RootUsers.Match(u => u.Email == userForm.Email).ExecuteAnyAsync();
					if (emailAlreadyUsed)
						return result.Invalidate(Localizer["Email '{0}' already taken.", userForm.Email]);
				}

				await DB.Update<RootUser>()
					.Match(u => u.ID == userId)
					.Modify(u => u.Email, userForm.Email)
					.ExecuteAsync();

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(UpdateUserAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> UpdateUserSettingsAsync(ViewAvatarServer userSettings, string userId)
		{
			var result = new WebResult();
			try
			{
				var isSupportedLanguage = AppConfigurationService.AppConfiguration.SupportedLanguages.Contains(userSettings.LanguageCode);
				if (!isSupportedLanguage)
					return result.Invalidate(Localizer["Language code '{0}' unsupported.", userSettings.LanguageCode]);

				var languageCodeExists = await DbEntities.Languages
					.Match(l => l.International2Code == userSettings.LanguageCode).ExecuteAnyAsync();
				if (!languageCodeExists)
					return result.Invalidate(Localizer["Language code '{0}' doesn't exist.", userSettings.LanguageCode]);

				var language = await DbEntities.Languages.Match(l => l.International2Code == userSettings.LanguageCode)
					.ExecuteFirstAsync();
				_ = await DB.Update<RootUserSettings>()
					.Match(u => u.RootUserId == userId)
					.Modify(us => us.LanguageCode, language.International2Code)
					.Modify(us => us.LightThemeIndexColour, userSettings.LightThemeIndexColour)
					.Modify(us => us.DarkThemeIndexColour, userSettings.DarkThemeIndexColour)
					.Modify(us => us.PreferSystemTheming, userSettings.PreferSystemTheming)
					.Modify(us => us.ThemeIsDarkMode, userSettings.ThemeIsDarkMode)
					.Modify(us => us.ThemeIsDarkGray, userSettings.ThemeIsDarkGray)
					.Modify(us => us.ThemeIsLightGray, userSettings.ThemeIsLightGray)
					.Modify(us => us.IconsThemeIndexColour, userSettings.IconsThemeIndexColour)
					.ExecuteAsync();

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(UpdateUserSettingsAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> UpdateUserPasswordAsync(UserPasswordForm userPasswordForm, string userId)
		{
			var result = new WebResult();
			try
			{
				var user = await DbEntities.RootUsers.Match(u => u.ID == userId && u.DeletionDate == null).ExecuteFirstAsync();

				if (user == null)
					return result.Invalidate(Localizer["Username '{0}' not found.", userId]);

				var (verified, needsUpgrade) = PasswordHasher.Check(user.HashedPassword, userPasswordForm.OldPassword);

				if (!verified)
					return result.Invalidate(Localizer["Wrong password."]);

				var newPasswordHashed = PasswordHasher.Hash(userPasswordForm.NewPassword);
				user.HashedPassword = newPasswordHashed;
				await user.SaveAsync();

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(UpdateUserPasswordAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> RemoveUserAsync(UsersIds usersIds)
		{
			var result = new WebResult();
			try
			{
				var users = await DbEntities.RootUsers.Match(u => usersIds.UserIdList.Contains(u.ID) && u.DeletionDate == default).ExecuteAsync();
				if (users == null || users.Count == 0)
					return result.Invalidate(Localizer["User already deleted."]);

				foreach (var user in users)
				{
					user.Email = Localizer["Deleted user"];
					user.HashedPassword = null;
					user.Policies.Clear();
					user.IsBanned = false;
					user.IsEmailValidated = false;
					//user.TempSecret = null;
					user.UserName = Localizer["Deleted user"];
					user.DeletionDate = DateTime.UtcNow;

					await user.SaveAsync();
				}

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(RemoveUserAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> BanUserAsync(UsersIds usersIds)
		{
			var result = new WebResult();
			try
			{
				await DB.Update<RootUser>()
					.Match(u => usersIds.UserIdList.Contains(u.ID))
					.Modify(u => u.IsBanned, true)
					.ExecuteAsync();

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(BanUserAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> UnbanUserAsync(UsersIds usersIds)
		{
			var result = new WebResult();
			try
			{
				await DB.Update<RootUser>()
					.Match(u => usersIds.UserIdList.Contains(u.ID))
					.Modify(u => u.IsBanned, false)
					.ExecuteAsync();

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(UnbanUserAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> GetUserSettingsAsync(string userId, LoginForm loginForm = default)
		{
			var result = new WebResult();
			try
			{
				var userSettings = await DbEntities.RootUsersSettings.Match(u => u.RootUserId == userId).ExecuteFirstAsync();
				if (loginForm != default && (loginForm.ThemeIsDarkMode != userSettings.ThemeIsDarkMode))
				{
					userSettings.ThemeIsDarkMode = loginForm.ThemeIsDarkMode;
					await userSettings.SaveAsync();
				}

				result.Data = new ViewAvatarServer
				{
					LanguageCode = userSettings.LanguageCode,
					LightThemeIndexColour = userSettings.LightThemeIndexColour,
					DarkThemeIndexColour = userSettings.DarkThemeIndexColour,
					PreferSystemTheming = userSettings.PreferSystemTheming,
					ThemeIsDarkMode = userSettings.ThemeIsDarkMode,
					IconsThemeIndexColour = userSettings.IconsThemeIndexColour,
					ThemeIsDarkGray = userSettings.ThemeIsDarkGray,
					ThemeIsLightGray = userSettings.ThemeIsLightGray
				};
				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(GetUserSettingsAsync)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> SetupAndSendRecoveryEmail(PasswordRecoveryForm passwordRecoveryForm, string host)
		{
			var result = new WebResult();
			try
			{
				var usernameExists = false;
				if (passwordRecoveryForm.IsEmailDisabled)
				{
					if (!await DbEntities.RootUsers.Match(u => u.UserName == passwordRecoveryForm.UserName && u.DeletionDate == null)
								.ExecuteAnyAsync())
						return result.Invalidate(Localizer["Username '{0}' not found.", passwordRecoveryForm.UserName],
							StatusCodes.Status404NotFound);
					usernameExists = true;
				}
				else
				{
					if (!await DbEntities.RootUsers.Match(u => u.Email == passwordRecoveryForm.Email && u.DeletionDate == null)
								.ExecuteAnyAsync())
						return result.Invalidate(Localizer["Username '{0}' not found.", passwordRecoveryForm.UserName],
							StatusCodes.Status404NotFound);
				}

				var user = default(RootUser);
				if (usernameExists)
					user = await DbEntities.RootUsers.Match(u => u.UserName == passwordRecoveryForm.UserName).ExecuteFirstAsync();
				else
					user = await DbEntities.RootUsers.Match(u => u.Email == passwordRecoveryForm.Email).ExecuteFirstAsync();

				if (string.IsNullOrEmpty(user.Email))
					return result.Invalidate(Localizer["This User doesn't have an email, no way to recover."],
						StatusCodes.Status423Locked);

				var emailRecovery = await DbEntities.EmailRecoveries
					.Match(er => er.RootUserId == user.ID).ExecuteFirstAsync();

				if (emailRecovery is null)
				{
					emailRecovery = new()
					{
						RootUserId = user.ID
					};
					await emailRecovery.SaveAsync();
				}

				var recoveryCodeGenerator = new Password(true, true, true, false, 127);
				emailRecovery.RecoveryCode = recoveryCodeGenerator.Next();
				await emailRecovery.SaveAsync();

				using (var smtpClient = new SmtpClient())
				{
					try
					{
						await smtpClient.ConnectAsync(AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpServer, AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpPort,
							AppConfigurationService.AppConfiguration.EmailConfiguration.UseSSL);
						if (!smtpClient.IsConnected)
						{
							Logger.LogError($"Failed to connect to the SMTP server({AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpServer}).");
							return result.Invalidate(Localizer["Failed to send email."], (int)SmtpStatusCode.ServiceNotAvailable);
						}
					}
					catch (Exception ex)
					{
						Logger.LogError(ex, $"Error at connection to the SMTP server({AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpServer}).");
						return result.Invalidate(Localizer["Failed to send email."], (int)SmtpStatusCode.ServiceNotAvailable, exception: ex);
					}

					try
					{
						await smtpClient.AuthenticateAsync(AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpUsername, AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpPassword);
						if (!smtpClient.IsAuthenticated)
						{
							Logger.LogError($"Failed SMTP authentication of {AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpUsername}.");
							return result.Invalidate(Localizer["Failed to send email."],
								(int)SmtpStatusCode.TemporaryAuthenticationFailure);
						}
					}
					catch (Exception ex)
					{
						Logger.LogError(ex, $"Failed SMTP authentication of {AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpUsername}.");
						return result.Invalidate(Localizer["Failed to send email."],
							(int)SmtpStatusCode.TemporaryAuthenticationFailure, exception: ex);
					}

					try
					{
						var toParsed = await smtpClient.VerifyAsync(user.Email);
						if (toParsed == null)
							return result.Invalidate($"Invalid email of {user.Email}.", (int)SmtpStatusCode.MailboxUnavailable);
					}
					catch (OperationCanceledException ex)
					{
						Logger.LogWarning(
							$"SMTP operation canceled exception at email verification of {user.Email}. Exception=[{ex.Message}]");
					}
					catch (SmtpCommandException ex)
					{
						Logger.LogWarning(
							$"SMTP command exception at email verification of {user.Email}. Exception=[{ex.Message}]");
					}
					catch (SmtpProtocolException ex)
					{
						Logger.LogWarning(
							$"SMTP protocol exception at email verification of {user.Email}. Exception=[{ex.Message}]");
					}
					catch (Exception ex)
					{
						Logger.LogWarning($"General exception at email verification of {user.Email}. Exception=[{ex.Message}]");
					}

					var message = new MimeMessage();
					message.From.Add(new MailboxAddress(Localizer["Eugene - collAnon support"], AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpUsername));
					message.To.Add(MailboxAddress.Parse(user.Email));
					message.Subject = Localizer["PrivaPub - Password recovery link"];
					message.Body = new TextPart("plain")
					{
						Text = string.Format(Localizer[@"Hey {0},

Eugene from collAnon, following is the password recovery link:
{1}

-- Eugene"], user.UserName, $"{host}/password-recovery?rc={emailRecovery.RecoveryCode}")
					};
					try
					{
						await smtpClient.SendAsync(message);
					}
					catch (Exception ex)
					{
						Logger.LogError(ex, $"Error at email sending to {user.Email} from {AppConfigurationService.AppConfiguration.EmailConfiguration.SmtpUsername}.");
						return result.Invalidate(Localizer["Failed to send email."], (int)SmtpStatusCode.TransactionFailed, exception: ex);
					}

					await smtpClient.DisconnectAsync(quit: true);
				}

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(SetupAndSendRecoveryEmail)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> IsValidRecoveryCode(string recoveryCode)
		{
			var result = new WebResult();
			try
			{
				var isValidRecoveryCode = await DbEntities.EmailRecoveries
					.Match(er => er.RecoveryCode == recoveryCode).ExecuteAnyAsync();

				result.Data = isValidRecoveryCode;

				return result;
			}
			catch (Exception ex)
			{
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

		public async Task<WebResult> ChangePassword(NewPasswordForm newPasswordForm)
		{
			var result = new WebResult();
			try
			{
				var isValidRecoveryCode = await DbEntities.EmailRecoveries
					.Match(er => er.RecoveryCode == newPasswordForm.RecoveryCode).ExecuteAnyAsync();
				if (!isValidRecoveryCode)
					return result.Invalidate(Localizer["Invalid recovery code."], StatusCodes.Status404NotFound);

				var emailRecovery = await DbEntities.EmailRecoveries
					.Match(er => er.RecoveryCode == newPasswordForm.RecoveryCode)
					.Project(er => er.Include(nameof(EmailRecovery.RootUserId)))
					.ExecuteFirstAsync();

				if (emailRecovery is null || emailRecovery.RootUserId is null)
					return result.Invalidate(Localizer["User not found."]);

				var newHashedPassword = PasswordHasher.Hash(newPasswordForm.NewPassword);

				_ = await DB.Update<RootUser>()
					.Match(u => u.ID == emailRecovery.RootUserId && u.DeletionDate == null)
					.Modify(u => u.HashedPassword, newHashedPassword)
					.ExecuteAsync();

				_ = await DB.DeleteAsync<EmailRecovery>(er => er.RecoveryCode == newPasswordForm.RecoveryCode);

				return result;
			}
			catch (Exception ex)
			{
				Logger.LogError(ex, $"{nameof(RootUsersService)}.{nameof(ChangePassword)}()");
				return result.Invalidate(ex.Message, exception: ex);
			}
		}

	}
}