Wino-Mail/Wino.Services/MailService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using CommunityToolkit.Mvvm.Messaging;
using MimeKit;
using Serilog;
using SqlKata;
using Wino.Core.Domain;
using Wino.Core.Domain.Entities.Mail;
using Wino.Core.Domain.Entities.Shared;
using Wino.Core.Domain.Enums;
using Wino.Core.Domain.Exceptions;
using Wino.Core.Domain.Extensions;
using Wino.Core.Domain.Interfaces;
using Wino.Core.Domain.Models.Comparers;
using Wino.Core.Domain.Models.MailItem;
using Wino.Messaging.UI;
using Wino.Services.Extensions;

namespace Wino.Services;

public class MailService : BaseDatabaseService, IMailService
{
    private const int ItemLoadCount = 100;

    private readonly IFolderService _folderService;
    private readonly IContactService _contactService;
    private readonly IAccountService _accountService;
    private readonly ISignatureService _signatureService;
    private readonly IThreadingStrategyProvider _threadingStrategyProvider;
    private readonly IMimeFileService _mimeFileService;
    private readonly IPreferencesService _preferencesService;

    private readonly ILogger _logger = Log.ForContext<MailService>();

    public MailService(IDatabaseService databaseService,
                       IFolderService folderService,
                       IContactService contactService,
                       IAccountService accountService,
                       ISignatureService signatureService,
                       IThreadingStrategyProvider threadingStrategyProvider,
                       IMimeFileService mimeFileService,
                       IPreferencesService preferencesService) : base(databaseService)
    {
        _folderService = folderService;
        _contactService = contactService;
        _accountService = accountService;
        _signatureService = signatureService;
        _threadingStrategyProvider = threadingStrategyProvider;
        _mimeFileService = mimeFileService;
        _preferencesService = preferencesService;
    }

    public async Task<(MailCopy draftMailCopy, string draftBase64MimeMessage)> CreateDraftAsync(Guid accountId, DraftCreationOptions draftCreationOptions)
    {
        var composerAccount = await _accountService.GetAccountAsync(accountId).ConfigureAwait(false);
        var createdDraftMimeMessage = await CreateDraftMimeAsync(composerAccount, draftCreationOptions);

        var draftFolder = await _folderService.GetSpecialFolderByAccountIdAsync(composerAccount.Id, SpecialFolderType.Draft);

        if (draftFolder == null)
            throw new UnavailableSpecialFolderException(SpecialFolderType.Draft, accountId);

        // Get locally created unique id from the mime headers.
        // This header will be used to map the local draft copy with the remote draft copy.
        var mimeUniqueId = createdDraftMimeMessage.Headers[Constants.WinoLocalDraftHeader];

        var primaryAlias = await _accountService.GetPrimaryAccountAliasAsync(accountId).ConfigureAwait(false);

        var copy = new MailCopy
        {
            UniqueId = Guid.Parse(mimeUniqueId),
            Id = Guid.NewGuid().ToString(), // This will be replaced after network call with the remote draft id.
            CreationDate = DateTime.UtcNow,
            FromAddress = primaryAlias?.AliasAddress ?? composerAccount.Address,
            FromName = composerAccount.SenderName,
            HasAttachments = false,
            Importance = MailImportance.Normal,
            Subject = createdDraftMimeMessage.Subject,
            PreviewText = createdDraftMimeMessage.TextBody,
            IsRead = true,
            IsDraft = true,
            FolderId = draftFolder.Id,
            DraftId = $"{Constants.LocalDraftStartPrefix}{Guid.NewGuid()}",
            AssignedFolder = draftFolder,
            AssignedAccount = composerAccount,
            FileId = Guid.NewGuid()
        };

        // If replying, add In-Reply-To, ThreadId and References.
        if (draftCreationOptions.ReferencedMessage != null)
        {
            if (draftCreationOptions.ReferencedMessage.MimeMessage.References != null)
                copy.References = string.Join(",", draftCreationOptions.ReferencedMessage.MimeMessage.References);

            if (!string.IsNullOrEmpty(draftCreationOptions.ReferencedMessage.MimeMessage.MessageId))
                copy.InReplyTo = draftCreationOptions.ReferencedMessage.MimeMessage.MessageId;

            if (!string.IsNullOrEmpty(draftCreationOptions.ReferencedMessage.MailCopy?.ThreadId))
                copy.ThreadId = draftCreationOptions.ReferencedMessage.MailCopy.ThreadId;
        }

        await Connection.InsertAsync(copy);

        await _mimeFileService.SaveMimeMessageAsync(copy.FileId, createdDraftMimeMessage, composerAccount.Id);

        ReportUIChange(new DraftCreated(copy, composerAccount));

        return (copy, createdDraftMimeMessage.GetBase64MimeMessage());
    }

    public async Task<List<MailCopy>> GetMailsByFolderIdAsync(Guid folderId)
    {
        var mails = await Connection.QueryAsync<MailCopy>("SELECT * FROM MailCopy WHERE FolderId = ?", folderId);

        foreach (var mail in mails)
        {
            await LoadAssignedPropertiesAsync(mail).ConfigureAwait(false);
        }

        return mails;
    }

    public async Task<bool> HasAccountAnyDraftAsync(Guid accountId)
    {
        // Get the draft folder.
        var draftFolder = await _folderService.GetSpecialFolderByAccountIdAsync(accountId, SpecialFolderType.Draft);

        if (draftFolder == null) return false;

        var draftCount = await Connection.Table<MailCopy>().Where(a => a.FolderId == draftFolder.Id).CountAsync();

        return draftCount > 0;
    }

    public async Task<List<MailCopy>> GetUnreadMailsByFolderIdAsync(Guid folderId)
    {
        var unreadMails = await Connection.QueryAsync<MailCopy>("SELECT * FROM MailCopy WHERE FolderId = ? AND IsRead = 0", folderId);

        foreach (var mail in unreadMails)
        {
            await LoadAssignedPropertiesAsync(mail).ConfigureAwait(false);
        }

        return unreadMails;
    }

    private static string BuildMailFetchQuery(MailListInitializationOptions options)
    {
        // If the search query is there, we should ignore some properties and trim it.
        //if (!string.IsNullOrEmpty(options.SearchQuery))
        //{
        //    options.IsFocusedOnly = null;
        //    filterType = FilterOptionType.All;

        //    searchQuery = searchQuery.Trim();
        //}

        // SQLite PCL doesn't support joins.
        // We make the query using SqlKata and execute it directly on SQLite-PCL.

        var query = new Query("MailCopy")
                    .Join("MailItemFolder", "MailCopy.FolderId", "MailItemFolder.Id")
                    .WhereIn("MailCopy.FolderId", options.Folders.Select(a => a.Id))
                    .Take(ItemLoadCount)
                    .SelectRaw("MailCopy.*");

        if (options.SortingOptionType == SortingOptionType.ReceiveDate)
            query.OrderByDesc("CreationDate");
        else if (options.SortingOptionType == SortingOptionType.Sender)
            query.OrderBy("FromName");

        // Conditional where.
        switch (options.FilterType)
        {
            case FilterOptionType.Unread:
                query.Where("MailCopy.IsRead", false);
                break;
            case FilterOptionType.Flagged:
                query.Where("MailCopy.IsFlagged", true);
                break;
            case FilterOptionType.Files:
                query.Where("MailCopy.HasAttachments", true);
                break;
        }

        if (options.IsFocusedOnly != null)
            query.Where("MailCopy.IsFocused", options.IsFocusedOnly.Value);

        if (!string.IsNullOrEmpty(options.SearchQuery))
            query.Where(a =>
                        a.OrWhereContains("MailCopy.PreviewText", options.SearchQuery)
                        .OrWhereContains("MailCopy.Subject", options.SearchQuery)
                        .OrWhereContains("MailCopy.FromName", options.SearchQuery)
                        .OrWhereContains("MailCopy.FromAddress", options.SearchQuery));

        if (options.ExistingUniqueIds?.Any() ?? false)
        {
            query.WhereNotIn("MailCopy.UniqueId", options.ExistingUniqueIds);
        }

        //if (options.Skip > 0)
        //{
        //    query.Skip(options.Skip);
        //}

        return query.GetRawQuery();
    }

    public async Task<List<IMailItem>> FetchMailsAsync(MailListInitializationOptions options, CancellationToken cancellationToken = default)
    {
        List<MailCopy> mails = null;

        // If user performs an online search, mail copies are passed to options.
        if (options.PreFetchMailCopies != null)
        {
            mails = options.PreFetchMailCopies;
        }
        else
        {
            // If not just do the query.
            var query = BuildMailFetchQuery(options);

            mails = await Connection.QueryAsync<MailCopy>(query);
        }

        Dictionary<Guid, MailItemFolder> folderCache = [];
        Dictionary<Guid, MailAccount> accountCache = [];
        Dictionary<string, AccountContact> contactCache = [];

        // Populate Folder Assignment for each single mail, to be able later group by "MailAccountId".
        // This is needed to execute threading strategy by account type.
        // Avoid DBs calls as possible, storing info in a dictionary.
        foreach (var mail in mails)
        {
            await LoadAssignedPropertiesWithCacheAsync(mail, folderCache, accountCache, contactCache).ConfigureAwait(false);
        }

        // Remove items that has no assigned account or folder.
        mails.RemoveAll(a => a.AssignedAccount == null || a.AssignedFolder == null);

        if (!options.CreateThreads)
        {
            cancellationToken.ThrowIfCancellationRequested();

            // Threading is disabled. Just return everything as it is.
            mails.Sort(options.SortingOptionType == SortingOptionType.ReceiveDate ? new DateComparer() : new NameComparer());

            return [.. mails];
        }

        // Populate threaded items.

        List<IMailItem> threadedItems = [];

        // Each account items must be threaded separately.
        foreach (var group in mails.GroupBy(a => a.AssignedAccount.Id))
        {
            cancellationToken.ThrowIfCancellationRequested();

            var accountId = group.Key;
            var groupAccount = mails.First(a => a.AssignedAccount.Id == accountId).AssignedAccount;

            var threadingStrategy = _threadingStrategyProvider.GetStrategy(groupAccount.ProviderType);

            // Only thread items from Draft and Sent folders must present here.
            // Otherwise this strategy will fetch the items that are in Deleted folder as well.
            var accountThreadedItems = await threadingStrategy.ThreadItemsAsync([.. group], options.Folders.First());

            // Populate threaded items with folder and account assignments.
            // Almost everything already should be in cache from initial population.
            foreach (var mail in accountThreadedItems)
            {
                cancellationToken.ThrowIfCancellationRequested();
                await LoadAssignedPropertiesWithCacheAsync(mail, folderCache, accountCache, contactCache).ConfigureAwait(false);
            }

            if (accountThreadedItems != null)
            {
                threadedItems.AddRange(accountThreadedItems);
            }
        }

        threadedItems.Sort(options.SortingOptionType == SortingOptionType.ReceiveDate ? new DateComparer() : new NameComparer());
        cancellationToken.ThrowIfCancellationRequested();

        return threadedItems;
    }

    /// <summary>
    /// This method should used for operations with multiple mailItems. Don't use this for single mail items.
    /// Called method should provide own instances for caches.
    /// </summary>
    private async Task LoadAssignedPropertiesWithCacheAsync(IMailItem mail, Dictionary<Guid, MailItemFolder> folderCache, Dictionary<Guid, MailAccount> accountCache, Dictionary<string, AccountContact> contactCache)
    {
        if (mail is ThreadMailItem threadMailItem)
        {
            foreach (var childMail in threadMailItem.ThreadItems)
            {
                await LoadAssignedPropertiesWithCacheAsync(childMail, folderCache, accountCache, contactCache).ConfigureAwait(false);
            }
        }

        if (mail is MailCopy mailCopy)
        {
            var isFolderCached = folderCache.TryGetValue(mailCopy.FolderId, out MailItemFolder folderAssignment);
            MailAccount accountAssignment = null;
            if (!isFolderCached)
            {
                folderAssignment = await _folderService.GetFolderAsync(mailCopy.FolderId).ConfigureAwait(false);
                folderCache.TryAdd(mailCopy.FolderId, folderAssignment);
            }

            if (folderAssignment != null)
            {
                var isAccountCached = accountCache.TryGetValue(folderAssignment.MailAccountId, out accountAssignment);
                if (!isAccountCached)
                {
                    accountAssignment = await _accountService.GetAccountAsync(folderAssignment.MailAccountId).ConfigureAwait(false);

                    accountCache.TryAdd(folderAssignment.MailAccountId, accountAssignment);
                }
            }

            AccountContact contactAssignment = null;

            bool isContactCached = !string.IsNullOrEmpty(mailCopy.FromAddress) &&
                contactCache.TryGetValue(mailCopy.FromAddress, out contactAssignment);

            if (!isContactCached && accountAssignment != null)
            {
                contactAssignment = await GetSenderContactForAccountAsync(accountAssignment, mailCopy.FromAddress).ConfigureAwait(false);

                if (contactAssignment != null)
                {
                    contactCache.TryAdd(mailCopy.FromAddress, contactAssignment);
                }
            }

            mailCopy.AssignedFolder = folderAssignment;
            mailCopy.AssignedAccount = accountAssignment;
            mailCopy.SenderContact = contactAssignment ?? CreateUnknownContact(mailCopy.FromName, mailCopy.FromAddress);
        }
    }

    private static AccountContact CreateUnknownContact(string fromName, string fromAddress)
    {
        if (string.IsNullOrEmpty(fromName) && string.IsNullOrEmpty(fromAddress))
        {
            return new AccountContact()
            {
                Name = Translator.UnknownSender,
                Address = Translator.UnknownAddress
            };
        }
        else
        {
            if (string.IsNullOrEmpty(fromName)) fromName = fromAddress;

            return new AccountContact()
            {
                Name = fromName,
                Address = fromAddress
            };
        }
    }

    private async Task<List<MailCopy>> GetMailItemsAsync(string mailCopyId)
    {
        var mailCopies = await Connection.Table<MailCopy>().Where(a => a.Id == mailCopyId).ToListAsync();

        foreach (var mailCopy in mailCopies)
        {
            await LoadAssignedPropertiesAsync(mailCopy).ConfigureAwait(false);
        }

        return mailCopies;
    }

    private Task<AccountContact> GetSenderContactForAccountAsync(MailAccount account, string fromAddress)
    {
        // Make sure to return the latest up to date contact information for the original account.
        if (fromAddress == account.Address)
        {
            return Task.FromResult(new AccountContact() { Address = account.Address, Name = account.SenderName, Base64ContactPicture = account.Base64ProfilePictureData });
        }
        else
        {
            return _contactService.GetAddressInformationByAddressAsync(fromAddress);
        }
    }

    private async Task LoadAssignedPropertiesAsync(MailCopy mailCopy)
    {
        if (mailCopy == null) return;

        // Load AssignedAccount, AssignedFolder and SenderContact.

        var folder = await _folderService.GetFolderAsync(mailCopy.FolderId);

        if (folder == null) return;

        var account = await _accountService.GetAccountAsync(folder.MailAccountId);

        if (account == null) return;

        mailCopy.AssignedAccount = account;
        mailCopy.AssignedFolder = folder;
        mailCopy.SenderContact = await GetSenderContactForAccountAsync(account, mailCopy.FromAddress).ConfigureAwait(false);
    }

    public async Task<MailCopy> GetSingleMailItemWithoutFolderAssignmentAsync(string mailCopyId)
    {
        var mailCopy = await Connection.Table<MailCopy>().FirstOrDefaultAsync(a => a.Id == mailCopyId);

        if (mailCopy == null) return null;

        await LoadAssignedPropertiesAsync(mailCopy).ConfigureAwait(false);

        return mailCopy;
    }

    /// <summary>
    /// Using this override is dangerous.
    /// Gmail stores multiple copies of same mail in different folders.
    /// This one will always return the first one. Use with caution.
    /// </summary>
    /// <param name="mailCopyId">Mail copy id.</param>
    public async Task<MailCopy> GetSingleMailItemAsync(string mailCopyId)
    {
        var query = new Query("MailCopy")
                       .Where("MailCopy.Id", mailCopyId)
                       .SelectRaw("MailCopy.*")
                       .GetRawQuery();

        var mailCopy = await Connection.FindWithQueryAsync<MailCopy>(query);
        if (mailCopy == null) return null;

        await LoadAssignedPropertiesAsync(mailCopy).ConfigureAwait(false);

        return mailCopy;
    }

    public async Task<MailCopy> GetSingleMailItemAsync(string mailCopyId, string remoteFolderId)
    {
        var query = new Query("MailCopy")
                        .Join("MailItemFolder", "MailCopy.FolderId", "MailItemFolder.Id")
                        .Where("MailCopy.Id", mailCopyId)
                        .Where("MailItemFolder.RemoteFolderId", remoteFolderId)
                        .SelectRaw("MailCopy.*")
                        .GetRawQuery();

        var mailItem = await Connection.FindWithQueryAsync<MailCopy>(query);

        if (mailItem == null) return null;

        await LoadAssignedPropertiesAsync(mailItem).ConfigureAwait(false);

        return mailItem;
    }

    public async Task<MailCopy> GetSingleMailItemAsync(Guid uniqueMailId)
    {
        var mailItem = await Connection.FindAsync<MailCopy>(uniqueMailId);

        if (mailItem == null) return null;

        await LoadAssignedPropertiesAsync(mailItem).ConfigureAwait(false);

        return mailItem;
    }

    // v2

    public async Task DeleteMailAsync(Guid accountId, string mailCopyId)
    {
        var allMails = await GetMailItemsAsync(mailCopyId).ConfigureAwait(false);

        foreach (var mailItem in allMails)
        {
            // Delete mime file as well.
            // Even though Gmail might have multiple copies for the same mail, we only have one MIME file for all.
            // Their FileId is inserted same.

            await DeleteMailInternalAsync(mailItem, preserveMimeFile: false).ConfigureAwait(false);
        }
    }

    #region Repository Calls

    private async Task InsertMailAsync(MailCopy mailCopy)
    {
        if (mailCopy == null)
        {
            _logger.Warning("Null mail passed to InsertMailAsync call.");
            return;
        }

        if (mailCopy.FolderId == Guid.Empty)
        {
            _logger.Warning("Invalid FolderId for MailCopyId {Id} for InsertMailAsync", mailCopy.Id);
            return;
        }

        _logger.Debug("Inserting mail {MailCopyId} to {FolderName}", mailCopy.Id, mailCopy.AssignedFolder.FolderName);

        await Connection.InsertAsync(mailCopy).ConfigureAwait(false);

        ReportUIChange(new MailAddedMessage(mailCopy));
    }

    public async Task UpdateMailAsync(MailCopy mailCopy)
    {
        if (mailCopy == null)
        {
            _logger.Warning("Null mail passed to UpdateMailAsync call.");

            return;
        }

        _logger.Debug("Updating mail {MailCopyId} with Folder {FolderId}", mailCopy.Id, mailCopy.FolderId);

        await Connection.UpdateAsync(mailCopy).ConfigureAwait(false);

        ReportUIChange(new MailUpdatedMessage(mailCopy));
    }

    private async Task DeleteMailInternalAsync(MailCopy mailCopy, bool preserveMimeFile)
    {
        if (mailCopy == null)
        {
            _logger.Warning("Null mail passed to DeleteMailAsync call.");

            return;
        }

        _logger.Debug("Deleting mail {Id} from folder {FolderName}", mailCopy.Id, mailCopy.AssignedFolder.FolderName);

        await Connection.DeleteAsync(mailCopy).ConfigureAwait(false);

        // If there are no more copies exists of the same mail, delete the MIME file as well.
        var isMailExists = await IsMailExistsAsync(mailCopy.Id).ConfigureAwait(false);

        if (!isMailExists && !preserveMimeFile)
        {
            await _mimeFileService.DeleteMimeMessageAsync(mailCopy.AssignedAccount.Id, mailCopy.FileId).ConfigureAwait(false);
        }

        ReportUIChange(new MailRemovedMessage(mailCopy));
    }

    #endregion

    private async Task UpdateAllMailCopiesAsync(string mailCopyId, Func<MailCopy, bool> action)
    {
        var mailCopies = await GetMailItemsAsync(mailCopyId);

        if (mailCopies == null || !mailCopies.Any())
        {
            _logger.Warning("Updating mail copies failed because there are no copies available with Id {MailCopyId}", mailCopyId);

            return;
        }

        _logger.Debug("Updating {MailCopyCount} mail copies with Id {MailCopyId}", mailCopies.Count, mailCopyId);

        foreach (var mailCopy in mailCopies)
        {
            bool shouldUpdateItem = action(mailCopy);

            if (shouldUpdateItem)
            {
                await UpdateMailAsync(mailCopy).ConfigureAwait(false);
            }
            else
                _logger.Debug("Skipped updating mail because it is already in the desired state.");
        }
    }

    public Task ChangeReadStatusAsync(string mailCopyId, bool isRead)
        => UpdateAllMailCopiesAsync(mailCopyId, (item) =>
        {
            if (item.IsRead == isRead) return false;

            item.IsRead = isRead;
            if (isRead && item.UniqueId != Guid.Empty)
            {
                WeakReferenceMessenger.Default.Send(new MailReadStatusChanged(item.UniqueId));
            }

            return true;
        });

    public Task ChangeFlagStatusAsync(string mailCopyId, bool isFlagged)
        => UpdateAllMailCopiesAsync(mailCopyId, (item) =>
        {
            if (item.IsFlagged == isFlagged) return false;

            item.IsFlagged = isFlagged;

            return true;
        });

    public async Task CreateAssignmentAsync(Guid accountId, string mailCopyId, string remoteFolderId)
    {
        // Note: Folder might not be available at the moment due to user not syncing folders before the delta processing.
        // This is a problem, because assignments won't be created.
        // Therefore we sync folders every time before the delta processing.

        var localFolder = await _folderService.GetFolderAsync(accountId, remoteFolderId);

        if (localFolder == null)
        {
            _logger.Warning("Local folder not found for remote folder {RemoteFolderId}", remoteFolderId);
            _logger.Warning("Skipping assignment creation for the the message {MailCopyId}", mailCopyId);

            return;
        }

        var mailCopy = await GetSingleMailItemWithoutFolderAssignmentAsync(mailCopyId);

        if (mailCopy == null)
        {
            _logger.Warning("Can't create assignment for mail {MailCopyId} because it does not exist.", mailCopyId);

            return;
        }

        if (mailCopy.AssignedFolder.SpecialFolderType == SpecialFolderType.Sent &&
            localFolder.SpecialFolderType == SpecialFolderType.Deleted)
        {
            // Sent item is deleted.
            // Gmail does not delete the sent items, but moves them to the deleted folder.
            // API doesn't allow removing Sent label.
            // Here we intercept this behavior, removing the Sent copy of the mail and adding the Deleted copy.
            // This way item will only be visible in Trash folder as in Gmail Web UI.
            // Don't delete MIME file since if exists.

            await DeleteMailInternalAsync(mailCopy, preserveMimeFile: true).ConfigureAwait(false);
        }

        // Copy one of the mail copy and assign it to the new folder.
        // We don't need to create a new MIME pack.
        // Therefore FileId is not changed for the new MailCopy.

        mailCopy.UniqueId = Guid.NewGuid();
        mailCopy.FolderId = localFolder.Id;
        mailCopy.AssignedFolder = localFolder;

        await InsertMailAsync(mailCopy).ConfigureAwait(false);
    }

    public async Task DeleteAssignmentAsync(Guid accountId, string mailCopyId, string remoteFolderId)
    {
        var mailItem = await GetSingleMailItemAsync(mailCopyId, remoteFolderId).ConfigureAwait(false);

        if (mailItem == null)
        {
            _logger.Warning("Mail not found with id {MailCopyId} with remote folder {RemoteFolderId}", mailCopyId, remoteFolderId);

            return;
        }

        var localFolder = await _folderService.GetFolderAsync(accountId, remoteFolderId);

        if (localFolder == null)
        {
            _logger.Warning("Local folder not found for remote folder {RemoteFolderId}", remoteFolderId);

            return;
        }

        await DeleteMailInternalAsync(mailItem, preserveMimeFile: false).ConfigureAwait(false);
    }

    public async Task CreateMailRawAsync(MailAccount account, MailItemFolder mailItemFolder, NewMailItemPackage package)
    {
        var mailCopy = package.Copy;
        var mimeMessage = package.Mime;

        mailCopy.UniqueId = Guid.NewGuid();
        mailCopy.AssignedAccount = account;
        mailCopy.AssignedFolder = mailItemFolder;
        mailCopy.SenderContact = await GetSenderContactForAccountAsync(account, mailCopy.FromAddress).ConfigureAwait(false);
        mailCopy.FolderId = mailItemFolder.Id;

        var mimeSaveTask = _mimeFileService.SaveMimeMessageAsync(mailCopy.FileId, mimeMessage, account.Id);
        var contactSaveTask = _contactService.SaveAddressInformationAsync(mimeMessage);
        var insertMailTask = InsertMailAsync(mailCopy);

        await Task.WhenAll(mimeSaveTask, contactSaveTask, insertMailTask).ConfigureAwait(false);
    }

    public async Task<bool> CreateMailAsync(Guid accountId, NewMailItemPackage package)
    {
        var account = await _accountService.GetAccountAsync(accountId).ConfigureAwait(false);

        if (account == null) return false;

        if (string.IsNullOrEmpty(package.AssignedRemoteFolderId))
        {
            _logger.Warning("Remote folder id is not set for {MailCopyId}.", package.Copy.Id);
            _logger.Warning("Ignoring creation of mail.");

            return false;
        }

        var assignedFolder = await _folderService.GetFolderAsync(accountId, package.AssignedRemoteFolderId).ConfigureAwait(false);

        if (assignedFolder == null)
        {
            _logger.Warning("Assigned folder not found for {MailCopyId}.", package.Copy.Id);
            _logger.Warning("Ignoring creation of mail.");

            return false;
        }

        var mailCopy = package.Copy;
        var mimeMessage = package.Mime;

        mailCopy.UniqueId = Guid.NewGuid();
        mailCopy.AssignedAccount = account;
        mailCopy.AssignedFolder = assignedFolder;
        mailCopy.SenderContact = await GetSenderContactForAccountAsync(account, mailCopy.FromAddress).ConfigureAwait(false);
        mailCopy.FolderId = assignedFolder.Id;

        // Only save MIME files if they don't exists.
        // This is because 1 mail may have multiple copies in different folders.
        // but only single MIME to represent all.

        // Save mime file to disk.
        var isMimeExists = await _mimeFileService.IsMimeExistAsync(accountId, mailCopy.FileId).ConfigureAwait(false);

        if (!isMimeExists)
        {
            bool isMimeSaved = await _mimeFileService.SaveMimeMessageAsync(mailCopy.FileId, mimeMessage, accountId).ConfigureAwait(false);

            if (!isMimeSaved)
            {
                _logger.Warning("Failed to save mime file for {MailCopyId}.", mailCopy.Id);
            }
        }

        // Save contact information.
        await _contactService.SaveAddressInformationAsync(mimeMessage).ConfigureAwait(false);

        // Create mail copy in the database.
        // Update if exists.

        var existingCopyItem = await Connection.Table<MailCopy>()
                                                .FirstOrDefaultAsync(a => a.Id == mailCopy.Id && a.FolderId == assignedFolder.Id);

        if (existingCopyItem != null)
        {
            mailCopy.UniqueId = existingCopyItem.UniqueId;

            await UpdateMailAsync(mailCopy).ConfigureAwait(false);

            return false;
        }
        else
        {
            if (account.ProviderType != MailProviderType.Gmail)
            {
                // Make sure there is only 1 instance left of this mail copy id.
                var allMails = await GetMailItemsAsync(mailCopy.Id).ConfigureAwait(false);

                await DeleteMailAsync(accountId, mailCopy.Id).ConfigureAwait(false);
            }

            await InsertMailAsync(mailCopy).ConfigureAwait(false);

            return true;
        }
    }

    private async Task<MimeMessage> CreateDraftMimeAsync(MailAccount account, DraftCreationOptions draftCreationOptions)
    {
        // This unique id is stored in mime headers for Wino to identify remote message with local copy.
        // Same unique id will be used for the local copy as well.
        // Synchronizer will map this unique id to the local draft copy after synchronization.

        var message = new MimeMessage()
        {
            Headers = { { Constants.WinoLocalDraftHeader, Guid.NewGuid().ToString() } },
        };

        var primaryAlias = await _accountService.GetPrimaryAccountAliasAsync(account.Id) ?? throw new MissingAliasException();

        // Set FromName and FromAddress by alias.
        message.From.Add(new MailboxAddress(account.SenderName, primaryAlias.AliasAddress));

        var builder = new BodyBuilder();

        var signature = await GetSignature(account, draftCreationOptions.Reason);

        _ = draftCreationOptions.Reason switch
        {
            DraftCreationReason.Empty => CreateEmptyDraft(builder, message, draftCreationOptions, signature),
            _ => CreateReferencedDraft(builder, message, draftCreationOptions, account, signature),
        };

        // TODO: Migration
        // builder.SetHtmlBody(builder.HtmlBody);

        message.Body = builder.ToMessageBody();

        return message;
    }

    private string CreateHtmlGap()
    {
        var template = $"""<div style="font-family: '{_preferencesService.ComposerFont}', Arial, sans-serif; font-size: {_preferencesService.ComposerFontSize}px"><br></div>""";
        return string.Concat(Enumerable.Repeat(template, 2));
    }

    private async Task<string> GetSignature(MailAccount account, DraftCreationReason reason)
    {
        if (account.Preferences.IsSignatureEnabled)
        {
            var signatureId = reason == DraftCreationReason.Empty ?
                account.Preferences.SignatureIdForNewMessages :
                account.Preferences.SignatureIdForFollowingMessages;

            if (signatureId != null)
            {
                var signature = await _signatureService.GetSignatureAsync(signatureId.Value);

                return signature.HtmlBody;
            }
        }

        return null;
    }

    private MimeMessage CreateEmptyDraft(BodyBuilder builder, MimeMessage message, DraftCreationOptions draftCreationOptions, string signature)
    {
        builder.HtmlBody = CreateHtmlGap();
        if (draftCreationOptions.MailToUri != null)
        {
            if (draftCreationOptions.MailToUri.Subject != null)
                message.Subject = draftCreationOptions.MailToUri.Subject;

            if (draftCreationOptions.MailToUri.Body != null)
            {
                // TODO: In .NET 6+ replace with string "ReplaceLineEndings" method.
                var escapedBody = draftCreationOptions.MailToUri.Body.Replace("\r\n", "<br>").Replace("\n", "<br>").Replace("\r", "<br>");
                builder.HtmlBody = $"""<div style="font-family: '{_preferencesService.ComposerFont}', Arial, sans-serif; font-size: {_preferencesService.ComposerFontSize}px">{escapedBody}</div>""" + builder.HtmlBody;
            }

            if (draftCreationOptions.MailToUri.To.Any())
                message.To.AddRange(draftCreationOptions.MailToUri.To.Select(x => new MailboxAddress(x, x)));

            if (draftCreationOptions.MailToUri.Cc.Any())
                message.Cc.AddRange(draftCreationOptions.MailToUri.Cc.Select(x => new MailboxAddress(x, x)));

            if (draftCreationOptions.MailToUri.Bcc.Any())
                message.Bcc.AddRange(draftCreationOptions.MailToUri.Bcc.Select(x => new MailboxAddress(x, x)));
        }

        if (signature != null)
            builder.HtmlBody += signature;

        return message;
    }

    private MimeMessage CreateReferencedDraft(BodyBuilder builder, MimeMessage message, DraftCreationOptions draftCreationOptions, MailAccount account, string signature)
    {
        var reason = draftCreationOptions.Reason;
        var referenceMessage = draftCreationOptions.ReferencedMessage.MimeMessage;

        var gap = CreateHtmlGap();
        builder.HtmlBody = gap + CreateHtmlForReferencingMessage(referenceMessage);

        if (signature != null)
        {
            builder.HtmlBody = gap + signature + builder.HtmlBody;
        }

        // Manage "To"
        if (reason == DraftCreationReason.Reply || reason == DraftCreationReason.ReplyAll)
        {
            // Reply to the sender of the message
            if (referenceMessage.ReplyTo.Count > 0)
                message.To.AddRange(referenceMessage.ReplyTo);
            else if (referenceMessage.From.Count > 0)
                message.To.AddRange(referenceMessage.From);
            else if (referenceMessage.Sender != null)
                message.To.Add(referenceMessage.Sender);

            if (reason == DraftCreationReason.ReplyAll)
            {
                // Include all of the other original recipients
                message.To.AddRange(referenceMessage.To.Where(x => x is MailboxAddress mailboxAddress && !mailboxAddress.Address.Equals(account.Address, StringComparison.OrdinalIgnoreCase)));
                message.Cc.AddRange(referenceMessage.Cc.Where(x => x is MailboxAddress mailboxAddress && !mailboxAddress.Address.Equals(account.Address, StringComparison.OrdinalIgnoreCase)));
            }

            // Self email can be present at this step, when replying to own message. It should be removed only in case there no other recipients.
            if (message.To.Count > 1)
            {
                var self = message.To.FirstOrDefault(x => x is MailboxAddress mailboxAddress && mailboxAddress.Address.Equals(account.Address, StringComparison.OrdinalIgnoreCase));
                if (self != null)
                    message.To.Remove(self);
            }

            // Manage "ThreadId-ConversationId"
            if (!string.IsNullOrEmpty(referenceMessage.MessageId))
            {
                message.InReplyTo = referenceMessage.MessageId;
                message.References.AddRange(referenceMessage.References);
                message.References.Add(referenceMessage.MessageId);
            }

            message.Headers.Add("Thread-Topic", referenceMessage.Subject);
        }

        // Manage Subject
        if (reason == DraftCreationReason.Forward && !referenceMessage.Subject.StartsWith("FW: ", StringComparison.OrdinalIgnoreCase))
            message.Subject = $"FW: {referenceMessage.Subject}";
        else if ((reason == DraftCreationReason.Reply || reason == DraftCreationReason.ReplyAll) && !referenceMessage.Subject.StartsWith("RE: ", StringComparison.OrdinalIgnoreCase))
            message.Subject = $"RE: {referenceMessage.Subject}";
        else if (referenceMessage != null)
            message.Subject = referenceMessage.Subject;

        // Only include attachments if forwarding.
        if (reason == DraftCreationReason.Forward && (referenceMessage?.Attachments?.Any() ?? false))
        {
            foreach (var attachment in referenceMessage.Attachments)
            {
                builder.Attachments.Add(attachment);
            }
        }

        return message;

        // Generates html representation of To/Cc/From/Time and so on from referenced message.
        string CreateHtmlForReferencingMessage(MimeMessage referenceMessage)
        {
            var htmlMimeInfo = string.Empty;
            // Separation Line
            htmlMimeInfo += "<hr style='display:inline-block;width:100%' tabindex='-1'>";

            var visitor = _mimeFileService.CreateHTMLPreviewVisitor(referenceMessage, string.Empty);
            visitor.Visit(referenceMessage);

            htmlMimeInfo += $"""
                <div id="divRplyFwdMsg" dir="ltr">
                  <font face="Calibri, sans-serif" style="font-size: 11pt;" color="#000000">
                    <b>From:</b> {ParticipantsToHtml(referenceMessage.From)}<br>
                    <b>Sent:</b> {referenceMessage.Date.ToLocalTime()}<br>
                    <b>To:</b> {ParticipantsToHtml(referenceMessage.To)}<br>
                    {(referenceMessage.Cc.Count > 0 ? $"<b>Cc:</b> {ParticipantsToHtml(referenceMessage.Cc)}<br>" : string.Empty)}
                    <b>Subject:</b> {referenceMessage.Subject}
                  </font>
                  <div>&nbsp;</div>
                  {visitor.HtmlBody}
                </div>
                """;

            return htmlMimeInfo;
        }

        static string ParticipantsToHtml(InternetAddressList internetAddresses) =>
            string.Join("; ", internetAddresses.Mailboxes
                                        .Select(x => $"{x.Name ?? Translator.UnknownSender} &lt;<a href=\"mailto:{x.Address ?? Translator.UnknownAddress}\">{x.Address ?? Translator.UnknownAddress}</a>&gt;"));
    }

    public async Task<bool> MapLocalDraftAsync(Guid accountId, Guid localDraftCopyUniqueId, string newMailCopyId, string newDraftId, string newThreadId)
    {
        var query = new Query("MailCopy")
                        .Join("MailItemFolder", "MailCopy.FolderId", "MailItemFolder.Id")
                        .Where("MailCopy.UniqueId", localDraftCopyUniqueId)
                        .Where("MailItemFolder.MailAccountId", accountId)
                        .SelectRaw("MailCopy.*")
                        .GetRawQuery();

        var localDraftCopy = await Connection.FindWithQueryAsync<MailCopy>(query);

        if (localDraftCopy == null)
        {
            _logger.Warning("Draft mapping failed because local draft copy with unique id {LocalDraftCopyUniqueId} does not exist.", localDraftCopyUniqueId);

            return false;
        }

        var oldLocalDraftId = localDraftCopy.Id;

        await LoadAssignedPropertiesAsync(localDraftCopy).ConfigureAwait(false);

        bool isIdChanging = localDraftCopy.Id != newMailCopyId;

        localDraftCopy.Id = newMailCopyId;
        localDraftCopy.DraftId = newDraftId;
        localDraftCopy.ThreadId = newThreadId;

        await UpdateMailAsync(localDraftCopy).ConfigureAwait(false);

        ReportUIChange(new DraftMapped(oldLocalDraftId, newDraftId));

        return true;
    }

    public Task MapLocalDraftAsync(string mailCopyId, string newDraftId, string newThreadId)
    {
        return UpdateAllMailCopiesAsync(mailCopyId, (item) =>
        {
            if (item.ThreadId != newThreadId || item.DraftId != newDraftId)
            {
                var oldDraftId = item.DraftId;

                item.DraftId = newDraftId;
                item.ThreadId = newThreadId;

                ReportUIChange(new DraftMapped(oldDraftId, newDraftId));

                return true;
            }

            return false;
        });
    }

    public Task<List<MailCopy>> GetDownloadedUnreadMailsAsync(Guid accountId, IEnumerable<string> downloadedMailCopyIds)
    {
        var rawQuery = new Query("MailCopy")
                        .Join("MailItemFolder", "MailCopy.FolderId", "MailItemFolder.Id")
                        .WhereIn("MailCopy.Id", downloadedMailCopyIds)
                        .Where("MailCopy.IsRead", false)
                        .Where("MailItemFolder.MailAccountId", accountId)
                        .Where("MailItemFolder.SpecialFolderType", SpecialFolderType.Inbox)
                        .SelectRaw("MailCopy.*")
                        .GetRawQuery();

        return Connection.QueryAsync<MailCopy>(rawQuery);
    }

    public Task<MailAccount> GetMailAccountByUniqueIdAsync(Guid uniqueMailId)
    {
        var query = new Query("MailCopy")
                        .Join("MailItemFolder", "MailCopy.FolderId", "MailItemFolder.Id")
                        .Join("MailAccount", "MailItemFolder.MailAccountId", "MailAccount.Id")
                        .Where("MailCopy.UniqueId", uniqueMailId)
                        .SelectRaw("MailAccount.*")
                        .GetRawQuery();

        return Connection.FindWithQueryAsync<MailAccount>(query);
    }

    public Task<bool> IsMailExistsAsync(string mailCopyId)
        => Connection.ExecuteScalarAsync<bool>("SELECT EXISTS(SELECT 1 FROM MailCopy WHERE Id = ?)", mailCopyId);

    public async Task<List<MailCopy>> GetExistingMailsAsync(Guid folderId, IEnumerable<MailKit.UniqueId> uniqueIds)
    {
        var localMailIds = uniqueIds.Where(a => a != null).Select(a => MailkitClientExtensions.CreateUid(folderId, a.Id)).ToArray();

        var query = new Query(nameof(MailCopy))
                        .WhereIn("Id", localMailIds)
                        .GetRawQuery();

        return await Connection.QueryAsync<MailCopy>(query);
    }

    public Task<bool> IsMailExistsAsync(string mailCopyId, Guid folderId)
        => Connection.ExecuteScalarAsync<bool>("SELECT EXISTS(SELECT 1 FROM MailCopy WHERE Id = ? AND FolderId = ?)", mailCopyId, folderId);

    public async Task<GmailArchiveComparisonResult> GetGmailArchiveComparisonResultAsync(Guid archiveFolderId, List<string> onlineArchiveMailIds)
    {
        var localArchiveMails = await Connection.Table<MailCopy>()
                                            .Where(a => a.FolderId == archiveFolderId)
                                            .ToListAsync().ConfigureAwait(false);

        var removedMails = localArchiveMails.Where(a => !onlineArchiveMailIds.Contains(a.Id)).Select(a => a.Id).Distinct().ToArray();
        var addedMails = onlineArchiveMailIds.Where(a => !localArchiveMails.Select(b => b.Id).Contains(a)).Distinct().ToArray();

        return new GmailArchiveComparisonResult(addedMails, removedMails);
    }

    public async Task<List<MailCopy>> GetMailItemsAsync(IEnumerable<string> mailCopyIds)
    {
        if (!mailCopyIds.Any()) return [];

        var query = new Query("MailCopy")
                       .WhereIn("MailCopy.Id", mailCopyIds)
                       .SelectRaw("MailCopy.*")
                       .GetRawQuery();

        var mailCopies = await Connection.QueryAsync<MailCopy>(query);
        if (mailCopies?.Count == 0) return [];

        Dictionary<Guid, MailItemFolder> folderCache = [];
        Dictionary<Guid, MailAccount> accountCache = [];
        Dictionary<string, AccountContact> contactCache = [];

        foreach (var mail in mailCopies)
        {
            await LoadAssignedPropertiesWithCacheAsync(mail, folderCache, accountCache, contactCache).ConfigureAwait(false);
        }

        return mailCopies;
    }

    public async Task<List<string>> AreMailsExistsAsync(IEnumerable<string> mailCopyIds)
    {
        var query = new Query(nameof(MailCopy))
                        .WhereIn("Id", mailCopyIds)
                        .Select("Id")
                        .GetRawQuery();

        return await Connection.QueryScalarsAsync<string>(query);
    }
}