EmailSearch/EmailSearch/Agents/EmailWatcherAgent.cs

using Microsoft.Extensions.Hosting;
using System.Net.Http.Json;
using NetOffice.OutlookApi;
using NetOffice.OutlookApi.Enums;
using EmailSearch.SpamDetection;
using OutlookApp = NetOffice.OutlookApi.Application;
using Exception = System.Exception;

namespace EmailSearch.Agents;

/// <summary>
/// Background agent that watches for new emails and sends notifications
/// when interesting emails arrive (e.g., high-priority, from specific senders, or spam detected).
/// </summary>
public class EmailWatcherAgent : BackgroundService
{
    private readonly EmailWatcherConfig _config;
    private readonly HttpClient _httpClient;
    private readonly SpamDetector _spamDetector;
    private OutlookApp? _outlookApp;
    private _NameSpace? _namespace;
    private MAPIFolder? _watchFolder;
    private Items? _items;

    public EmailWatcherAgent(EmailWatcherConfig config)
    {
        _config = config;
        _httpClient = new HttpClient();
        _spamDetector = new SpamDetector();
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        Console.WriteLine($"[EmailWatcher] Starting... watching folder: {_config.WatchFolder}");

        try
        {
            InitializeOutlook();
            Console.WriteLine("[EmailWatcher] Connected to Outlook. Waiting for new emails...");

            // Keep service alive
            while (!stoppingToken.IsCancellationRequested)
            {
                await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[EmailWatcher] Error: {ex.Message}");
        }
    }

    private void InitializeOutlook()
    {
        _outlookApp = new OutlookApp();
        _namespace = _outlookApp.GetNamespace("MAPI");

        // Get the folder to watch
        _watchFolder = _config.WatchFolder.Equals("Inbox", StringComparison.OrdinalIgnoreCase)
            ? _namespace.GetDefaultFolder(OlDefaultFolders.olFolderInbox)
            : FindFolder(_namespace, _config.WatchFolder);

        if (_watchFolder == null)
            throw new Exception($"Folder '{_config.WatchFolder}' not found");

        _items = (Items)_watchFolder.Items;

        // Subscribe to new email events
        _items.ItemAddEvent += OnNewEmailReceived;

        Console.WriteLine($"[EmailWatcher] Watching folder: {_watchFolder.Name}");
    }

    private void OnNewEmailReceived(object item)
    {
        if (item is not MailItem mail)
            return;

        try
        {
            Console.WriteLine($"[EmailWatcher] New email: {mail.Subject}");

            // Check if this email is "interesting" based on configured rules
            var notification = EvaluateEmail(mail);

            if (notification != null)
            {
                // Fire and forget the notification
                _ = Task.Run(() => SendNotificationAsync(notification));
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[EmailWatcher] Error processing email: {ex.Message}");
        }
    }

    private NotificationPayload? EvaluateEmail(MailItem mail)
    {
        var subject = mail.Subject ?? "(No Subject)";
        var sender = mail.SenderName ?? mail.SenderEmailAddress ?? "Unknown";
        var senderEmail = mail.SenderEmailAddress ?? "";

        // Rule 1: High importance emails
        if (_config.NotifyOnHighImportance && mail.Importance == OlImportance.olImportanceHigh)
        {
            return new NotificationPayload
            {
                Title = "High Priority Email",
                Message = $"From: {sender}\n{subject}",
                Priority = 8
            };
        }

        // Rule 2: Specific senders
        if (_config.WatchedSenders.Any(s =>
            senderEmail.Contains(s, StringComparison.OrdinalIgnoreCase) ||
            sender.Contains(s, StringComparison.OrdinalIgnoreCase)))
        {
            return new NotificationPayload
            {
                Title = $"Email from {sender}",
                Message = subject,
                Priority = 7
            };
        }

        // Rule 3: Keyword matches in subject
        var matchedKeyword = _config.WatchedKeywords
            .FirstOrDefault(k => subject.Contains(k, StringComparison.OrdinalIgnoreCase));

        if (matchedKeyword != null)
        {
            return new NotificationPayload
            {
                Title = $"Email matching '{matchedKeyword}'",
                Message = $"From: {sender}\n{subject}",
                Priority = 6
            };
        }

        // Rule 4: Spam detection alert
        if (_config.NotifyOnSpam)
        {
            var spamResult = _spamDetector.Analyze(mail);
            if (spamResult.FinalScore >= _config.SpamThreshold)
            {
                return new NotificationPayload
                {
                    Title = $"Spam Detected ({spamResult.FinalScore:P0})",
                    Message = $"From: {sender}\n{subject}\nFlags: {string.Join(", ", spamResult.RedFlags.Take(3))}",
                    Priority = 5
                };
            }
        }

        // Rule 5: Notify on all emails (if enabled)
        if (_config.NotifyOnAll)
        {
            return new NotificationPayload
            {
                Title = "New Email",
                Message = $"From: {sender}\n{subject}",
                Priority = 3
            };
        }

        return null; // Not interesting
    }

    private async Task SendNotificationAsync(NotificationPayload notification)
    {
        try
        {
            if (!string.IsNullOrEmpty(_config.GotifyUrl) && !string.IsNullOrEmpty(_config.GotifyToken))
            {
                await SendGotifyAsync(notification);
            }

            if (!string.IsNullOrEmpty(_config.WebhookUrl))
            {
                await SendWebhookAsync(notification);
            }

            // Console output as fallback
            Console.WriteLine($"[NOTIFY] {notification.Title}: {notification.Message}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[EmailWatcher] Failed to send notification: {ex.Message}");
        }
    }

    private async Task SendGotifyAsync(NotificationPayload notification)
    {
        var url = $"{_config.GotifyUrl.TrimEnd('/')}/message?token={_config.GotifyToken}";

        var payload = new
        {
            title = notification.Title,
            message = notification.Message,
            priority = notification.Priority
        };

        var response = await _httpClient.PostAsJsonAsync(url, payload);

        if (!response.IsSuccessStatusCode)
        {
            Console.WriteLine($"[Gotify] Failed: {response.StatusCode}");
        }
    }

    private async Task SendWebhookAsync(NotificationPayload notification)
    {
        var payload = new
        {
            title = notification.Title,
            message = notification.Message,
            priority = notification.Priority,
            timestamp = DateTime.UtcNow
        };

        await _httpClient.PostAsJsonAsync(_config.WebhookUrl!, payload);
    }

    private static MAPIFolder? FindFolder(_NameSpace ns, string folderName)
    {
        foreach (var store in ns.Stores)
        {
            if (store is Store s)
            {
                try
                {
                    var rootFolder = s.GetRootFolder() as MAPIFolder;
                    if (rootFolder != null)
                    {
                        var found = SearchFolderRecursive(rootFolder, folderName);
                        if (found != null)
                            return found;
                    }
                }
                catch { }
            }
        }
        return null;
    }

    private static MAPIFolder? SearchFolderRecursive(MAPIFolder parent, string folderName)
    {
        foreach (var subfolder in parent.Folders)
        {
            if (subfolder is MAPIFolder folder)
            {
                if (folder.Name.Equals(folderName, StringComparison.OrdinalIgnoreCase))
                    return folder;

                var found = SearchFolderRecursive(folder, folderName);
                if (found != null)
                    return found;
            }
        }
        return null;
    }

    public override void Dispose()
    {
        Console.WriteLine("[EmailWatcher] Shutting down...");

        _items?.Dispose();
        _watchFolder?.Dispose();
        _namespace?.Dispose();
        _outlookApp?.Dispose();
        _httpClient.Dispose();

        base.Dispose();
    }
}

public class NotificationPayload
{
    public string Title { get; set; } = "";
    public string Message { get; set; } = "";
    public int Priority { get; set; } = 5; // Gotify: 1-10
}

public class EmailWatcherConfig
{
    public string WatchFolder { get; set; } = "Inbox";

    // Notification destinations
    public string? GotifyUrl { get; set; }      // e.g., "http://gotify.local:8080"
    public string? GotifyToken { get; set; }    // App token from Gotify
    public string? WebhookUrl { get; set; }     // Generic webhook endpoint

    // What to notify on
    public bool NotifyOnHighImportance { get; set; } = true;
    public bool NotifyOnSpam { get; set; } = true;
    public double SpamThreshold { get; set; } = 0.7;
    public bool NotifyOnAll { get; set; } = false;

    // Watch lists
    public List<string> WatchedSenders { get; set; } = new();   // Email addresses or names
    public List<string> WatchedKeywords { get; set; } = new();  // Subject keywords
}