using RelayClient.Crypto;
using RelayClient.Models;
using WebSocketSharp;
using System.Text.Json;

namespace RelayClient;

public partial class MainPage : ContentPage
{
    private readonly string _username;
    private readonly WebSocket _wsc;
    private string? _serverPublicKey;
    private string? _currentChannelId;
    private string? _currentChannelName;

    private readonly Dictionary<string, List<ChatMessage>> _messagesByChannel = new();
    private readonly List<ChannelItem> _channels = new();

    public MainPage(string username)
    {
        InitializeComponent();

        _username = username;
        UserLabel.Text = $"Logged in as: {_username}";
        
        if (!KeyStorage.HasKeys(_username))
        {
            var keys = E2EeHelper.GenerateRsaKeyPair();
            KeyStorage.SavePrivateKey(_username, keys.privateKey);
            KeyStorage.SavePublicKey(_username, keys.publicKey);
        }

        _wsc = new WebSocket("ws://localhost:1337/");

        _wsc.OnMessage += WscOnMessage;
        _wsc.Connect();
        
        var publicKey = KeyStorage.LoadPublicKey(_username);
        _wsc.Send($"REGISTER_KEY|{_username}|{publicKey}");
        _wsc.Send("GET_SERVER_KEY");
        _wsc.Send("GET_CHANNELS");
    }

    private void SendButton_OnClicked(object? sender, EventArgs e)
    {
        SendMessage();
    }

    private void MessageEntry_OnCompleted(object? sender, EventArgs e)
    {
        SendMessage();
    }

    private void SendMessage()
    {
        var text = MessageEntry.Text?.Trim();

        if (string.IsNullOrWhiteSpace(text))
            return;

        if (string.IsNullOrWhiteSpace(_serverPublicKey))
        {
            Console.WriteLine("Server public key not loaded yet.");
            return;
        }

        var encrypted = E2EeHelper.EncryptForRecipient(text, _serverPublicKey);

        var payload = new SocketEncryptedMessage
        {
            ChannelId = _currentChannelId!,
            Type = "client_encrypted_chat",
            SenderUsername = _username,
            CipherText = encrypted.CipherText,
            Nonce = encrypted.Nonce,
            Tag = encrypted.Tag,
            EncryptedKey = encrypted.EncryptedKey
        };

        var json = JsonSerializer.Serialize(payload);
        _wsc.Send(json);

        Console.WriteLine($"[{_username}] sent encrypted message.");

        MessageEntry.Text = string.Empty;
        MessageEntry.Focus();
    }

    private void WscOnMessage(object? sender, MessageEventArgs e)
    {
        if (e.Data.StartsWith("SERVER:REGISTERED_KEY:"))
        {
            Console.WriteLine(e.Data);
            return;
        }

        Console.WriteLine($"[{_username}] RAW WS DATA: {e.Data}");

        try
        {
            using var doc = JsonDocument.Parse(e.Data);
            var root = doc.RootElement;

            if (!root.TryGetProperty("Type", out var typeElement))
                return;

            var type = typeElement.GetString();

            if (type == "channel_list")
            {
                var channelList = JsonSerializer.Deserialize<SocketChannelList>(e.Data);
                if (channelList is null)
                    return;

                _channels.Clear();
                _channels.AddRange(channelList.Channels.OrderBy(c => c.CreatedAt));

                var defaultChannel = _channels
                                         .Where(c => c.Name.Equals("welcome", StringComparison.OrdinalIgnoreCase))
                                         .OrderBy(c => c.CreatedAt)
                                         .FirstOrDefault()
                                     ?? _channels.OrderBy(c => c.CreatedAt).FirstOrDefault();

                if (defaultChannel is not null)
                {
                    _currentChannelId = defaultChannel.ChannelId;
                    _currentChannelName = defaultChannel.Name;

                    MainThread.BeginInvokeOnMainThread(() =>
                    {
                        ChannelLabel.Text = $"#{_currentChannelName}";
                        RenderChannelList();
                    });

                    _wsc.Send($"GET_HISTORY|{_username}|{_currentChannelId}");
                }

                return;
            }

            if (type == "server_public_key")
            {
                var serverKeyMessage = JsonSerializer.Deserialize<ServerPublicKeyMessage>(e.Data);
                if (serverKeyMessage is not null)
                {
                    _serverPublicKey = serverKeyMessage.PublicKey;
                    Console.WriteLine($"[{_username}] loaded server public key.");
                }

                return;
            }

            if (type != "encrypted_chat")
                return;

            var payload = JsonSerializer.Deserialize<SocketEncryptedMessage>(e.Data);
            if (payload is null)
                return;

            if (payload.RecipientUsername != _username)
                return;

            Console.WriteLine($"[{_username}] received encrypted payload for {payload.RecipientUsername}");

            var privateKey = KeyStorage.LoadPrivateKey(_username);

            var decryptedText = E2EeHelper.DecryptForRecipient(
                new EncryptedPayload
                {
                    CipherText = payload.CipherText,
                    Nonce = payload.Nonce,
                    Tag = payload.Tag,
                    EncryptedKey = payload.EncryptedKey
                },
                privateKey
            );

            Console.WriteLine($"[{_username}] decrypted message from {payload.SenderUsername}: {decryptedText}");

            var message = new ChatMessage
            {
                SenderUsername = payload.SenderUsername,
                Text = decryptedText,
                Timestamp = DateTime.Now
            };

            if (!_messagesByChannel.ContainsKey(payload.ChannelId))
            {
                _messagesByChannel[payload.ChannelId] = [];
            }

            _messagesByChannel[payload.ChannelId].Add(message);

            if (payload.ChannelId == _currentChannelId)
            {
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    RenderSingleMessage(message);
                });
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[{_username}] failed to process websocket message: {ex.Message}");
        }
    }

    protected override void OnDisappearing()
    {
        _wsc.OnMessage -= WscOnMessage;
        _wsc.Close();
        base.OnDisappearing();
    }
    
    private void RenderChannelList()
    {
        SidebarList.Children.Clear();

        foreach (var channel in _channels.OrderBy(c => c.CreatedAt))
        {
            var button = new Button
            {
                Text = $"#{channel.Name}"
            };

            button.Clicked += (_, _) =>
            {
                _currentChannelId = channel.ChannelId;
                _currentChannelName = channel.Name;

                ChannelLabel.Text = $"#{_currentChannelName}";
                RenderCurrentChannelMessages();

                if (!_messagesByChannel.ContainsKey(channel.ChannelId))
                {
                    _wsc.Send($"GET_HISTORY|{_username}|{channel.ChannelId}");
                }
            };

            SidebarList.Children.Add(button);
        }
    }
    
    private void RenderCurrentChannelMessages()
    {
        MessagesLayout.Children.Clear();

        if (_currentChannelId is null)
            return;

        if (!_messagesByChannel.TryGetValue(_currentChannelId, out var messages))
            return;

        foreach (var message in messages.OrderBy(m => m.Timestamp))
        {
            RenderSingleMessage(message);
        }
    }
        
    private async void RenderSingleMessage(ChatMessage message)
    {
        bool isOwnMessage = message.SenderUsername == _username;

        var bubble = new Border
        {
            StrokeThickness = 1,
            Padding = 10,
            Margin = isOwnMessage
                ? new Thickness(40, 0, 0, 0)
                : new Thickness(0, 0, 40, 0),
            HorizontalOptions = isOwnMessage
                ? LayoutOptions.End
                : LayoutOptions.Start,
            Content = new VerticalStackLayout
            {
                Spacing = 2,
                Children =
                {
                    new Label { Text = message.SenderUsername, FontAttributes = FontAttributes.Bold, FontSize = 12 },
                    new Label { Text = message.Text, FontSize = 14 },
                    new Label { Text = message.Timestamp.ToString("h:mm tt"), FontSize = 10 }
                }
            }
        };

        MessagesLayout.Children.Add(bubble);
        await MessagesScrollView.ScrollToAsync(MessagesLayout, ScrollToPosition.End, true);
    }
}