using System.Collections.ObjectModel;
using EchoHub.Client.Config;
using Terminal.Gui.App;
using Terminal.Gui.Views;
using Terminal.Gui.ViewBase;

namespace EchoHub.Client.UI.Dialogs;

/// <summary>
/// Result returned from the connect dialog.
/// </summary>
public record ConnectDialogResult(
    string ServerUrl, string Username, string Password,
    bool IsRegister, bool RememberMe, string? SavedRefreshToken);

/// <summary>
/// A Terminal.Gui dialog for entering server connection and authentication details.
/// Includes a saved servers selector when saved servers are available.
/// </summary>
public sealed class ConnectDialog
{
    /// <summary>
    /// Shows the connect dialog with an optional list of saved servers.
    /// Returns the result, or null if cancelled.
    /// </summary>
    public static ConnectDialogResult? Show(IApplication app, List<SavedServer>? savedServers = null)
    {
        ConnectDialogResult? result = null;
        savedServers ??= [];

        var hasSavedServers = savedServers.Count > 0;
        var dialogHeight = hasSavedServers ? 22 : 18;

        var dialog = new Dialog { Title = "Connect to Server", Width = 60, Height = dialogHeight };

        int yOffset = 0;
        SavedServer? selectedSavedServer = null;

        // -- Saved Servers section (if any) -----------------------------------
        ListView? savedServerList = null;
        if (hasSavedServers)
        {
            var savedLabel = new Label
            {
                Text = "Saved Servers:",
                X = 1,
                Y = 1
            };
            dialog.Add(savedLabel);

            var serverDisplayNames = savedServers
                .Select(s =>
                {
                    var session = !string.IsNullOrEmpty(s.RefreshToken) ? " [session]" : "";
                    return $"{s.Name} ({s.Username ?? "?"}){session}";
                })
                .ToList();

            savedServerList = new ListView
            {
                Source = new ListWrapper<string>(new ObservableCollection<string>(serverDisplayNames)),
                X = 1,
                Y = 2,
                Width = Dim.Fill(2),
                Height = 3
            };
            dialog.Add(savedServerList);

            // Visual separator
            var separator = new Label
            {
                Text = new string('-', 56),
                X = 1,
                Y = 5
            };
            dialog.Add(separator);

            yOffset = 5;
        }

        // -- Manual entry fields ----------------------------------------------
        var urlLabel = new Label
        {
            Text = "Server URL:",
            X = 1,
            Y = yOffset + 1
        };
        var urlField = new TextField
        {
            Text = "http://localhost:5000",
            X = 15,
            Y = yOffset + 1,
            Width = Dim.Fill(2)
        };

        var userLabel = new Label
        {
            Text = "Username:",
            X = 1,
            Y = yOffset + 3
        };
        var userField = new TextField
        {
            Text = "",
            X = 15,
            Y = yOffset + 3,
            Width = Dim.Fill(2)
        };

        var passLabel = new Label
        {
            Text = "Password:",
            X = 1,
            Y = yOffset + 5
        };
        var passField = new TextField
        {
            Text = "",
            X = 15,
            Y = yOffset + 5,
            Width = Dim.Fill(2),
            Secret = true
        };

        var tokenHintLabel = new Label
        {
            Text = "Session saved \u2014 password optional",
            X = 15,
            Y = yOffset + 6,
            Width = Dim.Fill(2),
            Visible = false
        };

        var rememberMeCheckbox = new CheckBox
        {
            Text = "Remember me",
            X = 15,
            Y = yOffset + 7,
            Value = CheckState.UnChecked
        };

        var displayLabel = new Label
        {
            Text = "Display Name:",
            X = 1,
            Y = yOffset + 9
        };
        var displayField = new TextField
        {
            Text = "",
            X = 15,
            Y = yOffset + 9,
            Width = Dim.Fill(2)
        };

        var loginButton = new Button
        {
            Text = "Login",
            IsDefault = true,
            X = Pos.Center() - 20,
            Y = yOffset + 11
        };

        var registerButton = new Button
        {
            Text = "Register",
            X = Pos.Center() - 5,
            Y = yOffset + 11
        };

        var cancelButton = new Button
        {
            Text = "Cancel",
            X = Pos.Center() + 10,
            Y = yOffset + 11
        };

        // Wire saved server selection to auto-fill fields
        if (savedServerList is not null && savedServers.Count > 0)
        {
            savedServerList.ValueChanged += (sender, e) =>
            {
                var index = e.NewValue;
                if (index.HasValue && index.Value >= 0 && index.Value < savedServers.Count)
                {
                    selectedSavedServer = savedServers[index.Value];
                    urlField.Text = selectedSavedServer.Url;
                    userField.Text = selectedSavedServer.Username ?? "";
                    rememberMeCheckbox.Value = selectedSavedServer.RememberMe
                        ? CheckState.Checked : CheckState.UnChecked;

                    if (!string.IsNullOrEmpty(selectedSavedServer.RefreshToken))
                    {
                        passField.Text = "";
                        tokenHintLabel.Visible = true;
                    }
                    else
                    {
                        tokenHintLabel.Visible = false;
                    }
                }
            };

            // Pre-fill with the first saved server
            selectedSavedServer = savedServers[0];
            urlField.Text = savedServers[0].Url;
            userField.Text = savedServers[0].Username ?? "";
            rememberMeCheckbox.Value = savedServers[0].RememberMe
                ? CheckState.Checked : CheckState.UnChecked;
            if (!string.IsNullOrEmpty(savedServers[0].RefreshToken))
                tokenHintLabel.Visible = true;
        }

        loginButton.Accepting += (s, e) =>
        {
            var url = urlField.Text?.Trim() ?? string.Empty;
            var user = userField.Text?.Trim() ?? string.Empty;
            var pass = passField.Text ?? string.Empty;
            var rememberMe = rememberMeCheckbox.Value == CheckState.Checked;

            if (string.IsNullOrEmpty(url) || string.IsNullOrEmpty(user))
            {
                MessageBox.ErrorQuery(app, "Validation", "Server URL and username are required.", "OK");
                e.Handled = true;
                return;
            }

            // Determine if we can use a saved token
            string? savedRefreshToken = null;
            if (string.IsNullOrEmpty(pass)
                && selectedSavedServer is not null
                && !string.IsNullOrEmpty(selectedSavedServer.RefreshToken)
                && string.Equals(selectedSavedServer.Url, url, StringComparison.OrdinalIgnoreCase)
                && string.Equals(selectedSavedServer.Username, user, StringComparison.OrdinalIgnoreCase))
            {
                savedRefreshToken = selectedSavedServer.RefreshToken;
            }

            if (string.IsNullOrEmpty(pass) && savedRefreshToken is null)
            {
                MessageBox.ErrorQuery(app, "Validation", "Password is required.", "OK");
                e.Handled = true;
                return;
            }

            result = new ConnectDialogResult(url, user, pass, IsRegister: false, rememberMe, savedRefreshToken);
            e.Handled = true;
            app.RequestStop();
        };

        registerButton.Accepting += (s, e) =>
        {
            var url = urlField.Text?.Trim() ?? string.Empty;
            var user = userField.Text?.Trim() ?? string.Empty;
            var pass = passField.Text ?? string.Empty;
            var rememberMe = rememberMeCheckbox.Value == CheckState.Checked;

            if (string.IsNullOrEmpty(url) || string.IsNullOrEmpty(user) || string.IsNullOrEmpty(pass))
            {
                MessageBox.ErrorQuery(app, "Validation", "Server URL, username, and password are required.", "OK");
                e.Handled = true;
                return;
            }

            result = new ConnectDialogResult(url, user, pass, IsRegister: true, rememberMe, SavedRefreshToken: null);
            e.Handled = true;
            app.RequestStop();
        };

        cancelButton.Accepting += (s, e) =>
        {
            result = null;
            e.Handled = true;
            app.RequestStop();
        };

        dialog.Add(urlLabel, urlField, userLabel, userField, passLabel, passField,
            tokenHintLabel, rememberMeCheckbox, displayLabel, displayField,
            loginButton, registerButton, cancelButton);

        if (hasSavedServers && savedServerList is not null)
            savedServerList.SetFocus();
        else
            urlField.SetFocus();

        app.Run(dialog);

        return result;
    }
}