chameleon/Assets/Scripts/Network/UI/OnlineSessionBrowserUI.cs

using System.Collections.Generic;
using TMPro;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

/// <summary>
/// uGUI binding for <see cref="OnlineSessionManager"/>: Host / Refresh / row select / Join / Disconnect
/// plus a status line, mirroring the manager through its <see cref="OnlineSessionManager.Changed"/> /
/// <see cref="OnlineSessionManager.SessionsChanged"/> events; the session logic stays on the manager.
///
/// The panel is always shown in Main (not connected); once a connection is up it hides, and in the
/// lobby/map the overview (Esc) menu reopens it via <see cref="Open"/> as a modal pause overlay
/// (cursor freed, gameplay suspended via <see cref="GameModeManager.SetPaused"/>) - all Esc key
/// handling lives in <see cref="OverviewMenu"/>, which closes this overlay through <see cref="Close"/>.
/// The Disconnect button is context-sensitive: in Main it is an
/// application "Exit"; on the map it becomes "Back to Lobby" for the match authority (ends the match);
/// everyone else gets a plain disconnect. Only the visual <see cref="panelRoot"/> is toggled - this binder
/// stays alive on its (always-active) canvas so it keeps tracking state while the panel is hidden.
/// </summary>
public class OnlineSessionBrowserUI : MonoBehaviour
{
    [SerializeField] private OnlineSessionManager manager;

    [Header("Buttons")]
    [SerializeField] private Button hostButton;
    [SerializeField] private Button refreshButton;
    [SerializeField] private Button joinButton;
    [SerializeField] private Button disconnectButton;

    [Header("List")]
    [Tooltip("Content RectTransform of the session ScrollRect (rows are added here).")]
    [SerializeField] private RectTransform listContent;
    [Tooltip("A row prototype kept disabled; cloned once per session. Children named 'Name' and 'Players' carry the text.")]
    [SerializeField] private GameObject entryTemplate;

    [Header("Status")]
    [SerializeField] private TMP_Text statusLabel;

    [Header("Overlay")]
    [Tooltip("Visual container toggled while connected (the panel root). Must be a CHILD of this " +
             "binder's object so the binder keeps running while the panel is hidden.")]
    [SerializeField] private GameObject panelRoot;

    [Tooltip("Background tint of the selected row.")]
    [SerializeField] private Color selectedTint = new Color(0.26f, 0.52f, 0.96f, 1f);
    [Tooltip("Background tint of an unselected row.")]
    [SerializeField] private Color normalTint = new Color(1f, 1f, 1f, 0.05f);

    private struct Row { public string id; public Image image; public GameObject go; }
    private readonly List<Row> _rows = new List<Row>();
    private string _selectedId;

    private MatchManager _match;          // local match state (scene kind + authority); found at runtime
    private GameModeManager _gameMode;    // pause hook for the modal overlay; found at runtime
    private TMP_Text _disconnectLabel;    // disconnect button caption (relabelled to "Back to Lobby")

    private bool _open;                   // overlay visibility while connected (toggled via Open/Close)
    private bool _connected;              // last-seen connection state (to detect transitions)
    private Scene _lastScene;             // last-seen active scene (to auto-close on a scene change)
    private string _disconnectText;       // last applied caption (avoids per-frame TMP churn)

    private void Awake()
    {
        // The template is the prototype, never shown itself - layout ignores it while disabled.
        if (entryTemplate) entryTemplate.SetActive(false);

        _match = FindFirstObjectByType<MatchManager>();
        _gameMode = FindFirstObjectByType<GameModeManager>();
    }

    private void OnEnable()
    {
        if (hostButton) hostButton.onClick.AddListener(OnHost);
        if (refreshButton) refreshButton.onClick.AddListener(OnRefresh);
        if (joinButton) joinButton.onClick.AddListener(OnJoin);
        if (disconnectButton)
        {
            disconnectButton.onClick.AddListener(OnDisconnect);
            _disconnectLabel = disconnectButton.GetComponentInChildren<TMP_Text>(true);
        }

        if (manager)
        {
            manager.Changed += OnManagerChanged;
            manager.SessionsChanged += RebuildList;
        }

        _connected = manager && manager.IsConnected;
        RebuildList();
        OnManagerChanged();
        ApplyVisibility();
    }

    private void OnDisable()
    {
        if (hostButton) hostButton.onClick.RemoveListener(OnHost);
        if (refreshButton) refreshButton.onClick.RemoveListener(OnRefresh);
        if (joinButton) joinButton.onClick.RemoveListener(OnJoin);
        if (disconnectButton) disconnectButton.onClick.RemoveListener(OnDisconnect);

        if (manager)
        {
            manager.Changed -= OnManagerChanged;
            manager.SessionsChanged -= RebuildList;
        }
    }

    private void Update()
    {
        if (!manager) return;
        bool connected = manager.IsConnected;

        // Auto-close the overlay if the scene changed underneath it (a remote ended/started the match, or
        // we walked into Start Match) so it never lingers as a stale pause across a transition.
        // Compared as Scene structs (handles), not names, so nothing is allocated per frame.
        Scene scene = SceneManager.GetActiveScene();
        if (connected && _open && _lastScene.IsValid() && scene != _lastScene)
            SetOpen(false);
        _lastScene = scene;

        if (!connected) return;                                   // Main: panel always shown

        RefreshDisconnectLabel();
    }

    /// <summary>True while the modal overlay is open on a live connection (the always-shown Main panel
    /// does not count). The overview menu yields Esc to this overlay while it is open.</summary>
    public bool IsOpen => _open;

    /// <summary>Opens the modal overlay (used by the overview menu's Session button); false when
    /// not connected - in Main the panel is always visible and never a pause overlay.</summary>
    public bool Open()
    {
        if (!(manager && manager.IsConnected)) return false;
        SetOpen(true);
        return true;
    }

    /// <summary>Closes the modal overlay and resumes gameplay (Esc handling in <see cref="OverviewMenu"/>).</summary>
    public void Close() => SetOpen(false);

    private void OnHost() { if (manager) manager.Host(); }
    private void OnRefresh() { if (manager) manager.Refresh(); }
    private void OnJoin() { if (manager && !string.IsNullOrEmpty(_selectedId)) manager.Join(_selectedId); }

    private void OnDisconnect()
    {
        if (!manager) return;

        // In Main (no session) the button is an application Exit, so the player can quit the build
        // without Alt+F4.
        if (!manager.IsConnected)
        {
            QuitApplication();
            return;
        }

        // On the map, the match AUTHORITY's button means "Back to Lobby" (end the match for everyone)
        // rather than leaving the session. Everyone else - in the lobby, or a non-authority client on the
        // map - does a plain disconnect.
        if (_match && _match.IsLocalSceneMap && _match.IsLocalMatchAuthority)
        {
            _match.RequestEndMatch();
            SetOpen(false);            // heading back to the lobby; close the overlay + resume input
            return;
        }

        manager.Disconnect();
    }

    private static void QuitApplication()
    {
#if UNITY_EDITOR
        UnityEditor.EditorApplication.isPlaying = false;
#else
        Application.Quit();
#endif
    }

    private void OnManagerChanged()
    {
        if (!manager) return;

        bool connected = manager.IsConnected;
        if (connected != _connected)
        {
            _connected = connected;
            // Connection up (hosted/joined) -> hide the panel; Esc reopens it in the lobby/map.
            // Back to Main (disconnect/shutdown) -> show it again and drop any pause.
            _open = false;
            if (!connected && _gameMode) _gameMode.SetPaused(false);
            ApplyVisibility();
        }

        if (statusLabel) statusLabel.text = manager.Status;
        UpdateButtons();
        RefreshDisconnectLabel();
    }

    private void SetOpen(bool open)
    {
        _open = open;
        ApplyVisibility();
        if (_gameMode) _gameMode.SetPaused(open);
    }

    private void ApplyVisibility()
    {
        bool show = !(manager && manager.IsConnected) || _open;
        if (panelRoot && panelRoot.activeSelf != show)
            panelRoot.SetActive(show);
    }

    private void RefreshDisconnectLabel()
    {
        if (!_disconnectLabel) return;
        string text;
        if (!(manager && manager.IsConnected))
            text = "Exit";                                                       // Main: quit the application
        else if (_match && _match.IsLocalSceneMap && _match.IsLocalMatchAuthority)
            text = "Back to Lobby";
        else
            text = "Disconnect";
        if (text != _disconnectText)
        {
            _disconnectText = text;
            _disconnectLabel.text = text;
        }
    }

    private void UpdateButtons()
    {
        if (!manager) return;
        bool busy = manager.IsBusy;
        bool connected = manager.IsConnected;
        bool hasSelection = !string.IsNullOrEmpty(_selectedId);

        if (hostButton) hostButton.interactable = !busy && !connected;
        if (refreshButton) refreshButton.interactable = !busy && !connected;
        if (joinButton) joinButton.interactable = !busy && !connected && hasSelection;
        // Usable whenever idle: connected -> Disconnect / Back to Lobby; in Main -> Exit.
        if (disconnectButton) disconnectButton.interactable = !busy;
    }

    private void RebuildList()
    {
        for (int i = 0; i < _rows.Count; i++)
            if (_rows[i].go) Destroy(_rows[i].go);
        _rows.Clear();

        if (manager && entryTemplate && listContent)
        {
            var sessions = manager.Sessions;
            bool selectionStillPresent = false;

            for (int i = 0; i < sessions.Count; i++)
            {
                var s = sessions[i];
                var go = Instantiate(entryTemplate, listContent);
                go.SetActive(true);

                var nameText = FindText(go.transform, "Name");
                if (nameText) nameText.text = s.Name;

                var playersText = FindText(go.transform, "Players");
                if (playersText)
                {
                    int taken = Mathf.Max(0, s.MaxPlayers - s.AvailableSlots);
                    playersText.text = $"{taken}/{s.MaxPlayers}";
                }

                string id = s.Id;                       // capture per-row for the click closure
                var button = go.GetComponent<Button>();
                if (button) button.onClick.AddListener(() => Select(id));

                _rows.Add(new Row { id = id, image = go.GetComponent<Image>(), go = go });
                if (id == _selectedId) selectionStillPresent = true;
            }

            if (!selectionStillPresent) _selectedId = null;
        }

        ApplyTints();
        UpdateButtons();
    }

    private void Select(string id)
    {
        _selectedId = id;
        ApplyTints();
        UpdateButtons();
    }

    private void ApplyTints()
    {
        for (int i = 0; i < _rows.Count; i++)
            if (_rows[i].image)
                _rows[i].image.color = _rows[i].id == _selectedId ? selectedTint : normalTint;
    }

    private static TMP_Text FindText(Transform root, string childName)
    {
        var t = root.Find(childName);
        return t ? t.GetComponent<TMP_Text>() : null;
    }

}