using System.Collections.Generic;
using UnityEngine;
using Unity.Cinemachine;
#if ENABLE_INPUT_SYSTEM
using UnityEngine.InputSystem;
#endif

/// <summary>
/// Switches the game between high-level modes. The switch key (Tab) cycles to the next registered
/// mode. The mode set is scoped to the local avatar's <see cref="PlayerRole"/> when it spawns
/// (Hunter: First Person + Paint; Hider: Player Control + Paint + Free Cam); a non-networked scene
/// uses the full set. Attach to a single, persistent scene GameObject.
/// </summary>
[DisallowMultipleComponent]
public class GameModeManager : MonoBehaviour
{
    [Header("Controlled Systems")]
    [Tooltip("Player movement controller. Empty = found automatically.")]
    public PlayerCharacterController player;

    [Tooltip("Third-person orbit camera input. Empty = found automatically.")]
    public ThirdPersonOrbitInput cameraInput;

    [Tooltip("Mesh painter. Empty = found automatically.")]
    public MeshPainter painter;

    [Tooltip("Free-fly spectator camera. Empty = found automatically. Absent = Free Cam is left out of the cycle.")]
    public FreeCamController freeCam;

    [Tooltip("First-person camera. Empty = found automatically. Absent = First Person is left out of the cycle.")]
    public FirstPersonController firstPerson;

    [Header("Switching")]
    [Tooltip("Key that cycles to the next mode.")]
#if ENABLE_INPUT_SYSTEM
    public Key switchKey = Key.Tab;
#else
    public KeyCode switchKey = KeyCode.Tab;
#endif

    [Tooltip("Mode active at startup (0 = Player Control).")]
    public int startModeIndex = 0;

    public PlayerCharacterController Player => player;
    public ThirdPersonOrbitInput CameraInput => cameraInput;
    public MeshPainter Painter => painter;
    public FreeCamController FreeCam => freeCam;
    public FirstPersonController FirstPerson => firstPerson;

    /// <summary>Raised after a mode switch finishes (the new mode's Enter has already run).
    /// Argument = the now-active mode. Used by UI (e.g. the paint HUD) to follow the mode.</summary>
    public event System.Action<GameMode> ModeChanged;

    /// <summary>Raised when the painter the HUD should edit changes - i.e. when the local
    /// networked avatar spawns and <see cref="BindLocalPlayer"/> binds its per-avatar painter.
    /// With spawn-on-connect there is no painter at scene start, so the paint HUD follows this
    /// to (re)bind its widgets to the live painter once it exists.</summary>
    public event System.Action<MeshPainter> PainterChanged;

    private readonly List<GameMode> _modes = new List<GameMode>();
    private int _activeIndex = -1;
    private bool _paused;
    private int _resumeIndex = -1;

    /// <summary>The currently active mode (null before startup).</summary>
    public GameMode ActiveMode =>
        (_activeIndex >= 0 && _activeIndex < _modes.Count) ? _modes[_activeIndex] : null;

    private void Awake()
    {
        if (!player) player = FindFirstObjectByType<PlayerCharacterController>();
        if (!cameraInput) cameraInput = FindFirstObjectByType<ThirdPersonOrbitInput>();
        if (!painter) painter = FindFirstObjectByType<MeshPainter>();
        // Include inactive so a freecam rig that starts disabled is still found and wired.
        if (!freeCam) freeCam = FindFirstObjectByType<FreeCamController>(FindObjectsInactive.Include);
        if (!firstPerson) firstPerson = FindFirstObjectByType<FirstPersonController>(FindObjectsInactive.Include);

        BuildModes();
    }

    private void Start()
    {
        if (_modes.Count > 0)
            SwitchTo(Mathf.Clamp(startModeIndex, 0, _modes.Count - 1));
    }

    /// <summary>Registers the modes for the current context. Without a role (no networked avatar yet,
    /// or a non-networked scene) the full set is built from whichever rigs are present. With a role the
    /// set is scoped to that side and ordered so index 0 is its intended start mode. Add new modes here.</summary>
    private void BuildModes() => BuildModes(null);

    private void BuildModes(PlayerRole? role)
    {
        _modes.Clear();

        switch (role)
        {
            case PlayerRole.Hunter:
                if (firstPerson) _modes.Add(new FirstPersonMode());
                _modes.Add(new PaintMode());
                break;

            case PlayerRole.Hider:
                if (player) _modes.Add(new PlayerControlMode());
                _modes.Add(new PaintMode());
                if (freeCam) _modes.Add(new FreeCamMode());
                break;

            default:
                // No role: legacy full set, gated on whichever rigs exist (a player-less pre-spawn
                // stays in Paint rather than a dead frozen Player Control).
                if (player) _modes.Add(new PlayerControlMode());
                _modes.Add(new PaintMode());
                if (freeCam) _modes.Add(new FreeCamMode());
                if (firstPerson) _modes.Add(new FirstPersonMode());
                break;
        }

        foreach (var m in _modes)
            m.Bind(this);
    }

    /// <summary>Spectator mode set for a mid-match joiner: free-fly camera only (no player control, no
    /// paint). They can fly around and watch, but not play, until the host ends the match (then they
    /// respawn as a neutral lobby Player). Falls back to nothing if the scene has no free-cam rig.</summary>
    private void BuildSpectatorModes()
    {
        _modes.Clear();
        if (freeCam) _modes.Add(new FreeCamMode());
        foreach (var m in _modes)
            m.Bind(this);
    }

    /// <summary>
    /// Binds a mid-match spectator. The spectator object is empty (no body/painter to bind), so just clear
    /// the player/painter and switch the cycle to free-cam-only. The free-cam rig is a separate persistent
    /// scene object that flies off Camera.main, so it needs nothing from the spectator. Called from
    /// <see cref="SpectatorSetup"/> on the owning client.
    /// </summary>
    public void BindSpectator()
    {
        _paused = false;
        _resumeIndex = -1;

        ClearPlayerBindings();
        TearDownActiveMode();
        BuildSpectatorModes();
        SwitchTo(0);
    }

    /// <summary>Drops the player/painter bindings and notifies painter-following UI.</summary>
    private void ClearPlayerBindings()
    {
        player = null;
        painter = null;
        PainterChanged?.Invoke(null);
    }

    /// <summary>Exits the active mode and marks no mode active.</summary>
    private void TearDownActiveMode()
    {
        ActiveMode?.Exit();
        _activeIndex = -1;
    }

    /// <summary>
    /// Binds the scene singletons (this manager, the orbit/first-person cameras, the painter) to the
    /// locally-owned networked player after it spawns, then enters Player Control. Called from
    /// <see cref="NetworkPlayerSetup"/> on the owning client. Before this runs the scene has no player,
    /// so the cycle sits in a player-less mode (Paint); this promotes it once the avatar exists.
    /// </summary>
    public void BindLocalPlayer(PlayerCharacterController localPlayer)
    {
        if (!localPlayer) return;

        // A fresh bind is a definitive state reset - drop any modal pause so the new avatar starts live.
        _paused = false;
        _resumeIndex = -1;

        var setup = localPlayer.GetComponent<NetworkPlayerSetup>();

        player = localPlayer;

        // Re-point UNCONDITIONALLY: on a lobby->match respawn the old painter is Destroy-pending (still
        // non-null), so a `if (!painter)` guard would keep the stale reference and the new avatar's
        // painter would never be mode-toggled.
        painter = localPlayer.GetComponentInChildren<MeshPainter>(true);
        PainterChanged?.Invoke(painter);

        Transform camTarget = localPlayer.transform.Find("CameraTarget");
        if (cameraInput)
        {
            var vcam = cameraInput.GetComponent<CinemachineCamera>();
            if (vcam)
            {
                vcam.Follow = camTarget;
                vcam.LookAt = camTarget;
                // Follow (and its lossyScale) is live now - start at this avatar's scaled default zoom
                // instead of inheriting the previous avatar's radius.
                cameraInput.ResetZoom();
            }
        }

        if (firstPerson)
            firstPerson.SetPlayer(localPlayer);

        // Tear down the pre-spawn (player-less) mode and rebuild scoped to this avatar's role.
        TearDownActiveMode();

        // Lobby avatar -> full set; match variant -> its role's modes. Scope is baked per prefab
        // variant, so it follows the spawned avatar with no replicated-phase timing race.
        if (setup && setup.ScopedModes)
            BuildModes(setup.Role);
        else
            BuildModes(null);

        // Index 0 is each set's intended start mode.
        SwitchTo(0);
    }

    /// <summary>
    /// Drops back to a player-less state when the local avatar is gone (disconnect / server shutdown
    /// returns the session to the empty Main scene). Tears down the active mode so any FreeCam/First-Person
    /// camera takeover is undone (which unlocks the cursor), clears the mode cycle, and - crucially - parks
    /// the persistent orbit input in Disabled: it otherwise re-locks the cursor every frame while
    /// AlwaysActive, so a one-off unlock would be reverted next frame and the OS cursor would stay captured
    /// with no avatar to control. A reconnect's <see cref="BindLocalPlayer"/> restores everything.
    /// </summary>
    public void ReleaseToNoPlayer()
    {
        _paused = false;
        _resumeIndex = -1;

        TearDownActiveMode();
        _modes.Clear();
        ClearPlayerBindings();

        // The cycle is empty (no SwitchTo runs), so notify mode-following UI explicitly - otherwise the
        // paint HUD (hides only via ModeChanged) would stay open after a shutdown during PaintMode.
        ModeChanged?.Invoke(null);

        if (cameraInput)
            cameraInput.LookMode = ThirdPersonOrbitInput.OrbitLookMode.Disabled;

        // Belt-and-braces explicit release (covers the orbit input being absent/disabled).
        InputUtil.SetCursorLocked(false);
    }

    /// <summary>
    /// Pauses/resumes local gameplay for a full-screen modal overlay (the Esc session panel). Suppresses
    /// ALL local input and frees the cursor WITHOUT tearing down the mode cycle, so resuming re-enters
    /// the exact mode that was active. Deliberately never Exits the active mode: the FP/free-cam vcam
    /// keeps its priority, so the view stays frozen instead of blending back to the orbit camera (no
    /// jump on open), and the resumed mode's snap-to-current-view is a no-op (no jump on close).
    /// </summary>
    public void SetPaused(bool paused)
    {
        if (paused == _paused) return;
        _paused = paused;

        if (paused)
        {
            _resumeIndex = _activeIndex;
            _activeIndex = -1;           // bookkeeping: no live mode while paused (Tick won't run)

            // Freeze every input source without touching vcam priorities: dropping the FP/freecam
            // `enabled` freezes their look in place; a Disabled orbit look-mode stops the per-frame
            // cursor re-grab. At most one rig is ever enabled, so disabling both is safe.
            if (player) player.ControlEnabled = false;
            if (painter) painter.PaintingEnabled = false;
            if (firstPerson) firstPerson.enabled = false;
            if (freeCam) freeCam.enabled = false;
            if (cameraInput)
            {
                cameraInput.enabled = true;
                cameraInput.LookMode = ThirdPersonOrbitInput.OrbitLookMode.Disabled;
            }
            InputUtil.SetCursorLocked(false);

            ModeChanged?.Invoke(null);   // hide mode-following UI (the paint HUD) beneath the overlay
        }
        else
        {
            int resume = _resumeIndex;
            _resumeIndex = -1;
            if (resume >= 0 && resume < _modes.Count)
            {
                // Re-Enter the SAME mode (never Exited): its sync-to-current-view is a no-op -> no jump.
                _activeIndex = resume;
                ActiveMode.Enter();
                ModeChanged?.Invoke(ActiveMode);
            }
            else
                ModeChanged?.Invoke(ActiveMode);
        }
    }

    private void Update()
    {
        if (_paused) return;
        if (_modes.Count == 0) return;

        // Resolution (the reveal window) is watch-only: force out of Paint and keep the switch key from
        // re-entering. No restore needed - the end-of-match respawn rebuilds the cycle at index 0.
        bool suppressPaint = PaintSuppressed();
        if (suppressPaint && ActiveMode is PaintMode)
        {
            int fallback = FirstNonPaintFrom(0);
            if (fallback >= 0) SwitchTo(fallback);
            else if (painter) painter.PaintingEnabled = false; // degenerate paint-only set: at least stop painting
        }

        if (InputUtil.GameplayKeyPressed(switchKey))
        {
            int next = (_activeIndex + 1) % _modes.Count;
            if (suppressPaint && _modes[next] is PaintMode)
            {
                int skip = FirstNonPaintFrom(next);
                if (skip >= 0) next = skip;
            }
            SwitchTo(next);
        }

        ActiveMode?.Tick();
    }

    /// <summary>True while the local match is in its resolution (reveal) phase, during which painting is
    /// disabled for the local player regardless of role.</summary>
    private bool PaintSuppressed()
    {
        var match = MatchManager.Instance;
        return match && match.MatchActive &&
               match.LocalSubPhase == MatchManager.MatchSubPhase.Resolution;
    }

    /// <summary>First non-Paint mode index at or after <paramref name="start"/> (wrapping once through the
    /// cycle); -1 if the set has no non-paint mode (a degenerate paint-only configuration).</summary>
    private int FirstNonPaintFrom(int start)
    {
        for (int step = 0; step < _modes.Count; step++)
        {
            int i = (start + step) % _modes.Count;
            if (!(_modes[i] is PaintMode)) return i;
        }
        return -1;
    }

    /// <summary>Activates the mode at <paramref name="index"/> (Exit old, Enter new).</summary>
    public void SwitchTo(int index)
    {
        if (index < 0 || index >= _modes.Count || index == _activeIndex) return;

        ActiveMode?.Exit();
        _activeIndex = index;
        ActiveMode.Enter();

        Debug.Log($"[GameModeManager] Mode -> {ActiveMode.DisplayName}", this);
        ModeChanged?.Invoke(ActiveMode);
    }
}