using UnityEngine;
using Unity.Cinemachine;

/// <summary>
/// Feeds mouse input into a <see cref="CinemachineOrbitalFollow"/> so the camera
/// orbits the follow target. Mouse movement drives yaw/pitch, the wheel zooms.
/// The orbit behaviour depends on <see cref="LookMode"/> (usually set by the
/// GameModeManager). Attach to the camera rig (the CinemachineOrbitalFollow).
/// </summary>
[RequireComponent(typeof(CinemachineOrbitalFollow))]
[DisallowMultipleComponent]
public class ThirdPersonOrbitInput : MonoBehaviour
{
    public enum OrbitLookMode
    {
        /// <summary>Rotate with every mouse move; cursor locked/hidden.</summary>
        AlwaysActive,
        /// <summary>Rotate only while the right mouse button is held; cursor free otherwise.</summary>
        HoldRightMouseButton,
        /// <summary>No rotation; cursor free.</summary>
        Disabled
    }

    [Header("Look Mode")]
    [Tooltip("How the camera orbit is driven (usually set by GameModeManager).")]
    [SerializeField] private OrbitLookMode lookMode = OrbitLookMode.AlwaysActive;

    [Header("Rotation")]
    [Tooltip("Horizontal look sensitivity (degrees of yaw per pixel).")]
    public float horizontalSensitivity = 0.2f;

    [Tooltip("Vertical look sensitivity (degrees of pitch per pixel).")]
    public float verticalSensitivity = 0.15f;

    [Tooltip("Invert vertical look (mouse up tilts the camera down).")]
    public bool invertY = false;

    [Tooltip("Eases orbit rotation so quick mouse moves ramp in/out (higher = snappier, 0 = raw/instant).")]
    public float rotationSmoothing = 20f;

    [Header("Zoom")]
    [Tooltip("Mouse wheel zooms the camera in and out (changes orbit radius).")]
    public bool enableZoom = true;

    [Tooltip("Scale the zoom range, step and default radius by the follow target's size (PlayerScaler), " +
             "so a small (Hider) or large (Hunter) player is framed at the same body-relative distance. " +
             "The radius fields below are then size-1 design values, multiplied by the target's scale at " +
             "runtime. Off = absolute world units regardless of player size.")]
    public bool scaleWithTarget = true;

    [Tooltip("World units the orbit radius changes per mouse wheel notch (size-1 design value; scaled by " +
             "the target when Scale With Target is on).")]
    public float zoomSpeed = 0.5f;

    [Tooltip("Eases the orbit radius toward the zoom target (higher = snappier, 0 = instant).")]
    public float zoomSmoothing = 10f;

    [Tooltip("Closest orbit radius / zoom in (size-1 design value; scaled by the target).")]
    public float minRadius = 1.5f;

    [Tooltip("Farthest orbit radius / zoom out (size-1 design value; scaled by the target).")]
    public float maxRadius = 8f;

    [Tooltip("Orbit radius applied when the camera (re)binds to a player - the starting zoom level " +
             "(size-1 design value; scaled by the target). Set so the bound player is comfortably framed.")]
    public float defaultRadius = 4.5f;

    [Header("Pan (middle mouse)")]
    [Tooltip("Hold the middle mouse button and drag to pan the camera framing - a temporary offset to bring an " +
             "awkward spot of the model in front of the lens for painting. The pan stays put on release and only " +
             "glides back to center when paint mode is left. Enabled only while PaintMode is active.")]
    public bool enablePan = true;

    [Tooltip("World units the pan offset moves per pixel of mouse drag, measured at the default zoom. It then " +
             "scales with the live zoom distance so the model slides the same amount on screen per pixel at any " +
             "zoom (closer in = finer). Body scale is folded in automatically via the orbit radius.")]
    public float panSensitivity = 0.004f;

    [Tooltip("Farthest the framing can pan from center, in world units (body scale folded in). This is NOT scaled " +
             "by zoom, so the maximum pan distance stays the same at every zoom level - only the sensitivity changes.")]
    public float panMaxDistance = 1f;

    [Tooltip("How snappily the pan glides back to center when paint mode is left (1/second; 0 = snaps home " +
             "instantly). The pan stays put on middle-button release - it only returns on leaving paint mode.")]
    public float panReturnSpeed = 14f;

    [Header("Cursor")]
    [Tooltip("Lock and hide the cursor while the camera is actively rotating.")]
    public bool manageCursor = true;

    CinemachineOrbitalFollow _orbit;
    Vector2 _smoothedLook;     // low-pass-filtered look delta (deg/frame) for eased rotation
    float _targetRadius;       // zoom radius the actual radius eases toward
    bool _zoomInit;            // _targetRadius seeded from the live radius yet?
    Vector2 _pan;                       // accumulated pan in camera-space units (x=right, y=up); stays put on release, eases to 0 on leaving paint mode
    CinemachineCameraOffset _camOffset;  // post-aim extension that slides the whole framing (true pan, not an orbit arc)

    /// <summary>Current orbit mode. Setting it also refreshes the cursor state.</summary>
    public OrbitLookMode LookMode
    {
        get => lookMode;
        set { lookMode = value; ApplyCursorState(); }
    }

    /// <summary>
    /// While true, mouse-look is paused (orbit frozen) without changing the cursor
    /// state. The player controller sets this while dragging the wall-climb offset so
    /// the same mouse motion is not also spent orbiting the camera.
    /// </summary>
    public bool LookSuppressed { get; set; }

    /// <summary>While true, holding the middle mouse button and dragging pans the camera framing - a temporary
    /// look-point offset that stays put on release. Set by PaintMode so the pan is only available while painting;
    /// clearing it (on leaving paint mode) is what glides the framing back home.</summary>
    public bool PanEnabled { get; set; }

    void Awake()
    {
        _orbit = GetComponent<CinemachineOrbitalFollow>();
        if (!_orbit)
            Debug.LogError("[ThirdPersonOrbitInput] No CinemachineOrbitalFollow found on this GameObject.", this);

        // The pan rides a CinemachineCameraOffset extension applied AFTER aim with PreserveComposition off: it
        // shifts the camera position AND the look-at point by the same world vector, so the framing translates
        // (the model slides across the screen) instead of re-aiming back to center like a body TargetOffset
        // would. Offset is camera-local (x=right, y=up). Added at runtime so no scene/prefab authoring is needed.
        if (enablePan)
        {
            _camOffset = GetComponent<CinemachineCameraOffset>();
            if (!_camOffset) _camOffset = gameObject.AddComponent<CinemachineCameraOffset>();
            _camOffset.ApplyAfter = CinemachineCore.Stage.Aim;
            _camOffset.PreserveComposition = false;
            _camOffset.Offset = Vector3.zero;
        }
    }

    void OnEnable() => ApplyCursorState();

    void OnDisable()
    {
        InputUtil.SetCursorLocked(false);
        // Deliberately DON'T zero the pan: only FreeCamMode disables this component, and the freecam
        // snaps to the live (still panned) view - resetting now would jump the blend-FROM camera to
        // center while the freecam sits at the panned pose (the visible snap on the paint->freecam
        // switch). Frozen offset = blend-from == blend-to; the pan glides home once the orbit runs again.
    }

    /// <summary>Uniform scale of the current follow target (1 when none, or when Scale With Target is off).
    /// The zoom range, step and default radius are multiplied by this so the framing is body-relative across
    /// player sizes. PlayerScaler keeps the player uniformly scaled, so a single lossyScale component is exact.</summary>
    float CurrentScale()
    {
        if (!scaleWithTarget || !_orbit) return 1f;
        Transform t = _orbit.FollowTarget;
        return t ? Mathf.Max(0.0001f, t.lossyScale.x) : 1f;
    }

    /// <summary>Pan-SENSITIVITY scale with the live zoom: radius / defaultRadius = 1 at the default zoom,
    /// finer zoomed in, coarser zoomed out - the model slides the same amount ON SCREEN per pixel at any
    /// zoom. Body scale cancels out (the radius already embeds it). The clamp deliberately does NOT use
    /// this: panMaxDistance stays body-relative only, constant across zoom levels.</summary>
    float PanZoomScale() => _orbit ? _orbit.Radius / Mathf.Max(0.0001f, defaultRadius) : 1f;

    /// <summary>Snaps the zoom to the scaled default radius. Called when a new avatar binds (see
    /// GameModeManager.BindLocalPlayer) so each player starts at its body-relative default zoom instead of
    /// inheriting the previous avatar's radius.</summary>
    public void ResetZoom()
    {
        if (!_orbit) return;
        _targetRadius = defaultRadius * CurrentScale();
        _orbit.Radius = _targetRadius;
        _zoomInit = true;
    }

    /// <summary>Snaps the orbit axes to Camera.main's current view direction so the next orbit mode keeps
    /// that facing instead of the orbit's last-used angle. Called when switching out of a non-orbit rig:
    /// Camera.main still shows that rig's view this frame (the brain hasn't blended yet), so the read is
    /// exact. With WorldSpace binding + Sphere orbit + a centered composer the look rotation is exactly
    /// Euler(VerticalAxis, HorizontalAxis, 0).</summary>
    public void SyncToView()
    {
        if (!_orbit) return;
        var cam = Camera.main;
        if (!cam) return;

        Vector3 e = cam.transform.rotation.eulerAngles;
        SetAxisValue(ref _orbit.HorizontalAxis, e.y > 180f ? e.y - 360f : e.y);
        SetAxisValue(ref _orbit.VerticalAxis, e.x > 180f ? e.x - 360f : e.x);

        // Drop any eased look carry-over so the snapped angle isn't immediately dragged back.
        _smoothedLook = Vector2.zero;
    }

    void Update()
    {
        if (!_orbit)
            return;

        bool modeWantsLook = ShouldRotate();

        if (manageCursor)
            InputUtil.SetCursorLocked(modeWantsLook);

        if (modeWantsLook && !LookSuppressed)
        {
            Vector2 delta = InputUtil.ReadMouseDelta() * MouseSensitivity.Multiplier;
            Vector2 raw = new Vector2(
                delta.x * horizontalSensitivity,
                delta.y * verticalSensitivity * (invertY ? 1f : -1f));

            // Ease the per-frame look toward the raw delta so fast flicks ramp in/out
            // instead of snapping; steady motion still converges to full sensitivity.
            Vector2 applied = rotationSmoothing > 0f
                ? (_smoothedLook = Vector2.Lerp(_smoothedLook, raw, 1f - Mathf.Exp(-rotationSmoothing * Time.deltaTime)))
                : raw;

            if (applied.sqrMagnitude > 0f)
            {
                ApplyAxisDelta(ref _orbit.HorizontalAxis, applied.x);
                ApplyAxisDelta(ref _orbit.VerticalAxis, applied.y);
            }
        }
        else
        {
            _smoothedLook = Vector2.zero;
        }

        if (enableZoom)
        {
            if (!_zoomInit)
            {
                // Seed the starting zoom at the scaled default (not the live radius) so a fresh bind frames
                // the player body-relative; ResetZoom() does the same on an explicit (re)bind.
                _targetRadius = defaultRadius * CurrentScale();
                _orbit.Radius = _targetRadius;
                _zoomInit = true;
            }

            float scale = CurrentScale();

            // Shift/Ctrl+wheel is reserved for the paint brush resize (MeshPainter) - but only in paint
            // mode (PanEnabled), where the resize actually claims the wheel. Outside paint mode Shift is
            // the sprint key, so the wheel must still zoom.
            bool brushResizeClaimsWheel = PanEnabled && (InputUtil.ShiftHeld() || InputUtil.CtrlHeld());
            float scroll = brushResizeClaimsWheel ? 0f : InputUtil.ReadScroll();
            if (!Mathf.Approximately(scroll, 0f))
            {
                // One wheel notch = one zoom step (sign only, platform-independent). The step scales with
                // the player so the notch count to cross the range is the same at every size.
                _targetRadius -= Mathf.Sign(scroll) * zoomSpeed * scale;
            }

            // Clamp every frame against the scaled range so a runtime size change (PlayerScaler grow/shrink)
            // keeps the target in-range instead of sticking at a stale absolute bound.
            _targetRadius = Mathf.Clamp(_targetRadius, minRadius * scale, maxRadius * scale);

            // Ease the actual radius toward the target (frame-rate independent).
            _orbit.Radius = zoomSmoothing > 0f
                ? Mathf.Lerp(_orbit.Radius, _targetRadius, 1f - Mathf.Exp(-zoomSmoothing * Time.deltaTime))
                : _targetRadius;
        }

        UpdatePan(Time.deltaTime);
    }

    bool ShouldRotate()
    {
        switch (lookMode)
        {
            case OrbitLookMode.AlwaysActive: return true;
            case OrbitLookMode.HoldRightMouseButton: return InputUtil.RightMouseHeld();
            default: return false;
        }
    }

    void ApplyCursorState()
    {
        if (manageCursor)
            InputUtil.SetCursorLocked(ShouldRotate());
    }

    /// <summary>Adds to an input axis; wrapping axes wrap, others clamp to their range.</summary>
    static void ApplyAxisDelta(ref InputAxis axis, float amount)
        => SetAxisValue(ref axis, axis.Value + amount);

    /// <summary>Sets an input axis to an absolute value; wrapping axes wrap, others clamp to their range.</summary>
    static void SetAxisValue(ref InputAxis axis, float value)
    {
        float min = axis.Range.x;
        float max = axis.Range.y;

        if (axis.Wrap && max > min)
        {
            float span = max - min;
            value = ((value - min) % span + span) % span + min;
        }
        else
        {
            value = Mathf.Clamp(value, min, max);
        }

        axis.Value = value;
    }

    /// <summary>Middle-mouse pan (while PaintMode enables it): slides the whole framing along the screen
    /// right/up axes via the camera-offset extension - a temporary offset to line up an awkward spot of
    /// the model for painting. Eases home outside paint mode / while the orbit is Disabled.</summary>
    void UpdatePan(float dt)
    {
        if (!enablePan || !_camOffset)
            return;

        bool active = PanEnabled && lookMode != OrbitLookMode.Disabled;
        float zoom = PanZoomScale();

        if (active && InputUtil.MiddleMouseHeld())
        {
            Vector2 d = InputUtil.ReadMouseDelta() * MouseSensitivity.Multiplier;
            // Subtracting gives a hand-tool feel (the model follows the cursor). The step scales with the
            // zoom (same on-screen feel, see PanZoomScale); the clamp stays body-relative only.
            _pan -= d * (panSensitivity * zoom);
            _pan = Vector2.ClampMagnitude(_pan, panMaxDistance * CurrentScale());
        }
        else if (active)
        {
            return; // still painting, middle button released - hold the pan where it was left
        }
        else if (_pan != Vector2.zero)
        {
            // Left paint mode (or look disabled) - glide the framing back to center.
            if (panReturnSpeed > 0f)
                _pan = Vector2.Lerp(_pan, Vector2.zero, 1f - Mathf.Exp(-panReturnSpeed * dt));
            else
                _pan = Vector2.zero;
            // Snap the last sliver so the offset settles exactly on center and this branch stops running.
            if (_pan.sqrMagnitude < 1e-8f)
                _pan = Vector2.zero;
        }
        else
        {
            return; // at rest and not panning - nothing to write
        }

        // Offset is camera-local (x=right, y=up); the extension translates eye + look-at together -> true pan.
        _camOffset.Offset = new Vector3(_pan.x, _pan.y, 0f);
    }

}