using Sandbox;

namespace NZombies;

/// <summary>
/// Free-fly camera for Spectator mode.
///
/// ⚠️ SOMETHING HAS TO DRIVE THE VIEW ONCE THE BODY IS GONE. PlayerController
/// is what positions the camera normally, and disabling the player stops it —
/// so without this, entering spectator freezes the view wherever the player was
/// last standing and nothing moves it again.
///
/// No collision on purpose: a spectator that can be stopped by a wall is worse
/// than useless for checking a map you are building.
/// </summary>
public sealed class SpectatorCamera : Component
{
	public static SpectatorCamera Instance { get; private set; }

	[Property] public float Speed { get; set; } = 400f;

	/// <summary>Hold Run to move faster. The map is big and 400u/s is a walk.</summary>
	[Property] public float FastMultiplier { get; set; } = 3f;

	Angles _look;
	bool _wasActive;

	protected override void OnAwake() => Instance = this;
	protected override void OnDestroy() { if ( Instance == this ) Instance = null; }

	protected override void OnUpdate()
	{
		var cam = Scene.Camera;
		if ( !cam.IsValid() ) return;

		if ( !NZGame.IsSpectator )
		{
			_wasActive = false;
			return;
		}

		// ⚠️ Adopt the camera's CURRENT angles on the frame spectating starts,
		// not a zeroed default. Snapping the view to face world-forward the
		// instant you enter spectator is disorienting and makes it feel broken.
		if ( !_wasActive )
		{
			_wasActive = true;
			_look = cam.WorldRotation.Angles();
		}

		_look += Input.AnalogLook;
		_look.pitch = _look.pitch.Clamp( -89f, 89f );
		_look.roll = 0f;

		cam.WorldRotation = _look.ToRotation();

		var speed = Speed * (Input.Down( "Run" ) ? FastMultiplier : 1f);
		var move = Input.AnalogMove;

		// AnalogMove is forward/left in LOCAL space — rotate it by where we are
		// looking, or the controls only make sense facing one direction.
		var wish = cam.WorldRotation * new Vector3( move.x, move.y, 0f );

		// Up and down on jump/duck, since a free camera without vertical is
		// stuck at whatever height it inherited.
		if ( Input.Down( "Jump" ) ) wish += Vector3.Up;
		if ( Input.Down( "Duck" ) ) wish += Vector3.Down;

		if ( !wish.IsNearlyZero() )
			cam.WorldPosition += wish.Normal * speed * Time.Delta;
	}
}