using BansheeEngine;

namespace BansheeEditor
{
    /// <summary>
    /// Handles drawing of gizmos for the <see cref="Light"/> component.
    /// </summary>
    internal class LightGizmos
    {
        /// <summary>
        /// Method called by the runtime when gizmos are meant to be drawn.
        /// </summary>
        /// <param name="light">Light to draw gizmos for.</param>
        [DrawGizmo(DrawGizmoFlags.Selected)]
        private static void Draw(Light light)
        {
            Vector3 position = light.SceneObject.Position;

            Gizmos.Color = Color.Yellow;
            switch (light.Type)
            {
                case LightType.Directional:
                {
                    Vector3 right = light.SceneObject.Rotation.Rotate(Vector3.XAxis);
                    Vector3 up = light.SceneObject.Rotation.Rotate(Vector3.YAxis);
                    Vector3 forward = light.SceneObject.Forward;

                    Vector3 topLeft = position - right + up;
                    Vector3 topRight = position + right + up;
                    Vector3 botLeft = position - right - up;
                    Vector3 botRight = position + right - up;

                    Gizmos.DrawLine(topLeft, topRight);
                    Gizmos.DrawLine(topRight, botRight);
                    Gizmos.DrawLine(botRight, botLeft);
                    Gizmos.DrawLine(botLeft, topLeft);

                    Gizmos.DrawLine(topLeft, topLeft + forward*5.0f);
                    Gizmos.DrawLine(topRight, topRight + forward*5.0f);
                    Gizmos.DrawLine(botRight, botRight + forward*5.0f);
                    Gizmos.DrawLine(botLeft, botLeft + forward*5.0f);
                }
                    break;
                case LightType.Point:
                    Gizmos.DrawWireSphere(position, light.Range);

                    break;
                case LightType.Spot:
                {
                    Vector3 right = light.SceneObject.Rotation.Rotate(Vector3.XAxis);
                    Vector3 up = light.SceneObject.Rotation.Rotate(Vector3.YAxis);
                    Vector3 forward = light.SceneObject.Forward;

                    float discRadius = light.Range*MathEx.Tan(light.SpotAngle*0.5f);

                    Gizmos.DrawLine(position, position + forward * light.Range + up * discRadius);
                    Gizmos.DrawLine(position, position + forward * light.Range - up * discRadius);
                    Gizmos.DrawLine(position, position + forward * light.Range + right * discRadius);
                    Gizmos.DrawLine(position, position + forward * light.Range - right * discRadius);

                    float falloffDiscRadius = light.Range * MathEx.Tan(light.SpotFalloffAngle * 0.5f);

                    Gizmos.DrawWireDisc(position + forward * light.Range, forward, discRadius);
                    Gizmos.DrawWireDisc(position + forward * light.Range, forward, falloffDiscRadius);
                }
                    break;
            }
        }
    }
}