//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera (marko.pintera@gmail.com). All rights reserved. **********************//
using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using bs;

namespace bs.Editor
{
    /** @addtogroup Scene-Editor
     *  @{
     */

    /// <summary>
    /// Contains world position and normal of the surface of the object in a snap operation.
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    struct SnapData
    {
        /// <summary>
        /// The normal to the object surface at the snapping point.
        /// </summary>
        public Vector3 normal;

        /// <summary>
        /// The world position on the surface of the object.
        /// </summary>
        public Vector3 position;
    }

    /// <summary>
    /// Handles rendering of the selection overlay and picking of objects in the target camera's view.
    /// </summary>
    internal sealed class SceneSelection : ScriptObject
    {
        /// <summary>
        /// Creates a new scene selection manager.
        /// </summary>
        /// <param name="sceneCamera">Camera into which to render the selection overlay, and perform picking from.</param>
        internal SceneSelection(Camera sceneCamera)
        {
            Internal_Create(this, sceneCamera.GetCachedPtr());
        }

        /// <summary>
        /// Queues selection overlay drawing for this frame.
        /// </summary>
        internal void Draw()
        {
            Internal_Draw(mCachedPtr);
        }

        /// <summary>
        /// Attempts to select a scene object under the pointer position.
        /// </summary>
        /// <param name="pointerPos">Position of the pointer relative to the scene camera viewport.</param>
        /// <param name="controlHeld">Should this selection add to the existing selection, or replace it.</param>
        /// <param name="ignoreSceneObjects">Optional set of objects to ignore during scene picking.</param>
        internal void PickObject(Vector2I pointerPos, bool controlHeld, SceneObject[] ignoreSceneObjects = null)
        {
            Internal_PickObject(mCachedPtr, ref pointerPos, controlHeld, ignoreSceneObjects);
        }

        /// <summary>
        /// Attempts to select a scene object in the specified area.
        /// </summary>
        /// <param name="pointerPos">Position of the pointer relative to the scene camera viewport.</param>
        /// <param name="area">Size of the in which objects will be selected, in pixels and relative to 
        ///                    <paramref name="pointerPos"/>.</param>
        /// <param name="controlHeld">Should this selection add to the existing selection, or replace it.</param>
        /// <param name="ignoreSceneObjects">Optional set of objects to ignore during scene picking.</param>
        internal void PickObjects(Vector2I pointerPos, Vector2I area, bool controlHeld, 
            SceneObject[] ignoreSceneObjects = null)
        {
            Internal_PickObjects(mCachedPtr, ref pointerPos, ref area, controlHeld, ignoreSceneObjects);
        }

        /// <summary>
        /// Attempts to find a scene object under the provided position, while also returning the world position and normal
        /// of the point that was hit.
        /// </summary>
        /// <param name="pointerPos">Position of the pointer relative to the scene camera viewport.</param>
        /// <param name="data">Position and normal on the object surface at the point that was hit.</param>
        /// <param name="ignoreSceneObjects">Optional set of objects to ignore during scene picking.</param>
        /// <returns>The object the pointer is snapping to.</returns>
        internal SceneObject Snap(Vector2I pointerPos, out SnapData data, SceneObject[] ignoreSceneObjects = null)
        {
            return Internal_Snap(mCachedPtr, ref pointerPos, out data, ignoreSceneObjects);
        }

        [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern void Internal_Create(SceneSelection managedInstance, IntPtr camera);

        [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern void Internal_Draw(IntPtr thisPtr);

        [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern void Internal_PickObject(IntPtr thisPtr, ref Vector2I pointerPos, bool controlHeld, SceneObject[] ignoreRenderables);

        [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern void Internal_PickObjects(IntPtr thisPtr, ref Vector2I pointerPos, ref Vector2I extents, bool controlHeld, SceneObject[] ignoreRenderables);

        [MethodImpl(MethodImplOptions.InternalCall)]
        private static extern SceneObject Internal_Snap(IntPtr thisPtr, ref Vector2I pointerPos, out SnapData data, SceneObject[] ignoreRenderables);
    }

    /** @} */
}