//
// Copyright (c) 2008-2015 the Urho3D project.
// Copyright (c) 2015 Xamarin Inc
// Copyright (c) 2016 THUNDERBEAST GAMES LLC
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

using System;
using System.Linq;
using AtomicEngine;

namespace FeatureExamples
{
    public class DecalSample : Sample
    {
        bool drawDebug;
        Camera camera;

        public DecalSample() : base() { }

        public override void Start()
        {
            base.Start();
            CreateScene();
            CreateUI();
            SetupViewport();
            SubscribeToEvents();
        }

        void CreateUI()
        {
            SimpleCreateInstructionsWithWasd(
                "\nLMB to paint decals, RMB to rotate view\n" +
                "Space to toggle debug geometry\n" +
                "7 to toggle occlusion culling");
        }

        void SubscribeToEvents()
        {
            // Subscribe HandlePostRenderUpdate() function for
            // processing the post-render update event, sent after
            // Renderer subsystem is done with defining the draw
            // calls for the viewports (but before actually
            // executing them.) We will request debug geometry
            // rendering during that event

            SubscribeToEvent<PostRenderUpdateEvent>(e =>
            {
                // If draw debug mode is enabled, draw viewport debug geometry, which will show eg. drawable bounding boxes and skeleton
                // bones. Note that debug geometry has to be separately requested each frame. Disable depth test so that we can see the
                // bones properly
                if (drawDebug)
                {
                    GetSubsystem<Renderer>().DrawDebugGeometry(false);
                }
            });
        }

        protected override void Update(float timeStep)
        {
            UI ui = GetSubsystem<UI>();
            var input = GetSubsystem<Input>();


            const float mouseSensitivity = .1f;
            const float moveSpeed = 40f;

            if (input.GetMouseButtonDown(Constants.MOUSEB_RIGHT))
            {
                var mouseMove = input.MouseMove;
                Yaw += mouseSensitivity * mouseMove.X;
                Pitch += mouseSensitivity * mouseMove.Y;
                Pitch = MathHelper.Clamp(Pitch, -90, 90);
            }

            CameraNode.Rotation = new Quaternion(Pitch, Yaw, 0);

            if (input.GetKeyDown(Constants.KEY_W))
                CameraNode.Translate(Vector3.UnitZ * moveSpeed * timeStep);
            if (input.GetKeyDown(Constants.KEY_S))
                CameraNode.Translate(-Vector3.UnitZ * moveSpeed * timeStep);
            if (input.GetKeyDown(Constants.KEY_A))
                CameraNode.Translate(-Vector3.UnitX * moveSpeed * timeStep);
            if (input.GetKeyDown(Constants.KEY_D))
                CameraNode.Translate(Vector3.UnitX * moveSpeed * timeStep);

            if (input.GetKeyPress(Constants.KEY_SPACE))
                drawDebug = !drawDebug;

            if (input.GetMouseButtonPress(Constants.MOUSEB_LEFT))
                PaintDecal();

            base.Update(timeStep);
        }

        void SetupViewport()
        {
            var renderer = GetSubsystem<Renderer>();
            renderer.SetViewport(0, new Viewport(scene, CameraNode.GetComponent<Camera>()));
        }

        void CreateScene()
        {
            var cache = GetSubsystem<ResourceCache>();
            scene = new Scene();

            // Create octree, use default volume (-1000, -1000, -1000) to (1000, 1000, 1000)
            // Also create a DebugRenderer component so that we can draw debug geometry
            scene.CreateComponent<Octree>();
            scene.CreateComponent<DebugRenderer>();

            // Create scene node & StaticModel component for showing a static plane
            var planeNode = scene.CreateChild("Plane");
            planeNode.Scale = new Vector3(100.0f, 1.0f, 100.0f);
            var planeObject = planeNode.CreateComponent<StaticModel>();
            planeObject.Model = cache.Get<Model>("Models/Plane.mdl");
            planeObject.SetMaterial(cache.Get<Material>("Materials/StoneTiled.xml"));

            // Create a Zone component for ambient lighting & fog control
            var zoneNode = scene.CreateChild("Zone");
            var zone = zoneNode.CreateComponent<Zone>();
            zone.SetBoundingBox(new BoundingBox(-1000.0f, 1000.0f));
            zone.AmbientColor = new Color(0.15f, 0.15f, 0.15f);
            zone.FogColor = new Color(0.5f, 0.5f, 0.7f);
            zone.FogStart = 100.0f;
            zone.FogEnd = 300.0f;

            // Create a directional light to the world. Enable cascaded shadows on it
            var lightNode = scene.CreateChild("DirectionalLight");
            lightNode.SetDirection(new Vector3(0.6f, -1.0f, 0.8f));
            var light = lightNode.CreateComponent<Light>();
            light.LightType = LightType.LIGHT_DIRECTIONAL;
            light.CastShadows = true;
            light.ShadowBias = new BiasParameters(0.00025f, 0.5f);
            // Set cascade splits at 10, 50 and 200 world units, fade shadows out at 80% of maximum shadow distance
            light.ShadowCascade = new CascadeParameters(10.0f, 50.0f, 200.0f, 0.0f, 0.8f);

            // Create some mushrooms
            const uint numMushrooms = 240;
            for (uint i = 0; i < numMushrooms; ++i)
            {
                var mushroomNode = scene.CreateChild("Mushroom");
                mushroomNode.Position = new Vector3(NextRandom(90.0f) - 45.0f, 0.0f, NextRandom(90.0f) - 45.0f);
                mushroomNode.Rotation = new Quaternion(0.0f, NextRandom(360.0f), 0.0f);
                mushroomNode.SetScale(0.5f + NextRandom(2.0f));
                var mushroomObject = mushroomNode.CreateComponent<StaticModel>();
                mushroomObject.Model = cache.Get<Model>("Models/Mushroom.mdl");
                mushroomObject.SetMaterial(cache.Get<Material>("Materials/Mushroom.xml"));
                mushroomObject.CastShadows = true;
            }

            // Create randomly sized boxes. If boxes are big enough, make them occluders. Occluders will be software rasterized before
            // rendering to a low-resolution depth-only buffer to test the objects in the view frustum for visibility
            const uint numBoxes = 20;
            for (uint i = 0; i < numBoxes; ++i)
            {
                var boxNode = scene.CreateChild("Box");
                float size = 1.0f + NextRandom(10.0f);
                boxNode.Position = new Vector3(NextRandom(80.0f) - 40.0f, size * 0.5f, NextRandom(80.0f) - 40.0f);
                boxNode.SetScale(size);
                var boxObject = boxNode.CreateComponent<StaticModel>();
                boxObject.Model = cache.Get<Model>("Models/Box.mdl");
                boxObject.SetMaterial(cache.Get<Material>("Materials/Stone.xml"));
                boxObject.CastShadows = true;
                if (size >= 3.0f)
                    boxObject.Occluder = true;
            }

            // Create the camera. Limit far clip distance to match the fog
            CameraNode = scene.CreateChild("Camera");
            camera = CameraNode.CreateComponent<Camera>();
            camera.FarClip = 300.0f;
            // Set an initial position for the camera scene node above the plane
            CameraNode.Position = new Vector3(0.0f, 5.0f, 0.0f);
        }

        bool Raycast(float maxDistance, out Vector3 hitPos, out Drawable hitDrawable)
        {
            hitDrawable = null;
            hitPos = Vector3.Zero;

            var graphics = GetSubsystem<Graphics>();
            var input = GetSubsystem<Input>();

            IntVector2 pos = input.MousePosition;
            Ray cameraRay = camera.GetScreenRay((float)pos.X / graphics.Width, (float)pos.Y / graphics.Height);

            RayOctreeQuery query = new RayOctreeQuery(cameraRay, RayQueryLevel.RAY_TRIANGLE, maxDistance, Constants.DRAWABLE_GEOMETRY);

            scene.GetComponent<Octree>().RaycastSingle(query);

            if (query.Results.Count > 0)
            {
                var first = query.Results.First();
                hitPos = first.Position;
                hitDrawable = first.Drawable;
                return true;
            }
            return false;
        }

        void PaintDecal()
        {
            Vector3 hitPos;
            Drawable hitDrawable;

            if (Raycast(250.0f, out hitPos, out hitDrawable))
            {
                var targetNode = hitDrawable.Node;
                var decal = targetNode.GetComponent<DecalSet>();

                if (decal == null)
                {
                    var cache = GetSubsystem<ResourceCache>();
                    decal = targetNode.CreateComponent<DecalSet>();
                    decal.Material = cache.Get<Material>("Materials/UrhoDecal.xml");
                }

                // Add a square decal to the decal set using the geometry of the drawable that was hit, orient it to face the camera,
                // use full texture UV's (0,0) to (1,1). Note that if we create several decals to a large object (such as the ground
                // plane) over a large area using just one DecalSet component, the decals will all be culled as one unit. If that is
                // undesirable, it may be necessary to create more than one DecalSet based on the distance
                decal.AddDecal(hitDrawable, hitPos, CameraNode.Rotation, 0.5f, 1.0f, 1.0f, Vector2.Zero,
                    Vector2.One, 0.0f, 0.1f, uint.MaxValue);
            }
        }

    }
}