//
// 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.Collections.Generic;
using System.Linq;
using AtomicEngine;

namespace FeatureExamples
{
    public class NavigationSample : Sample
    {
        float yaw;
        float pitch;
        bool drawDebug;
        Node jackNode;
        Vector3 endPos;
        List<Vector3> currentPath = new List<Vector3>();

        public NavigationSample() : base() { }

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

        void SubscribeToEvents()
        {
            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);

                if (currentPath.Count > 0)
                {
                    // Visualize the current calculated path
                    DebugRenderer debug = scene.GetComponent<DebugRenderer>();
                    debug.AddBoundingBox(new BoundingBox(endPos - new Vector3(0.1f, 0.1f, 0.1f), endPos + new Vector3(0.1f, 0.1f, 0.1f)),
                        new Color(1.0f, 1.0f, 1.0f), true);

                    // Draw the path with a small upward bias so that it does not clip into the surfaces
                    Vector3 bias = new Vector3(0.0f, 0.05f, 0.0f);
                    debug.AddLine(jackNode.Position + bias, currentPath[0] + bias, new Color(1.0f, 1.0f, 1.0f), true);

                    if (currentPath.Count > 1)
                    {
                        for (int i = 0; i < currentPath.Count - 1; ++i)
                            debug.AddLine(currentPath[i] + bias, currentPath[i + 1] + bias, new Color(1.0f, 1.0f, 1.0f), true);
                    }
                }
            });
        }

        protected override void Update(float timeStep)
        {
            base.Update(timeStep);
            MoveCamera(timeStep);
            FollowPath(timeStep);
        }

        void MoveCamera(float timeStep)
        {
            var input = GetSubsystem<Input>();

            // Right mouse button controls mouse cursor visibility: hide when pressed
            bool rightMouseDown = input.GetMouseButtonDown(Constants.MOUSEB_RIGHT);

            // Movement speed as world units per second
            const float moveSpeed = 20.0f;
            // Mouse sensitivity as degrees per pixel
            const float mouseSensitivity = 0.1f;

            // Use this frame's mouse motion to adjust camera node yaw and pitch. Clamp the pitch between -90 and 90 degrees
            // Only move the camera when the cursor is hidden
            if (rightMouseDown)
            {
                IntVector2 mouseMove = input.MouseMove;
                yaw += mouseSensitivity * mouseMove.X;
                pitch += mouseSensitivity * mouseMove.Y;
                pitch = MathHelper.Clamp(pitch, -90.0f, 90.0f);

                // Construct new orientation for the camera scene node from yaw and pitch. Roll is fixed to zero
                CameraNode.Rotation = new Quaternion(pitch, yaw, 0.0f);
            }

            // Read WASD keys and move the camera scene node to the corresponding direction if they are pressed
            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);

            // Set destination or teleport with left mouse button
            if (input.GetMouseButtonPress(Constants.MOUSEB_LEFT))
                SetPathPoint();
            // Add or remove objects with middle mouse button, then rebuild navigation mesh partially
            if (input.GetMouseButtonPress(Constants.MOUSEB_MIDDLE))
                AddOrRemoveObject();

            // Toggle debug geometry with space
            if (input.GetKeyPress(Constants.KEY_SPACE))
                drawDebug = !drawDebug;
        }

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

        void CreateUI()
        {

            SimpleCreateInstructions(
                "Use WASD keys to move, RMB to rotate view\n" +
                "LMB to set destination, SHIFT+LMB to teleport\n" +
                "MMB to add or remove obstacles\n" +
                "Space to toggle debug geometry");
        }

        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
            Node planeNode = scene.CreateChild("Plane");
            planeNode.Scale = new Vector3(100.0f, 1.0f, 100.0f);
            StaticModel 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
            Node zoneNode = scene.CreateChild("Zone");
            Zone 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
            Node lightNode = scene.CreateChild("DirectionalLight");
            lightNode.SetDirection(new Vector3(0.6f, -1.0f, 0.8f));
            Light 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 = 100;
            for (uint i = 0; i < numMushrooms; ++i)
                CreateMushroom(new Vector3(NextRandom(90.0f) - 45.0f, 0.0f, NextRandom(90.0f) - 45.0f));

            // Create randomly sized boxes. If boxes are big enough, make them occluders
            const uint numBoxes = 20;
            for (uint i = 0; i < numBoxes; ++i)
            {
                Node 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);
                StaticModel 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 Jack node that will follow the path
            jackNode = scene.CreateChild("Jack");
            jackNode.Position = new Vector3(-5.0f, 0.0f, 20.0f);
            AnimatedModel modelObject = jackNode.CreateComponent<AnimatedModel>();
            modelObject.Model = cache.Get<Model>("Models/Jack.mdl");
            modelObject.SetMaterial(cache.Get<Material>("Materials/Jack.xml"));
            modelObject.CastShadows = true;

            // Create a NavigationMesh component to the scene root
            NavigationMesh navMesh = scene.CreateComponent<NavigationMesh>();
            // Create a Navigable component to the scene root. This tags all of the geometry in the scene as being part of the
            // navigation mesh. By default this is recursive, but the recursion could be turned off from Navigable
            scene.CreateComponent<Navigable>();
            // Add padding to the navigation mesh in Y-direction so that we can add objects on top of the tallest boxes
            // in the scene and still update the mesh correctly
            navMesh.Padding = new Vector3(0.0f, 10.0f, 0.0f);
            // Now build the navigation geometry. This will take some time. Note that the navigation mesh will prefer to use
            // physics geometry from the scene nodes, as it often is simpler, but if it can not find any (like in this example)
            // it will use renderable geometry instead
            navMesh.Build();

            // Create the camera. Limit far clip distance to match the fog
            CameraNode = scene.CreateChild("Camera");
            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);
        }

        void SetPathPoint()
        {
            var input = GetSubsystem<Input>();

            Vector3 hitPos;
            Drawable hitDrawable;
            NavigationMesh navMesh = scene.GetComponent<NavigationMesh>();

            if (Raycast(250.0f, out hitPos, out hitDrawable))
            {
                Vector3 pathPos = navMesh.FindNearestPoint(hitPos, new Vector3(1.0f, 1.0f, 1.0f));

                if (input.GetQualifierDown(Constants.QUAL_SHIFT))
                {
                    // Teleport
                    currentPath.Clear();
                    jackNode.LookAt(new Vector3(pathPos.X, jackNode.Position.Y, pathPos.Z), Vector3.UnitY, TransformSpace.TS_WORLD);
                    jackNode.Position = (pathPos);
                }
                else
                {
                    // Calculate path from Jack's current position to the end point
                    endPos = pathPos;
                    var result = navMesh.FindPath(currentPath, jackNode.Position, endPos);
                }
            }
        }

        void AddOrRemoveObject()
        {
            // Raycast and check if we hit a mushroom node. If yes, remove it, if no, create a new one
            Vector3 hitPos;
            Drawable hitDrawable;

            if (Raycast(250.0f, out hitPos, out hitDrawable))
            {
                // The part of the navigation mesh we must update, which is the world bounding box of the associated
                // drawable component
                BoundingBox updateBox;

                Node hitNode = hitDrawable.Node;
                if (hitNode.Name == "Mushroom")
                {
                    updateBox = hitDrawable.WorldBoundingBox;
                    hitNode.Remove();
                }
                else
                {
                    Node newNode = CreateMushroom(hitPos);
                    updateBox = newNode.GetComponent<StaticModel>().WorldBoundingBox;
                }

                // Rebuild part of the navigation mesh, then recalculate path if applicable
                NavigationMesh navMesh = scene.GetComponent<NavigationMesh>();
                navMesh.Build(updateBox);
                if (currentPath.Count > 0)
                    navMesh.FindPath(currentPath, jackNode.Position, endPos);
            }
        }

        Node CreateMushroom(Vector3 pos)
        {
            var cache = GetSubsystem<ResourceCache>();

            Node mushroomNode = scene.CreateChild("Mushroom");
            mushroomNode.Position = pos;
            mushroomNode.Rotation = new Quaternion(0.0f, NextRandom(360.0f), 0.0f);
            mushroomNode.SetScale(2.0f + NextRandom(0.5f));
            StaticModel mushroomObject = mushroomNode.CreateComponent<StaticModel>();
            mushroomObject.Model = (cache.Get<Model>("Models/Mushroom.mdl"));
            mushroomObject.SetMaterial(cache.Get<Material>("Materials/Mushroom.xml"));
            mushroomObject.CastShadows = true;

            return mushroomNode;
        }

        bool Raycast(float maxDistance, out Vector3 hitPos, out Drawable hitDrawable)
        {
            var input = GetSubsystem<Input>();

            hitDrawable = null;
            hitPos = new Vector3();

            var graphics = GetSubsystem<Graphics>();
            Camera camera = CameraNode.GetComponent<Camera>();

            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);

            // Pick only geometry objects, not eg. zones or lights, only get the first (closest) hit
            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 FollowPath(float timeStep)
        {
            if (currentPath.Count > 0)
            {
                Vector3 nextWaypoint = currentPath[0]; // NB: currentPath[0] is the next waypoint in order

                // Rotate Jack toward next waypoint to reach and move. Check for not overshooting the target
                float move = 5.0f * timeStep;
                float distance = (jackNode.Position - nextWaypoint).Length;
                if (move > distance)
                    move = distance;

                jackNode.LookAt(nextWaypoint, Vector3.UnitY, TransformSpace.TS_WORLD);
                jackNode.Translate(Vector3.UnitZ * move, TransformSpace.TS_LOCAL);

                // Remove waypoint if reached it
                if (distance < 0.1f)
                    currentPath.RemoveAt(0);
            }
        }

    }
}