using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Storage;

using System.IO;


namespace XNAGame
{
    public class Water
    {
        GraphicsDevice device;
        Effect effect;

        //Water variables
        private VertexPositionTexture[] waterVertices;
        private float waterHeight;

        //Water bumpmapping variables
        private Texture2D waterBumpMap;

        private Matrix worldMatrix;

        public Water(float waterHeight)
        {
            this.waterHeight = waterHeight;
        }

        public void Initialize(GraphicsDevice gd, ContentManager cm)
        {
            SetUpXNADevice(gd);
            SetUpEffects(cm);
            SetUpWaterVertices();
        }

        private void SetUpXNADevice(GraphicsDevice gd)
        {
            device = gd;
        }

        private void SetUpEffects(ContentManager cm)
        {
            effect = cm.Load<Effect>("effect");
            waterBumpMap = cm.Load<Texture2D>("Models\\bumpmaps\\water");
        }

        private void SetUpWaterVertices()
        {
            int WIDTH = 500;
            int HEIGHT = 500;
            waterVertices = new VertexPositionTexture[6];

            waterVertices[0] = new VertexPositionTexture(new Vector3(0, 0, waterHeight), new Vector2(0, 1));
            waterVertices[2] = new VertexPositionTexture(new Vector3(WIDTH, HEIGHT, waterHeight), new Vector2(1, 0));
            waterVertices[1] = new VertexPositionTexture(new Vector3(0, HEIGHT, waterHeight), new Vector2(0, 0));

            waterVertices[3] = new VertexPositionTexture(new Vector3(0, 0, waterHeight), new Vector2(0, 1));
            waterVertices[5] = new VertexPositionTexture(new Vector3(WIDTH, 0, waterHeight), new Vector2(1, 1));
            waterVertices[4] = new VertexPositionTexture(new Vector3(WIDTH, HEIGHT, waterHeight), new Vector2(1, 0));
        }



        public void updateCamera(Matrix viewMatrix, Matrix projectionMatrix)
        {
            worldMatrix = Matrix.Identity;
            effect.Parameters["xCameraViewProjection"].SetValue(viewMatrix * projectionMatrix);
            effect.Parameters["xView"].SetValue(viewMatrix);
            effect.Parameters["xProjection"].SetValue(projectionMatrix);
            effect.Parameters["xWorld"].SetValue(worldMatrix);
        }

        private void DrawWater(Matrix viewMatrix, Matrix projectionMatrix, Matrix reflectionViewMatrix, Texture2D reflectionMap, Texture2D refractionMap, Vector3 cameraPosition, float elapsedTime)
        {
            effect.CurrentTechnique = effect.Techniques["Water"];
            Matrix worldMatrix = Matrix.Identity;
            effect.Parameters["xWorld"].SetValue(worldMatrix);
            effect.Parameters["xView"].SetValue(viewMatrix);
            effect.Parameters["xReflectionView"].SetValue(reflectionViewMatrix);
            effect.Parameters["xProjection"].SetValue(projectionMatrix);
            effect.Parameters["xReflectionMap"].SetValue(reflectionMap);
            effect.Parameters["xRefractionMap"].SetValue(refractionMap);

            //Set the wavelength and waveheight of the water
            effect.Parameters["xWaterBumpMap"].SetValue(waterBumpMap);
            effect.Parameters["xWaveLength"].SetValue(0.1f);
            effect.Parameters["xWaveHeight"].SetValue(0.3f);

            //For the Fresnel realization
            effect.Parameters["xCamPos"].SetValue(cameraPosition);

            //Set the effect file to let the water move
            effect.Parameters["xTime"].SetValue(elapsedTime);
            effect.Parameters["xWindForce"].SetValue(20.0f);
            Matrix windDirection = Matrix.CreateRotationZ(MathHelper.PiOver2);
            effect.Parameters["xWindDirection"].SetValue(windDirection);

            effect.Begin();
            foreach (EffectPass pass in effect.CurrentTechnique.Passes)
            {
                pass.Begin();
                device.VertexDeclaration = new VertexDeclaration(device, VertexPositionTexture.VertexElements);
                device.DrawUserPrimitives(PrimitiveType.TriangleList, waterVertices, 0, 2);
                pass.End();
            }
            effect.End();
        }

        public void Draw(Matrix viewMatrix, Matrix projectionMatrix, Matrix reflectionViewMatrix, Texture2D reflectionMap, Texture2D refractionMap, Vector3 cameraPosition, float elapsedTime)
        {
            DrawWater(viewMatrix, projectionMatrix, reflectionViewMatrix, reflectionMap, refractionMap, cameraPosition, elapsedTime);
        }
    }
}