using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Diagnostics;

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Input;

using FarseerPhysics.DebugViews;
using FarseerPhysics.Dynamics;
using FarseerPhysics.Dynamics.Contacts;
using FarseerPhysics.Dynamics.Joints;
using FarseerPhysics.Factories;
using FarseerPhysics.Collision;
using FarseerPhysics.Collision.Shapes;
using FarseerPhysics.Common;
using FarseerPhysics.SamplesFramework;

namespace RunGun
{
    class Hero
    {
        protected World world;

        protected Body rect;
        protected Vector2 rectSize = new Vector2(0.5f, 0.5f);
        
        protected Body circ;
        protected float circRadius = 0.4f;

        protected RevoluteJoint revJoint;
        protected FixedAngleJoint angJoint;
        
        protected float xVelocityGround = 10;
        protected float jumpForceGround = -900f * 1.4f;

        protected bool onWall;
        protected HashSet<Fixture> wallCache;
        protected bool onGround;
        protected HashSet<Fixture> groundCache;

        private static Vector2 MAX_VELOCITY = new Vector2(200f, 200f);
        private static Vector2 MIN_VELOCITY = new Vector2(-200f, -200f);

        public Hero(World world, Vector2 position)
        {
            this.world = world;

            onWall = false;
            wallCache = new HashSet<Fixture>();

            onGround = false;
            groundCache = new HashSet<Fixture>();

            rect = BodyFactory.CreateBody(world, position);
            rect.BodyType = BodyType.Dynamic;
            rect.Friction = 0f;
            rect.Mass = 1f;
            Vertices rectVerts = PolygonTools.CreateRectangle(rectSize.X, rectSize.Y);

            PolygonShape rectShape = new PolygonShape(rectVerts, 1.0f);
            Fixture rectFix = rect.CreateFixture(rectShape);
            rectFix.OnCollision += OnRectCollision;
            rectFix.OnSeparation += OnRectSeparation;
            rectFix.CollisionCategories = Category.Cat1;
            rectFix.CollidesWith = Category.All & ~Category.Cat1;
            
            circ = BodyFactory.CreateBody(world, new Vector2(position.X, position.Y + 0.5f));
            circ.Mass = 100f;
            circ.BodyType = BodyType.Dynamic;
            circ.Friction = 1000f;
            
            CircleShape circShape = new CircleShape(circRadius, 1f);
            Fixture circFix = circ.CreateFixture(circShape);
            revJoint = JointFactory.CreateRevoluteJoint(world, rect, circ, rect.LocalCenter);
            circFix.OnCollision += OnCircleCollision;
            circFix.OnSeparation += OnCircleSeparation;
            circFix.CollisionCategories = Category.Cat1;
            circFix.CollidesWith = Category.All & ~Category.Cat1;
            
            revJoint.MotorEnabled = true;
            revJoint.MaxMotorTorque = 1000f;
            revJoint.CollideConnected = false;

            // Make sure the body (rect) never rotates.
            angJoint = JointFactory.CreateFixedAngleJoint(world, rect);
        }

        private bool OnRectCollision(Fixture fixtureA, Fixture fixtureB, Contact contact)
        {
            onWall = true;
            wallCache.Add(fixtureB);
            
            return true;
        }

        private void OnRectSeparation(Fixture fixtureA, Fixture fixtureB)
        {
            if (wallCache.Contains(fixtureB))
            {
                wallCache.Remove(fixtureB);

                if (wallCache.Count == 0)
                {
                    onWall = false;
                }
            }
        }

        private bool OnCircleCollision(Fixture fixtureA, Fixture fixtureB, Contact contact)
        {
            groundCache.Add(fixtureB);
            onGround = true;
            return true;
        }

        private void OnCircleSeparation(Fixture fixtureA, Fixture fixtureB)
        {
            if (groundCache.Contains(fixtureB))
            {
                groundCache.Remove(fixtureB);

                if (groundCache.Count == 0)
                {
                    onGround = false;
                }
            }
        }
                

        public void Update(GameTime gameTime)
        {
            MathHelper.Clamp(circ.LinearVelocity.X, MIN_VELOCITY.X, MAX_VELOCITY.X);
            MathHelper.Clamp(circ.LinearVelocity.Y, MIN_VELOCITY.Y, MAX_VELOCITY.Y);

            MathHelper.Clamp(rect.LinearVelocity.X, MIN_VELOCITY.X, MAX_VELOCITY.X);
            MathHelper.Clamp(rect.LinearVelocity.Y, MIN_VELOCITY.Y, MAX_VELOCITY.Y);
        }

        public void HandleInput(InputHelper input, GameTime gameTime)
        {
            GamePadState padState = input.GamePadState;
            float stickY = padState.ThumbSticks.Left.Y;
            float stickX = padState.ThumbSticks.Left.X;

            if (onGround)
            {
                // On ground
                if (padState.Buttons.LeftShoulder == ButtonState.Pressed)
                {
                    circ.AngularVelocity = 0f;
                    revJoint.MotorSpeed = 0f;
                    if (onGround)
                    {
                        rect.LinearVelocity = Vector2.Zero;
                        circ.LinearVelocity = new Vector2(0, 0);
                        circ.Awake = false;
                    }
                }
                else if (stickX < -InputHelper.STICK_DEAD_ZONE)
                {
                    // Left
                    revJoint.MotorSpeed = -xVelocityGround / circRadius;
                }
                else if (stickX > InputHelper.STICK_DEAD_ZONE)
                {
                    // Right
                    revJoint.MotorSpeed = xVelocityGround / circRadius;
                }
                else
                {
                    revJoint.MotorSpeed = 0f;
                    circ.AngularVelocity = 0f;

                    // Prevent Hero from bouncing when coming to stop when
                    // moving up a hill
                    if (onGround)
                    {
                        rect.LinearVelocity = Vector2.Zero;
                        circ.LinearVelocity = new Vector2(0, 0);
                        circ.Awake = false;
                    }
                    else
                    {
                        circ.LinearVelocity = new Vector2(0, circ.LinearVelocity.Y);
                    }
                }
            }
            else if (!onWall)
            {
                // In air
                revJoint.MotorSpeed = 0f;

                if (input.GamePadState.ThumbSticks.Left.X < -InputHelper.STICK_DEAD_ZONE)
                {
                    // Left
                    if (rect.LinearVelocity.X > 0)
                    {
                        // Player is moving right, make them slowly move left
                        rect.LinearVelocity = new Vector2(-xVelocityGround / 8, rect.LinearVelocity.Y);
                    }
                    else
                    {
                        // Just move
                        rect.LinearVelocity = new Vector2(-xVelocityGround, rect.LinearVelocity.Y);
                    }
                }
                else if (input.GamePadState.ThumbSticks.Left.X > InputHelper.STICK_DEAD_ZONE)
                {
                    // Right
                    if (rect.LinearVelocity.X < 0)
                    {
                        rect.LinearVelocity = new Vector2(xVelocityGround / 8, rect.LinearVelocity.Y);
                    }
                    else
                    {
                        rect.LinearVelocity = new Vector2(xVelocityGround, rect.LinearVelocity.Y);
                    }
                }
            }
            else if (onWall)
            {
                rect.LinearVelocity = new Vector2(0, rect.LinearVelocity.Y);
            }
        }
    }
}