using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace SuperPolarity
{
    static class ActorManager
    {

        static SuperPolarity Game;
        static int OutlierBounds;
        static IList<Actor> Actors;

        static ActorManager()
        {
            OutlierBounds = 100;
            Actors = new List<Actor>();
        }

        static public void CheckIn(Actor actor)
        {
            Actors.Add(actor);
        }

        static public void CheckOut(Actor actor)
        {
            actor.CleanUp();
            Actors.Remove(actor);
            actor = null;
        }

        static public void Update(GameTime gameTime) 
        {
            CheckActors();
            CheckOutliers();
            foreach (Actor actor in Actors)
            {
                actor.Update(gameTime);
            }
        }

        static public void Draw(SpriteBatch spriteBatch)
        {
            foreach (Actor actor in Actors)
            {
                actor.Draw(spriteBatch);
            }
        }

        static void CheckActors()
        {
            for (var i = Actors.Count - 1; i >= 0; i--)
            {
                if (i >= Actors.Count) {
                    i = Actors.Count - 1;
                }

                if (Actors.Count == 0)
                {
                    return;
                }

                Actor actor = Actors[i];
                for (var j = i - 1; j >= 0; j--)
                {
                    Actor other = Actors[j];

                    CheckCollision(actor, other);

                    if (actor.GetType().IsSubclassOf(typeof(Ship)) && other.GetType().IsSubclassOf(typeof(Ship)))
                    {
                        CheckMagnetism((Ship)actor, (Ship)other);
                    }
                }
            }
        }

        static void CheckCollision(Actor actor, Actor other)
        {
            var collision = Rectangle.Intersect(actor.Box, other.Box);
            var inverseCollision = Rectangle.Intersect(other.Box, actor.Box);
            if (!collision.IsEmpty && !actor.Dying && !other.Dying)
            {
                actor.Collide(other, collision);
                other.Collide(actor, inverseCollision);
            }

        }

        static void CheckMagnetism(Ship actor, Ship other)
        {
            if (actor.CurrentPolarity != Ship.Polarity.Neutral && other.CurrentPolarity != Ship.Polarity.Neutral)
            {
                var dy = other.Position.Y - actor.Position.Y;
                var dx = other.Position.X - actor.Position.X;
                var linearDistance = Math.Sqrt(Math.Pow(dx, 2) + Math.Pow(dy, 2));
                var angle = (float) Math.Atan2(dy, dx);
                var otherAngle = (float)Math.Atan2(-dy, -dx);

                if (linearDistance < actor.MagneticRadius || linearDistance < other.MagneticRadius)
                {
                    actor.Magnetize(other, (float)linearDistance, angle);
                    other.Magnetize(actor, (float)linearDistance, otherAngle);
                }
            }
        }

        static void CheckOutliers()
        {
            for (var i = Actors.Count; i > 0; i--)
            {
                var actor = Actors[i-1];
                if (actor.Position.X < -OutlierBounds || actor.Position.Y < -OutlierBounds ||
                    actor.Position.X > Game.GraphicsDevice.Viewport.Width + OutlierBounds ||
                    actor.Position.Y > Game.GraphicsDevice.Viewport.Height + OutlierBounds)
                {
                    CheckOut(actor);
                    if (actor.Parent != null)
                    {
                        actor.Parent.Children.Remove(actor);
                    }
                }
            }
        }

        static public void Empty()
        {
            foreach (Actor actor in Actors) {
                actor.CleanUp();
            }
            Actors.Clear();
        }

        internal static void SetGame(SuperPolarity game)
        {
            Game = game;
        }

        public static void Bomb()
        {
            for (var i = Actors.Count - 1; i >= 0; i--)
            {
                var actor = Actors[i];
                if (actor.GetType() == typeof(StandardShip))
                {
                    CheckOut(actor);
                    Renderer.CheckOut(actor);
                }
            }
        }

        public static int CountBaddies()
        {
            return Actors.Where(a => a.GetType() == typeof(StandardShip)).Count();
        }
    }
}