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

namespace RhythmBullet.Zer01HD.Utilities.ScreenSystem
{
    public enum ScreenState { EnterTransition, ExitTransition, Normal }

    public class Screen
    {
        public List<ITransition> Transitions;
        public bool UseRenderTargetForExitTransition;
        public Color BackgroundColor;
        public GraphicsDevice GraphicsDevice { get; private set; }
        public Screen NextScreen { get; protected set; }
        public Rectangle ScreenSize { get; protected set; }
        public bool Initiated { get; private set; }

        public Screen(bool useEnterTransition = false)
        {
            State = useEnterTransition ? ScreenState.EnterTransition : ScreenState.Normal;
            Transitions = new List<ITransition>();
        }

        public void Initiate(GraphicsDevice graphicsDevice, Rectangle screenSize)
        {
            this.ScreenSize = screenSize;
            GraphicsDevice = graphicsDevice;
            Initiated = true;
        }

        public virtual void Update(GameTime gameTime)
        {

        }

        public virtual void Draw(SpriteBatch spriteBatch)
        {
            foreach (ITransition transition in Transitions)
            {
                transition.DrawTransition(spriteBatch);
            }
        }

        /// <summary>
        /// Updates the transition.
        /// </summary>
        /// <param name="delta">Time passed since last frame in seconds.</param>
        /// <param name="assetsLoaded">If waiting on assets.</param>
        /// <param name="previousScreenExitFrame">The previous screen's frame. May be null.</param>
        /// <returns>Only returns true if exit transition is complete. Returns false otherwise.</returns>
        public bool UpdateTransition(double delta, bool assetsLoaded)
        {
            switch (State)
            {
                case ScreenState.EnterTransition:
                    EnteringTransition(delta, assetsLoaded);
                    break;
                case ScreenState.ExitTransition:
                    return ExitingTransition(delta, assetsLoaded);
            }

            return false;
        }

        private void EnteringTransition(double delta, bool assetsLoaded)
        {
            bool complete = true;
            for (int transitionID = 0; transitionID < Transitions.Count; transitionID++)
            {
                ITransition transition = Transitions[transitionID];
                if (!transition.EnteringTransition(delta, assetsLoaded))
                {
                    complete = false;
                }
            }
            if (complete && State != ScreenState.ExitTransition)
            {
                State = ScreenState.Normal;
            }
        }

        private bool ExitingTransition(double delta, bool assetsLoaded)
        {
            bool complete = true;
            foreach (ITransition transition in Transitions)
            {
                if (!transition.ExitingTransition(delta, assetsLoaded))
                {
                    complete = false;
                }

            }
            return complete;
        }

        public virtual void Show()
        {
            foreach (ITransition transition in Transitions)
            {
                transition.InitiateTransition(ScreenSize);
            }
        }

        public virtual void Hide()
        {

        }

        public virtual void AssetLoadStateChange(bool state)
        {

        }

        public ScreenState State { get; private set; }

        public void StartExitTransition(bool UseRenderTargetForExitTransition = false)
        {
            this.UseRenderTargetForExitTransition = UseRenderTargetForExitTransition;
            State = ScreenState.ExitTransition;
        }
        
        public virtual void UpdatePreviousScreenFrame(RenderTarget2D previousScreenFrame)
        {
            foreach (ITransition transition in Transitions)
            {
                transition.UpdatePreviousScreenFrame(previousScreenFrame);
            }
        }
    }
}