using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using Console = Game.Console;

namespace Game
{
    public class PlayerInputDemo : PlayerInput
    {
        protected List<PlayerInputState> buffer = new List<PlayerInputState>();
        protected IEnumerator<PlayerInputState> bufferEnumerable;

        public PlayerInputDemo(string demoPath)
        {
            if (!File.Exists(demoPath))
                return;

            int expectedPlayerInputStateSize = Marshal.SizeOf(typeof(PlayerInputState));

            FileStream stream = File.OpenRead(demoPath);
            int ver = stream.ReadByte();
            int inputStateSize = stream.ReadByte();
            if (ver != DemoVer && inputStateSize != expectedPlayerInputStateSize)
            {
                Console.Print("demover mismatch: version " + ver + " != " + DemoVer + ", inputStateSize " +
                              inputStateSize + " != " + Marshal.SizeOf(typeof(PlayerInputState)));
                stream.Close();
                return;
            }

            T RawDeserialize<T>(byte[] rawData, int position)
            {
                int rawsize = Marshal.SizeOf(typeof(T));
                if (rawsize > rawData.Length - position)
                    throw new ArgumentException("Not enough data to fill struct. Array length from position: " +
                                                (rawData.Length - position) + ", Struct length: " + rawsize);
                IntPtr buffer = Marshal.AllocHGlobal(rawsize);
                Marshal.Copy(rawData, position, buffer, rawsize);
                T retobj = (T)Marshal.PtrToStructure(buffer, typeof(T));
                Marshal.FreeHGlobal(buffer);
                return retobj;
            }

            while (true)
            {
                byte[] b = new byte[expectedPlayerInputStateSize];
                int readBytes = stream.Read(b, 0, b.Length);
                if (readBytes < expectedPlayerInputStateSize)
                    break;

                buffer.Add(RawDeserialize<PlayerInputState>(b, 0));
            }

            bufferEnumerable = buffer.GetEnumerator();

            Console.Print("demo numstates: " + buffer.Count);

            OnEndFrame(); // advances to first frame
        }

        public override void OnEndFrame()
        {
            // TODO: check if the current state frame matches the current frame number before advancing

            /*asdf++;
            if (asdf < 8)
                return;*/

            if (bufferEnumerable == null || !bufferEnumerable.MoveNext())
            {
                if (buffer.Any())
                {
                    bufferEnumerable.Dispose();
                    bufferEnumerable = null;
                    buffer.Clear();
                    Console.Print("Demo ended");
                }

                return;
            }

            //var actorState = currentState.actor;
            currentState.input = bufferEnumerable.Current;
            //frame++;
            //currentState.actor = actorState;
        }
    }
}