using System;
using System.Collections;
using System.Collections.Generic;
using System.IO.MemoryMappedFiles;
using UnityEngine;

public class CameraServerMemory : MonoBehaviour 
{
    public Camera[] CameraSources;
    public string StreamFileName = "CameraStream";
    public float ScanTime = 0.04f;
    
    private MemoryMappedViewAccessor mapView;
    private MemoryMappedFile mapFile;        
    private List<Texture2D> grabbedImages = new List<Texture2D>();
    private List<int> imagePointers = new List<int>();
    private List<int> imageSizes = new List<int>();
    private int HeaderSize;
    private bool isStreamingEnable = true;

    //---------------------------------------------------------------------------------
    public void StreamingEnable(bool value) 
    {
        this.isStreamingEnable = value;
        foreach (var c in CameraSources)
        {
            c.enabled = value;
        }
    }

    //---------------------------------------------------------------------------------
    void Start () 
    {
        int totalimagesize = 0;
        foreach (var c in CameraSources)
        {
            grabbedImages.Add(new Texture2D(c.targetTexture.width, c.targetTexture.height, TextureFormat.RGB24, false));
            imagePointers.Add(totalimagesize);
            var imagesize = 3 * c.targetTexture.height * c.targetTexture.width;
            imageSizes.Add(imagesize);
            totalimagesize += imagesize;
        }

        HeaderSize = sizeof(Int32) + sizeof(Int32) * 2 * CameraSources.Length;
        mapFile = MemoryMappedFile.CreateOrOpen(StreamFileName, totalimagesize + HeaderSize);
        mapView = mapFile.CreateViewAccessor(0, totalimagesize + HeaderSize);
        mapView.Write(0, CameraSources.Length);
        for(int i = 0; i < CameraSources.Length; i++)
        {
            mapView.Write(4 + 8*i , CameraSources[i].targetTexture.width);
            mapView.Write(8 + 8*i , CameraSources[i].targetTexture.height);
        }
        StartCoroutine(Cameraframeloop());
    }

    //---------------------------------------------------------------------------------
    IEnumerator Cameraframeloop()
    {
        int i = 0;
        while (Application.isPlaying)
        {            
            if (ScanTime > 0)
                yield return new WaitForSecondsRealtime(ScanTime);
            else
                yield return new WaitForEndOfFrame();

            if (!this.isStreamingEnable)
                continue;

            RenderTexture.active = CameraSources[i].targetTexture;
            grabbedImages[i].ReadPixels(new Rect(0, 0, RenderTexture.active.width, RenderTexture.active.height), 0, 0);
            
            mapView.WriteArray(
                HeaderSize + imagePointers[i],
                grabbedImages[i].GetRawTextureData(),
                0,
                imageSizes[i]
                );
            i++;
            if (i == CameraSources.Length) i = 0;
        }
    }
}