using System.Collections;
using System.IO;
using UnityEngine;
using UnityEngine.Rendering;

namespace Winglett.RR.Utils
{
    [RequireComponent(typeof(Camera))]
    public class Screenshotter : MonoBehaviour
    {
        public bool m_TakeScreenshot;
        public CameraEvent m_CamEvent;

        private Camera m_Camera;
        private CommandBuffer m_Buffer;
        private RenderTexture m_Rt;

        private void Awake()
        {
            m_Camera = GetComponent<Camera>();
            m_Buffer = new CommandBuffer();
            m_Rt = new RenderTexture(m_Camera.pixelWidth, m_Camera.pixelHeight, 0);
        }

        private void Update()
        {
            if (m_TakeScreenshot)
            {
                TakeScreenshot();
                m_TakeScreenshot = false;
            }
        }

        public void TakeScreenshot()
        {
            m_Buffer.Blit(BuiltinRenderTextureType.CurrentActive, new RenderTargetIdentifier(m_Rt));

            m_Buffer.RequestAsyncReadback(m_Rt, (AsyncGPUReadbackRequest obj) =>
            {
                StartCoroutine(ProcessScreenshot(obj));
            });

            m_Camera.AddCommandBuffer(m_CamEvent, m_Buffer);
        }

        private IEnumerator ProcessScreenshot(AsyncGPUReadbackRequest request)
        {
            m_Camera.RemoveCommandBuffer(m_CamEvent, m_Buffer);
            var rawData = request.GetData<Color32>();
            Color32[] data = rawData.ToArray();

            yield return null;

            Texture2D tex = new Texture2D(m_Camera.pixelWidth, m_Camera.pixelHeight);
            tex.SetPixels32(data);
            tex.Apply();

            yield return null;

            string path = Path.Combine(UnityEngine.Application.persistentDataPath, "test.png");
            File.WriteAllBytes(path, tex.EncodeToPNG());

            yield return null;

            Debug.Log("Screenshot done");
            Destroy(tex);
        }

        private void OnDestroy() => m_Rt.Release();
    }
}