//======= Copyright (c) Valve Corporation, All rights reserved. ===============
//
// Purpose: Handles rendering of all SteamVR_Cameras
//
//=============================================================================

using UnityEngine;
using System.Collections;
using Valve.VR;

public class SteamVR_Render : MonoBehaviour
{
	public bool pauseGameWhenDashboardIsVisible = true;
	public bool lockPhysicsUpdateRateToRenderFrequency = true;

	public SteamVR_ExternalCamera externalCamera;
	public string externalCameraConfigPath = "externalcamera.cfg";

	public ETrackingUniverseOrigin trackingSpace = ETrackingUniverseOrigin.TrackingUniverseStanding;

	static public EVREye eye { get; private set; }

	static private SteamVR_Render _instance;
	static public SteamVR_Render instance
	{
		get
		{
			if (_instance == null)
			{
				_instance = GameObject.FindObjectOfType<SteamVR_Render>();

				if (_instance == null)
					_instance = new GameObject("[SteamVR]").AddComponent<SteamVR_Render>();
			}
			return _instance;
		}
	}

	void OnDestroy()
	{
		_instance = null;
	}

	static private bool isQuitting;
	void OnApplicationQuit()
	{
		isQuitting = true;
		SteamVR.SafeDispose();
	}

	static public void Add(SteamVR_Camera vrcam)
	{
		if (!isQuitting)
			instance.AddInternal(vrcam);
	}

	static public void Remove(SteamVR_Camera vrcam)
	{
		if (!isQuitting && _instance != null)
			instance.RemoveInternal(vrcam);
	}

	static public SteamVR_Camera Top()
	{
		if (!isQuitting)
			return instance.TopInternal();

		return null;
	}

	private SteamVR_Camera[] cameras = new SteamVR_Camera[0];

	void AddInternal(SteamVR_Camera vrcam)
	{
		var camera = vrcam.GetComponent<Camera>();
		var length = cameras.Length;
		var sorted = new SteamVR_Camera[length + 1];
		int insert = 0;
		for (int i = 0; i < length; i++)
		{
			var c = cameras[i].GetComponent<Camera>();
			if (i == insert && c.depth > camera.depth)
				sorted[insert++] = vrcam;

			sorted[insert++] = cameras[i];
		}
		if (insert == length)
			sorted[insert] = vrcam;

		cameras = sorted;
	}

	void RemoveInternal(SteamVR_Camera vrcam)
	{
		var length = cameras.Length;
		int count = 0;
		for (int i = 0; i < length; i++)
		{
			var c = cameras[i];
			if (c == vrcam)
				++count;
		}
		if (count == 0)
			return;

		var sorted = new SteamVR_Camera[length - count];
		int insert = 0;
		for (int i = 0; i < length; i++)
		{
			var c = cameras[i];
			if (c != vrcam)
				sorted[insert++] = c;
		}

		cameras = sorted;
	}

	SteamVR_Camera TopInternal()
	{
		if (cameras.Length > 0)
			return cameras[cameras.Length - 1];

		return null;
	}

	public TrackedDevicePose_t[] poses = new TrackedDevicePose_t[OpenVR.k_unMaxTrackedDeviceCount];
	public TrackedDevicePose_t[] gamePoses = new TrackedDevicePose_t[0];

	static private bool _pauseRendering;
	static public bool pauseRendering
	{
		get { return _pauseRendering; }
		set
		{
			_pauseRendering = value;

			var compositor = OpenVR.Compositor;
			if (compositor != null)
				compositor.SuspendRendering(value);
		}
	}

	private WaitForEndOfFrame waitForEndOfFrame = new WaitForEndOfFrame();

	private IEnumerator RenderLoop()
	{
		while (Application.isPlaying)
		{
			yield return waitForEndOfFrame;

			if (pauseRendering)
				continue;

			var compositor = OpenVR.Compositor;
			if (compositor != null)
			{
				if (!compositor.CanRenderScene())
					continue;

				compositor.SetTrackingSpace(trackingSpace);
			}

			var overlay = SteamVR_Overlay.instance;
			if (overlay != null)
				overlay.UpdateOverlay();

			RenderExternalCamera();
		}
	}

	void RenderExternalCamera()
	{
		if (externalCamera == null)
			return;

		if (!externalCamera.gameObject.activeInHierarchy)
			return;

		var frameSkip = (int)Mathf.Max(externalCamera.config.frameSkip, 0.0f);
		if (Time.frameCount % (frameSkip + 1) != 0)
			return;

		// Keep external camera relative to the most relevant vr camera.
		externalCamera.AttachToCamera(TopInternal());

		externalCamera.RenderNear();
		externalCamera.RenderFar();
	}

	float sceneResolutionScale = 1.0f, timeScale = 1.0f;

	private void OnInputFocus(bool hasFocus)
	{
		if (hasFocus)
		{
			if (pauseGameWhenDashboardIsVisible)
			{
				Time.timeScale = timeScale;
			}

			SteamVR_Camera.sceneResolutionScale = sceneResolutionScale;
		}
		else
		{
			if (pauseGameWhenDashboardIsVisible)
			{
				timeScale = Time.timeScale;
				Time.timeScale = 0.0f;
			}

			sceneResolutionScale = SteamVR_Camera.sceneResolutionScale;
			SteamVR_Camera.sceneResolutionScale = 0.5f;
		}
	}

	void OnQuit(VREvent_t vrEvent)
	{
#if UNITY_EDITOR
		foreach (System.Reflection.Assembly a in System.AppDomain.CurrentDomain.GetAssemblies())
		{
			var t = a.GetType("UnityEditor.EditorApplication");
			if (t != null)
			{
				t.GetProperty("isPlaying").SetValue(null, false, null);
				break;
			}
		}
#else
		Application.Quit();
#endif
	}

	private string GetScreenshotFilename(uint screenshotHandle, EVRScreenshotPropertyFilenames screenshotPropertyFilename)
	{
		var error = EVRScreenshotError.None;
		var capacity = OpenVR.Screenshots.GetScreenshotPropertyFilename(screenshotHandle, screenshotPropertyFilename, null, 0, ref error);
		if (error != EVRScreenshotError.None && error != EVRScreenshotError.BufferTooSmall)
			return null;
		if (capacity > 1)
		{
			var result = new System.Text.StringBuilder((int)capacity);
			OpenVR.Screenshots.GetScreenshotPropertyFilename(screenshotHandle, screenshotPropertyFilename, result, capacity, ref error);
			if (error != EVRScreenshotError.None)
				return null;
			return result.ToString();
		}
		return null;
	}

	private void OnRequestScreenshot(VREvent_t vrEvent)
	{
		var screenshotHandle = vrEvent.data.screenshot.handle;
		var screenshotType = (EVRScreenshotType)vrEvent.data.screenshot.type;

		if (screenshotType == EVRScreenshotType.StereoPanorama)
		{
			string previewFilename = GetScreenshotFilename(screenshotHandle, EVRScreenshotPropertyFilenames.Preview);
			string VRFilename = GetScreenshotFilename(screenshotHandle, EVRScreenshotPropertyFilenames.VR);

			if (previewFilename == null || VRFilename == null)
				return;

			// Do the stereo panorama screenshot
			// Figure out where the view is
			GameObject screenshotPosition = new GameObject("screenshotPosition");
			screenshotPosition.transform.position = SteamVR_Render.Top().transform.position;
			screenshotPosition.transform.rotation = SteamVR_Render.Top().transform.rotation;
			screenshotPosition.transform.localScale = SteamVR_Render.Top().transform.lossyScale;
			SteamVR_Utils.TakeStereoScreenshot(screenshotHandle, screenshotPosition, 32, 0.064f, ref previewFilename, ref VRFilename);

			// and submit it
			OpenVR.Screenshots.SubmitScreenshot(screenshotHandle, screenshotType, previewFilename, VRFilename);
		}
	}

	void OnEnable()
	{
		StartCoroutine(RenderLoop());
		SteamVR_Events.InputFocus.Listen(OnInputFocus);
		SteamVR_Events.System(EVREventType.VREvent_Quit).Listen(OnQuit);
		SteamVR_Events.System(EVREventType.VREvent_RequestScreenshot).Listen(OnRequestScreenshot);
#if UNITY_2017_1_OR_NEWER
		Application.onBeforeRender += OnBeforeRender;
#else
		Camera.onPreCull += OnCameraPreCull;
#endif
		var vr = SteamVR.instance;
		if (vr == null)
		{
			enabled = false;
			return;
		}
		var types = new EVRScreenshotType[] { EVRScreenshotType.StereoPanorama };
		OpenVR.Screenshots.HookScreenshot(types);
	}

	void OnDisable()
	{
		StopAllCoroutines();
		SteamVR_Events.InputFocus.Remove(OnInputFocus);
		SteamVR_Events.System(EVREventType.VREvent_Quit).Remove(OnQuit);
		SteamVR_Events.System(EVREventType.VREvent_RequestScreenshot).Remove(OnRequestScreenshot);
#if UNITY_2017_1_OR_NEWER
		Application.onBeforeRender -= OnBeforeRender;
#else
		Camera.onPreCull -= OnCameraPreCull;
#endif
	}

	void Awake()
	{
		if (externalCamera == null && System.IO.File.Exists(externalCameraConfigPath))
		{
			var prefab = Resources.Load<GameObject>("SteamVR_ExternalCamera");
			var instance = Instantiate(prefab);
			instance.gameObject.name = "External Camera";

			externalCamera = instance.transform.GetChild(0).GetComponent<SteamVR_ExternalCamera>();
			externalCamera.configPath = externalCameraConfigPath;
			externalCamera.ReadConfig();
		}
	}

	public void UpdatePoses()
	{
		var compositor = OpenVR.Compositor;
		if (compositor != null)
		{
			compositor.GetLastPoses(poses, gamePoses);
			SteamVR_Events.NewPoses.Send(poses);
			SteamVR_Events.NewPosesApplied.Send();
		}
	}

#if UNITY_2017_1_OR_NEWER
	void OnBeforeRender() { UpdatePoses(); }
#else
	void OnCameraPreCull(Camera cam)
	{
#if !( UNITY_5_4 )
		if (cam.cameraType != CameraType.VR)
			return;
#endif
		// Only update poses on the first camera per frame.
		if (Time.frameCount != lastFrameCount)
		{
			lastFrameCount = Time.frameCount;
			UpdatePoses();
		}
	}
	static int lastFrameCount = -1;
#endif

	void Update()
	{
		// Force controller update in case no one else called this frame to ensure prevState gets updated.
		SteamVR_Controller.Update();

		// Dispatch any OpenVR events.
		var system = OpenVR.System;
		if (system != null)
		{
			var vrEvent = new VREvent_t();
			var size = (uint)System.Runtime.InteropServices.Marshal.SizeOf(typeof(VREvent_t));
			for (int i = 0; i < 64; i++)
			{
				if (!system.PollNextEvent(ref vrEvent, size))
					break;

				switch ((EVREventType)vrEvent.eventType)
				{
					case EVREventType.VREvent_InputFocusCaptured: // another app has taken focus (likely dashboard)
						if (vrEvent.data.process.oldPid == 0)
						{
							SteamVR_Events.InputFocus.Send(false);
						}
						break;
					case EVREventType.VREvent_InputFocusReleased: // that app has released input focus
						if (vrEvent.data.process.pid == 0)
						{
							SteamVR_Events.InputFocus.Send(true);
						}
						break;
					case EVREventType.VREvent_ShowRenderModels:
						SteamVR_Events.HideRenderModels.Send(false);
						break;
					case EVREventType.VREvent_HideRenderModels:
						SteamVR_Events.HideRenderModels.Send(true);
						break;
					default:
						SteamVR_Events.System((EVREventType)vrEvent.eventType).Send(vrEvent);
						break;
				}
			}
		}

		// Ensure various settings to minimize latency.
		Application.targetFrameRate = -1;
		Application.runInBackground = true; // don't require companion window focus
		QualitySettings.maxQueuedFrames = -1;
		QualitySettings.vSyncCount = 0; // this applies to the companion window

		if (lockPhysicsUpdateRateToRenderFrequency && Time.timeScale > 0.0f)
		{
			var vr = SteamVR.instance;
			if (vr != null)
			{
				var timing = new Compositor_FrameTiming();
				timing.m_nSize = (uint)System.Runtime.InteropServices.Marshal.SizeOf(typeof(Compositor_FrameTiming));
				vr.compositor.GetFrameTiming(ref timing, 0);

				Time.fixedDeltaTime = Time.timeScale / vr.hmd_DisplayFrequency;
			}
		}
	}
}