using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class WorkingPortal : MonoBehaviour {
    [Header ("Main Settings")]
    public WorkingPortal linkedWorkingPortal;
    public MeshRenderer screen;
    public int recursionLimit = 5;
    public bool visibleFromCamera = true;

    [Header ("Advanced Settings")]
    public float nearClipOffset = 0.05f;
    public float nearClipLimit = 0.2f;

    public GameObject myGameObject;

    // Private variables
    public RenderTexture viewTexture;
    public Camera WorkingPortalCam;
    Camera playerCam;
    Material firstRecursionMat;
    MeshFilter screenMeshFilter;

    void Awake () {
        myGameObject = gameObject;
        WorkingPortalCam.enabled = false;
        screenMeshFilter = screen.GetComponent<MeshFilter> ();
        screen.material.SetInt ("displayMask", 1);
    }

    // Manually render the camera attached to this WorkingPortal
    // Called after PreWorkingPortalRender, and before PostWorkingPortalRender
    public void Render (Camera newplayerCam) {
        playerCam = newplayerCam;
        // Skip rendering the view from this WorkingPortal if player is not looking at the linked WorkingPortal
        if (!visibleFromCamera) {
            return;
        }

        CreateViewTexture ();

        var localToWorldMatrix = playerCam.transform.localToWorldMatrix;
        var renderPositions = new Vector3[recursionLimit];
        var renderRotations = new Quaternion[recursionLimit];

        int startIndex = 0;
        WorkingPortalCam.projectionMatrix = playerCam.projectionMatrix;
        for (int i = 0; i < recursionLimit; i++) {
            if (i > 0) {
                break;
            }
            localToWorldMatrix = transform.localToWorldMatrix * linkedWorkingPortal.transform.worldToLocalMatrix * localToWorldMatrix;
            int renderOrderIndex = recursionLimit - i - 1;
            renderPositions[renderOrderIndex] = localToWorldMatrix.GetColumn (3);
            renderRotations[renderOrderIndex] = localToWorldMatrix.rotation;

            WorkingPortalCam.transform.SetPositionAndRotation (renderPositions[renderOrderIndex], renderRotations[renderOrderIndex]);
            startIndex = renderOrderIndex;
        }

        // Hide screen so that camera can see through WorkingPortal
        screen.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.ShadowsOnly;
        linkedWorkingPortal.screen.material.SetInt ("displayMask", 0);

        for (int i = startIndex; i < recursionLimit; i++) {
            WorkingPortalCam.transform.SetPositionAndRotation (renderPositions[i], renderRotations[i]);
            Debug.Log(string.Format("rendering at: ", renderPositions[i].x, renderPositions[i].y, renderPositions[i].z));
            SetNearClipPlane ();
            WorkingPortalCam.Render ();

            if (i == startIndex) {
                linkedWorkingPortal.screen.material.SetInt ("displayMask", 1);
            }
        }

        // Unhide objects hidden at start of render
        screen.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.On;
    }

    void CreateViewTexture () {
        if (viewTexture == null || viewTexture.width != Screen.width || viewTexture.height != Screen.height) {
            if (viewTexture != null) {
                viewTexture.Release ();
            }
            viewTexture = new RenderTexture (Screen.width, Screen.height, 0);
            // Render the view from the WorkingPortal camera to the view texture
            WorkingPortalCam.targetTexture = viewTexture;
            // Display the view texture on the screen of the linked WorkingPortal
            linkedWorkingPortal.screen.material.SetTexture ("_MainTex", viewTexture);
        }
    }

 
    // Use custom projection matrix to align WorkingPortal camera's near clip plane with the surface of the WorkingPortal
    // Note that this affects precision of the depth buffer, which can cause issues with effects like screenspace AO
    void SetNearClipPlane () {
        // Learning resource:
        // http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
        Transform clipPlane = transform;
        int dot = System.Math.Sign (Vector3.Dot (clipPlane.forward, transform.position - WorkingPortalCam.transform.position));

        Vector3 camSpacePos = WorkingPortalCam.worldToCameraMatrix.MultiplyPoint (clipPlane.position);
        Vector3 camSpaceNormal = WorkingPortalCam.worldToCameraMatrix.MultiplyVector (clipPlane.forward) * dot;
        float camSpaceDst = -Vector3.Dot (camSpacePos, camSpaceNormal) + nearClipOffset;

        // Don't use oblique clip plane if very close to WorkingPortal as it seems this can cause some visual artifacts
        if (Mathf.Abs (camSpaceDst) > nearClipLimit) {
            Vector4 clipPlaneCameraSpace = new Vector4 (camSpaceNormal.x, camSpaceNormal.y, camSpaceNormal.z, camSpaceDst);

            // Update projection based on new clip plane
            // Calculate matrix with player cam so that player camera settings (fov, etc) are used
            WorkingPortalCam.projectionMatrix = playerCam.CalculateObliqueMatrix (clipPlaneCameraSpace);
        } else {
            WorkingPortalCam.projectionMatrix = playerCam.projectionMatrix;
        }
    }

    /*
     ** Some helper/convenience stuff:
     */

    int SideOfWorkingPortal (Vector3 pos) {
        return System.Math.Sign (Vector3.Dot (pos - transform.position, transform.forward));
    }

    bool SameSideOfWorkingPortal (Vector3 posA, Vector3 posB) {
        return SideOfWorkingPortal (posA) == SideOfWorkingPortal (posB);
    }

    Vector3 WorkingPortalCamPos {
        get {
            return WorkingPortalCam.transform.position;
        }
    }

    void OnValidate () {
        if (linkedWorkingPortal != null) {
            linkedWorkingPortal.linkedWorkingPortal = this;
        }
    }
}