using UnityEngine;
#if UC_VR
using Valve.VR;
#endif

namespace UC
{
    public static class RayCastUtils
    {
        public static void SetupMaterial(Material material/*, Camera camera*/)
        {
            Camera camera = Camera.current;
#if UC_VR
            if (SteamVR.enabled)
            {
				material.EnableKeyword ("VR");
                Matrix4x4 ptt_l = GetSteamVRProjectionMatrix(camera, EVREye.Eye_Left);
                Matrix4x4 ptt_r = GetSteamVRProjectionMatrix(camera, EVREye.Eye_Right);

                Matrix4x4 ttt_l = GetSteamVREyeToHeadTransform(EVREye.Eye_Left);
                ttt_l = transform.localToWorldMatrix * ttt_l;

                Matrix4x4 ttt_r = GetSteamVREyeToHeadTransform(EVREye.Eye_Right);
                ttt_r = transform.localToWorldMatrix * ttt_r;

                material.SetMatrix("_Cam2WorldMatrix_L", ttt_l);
                material.SetMatrix("_PVMMatrix_L", ttt_l.inverse);
                material.SetMatrix("_Cam2WorldMatrix_R", ttt_r);
                material.SetMatrix("_PVMMatrix_R", ttt_r.inverse);
            }
            else
#endif
            {
                material.DisableKeyword("VR");
                material.SetMatrix("_Cam2WorldMatrix", camera.cameraToWorldMatrix);
                material.SetMatrix("_PVMMatrix", camera.projectionMatrix * camera.worldToCameraMatrix);
            }
        }

#if UC_VR
        static Matrix4x4 GetSteamVRProjectionMatrix(Camera cam, EVREye eye)
        {
            HmdMatrix44_t proj = SteamVR.instance.hmd.GetProjectionMatrix(eye, cam.nearClipPlane, cam.farClipPlane, SteamVR.instance.graphicsAPI);
            Matrix4x4 m = new Matrix4x4();
            m.m00 = proj.m0;  m.m01 = proj.m1;  m.m02 = proj.m2;  m.m03 = proj.m3;
            m.m10 = proj.m4;  m.m11 = proj.m5;  m.m12 = proj.m6;  m.m13 = proj.m7;
            m.m20 = proj.m8;  m.m21 = proj.m9;  m.m22 = proj.m10; m.m23 = proj.m11;
            m.m30 = proj.m12; m.m31 = proj.m13; m.m32 = proj.m14; m.m33 = proj.m15;
            return m;
        }

        static Matrix4x4 GetSteamVREyeToHeadTransform(EVREye eye)
        {
            HmdMatrix34_t input = SteamVR.instance.hmd.GetEyeToHeadTransform(eye);
            var m = Matrix4x4.identity;
            m.m00 = input.m0;  m.m01 = input.m1;  m.m02 = input.m2;  m.m03 = input.m3;
            m.m10 = input.m4;  m.m11 = input.m5;  m.m12 = input.m6;  m.m13 = input.m7;
            m.m20 = input.m8;  m.m21 = input.m9;  m.m22 = input.m10; m.m23 = input.m11;
            return m;
        }
#endif
    }
}