// Copyright (c) 2023 Nico de Poel
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System.Collections;
using UnityEngine;

namespace FidelityFX
{
    /// <summary>
    /// Small helper script to be used in conjunction with the Fsr2ImageEffect script.
    /// The FSR2 image effect needs to be the last effect in the post-processing chain but for render scaling to work properly, it also needs to be the first to execute OnPreCull.
    /// Unfortunately altering the script execution order does not affect the order in which OnPreCull is executed. Only the order of scripts on the same game object matters. 
    /// 
    /// When combining FSR2 upscaling with other post-processing effects (most notably Unity's Post-Processing Stack V2),
    /// this script should be added to the same camera and moved up above any other scripts that have an OnPreCull method. 
    /// </summary>
    [RequireComponent(typeof(Camera), typeof(Fsr2ImageEffect))]
    public class Fsr2ImageEffectHelper : MonoBehaviour
    {
        private Camera _renderCamera;
        private Fsr2ImageEffect _imageEffect;

        private void OnEnable()
        {
            _renderCamera = GetComponent<Camera>();
            _imageEffect = GetComponent<Fsr2ImageEffect>();
        }

        private void OnPreCull()
        {
            if (_imageEffect == null || !_imageEffect.enabled)
                return;
            
            var originalRect = _renderCamera.rect;
            float upscaleRatio = Fsr2.GetUpscaleRatioFromQualityMode(_imageEffect.qualityMode);

            // Render to a smaller portion of the screen by manipulating the camera's viewport rect
            _renderCamera.aspect = (_renderCamera.pixelWidth * originalRect.width) / (_renderCamera.pixelHeight * originalRect.height);
            _renderCamera.rect = new Rect(0, 0, originalRect.width / upscaleRatio, originalRect.height / upscaleRatio);
        }
    }
}