using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
using System.Linq;
using System.Reflection;

namespace UnityEngine.Experimental.Rendering.HDPipeline
{
    [ExecuteInEditMode]
    [DisallowMultipleComponent]
    public class CommonSettings 
        : MonoBehaviour
    {
        [SerializeField] private string     m_SkyRendererTypeName = ""; // Serialize a string because serialize a Type.

        [SerializeField] float              m_ShadowMaxDistance = ShadowSettings.Default.maxShadowDistance;
        [SerializeField] int                m_ShadowCascadeCount = ShadowSettings.Default.directionalLightCascadeCount;
        [SerializeField] float              m_ShadowCascadeSplit0 = ShadowSettings.Default.directionalLightCascades.x;
        [SerializeField] float              m_ShadowCascadeSplit1 = ShadowSettings.Default.directionalLightCascades.y;
        [SerializeField] float              m_ShadowCascadeSplit2 = ShadowSettings.Default.directionalLightCascades.z;

        public Type skyRendererType
        {
            set { m_SkyRendererTypeName = value != null ? value.FullName : ""; OnSkyRendererChanged(); }
            get { return m_SkyRendererTypeName == "" ? null : Assembly.GetAssembly(typeof(CommonSettings)).GetType(m_SkyRendererTypeName); }
        }

        public float shadowMaxDistance { set { m_ShadowMaxDistance = value; OnValidate(); } get { return m_ShadowMaxDistance; } }
        public int shadowCascadeCount { set { m_ShadowCascadeCount = value; OnValidate(); } get { return m_ShadowCascadeCount; } }
        public float shadowCascadeSplit0 { set { m_ShadowCascadeSplit0 = value; OnValidate(); } get { return m_ShadowCascadeSplit0; } }
        public float shadowCascadeSplit1 { set { m_ShadowCascadeSplit1 = value; OnValidate(); } get { return m_ShadowCascadeSplit1; } }
        public float shadowCascadeSplit2 { set { m_ShadowCascadeSplit2 = value; OnValidate(); } get { return m_ShadowCascadeSplit2; } }

        void OnEnable()
        {
            HDRenderPipeline renderPipeline = Utilities.GetHDRenderPipeline();
            if (renderPipeline == null)
            {
                return;
            }

            if (renderPipeline.commonSettings == null)
                renderPipeline.commonSettings = this;
            else if (renderPipeline.commonSettings != this)
                Debug.LogWarning("Only one CommonSettings can be setup at a time.");

            OnSkyRendererChanged();
        }

        void OnDisable()
        {
            HDRenderPipeline renderPipeline = Utilities.GetHDRenderPipeline();
            if (renderPipeline == null)
            {
                return;
            }

            if (renderPipeline.commonSettings == this)
                renderPipeline.commonSettings = null;
        }

        void OnValidate()
        {
            m_ShadowMaxDistance = Mathf.Max(0.0f, m_ShadowMaxDistance);
            m_ShadowCascadeCount = Math.Min(4, Math.Max(1, m_ShadowCascadeCount));
            m_ShadowCascadeSplit0 = Mathf.Min(1.0f, Mathf.Max(0.0f, m_ShadowCascadeSplit0));
            m_ShadowCascadeSplit1 = Mathf.Min(1.0f, Mathf.Max(0.0f, m_ShadowCascadeSplit1));
            m_ShadowCascadeSplit2 = Mathf.Min(1.0f, Mathf.Max(0.0f, m_ShadowCascadeSplit2));

            OnSkyRendererChanged();
        }

        void OnSkyRendererChanged()
        {
            HDRenderPipeline renderPipeline = Utilities.GetHDRenderPipeline();
            if (renderPipeline == null)
            {
                return;
            }

            renderPipeline.InstantiateSkyRenderer(skyRendererType);

            List<SkyParameters> result = new List<SkyParameters>();
            gameObject.GetComponents<SkyParameters>(result);

            Type skyParamType = renderPipeline.skyManager.GetSkyParameterType();

            // Disable all incompatible sky parameters and enable the compatible one
            bool found = false;
            foreach (SkyParameters param in result)
            {
                if (param.GetType() == skyParamType)
                {
                    // This is a workaround the fact that we can't control the order in which components are initialized.
                    // So it can happen that a given SkyParameter is OnEnabled before the CommonSettings and so fail the setup because the SkyRenderer is not yet initialized.
                    // So we disable it to for OnEnable to be called again.
                    param.enabled = false;

                    param.enabled = true;
                    found = true;
                }
                else
                {
                    param.enabled = false;
                }
            }

            // If it does not exist, create the parameters
            if (!found && skyParamType != null)
            {
                gameObject.AddComponent(skyParamType);
            }
        }
    }
}