using UnityEngine;
using UnityEditor;

namespace BadDog.Rendering.AreaLight
{
    /// <summary>
    /// Custom property drawer for AreaLightShadowSettings
    /// </summary>
    [CustomPropertyDrawer(typeof(AreaLightShadowSettings))]
    public class AreaLightShadowSettingsDrawer : PropertyDrawer
    {
        private SerializedProperty m_ShadowAtlasResolution;
        private SerializedProperty m_MaxShadowCastingLights;
        private SerializedProperty m_ShadowFilter;
        private SerializedProperty m_PcssShadowSoftness;
        private SerializedProperty m_PcssBlockerSampleCount;
        private SerializedProperty m_PcssFilterSampleCount;
        
        private string m_CachedPropertyPath;

        private void FindProperties(SerializedProperty property)
        {
            string currentPath = property.propertyPath;
            
            if (m_CachedPropertyPath != currentPath)
            {
                m_ShadowAtlasResolution = property.FindPropertyRelative("shadowAtlasResolution");
                m_MaxShadowCastingLights = property.FindPropertyRelative("maxShadowCastingLights");
                m_ShadowFilter = property.FindPropertyRelative("shadowFilter");
                m_PcssShadowSoftness = property.FindPropertyRelative("pcssShadowSoftness");
                m_PcssBlockerSampleCount = property.FindPropertyRelative("pcssBlockerSampleCount");
                m_PcssFilterSampleCount = property.FindPropertyRelative("pcssFilterSampleCount");
                m_CachedPropertyPath = currentPath;
            }
        }

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            FindProperties(property);
            
            EditorGUI.BeginProperty(position, label, property);

            Rect foldoutRect = new Rect(position.x, position.y, position.width, EditorGUIUtility.singleLineHeight);
            property.isExpanded = EditorGUI.Foldout(foldoutRect, property.isExpanded, label, true);
            
            if (!property.isExpanded)
            {
                EditorGUI.EndProperty();
                return;
            }

            EditorGUI.indentLevel++;
            float yOffset = EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;

            DrawProperty(m_ShadowAtlasResolution, ref yOffset, position);
            DrawProperty(m_MaxShadowCastingLights, ref yOffset, position);

            Rect shadowFilterRect = new Rect(position.x, position.y + yOffset, position.width, EditorGUIUtility.singleLineHeight);
            EditorGUI.PropertyField(shadowFilterRect, m_ShadowFilter, new GUIContent("Shadow Filter"));
            yOffset += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;

            if (m_ShadowFilter != null)
            {
                AreaLightShadowSettings.BGAreaLightShadowMode shadowFilterMode = 
                    (AreaLightShadowSettings.BGAreaLightShadowMode)m_ShadowFilter.enumValueIndex;

                if (shadowFilterMode == AreaLightShadowSettings.BGAreaLightShadowMode.PCSS)
                {
                    Rect headerRect = new Rect(position.x, position.y + yOffset, position.width, EditorGUIUtility.singleLineHeight);
                    EditorGUI.LabelField(headerRect, "PCSS", EditorStyles.boldLabel);
                    yOffset += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;

                    DrawProperty(m_PcssShadowSoftness, ref yOffset, position);
                    DrawProperty(m_PcssBlockerSampleCount, ref yOffset, position);
                    DrawProperty(m_PcssFilterSampleCount, ref yOffset, position);
                }
            }

            EditorGUI.indentLevel--;
            EditorGUI.EndProperty();
        }

        private void DrawProperty(SerializedProperty prop, ref float yOffset, Rect position)
        {
            if (prop != null)
            {
                Rect rect = new Rect(position.x, position.y + yOffset, position.width, EditorGUI.GetPropertyHeight(prop));
                EditorGUI.PropertyField(rect, prop, true);
                yOffset += EditorGUI.GetPropertyHeight(prop) + EditorGUIUtility.standardVerticalSpacing;
            }
        }

        public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
        {
            float height = EditorGUIUtility.singleLineHeight;

            if (!property.isExpanded)
            {
                return height;
            }

            FindProperties(property);

            height += GetPropertyHeight(m_ShadowAtlasResolution);
            height += GetPropertyHeight(m_MaxShadowCastingLights);

            if (m_ShadowFilter != null)
            {
                height += EditorGUI.GetPropertyHeight(m_ShadowFilter) + EditorGUIUtility.standardVerticalSpacing;

                AreaLightShadowSettings.BGAreaLightShadowMode shadowFilterMode = 
                    (AreaLightShadowSettings.BGAreaLightShadowMode)m_ShadowFilter.enumValueIndex;

                if (shadowFilterMode == AreaLightShadowSettings.BGAreaLightShadowMode.PCSS)
                {
                    height += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
                    height += GetPropertyHeight(m_PcssShadowSoftness);
                    height += GetPropertyHeight(m_PcssBlockerSampleCount);
                    height += GetPropertyHeight(m_PcssFilterSampleCount);
                }
            }

            return height;
        }

        private float GetPropertyHeight(SerializedProperty prop)
        {
            if (prop != null)
            {
                return EditorGUI.GetPropertyHeight(prop) + EditorGUIUtility.standardVerticalSpacing;
            }
            return 0f;
        }
    }
}