using UnityEngine;
using UnityEditor;

namespace BadDog.Rendering.AreaLight
{
    /// <summary>
    /// Custom property drawer for AreaLightSettings
    /// </summary>
    [CustomPropertyDrawer(typeof(AreaLightSettings))]
    public class AreaLightSettingsDrawer : PropertyDrawer
    {
        private SerializedProperty m_MaxAreaLights;
        private SerializedProperty m_PreIntegratedFGD_GGXDisneyDiffuse;
        private SerializedProperty m_PreIntegratedFGD_CharlieFabricLambert;
        private SerializedProperty m_PreIntegratedFGD_Marschner;
        
        private string m_CachedPropertyPath;

        private void FindProperties(SerializedProperty property)
        {
            string currentPath = property.propertyPath;
            
            if (m_CachedPropertyPath != currentPath)
            {
                m_MaxAreaLights = property.FindPropertyRelative("maxAreaLights");
                m_PreIntegratedFGD_GGXDisneyDiffuse = property.FindPropertyRelative("preIntegratedFGD_GGXDisneyDiffuse");
                m_PreIntegratedFGD_CharlieFabricLambert = property.FindPropertyRelative("preIntegratedFGD_CharlieFabricLambert");
                m_PreIntegratedFGD_Marschner = property.FindPropertyRelative("preIntegratedFGD_Marschner");
                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;

            if (HasMissingShaders())
            {
                property.serializedObject.Update();
                AutoFindShaders();
                property.serializedObject.ApplyModifiedProperties();
            }

            DrawProperty(m_MaxAreaLights, ref yOffset, position);
            DrawProperty(m_PreIntegratedFGD_GGXDisneyDiffuse, ref yOffset, position);
            DrawProperty(m_PreIntegratedFGD_CharlieFabricLambert, ref yOffset, position);
            DrawProperty(m_PreIntegratedFGD_Marschner, ref yOffset, position);

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

        private void AutoFindShaders()
        {
            const string packageShadersPath = "Packages/com.baddog.rendering.arealight/Shaders/";
            
            TryLoadShader(m_PreIntegratedFGD_GGXDisneyDiffuse, packageShadersPath + "PreIntegratedFGD_GGXDisneyDiffuse.shader", "PreIntegratedFGD GGX Disney Diffuse");
            TryLoadShader(m_PreIntegratedFGD_CharlieFabricLambert, packageShadersPath + "PreIntegratedFGD_CharlieFabricLambert.shader", "PreIntegratedFGD Charlie Fabric Lambert");
            TryLoadShader(m_PreIntegratedFGD_Marschner, packageShadersPath + "PreIntegratedFGD_Marschner.shader", "PreIntegratedFGD Marschner");
        }
        
        private void TryLoadShader(SerializedProperty shaderRef, string path, string displayName)
        {
            if (shaderRef != null && shaderRef.objectReferenceValue == null)
            {
                var shader = AssetDatabase.LoadAssetAtPath<Shader>(path);
                if (shader != null)
                {
                    shaderRef.objectReferenceValue = shader;
                }
            }
        }

        private bool HasMissingShaders()
        {
            return (m_PreIntegratedFGD_GGXDisneyDiffuse != null && m_PreIntegratedFGD_GGXDisneyDiffuse.objectReferenceValue == null) || 
                   (m_PreIntegratedFGD_CharlieFabricLambert != null && m_PreIntegratedFGD_CharlieFabricLambert.objectReferenceValue == null) || 
                   (m_PreIntegratedFGD_Marschner != null && m_PreIntegratedFGD_Marschner.objectReferenceValue == null);
        }

        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)
        {
            // Base height for foldout
            float height = EditorGUIUtility.singleLineHeight;

            // If not expanded, return just the foldout height
            if (!property.isExpanded)
            {
                return height;
            }

            // Find properties to calculate height
            FindProperties(property);

            // Add height for all properties using cached references
            height += GetPropertyHeight(m_MaxAreaLights);
            height += GetPropertyHeight(m_PreIntegratedFGD_GGXDisneyDiffuse);
            height += GetPropertyHeight(m_PreIntegratedFGD_CharlieFabricLambert);
            height += GetPropertyHeight(m_PreIntegratedFGD_Marschner);

            return height;
        }

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