using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

namespace NanoBrain.Unity {

    [CustomPropertyDrawer(typeof(ClusterJson))]
    class ClusterJson_Drawer : PropertyDrawer {
        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label) {
            EditorGUI.BeginProperty(position, label, property);

            ClusterJson clusterJson = property.objectReferenceValue as ClusterJson;
            if (clusterJson == null) {
                clusterJson = ScriptableObject.CreateInstance<ClusterJson>();

                property.objectReferenceValue = clusterJson;
                property.serializedObject.ApplyModifiedProperties();

                EditorUtility.SetDirty(property.serializedObject.targetObject);
            }
            SerializedObject so = new(clusterJson);
            SerializedProperty jsonFileProp = so.FindProperty(nameof(ClusterJson.jsonFile));

            EditorGUI.BeginChangeCheck();

            TextAsset current = jsonFileProp.objectReferenceValue as TextAsset;
                Rect fieldRect = new(position.x, position.y, position.width, EditorGUIUtility.singleLineHeight);
            TextAsset newAsset = (TextAsset)EditorGUI.ObjectField(fieldRect, label, current, typeof(TextAsset), false);

            if (EditorGUI.EndChangeCheck()) {
                jsonFileProp.objectReferenceValue = newAsset;
                so.ApplyModifiedProperties();
            }
            bool showWarning = IsInvalidJson(jsonFileProp);
            if (showWarning) {
                Rect helpRect = new(
                    position.x,
                    position.y + EditorGUIUtility.singleLineHeight + 2f,
                    position.width,
                    EditorGUIUtility.singleLineHeight * 2f
                );
                propertyExtraHeight = 2 + 2 * EditorGUIUtility.singleLineHeight;
                EditorGUI.HelpBox(helpRect, "Selected asset is not a .json file.", MessageType.Error);
            } else 
                propertyExtraHeight = 0;

            EditorGUI.EndProperty();
        }

        private float propertyExtraHeight = 0;

        public override float GetPropertyHeight(SerializedProperty property, GUIContent label) {
            return EditorGUIUtility.singleLineHeight + propertyExtraHeight;
        }

        private readonly Dictionary<EntityId, bool> _invalidCache = new();

        private bool IsInvalidJson(SerializedProperty jsonFileProp) {
            TextAsset current = jsonFileProp.objectReferenceValue as TextAsset;
            if (current == null) return false;

            EntityId id = current.GetEntityId();
            if (_invalidCache.TryGetValue(id, out bool invalid))
                return invalid;

            string path = AssetDatabase.GetAssetPath(current);
            invalid = !path.EndsWith(".json", System.StringComparison.OrdinalIgnoreCase);
            _invalidCache[id] = invalid;
            return invalid;
        }
    }
}