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

namespace RunlevelSystems.DevPlus1.EditorTools
{
    public static class RLPrefabAnalyzer
    {
        public static List<RLPrefabInfo> AnalyzePrefabs()
        {
            List<RLPrefabInfo> results = new List<RLPrefabInfo>();
            string[] guids = AssetDatabase.FindAssets("t:Prefab");

            foreach (string guid in guids)
            {
                string path = AssetDatabase.GUIDToAssetPath(guid);
                GameObject prefab = AssetDatabase.LoadAssetAtPath<GameObject>(path);
                if (prefab == null)
                {
                    continue;
                }

                RLPrefabInfo info = new RLPrefabInfo();
                info.prefabPath = path;
                TraversePrefab(prefab, info);
                results.Add(info);
            }

            return results;
        }

        private static void TraversePrefab(GameObject gameObject, RLPrefabInfo info)
        {
            info.missingScriptCount += GameObjectUtility.GetMonoBehavioursWithMissingScriptCount(gameObject);

            Component[] components = gameObject.GetComponents<Component>();
            foreach (Component component in components)
            {
                if (component == null)
                {
                    AddUnique(info.components, "Missing Script");
                    continue;
                }

                AddUnique(info.components, component.GetType().Name);
                if (component is MonoBehaviour)
                {
                    AddUnique(info.attachedScripts, component.GetType().Name);
                }

                CollectReferences(component, info);
            }

            string prefabSource = PrefabUtility.GetPrefabAssetPathOfNearestInstanceRoot(gameObject);
            if (!string.IsNullOrEmpty(prefabSource) && prefabSource != info.prefabPath)
            {
                AddUnique(info.nestedPrefabs, prefabSource);
            }

            foreach (Transform child in gameObject.transform)
            {
                TraversePrefab(child.gameObject, info);
            }
        }

        private static void CollectReferences(Component component, RLPrefabInfo info)
        {
            SerializedObject serializedObject = new SerializedObject(component);
            SerializedProperty property = serializedObject.GetIterator();
            bool enterChildren = true;
            while (property.NextVisible(enterChildren))
            {
                enterChildren = false;
                if (property.propertyType != SerializedPropertyType.ObjectReference)
                {
                    continue;
                }

                if (property.objectReferenceValue != null)
                {
                    AddUnique(info.importantReferences, component.GetType().Name + "." + property.displayName + " -> " + property.objectReferenceValue.name);
                }
                else if (property.objectReferenceInstanceIDValue != 0)
                {
                    info.missingReferenceCount++;
                }
            }
        }

        private static void AddUnique(List<string> values, string value)
        {
            if (!values.Contains(value))
            {
                values.Add(value);
            }
        }
    }
}