using System;
using System.Collections.Generic;
using System.Linq;
using RPGCore.Editor.CoreManager.Validators;
using RPGCoreCommon.Helpers;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace RPGCore.Editor.CoreManager
{
    internal static class ValidationSolver
    {
        private static readonly List<IValidator> Validators =
            TypeCache.GetTypesDerivedFrom<IValidator>()
                .Select(Activator.CreateInstance)
                .Cast<IValidator>()
                .ToList();
        
        [InitializeOnLoadMethod]
        private static void AutomaticValidation_Initialize() => ObjectChangeEvents.changesPublished += AutomaticValidation;

        private static void AutomaticValidation(ref ObjectChangeEventStream stream)
        {
            var instanceIds = new List<int>();
            
            for (var i = 0; i < stream.length; i++)
            {
                if (stream.GetEventType(i) != ObjectChangeKind.ChangeGameObjectStructure) continue;
                
                stream.GetChangeGameObjectStructureEvent(0, out var ev);
                instanceIds.Add(ev.instanceId);
            }

            if (instanceIds.Count == 0) return;

            var validations = Check(instanceIds); 
            FixAll(validations);

            // Can't finish because of exception or error
            validations
                .Where(v => v.result == false)
                .Select(v => "--- ERROR: " + v.resultMessage +
                             "\n> " + v.contextPath +
                             "\n> " + v.hierarchyPath +
                             "\n> " + v.validator.GetType().Name +
                             "\n> " + v.message)
                .ForEach(Debug.LogError);

            // No fix defined
            validations
                .Where(v => v.result == null)
                .Select(v => "--- WARNING: " + v.resultMessage +
                             "\n> " + v.contextPath +
                             "\n> " + v.hierarchyPath +
                             "\n> " + v.validator.GetType().Name +
                             "\n> " + v.message)
                .ForEach(Debug.LogWarning);
        }
        
        internal static List<Validation> Check(List<int> instanceIds)
        {
            var validations = new List<Validation>();
            
            foreach (var instanceId in instanceIds)
            {
                var obj = EditorUtility.EntityIdToObject(instanceId);
                if (obj is not GameObject go) continue;
                
                Check(go, validations, false);
            }
            
            return validations;
        }

        internal static List<Validation> Check(string[] paths)
        {
            var validations = new List<Validation>();
            
            foreach (var guid in AssetDatabase.FindAssetGUIDs("t:Scene", paths))
            {
                var scene = EditorSceneManager.OpenPreviewScene(AssetDatabase.GUIDToAssetPath(guid));
                foreach (var go in scene.GetRootGameObjects())
                {
                    try
                    {
                        Check(go, validations, true);
                    }
                    catch (Exception)
                    {
                        // ignored
                    }
                }
                EditorSceneManager.ClosePreviewScene(scene);
            }

            foreach (var guid in AssetDatabase.FindAssetGUIDs("t:Prefab", paths))
            {
                var prefabPath =  AssetDatabase.GUIDToAssetPath(guid);
                var prefab = PrefabUtility.LoadPrefabContents(prefabPath);
                
                try
                {
                    Check(prefab, validations, true);
                }
                catch (Exception)
                {
                    // ignored
                }

                PrefabUtility.UnloadPrefabContents(prefab);
            }
            
            return validations;
        }

        internal static void Check(GameObject go, List<Validation> result, bool recursive)
        {
            // On scene and part of other prefab - don't validate that, it will be validated separately anyway
            if (PrefabUtility.IsPartOfPrefabInstance(go)) return;
                
            foreach (var validator in Validators)
            {
                var message = validator.Check(go);
                if (string.IsNullOrEmpty(message)) continue;

                result.Add(new Validation
                {
                    validator = validator,
                    message = message,
                    contextPath = GetContextPath(go),
                    hierarchyPath = GetHierarchyPath(go),
                });
            }

            if (!recursive) return;
            for (var i = 0; i < go.transform.childCount; i++)
                Check(go.transform.GetChild(i).gameObject, result, true);
        }

        internal static void FixAll(List<Validation> validations)
        {
            foreach (var validation in validations)
            {
                var contextType = AssetDatabase.GetMainAssetTypeAtPath(validation.contextPath);

                if (contextType == typeof(SceneAsset)) FixOnScene(validation);
                else if (contextType == typeof(GameObject)) FixOnPrefab(validation);
                else throw new Exception($"Given file '{validation.contextPath}' is not prefab nor scene!");
            }
        }

        private static void FixOnScene(Validation validation)
        {
            var scene = Enumerable.Range(0, SceneManager.loadedSceneCount)
                .Select(SceneManager.GetSceneAt)
                .FirstOrDefault(scene => scene.path == validation.contextPath);
            var isActive = scene.IsValid();
            if (!isActive) scene = EditorSceneManager.OpenPreviewScene(validation.contextPath);
            var go = FindGameObject(scene.GetRootGameObjects(), validation);
            FixGameObject(go, validation);
            if (isActive) EditorUtility.SetDirty(go);
            if (!isActive) EditorSceneManager.SaveScene(scene);
            if (!isActive) EditorSceneManager.ClosePreviewScene(scene);
        }

        private static void FixOnPrefab(Validation validation)
        {
            var prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
            var isActive = prefabStage && prefabStage.assetPath == validation.contextPath;
            var prefabRoot = isActive
                ? prefabStage.prefabContentsRoot
                : PrefabUtility.LoadPrefabContents(validation.contextPath);
            var go = FindGameObject(new[] { prefabRoot }, validation);
            FixGameObject(go, validation);
            if (isActive) EditorUtility.SetDirty(go);
            if (!isActive) PrefabUtility.SaveAsPrefabAsset(prefabRoot, validation.contextPath);
            if (!isActive) PrefabUtility.UnloadPrefabContents(prefabRoot);
        }
        
        private static GameObject FindGameObject(GameObject[] roots, Validation validation)
        {
            var hierarchyPathArray = validation.hierarchyPath.Split('/', 2);
            var root = roots.FirstOrDefault(go => go.name == hierarchyPathArray[0]);
            if (!root) throw new Exception($"Root '{hierarchyPathArray[0]}' not found in '{validation.contextPath}'!");
            var go = hierarchyPathArray.Length > 1 ? root.transform.Find(hierarchyPathArray[1])?.gameObject : root;
            if (!go) throw new Exception($"GameObject '{validation.hierarchyPath}' not found in '{validation.contextPath}'!");
            return go;
        }

        private static void FixGameObject(GameObject go, Validation validation)
        {
            try
            {
                validation.validator.Fix(go);
                validation.resultMessage = "Done.";
                validation.result = true;
            }
            catch (NotImplementedException)
            {
                validation.resultMessage = "No Auto-fix defined. Do it yourself.";
            }
            catch (Exception e)
            {
                validation.result = false;
                validation.resultMessage = e.Message;
            }
        }

        private static string GetContextPath(GameObject go)
        {
            // ON PREFAB STAGE - this one will be used only in realtime correcting, never in verify tab
            if (PrefabStageUtility.GetPrefabStage(go) is {} stage) return stage.assetPath;

            // ON SCENE
            if (go.scene.IsValid()) return go.scene.path;

            // PREFAB ASSET
            if (PrefabUtility.IsPartOfPrefabAsset(go)) return go.scene.path;

            throw new Exception("No valid context path found, sad pepe :(");
        }

        private static string GetHierarchyPath(GameObject go)
        {
            var path = new List<string>();

            while (go is not null)
            {
                path.Add(go.name);
                go = go.transform.parent?.gameObject;
            }

            return string.Join("/", path.AsEnumerable().Reverse());
        }
    }
}