using System.IO;
using System.Linq;
using SubAssetsToolbox.Utilities;
using UnityEditor;
using UnityEngine;
using Object = UnityEngine.Object;

namespace SubAssetsToolbox.Editor
{
    internal static class DragAndDropAddon
    {
#if UNITY_6000_3_OR_NEWER
        [InitializeOnLoadMethod]
        public static void AddDragProjectHandler()
        {
            DragAndDrop.AddDropHandlerV2(ProjectWindowHandler);
        }

        private static DragAndDropVisualMode ProjectWindowHandler(EntityId id, string destinationPath, bool released)
        {
#else
        [InitializeOnLoadMethod]
        public static void AddDragProjectHandler() => DragAndDrop.AddDropHandler(ProjectWindowHandler);

        private static DragAndDropVisualMode ProjectWindowHandler(int id, string destinationPath, bool released)
        {
#endif
            if (DragAndDrop.paths.Length == 0 || DragAndDrop.objectReferences.Length == 0)
                // Was not dragging from another window
                return DragAndDropVisualMode.None;

            bool destinationIsFolder = AssetDatabase.IsValidFolder(destinationPath);

            if (released)
            {
                bool isDraggingSubAssets = DragAndDrop.objectReferences.Any(AssetDatabase.IsSubAsset);

                foreach (string path in DragAndDrop.paths)
                {
                    if (string.Equals(path, destinationPath)) return DragAndDropVisualMode.None;
                    if (destinationIsFolder) continue;
                    if (isDraggingSubAssets) continue;

                    if (!TypeChecker.ValidateSubAssetType(path)) return DragAndDropVisualMode.Rejected;
                    if (!TypeChecker.ValidateDestinationType(destinationPath)) return DragAndDropVisualMode.Rejected;
                }

                if (!destinationIsFolder)
                {
                    // Adding sub-asset(s)
                    // (drag destination is an asset)

                    string objectName = Path.GetFileNameWithoutExtension(destinationPath);

                    bool isOne = DragAndDrop.objectReferences.Length == 1;

                    int choice = EditorUtility.DisplayDialogComplex(
                        isOne ? "Add as Sub-Asset" : "Add as Sub-Assets",
                        isOne
                            ? string.Format(Constants.ConfirmAddAsSubAsset, DragAndDrop.objectReferences[0].name,
                                objectName)
                            : string.Format(Constants.ConfirmAddAsSubAssets, DragAndDrop.objectReferences[0].name,
                                DragAndDrop.objectReferences[1].name, objectName),
                        isOne ? "Add" : "Add all",
                        "Cancel",
                        isOne ? "Add and Keep Original" : "Add and Keep Originals");

                    int redirectRefChoice = -1;

                    if (choice == 0)
                    {
                        ReferencePatchingMode mode = SubAssetsToolboxSettings.PatchReferences.value;
                        if (mode == ReferencePatchingMode.AutoApply)
                            redirectRefChoice = 0;
                        else if (mode == ReferencePatchingMode.AskEachTime)
                            redirectRefChoice = EditorUtility.DisplayDialogComplex("Patch references",
                                Constants.PatchRefsToSubAssetPrompt,
                                "Patch References", "Don't Patch", "Cancel Moving Assets");
                    }

                    // Cancelled the operation
                    if (choice == 1 || redirectRefChoice == 2) return DragAndDropVisualMode.Rejected;

                    foreach (Object draggedObject in DragAndDrop.objectReferences)
                    {
                        string draggedObjectPath = AssetDatabase.GetAssetPath(draggedObject);
                        string draggedObjectName = draggedObject.name;
                        bool wasMainAsset = AssetDatabase.IsMainAsset(draggedObject);

                        // TODO: preserve selection if the object selected was the one being destroyed
                        SubAssetsToolbox.AddSubAsset(destinationPath, draggedObject, out Object newSubasset);

                        if (choice == 2) continue; // Keep previous objects

                        if (redirectRefChoice == 0)
                        {
                            AssetDatabase.SaveAssets();
                            if (!AssetReferenceRedirector.RedirectToSubAsset(draggedObject, newSubasset))
                            {
                                Debug.LogWarning(string.Format(Constants.RedirectionFailed, draggedObjectName));
                                continue;
                            }
                        }

                        // Do not keep previous
                        if (wasMainAsset)
                        {
#if ADDRESSABLES_INSTALLED
                            AddressableEntryMigrator.MigrateOrRemoveEntry(
                                AssetDatabase.AssetPathToGUID(draggedObjectPath),
                                AssetDatabase.AssetPathToGUID(destinationPath),
                                objectName);
#endif
                            AssetDatabase.DeleteAsset(draggedObjectPath);
                        }
                        else
                        {
                            // After redirect, Refresh() may have invalidated the original reference.
                            // Reload the sub-asset from disk if needed.
                            Object objectToRemove = draggedObject;
                            if (objectToRemove == null)
                            {
                                Object[] subAssets = AssetDatabase.LoadAllAssetRepresentationsAtPath(draggedObjectPath);
                                objectToRemove = subAssets.FirstOrDefault(a => a.name == draggedObjectName);
                            }

                            if (objectToRemove != null)
                                SubAssetsToolbox.RemoveSubAsset(draggedObjectPath, objectToRemove);
                        }
                    }

                    AssetDatabase.SaveAssets();
                    AssetDatabase.Refresh();

                    return DragAndDropVisualMode.Link;
                }

                // Removing sub-asset(s)
                // (drag destination is a folder or an empty space)

                if (!DragAndDrop.objectReferences.Any(AssetDatabase.IsSubAsset))
                    return Path.GetDirectoryName(DragAndDrop.paths[0]) == destinationPath
                        ? DragAndDropVisualMode.Move
                        : DragAndDropVisualMode.None;

                ReferencePatchingMode redirectMode = SubAssetsToolboxSettings.PatchReferences.value;
                int redirectRefsChoice;
                if (redirectMode == ReferencePatchingMode.AutoApply)
                    redirectRefsChoice = 0;
                else if (redirectMode == ReferencePatchingMode.AskEachTime)
                    redirectRefsChoice = EditorUtility.DisplayDialogComplex("Patch references",
                        Constants.PatchRefsToStandalonePrompt,
                        "Patch References", "Don't Patch", "Cancel Sub-Asset Removal");
                else
                    redirectRefsChoice = 1;

                if (redirectRefsChoice == 2) return DragAndDropVisualMode.Rejected;

                int rejected = 0;

                foreach (Object draggedObject in DragAndDrop.objectReferences)
                {
                    string draggedObjectPath = AssetDatabase.GetAssetPath(draggedObject);

                    if (AssetDatabase.IsSubAsset(draggedObject))
                    {
                        // Was dragging a sub-asset: un-parent

                        // Check if its parent is in selection too
                        Object mainAssetAtPath = AssetDatabase.LoadMainAssetAtPath(draggedObjectPath);
                        string fileExtension = ExtensionMap.GetFileExtensionByType(draggedObject.GetType());
                        if (DragAndDrop.objectReferences.Contains(mainAssetAtPath)) continue;

                        // Verify if there's an object with the same name
                        string desiredName = Path.Combine(destinationPath, $"{draggedObject.name}.{fileExtension}");
                        if (AssetDatabase.LoadAssetAtPath<Object>(desiredName) != null)
                        {
                            Debug.LogWarning(string.Format(Constants.ImpossibleToExtract, draggedObject.name));

                            rejected++;
                            continue;
                        }

                        string draggedObjectName = draggedObject.name;
                        Object newObject = Object.Instantiate(draggedObject);
                        newObject.name = draggedObjectName;
                        AssetDatabase.CreateAsset(newObject, desiredName);

                        if (redirectRefsChoice == 0)
                        {
                            AssetDatabase.SaveAssets();
                            if (!AssetReferenceRedirector.RedirectToStandaloneAsset(draggedObject, newObject))
                            {
                                Debug.LogWarning(string.Format(Constants.RedirectionFailed, draggedObjectName));
                                continue;
                            }
                        }

                        // After redirect, Refresh() may have invalidated the original reference.
                        // Reload the sub-asset from disk if needed.
                        Object objectToRemove = draggedObject;
                        if (objectToRemove == null)
                        {
                            Object[] subAssets = AssetDatabase.LoadAllAssetRepresentationsAtPath(draggedObjectPath);
                            objectToRemove = subAssets.FirstOrDefault(a => a.name == draggedObjectName);
                        }

                        if (objectToRemove != null)
                            SubAssetsToolbox.RemoveSubAsset(draggedObjectPath, objectToRemove);
                    }
                }

                AssetDatabase.SaveAssets();
                AssetDatabase.Refresh();

                if (rejected != 0) return DragAndDropVisualMode.Rejected;
                if (Path.GetDirectoryName(DragAndDrop.paths[0]) != destinationPath)
                    return DragAndDropVisualMode.None; // Allows relocation of main assets

                return DragAndDropVisualMode.Move; // Avoid confirmation popup when drag/dropping in the same folder
            }

            // While dragging

            if (destinationIsFolder)
                return DragAndDropVisualMode.Generic;

            if (DragAndDrop.objectReferences.Any(AssetDatabase.IsSubAsset))
                return DragAndDropVisualMode.Link;

            foreach (string path in DragAndDrop.paths)
            {
                if (string.Equals(path, destinationPath)) return DragAndDropVisualMode.None;
                if (!TypeChecker.ValidateSubAssetType(path, true)) return DragAndDropVisualMode.Rejected;
                if (!TypeChecker.ValidateDestinationType(destinationPath, true)) return DragAndDropVisualMode.Rejected;
            }

            return DragAndDropVisualMode.Link;
        }
    }
}