using LunaWolfStudiosEditor.ScriptableSheets.Layout;
using LunaWolfStudiosEditor.ScriptableSheets.Shared;
using System;
using System.Collections.Generic;
using System.Linq;
using UnityEditor;
using UnityEngine;
using Object = UnityEngine.Object;

namespace LunaWolfStudiosEditor.ScriptableSheets.Scanning
{
	public class ObjectScanner
	{
		private const string ProgressBarTitle = "Scriptable Sheets - Object Scanner";

		private readonly Dictionary<Type, List<Object>> m_ObjectsByType = new Dictionary<Type, List<Object>>();
		public Dictionary<Type, List<Object>> ObjectsByType => m_ObjectsByType;

		private Type[] m_ObjectTypes;
		public Type[] ObjectTypes => m_ObjectTypes;

		private string[] m_ObjectTypeNames;
		public string[] ObjectTypeNames => m_ObjectTypeNames;

		private string[] m_FriendlyObjectTypeNames;
		public string[] FriendlyObjectTypeNames => m_FriendlyObjectTypeNames;

		private readonly Dictionary<Type, Dictionary<Object, List<Object>>> m_SubAssetsByTypeAndMainAsset = new Dictionary<Type, Dictionary<Object, List<Object>>>();
		public Dictionary<Type, Dictionary<Object, List<Object>>> SubAssetsByTypeAndMainAsset => m_SubAssetsByTypeAndMainAsset;

		public void ScanObjects(ScanSettings settings, SheetAsset sheetAsset)
		{
			try
			{
				m_ObjectsByType.Clear();
				m_SubAssetsByTypeAndMainAsset.Clear();

				// Refresh incase new folders or assets were created.
				AssetDatabase.Refresh();

				// Unity does not consider the root Packages folder as a valid folder so we need to check it separately.
				if (settings.PathOption == ScanPathOption.Default && !AssetDatabase.IsValidFolder(settings.Path) && settings.Path != UnityConstants.Packages)
				{
					settings.Path = UnityConstants.DefaultAssetPath;
				}

				var scanPaths = settings.GetScanPaths();
				var joinedPaths = settings.GetJoinedScanPaths(scanPaths);

				if (settings.ShowProgressBar)
				{
					EditorUtility.DisplayProgressBar(ProgressBarTitle, $"Scanning for assets of type {sheetAsset} at path(s) {joinedPaths}", 0.40f);
				}

				var guids = AssetDatabase.FindAssets($"t:{sheetAsset}", scanPaths);

				if (settings.ShowProgressBar)
				{
					EditorUtility.DisplayProgressBar(ProgressBarTitle, $"Loading assets of type {sheetAsset} at path(s) {joinedPaths}", 0.80f);
				}

				foreach (var guid in guids)
				{
					var path = AssetDatabase.GUIDToAssetPath(guid);
					var asset = AssetDatabase.LoadAssetAtPath<Object>(path);

					if (asset == null)
					{
						continue;
					}
					var assetType = asset.GetType();
					var nextAssetType = assetType;
					// Map the asset to its type and base types.
					while (nextAssetType.IsValidUnityObjectSubclass())
					{
						if (nextAssetType.IsValidConcreteType())
						{
							if (!m_ObjectsByType.TryGetValue(nextAssetType, out var objectsByType))
							{
								objectsByType = new List<Object>();
								m_ObjectsByType[nextAssetType] = objectsByType;
							}
							objectsByType.Add(asset);
						}
						nextAssetType = nextAssetType.BaseType;
					}

					if (sheetAsset == SheetAsset.Scene)
					{
						continue;
					}

					var subAssets = AssetDatabase.LoadAllAssetsAtPath(path);
					if (subAssets.Length <= 1)
					{
						continue;
					}

					foreach (var subAsset in subAssets)
					{
						if (subAsset == null || subAsset == asset)
						{
							continue;
						}
						if (sheetAsset == SheetAsset.Prefab)
						{
							if (subAsset is Component)
							{
								var subAssetGameObject = ((Component) subAsset).gameObject;
								var isRootPrefab = asset == subAssetGameObject;
								if (!settings.RootPrefabsOnly || isRootPrefab)
								{
									var subAssetType = subAsset.GetType();
									if (!m_ObjectsByType.TryGetValue(subAssetType, out var objectsByType))
									{
										objectsByType = new List<Object>();
										m_ObjectsByType[subAssetType] = objectsByType;
									}
									objectsByType.Add(subAsset);
								}
							}
						}
						else
						{
							if (AssetDatabase.IsSubAsset(subAsset))
							{
								var subAssetType = subAsset.GetType();
								var nextSubAssetType = subAssetType;
								while (nextSubAssetType.IsValidUnityObjectSubclass())
								{
									// For binary types like Textures we want to add all the valid subclass types.
									// For ScriptableObjects it must be a scriptable object type.
									if (sheetAsset != SheetAsset.ScriptableObject || nextSubAssetType.IsSubclassOf(typeof(ScriptableObject)))
									{
										if (!m_ObjectsByType.TryGetValue(nextSubAssetType, out var objectsByType))
										{
											objectsByType = new List<Object>();
											m_ObjectsByType[nextSubAssetType] = objectsByType;
										}
										objectsByType.Add(subAsset);
										if (!m_SubAssetsByTypeAndMainAsset.TryGetValue(nextSubAssetType, out var subAssetByMainAsset))
										{
											subAssetByMainAsset = new Dictionary<Object, List<Object>>();
											m_SubAssetsByTypeAndMainAsset[nextSubAssetType] = subAssetByMainAsset;
										}
										if (!subAssetByMainAsset.TryGetValue(asset, out var subAssetList))
										{
											subAssetList = new List<Object>();
											subAssetByMainAsset[asset] = subAssetList;
										}
										subAssetList.Add(subAsset);
									}
									nextSubAssetType = nextSubAssetType.BaseType;
								}
							}
						}
					}
				}

				if (settings.ShowProgressBar)
				{
					EditorUtility.DisplayProgressBar(ProgressBarTitle, $"Resolving {sheetAsset} types using {nameof(ScanOption)} {settings.Option}", 0.90f);
				}

				if (sheetAsset == SheetAsset.ScriptableObject && settings.Option == ScanOption.Assembly)
				{
					var assemblies = AppDomain.CurrentDomain.GetAssemblies();
					var objectTypes = new List<Type>();
					foreach (var assembly in assemblies)
					{
						var types = assembly.GetTypes().Where
						(
							type => type.IsSubclassOf(typeof(ScriptableObject))
								&& type.IsSerializable
								&& type.IsValidConcreteType()
								&& !type.IsSubclassOf(typeof(Editor))
								&& !type.IsSubclassOf(typeof(EditorWindow))
								&& !type.IsScriptableSingleton()
						);
						objectTypes.AddRange(types);
					}
					m_ObjectTypes = objectTypes.Concat(m_ObjectsByType.Keys).Distinct().OrderBy(type => type.FullName).ToArray();
				}
				else
				{
					m_ObjectTypes = m_ObjectsByType.Keys.OrderBy(type => type.FullName).ToArray();
				}

				if (settings.ShowProgressBar)
				{
					EditorUtility.DisplayProgressBar(ProgressBarTitle, $"Finalizing {sheetAsset} type names", 0.98f);
				}

				m_ObjectTypeNames = m_ObjectTypes.Select(type => type.FullName).ToArray();
				// Submenu once we start having a lot of Objects.
				var separator = '.';
				if (m_ObjectTypeNames.Length > SheetLayout.SubMenuThreshold)
				{
					var newSeparator = '/';
					m_ObjectTypeNames = m_ObjectTypeNames.Select(s => s.Replace(separator, newSeparator)).ToArray();
					separator = newSeparator;
				}
				m_FriendlyObjectTypeNames = m_ObjectTypeNames.Select(s => s.Substring(s.LastIndexOf(separator) + 1)).ToArray();
			}
			catch (Exception ex)
			{
				Debug.LogError($"{nameof(ScanObjects)} for {nameof(SheetAsset)} {sheetAsset} failed with error: {ex}");
			}
			finally
			{
				EditorUtility.ClearProgressBar();
			}
		}
	}
}