using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using UnityEngine;
using UnityObject = UnityEngine.Object;

namespace Unity.VisualScripting
{
    public class UnitOptionTree : ExtensibleFuzzyOptionTree
    {
        #region Initialization

        public UnitOptionTree(GUIContent label) : base(label)
        {
            favorites = new Favorites(this);

            showBackgroundWorkerProgress = true;
        }

        public override IFuzzyOption Option(object item)
        {
            if (item is Namespace @namespace)
            {
                return new NamespaceOption(@namespace, true);
            }

            if (item is Type type)
            {
                return new TypeOption(type, true);
            }

            return base.Option(item);
        }

        public override void Prewarm()
        {
            filter = filter ?? UnitOptionFilter.Any;

            try
            {
                options = new HashSet<IUnitOption>(UnitBase.Subset(filter, reference));
            }
            catch (Exception ex)
            {
                Debug.LogError($"Failed to fetch node options for fuzzy finder (error log below).\nTry rebuilding the node options from '{UnitOptionUtility.GenerateUnitDatabasePath}'.\n\n{ex}");
                options = new HashSet<IUnitOption>();
            }

            typesWithMembers = new HashSet<Type>();

            foreach (var option in options)
            {
                if (option is IMemberUnitOption memberUnitOption && memberUnitOption.targetType != null)
                {
                    typesWithMembers.Add(memberUnitOption.targetType);
                }
            }
        }

        private HashSet<IUnitOption> options;

        private HashSet<Type> typesWithMembers;

        #endregion


        #region Configuration

        public UnitOptionFilter filter { get; set; }
        public GraphReference reference { get; set; }
        public bool includeNone { get; set; }
        public bool surfaceCommonTypeLiterals { get; set; }
        public object[] rootOverride { get; set; }

        public FlowGraph graph => reference.graph as FlowGraph;
        public GameObject self => reference.self;

        public ActionDirection direction { get; set; } = ActionDirection.Any;

        #endregion


        #region Hierarchy

        private readonly FuzzyGroup enumsGroup = new FuzzyGroup("(Enums)", typeof(Enum).Icon());
        private readonly FuzzyGroup selfGroup = new FuzzyGroup("This", typeof(GameObject).Icon());

        private IEnumerable<UnitCategory> SpecialCategories()
        {
            yield return new UnitCategory("Codebase");
            yield return new UnitCategory("Events");
            yield return new UnitCategory("Variables");
            yield return new UnitCategory("Math");
            yield return new UnitCategory("Nesting");
            yield return new UnitCategory("Graphs");
        }

        public override IEnumerable<object> Root()
        {
            if (rootOverride != null && rootOverride.Length > 0)
            {
                foreach (var item in rootOverride)
                {
                    yield return item;
                }

                yield break;
            }

            if (filter.CompatibleOutputType != null)
            {
                var outputType = filter.CompatibleOutputType;

                var outputTypeLiteral = options.FirstOrDefault(option => option is LiteralOption literalOption && literalOption.literalType == outputType);

                if (outputTypeLiteral != null)
                {
                    yield return outputTypeLiteral;
                }

                HashSet<Type> noSurfaceConstructors = new HashSet<Type>()
                {
                    typeof(string),
                    typeof(object)
                };

                if (!noSurfaceConstructors.Contains(outputType))
                {
                    var outputTypeConstructors = options.Where(option => option is InvokeMemberOption invokeMemberOption &&
                        invokeMemberOption.targetType == outputType &&
                        invokeMemberOption.unit.member.isConstructor);

                    foreach (var outputTypeConstructor in outputTypeConstructors)
                    {
                        yield return outputTypeConstructor;
                    }
                }

                if (outputType == typeof(bool))
                {
                    foreach (var logicOperation in CategoryChildren(new UnitCategory("Logic")))
                    {
                        yield return logicOperation;
                    }
                }

                if (outputType.IsNumeric())
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Scalar")))
                    {
                        yield return mathOperation;
                    }
                }

                if (outputType == typeof(Vector2))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 2")))
                    {
                        yield return mathOperation;
                    }
                }

                if (outputType == typeof(Vector3))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 3")))
                    {
                        yield return mathOperation;
                    }
                }

                if (outputType == typeof(Vector4))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 4")))
                    {
                        yield return mathOperation;
                    }
                }
            }

            if (surfaceCommonTypeLiterals)
            {
                foreach (var commonType in EditorTypeUtility.commonTypes)
                {
                    if (commonType == filter.CompatibleOutputType)
                    {
                        continue;
                    }

                    var commonTypeLiteral = options.FirstOrDefault(option => option is LiteralOption literalOption && literalOption.literalType == commonType);

                    if (commonTypeLiteral != null)
                    {
                        yield return commonTypeLiteral;
                    }
                }
            }

            if (filter.CompatibleInputType != null)
            {
                var inputType = filter.CompatibleInputType;

                if (!inputType.IsPrimitive && inputType != typeof(object))
                {
                    yield return inputType;
                }

                if (inputType == typeof(bool))
                {
                    yield return options.Single(o => o.UnitIs<If>());
                    yield return options.Single(o => o.UnitIs<SelectUnit>());
                }

                if (inputType == typeof(bool) || inputType.IsNumeric())
                {
                    foreach (var logicOperation in CategoryChildren(new UnitCategory("Logic")))
                    {
                        yield return logicOperation;
                    }
                }

                if (inputType.IsNumeric())
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Scalar")))
                    {
                        yield return mathOperation;
                    }
                }

                if (inputType == typeof(Vector2))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 2")))
                    {
                        yield return mathOperation;
                    }
                }

                if (inputType == typeof(Vector3))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 3")))
                    {
                        yield return mathOperation;
                    }
                }

                if (inputType == typeof(Vector4))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Math/Vector 4")))
                    {
                        yield return mathOperation;
                    }
                }

                if (typeof(IEnumerable).IsAssignableFrom(inputType) && (inputType != typeof(string) && inputType != typeof(Transform)))
                {
                    foreach (var mathOperation in CategoryChildren(new UnitCategory("Collections"), false))
                    {
                        yield return mathOperation;
                    }
                }

                if (typeof(IList).IsAssignableFrom(inputType))
                {
                    foreach (var listOperation in CategoryChildren(new UnitCategory("Collections/Lists")))
                    {
                        yield return listOperation;
                    }
                }

                if (typeof(IDictionary).IsAssignableFrom(inputType))
                {
                    foreach (var dictionaryOperation in CategoryChildren(new UnitCategory("Collections/Dictionaries")))
                    {
                        yield return dictionaryOperation;
                    }
                }
            }

            if (filter.NoConnection)
            {
                yield return new StickyNoteOption();
            }

            if (UnityAPI.Await
                (
                    () =>
                    {
                        if (self != null)
                        {
                            selfGroup.label = self.name;
                            selfGroup.icon = self.Icon();
                            return true;
                        }

                        return false;
                    }
                )
            )
            {
                yield return selfGroup;
            }

            foreach (var category in options.Select(option => option.category?.root)
                     .NotNull()
                     .Concat(SpecialCategories())
                     .Distinct()
                     .OrderBy(c => c.name))
            {
                yield return category;
            }

            foreach (var extensionRootItem in base.Root())
            {
                yield return extensionRootItem;
            }

            if (filter.Self)
            {
                var self = options.FirstOrDefault(option => option.UnitIs<This>());

                if (self != null)
                {
                    yield return self;
                }
            }

            foreach (var unit in CategoryChildren(null))
            {
                yield return unit;
            }

            if (includeNone)
            {
                yield return null;
            }
        }

        public override IEnumerable<object> Children(object parent)
        {
            if (parent is Namespace @namespace)
            {
                return NamespaceChildren(@namespace);
            }
            else if (parent is Type type)
            {
                return TypeChildren(type);
            }
            else if (parent == enumsGroup)
            {
                return EnumsChildren();
            }
            else if (parent == selfGroup)
            {
                return SelfChildren();
            }
            else if (parent is UnitCategory unitCategory)
            {
                return CategoryChildren(unitCategory);
            }
            else if (parent is VariableKind variableKind)
            {
                return VariableKindChildren(variableKind);
            }
            else
            {
                return base.Children(parent);
            }
        }

        private IEnumerable<object> SelfChildren()
        {
            yield return typeof(GameObject);

            // Self components can be null if no script is assigned to them
            // https://support.ludiq.io/forums/5-bolt/topics/817-/
            foreach (var selfComponentType in UnityAPI.Await(() => self.GetComponents<Component>().NotUnityNull().Select(c => c.GetType())))
            {
                yield return selfComponentType;
            }
        }

        private IEnumerable<object> CodebaseChildren()
        {
            foreach (var rootNamespace in typesWithMembers.Where(t => !t.IsEnum)
                     .Select(t => t.Namespace().Root)
                     .OrderBy(ns => ns.DisplayName(false))
                     .Distinct())
            {
                yield return rootNamespace;
            }

            if (filter.Literals && options.Any(option => option is LiteralOption literalOption && literalOption.literalType.IsEnum))
            {
                yield return enumsGroup;
            }
        }

        private IEnumerable<object> MathChildren()
        {
            foreach (var mathMember in GetMembers(typeof(Mathf)).Where(option => !((MemberUnit)option.unit).member.requiresTarget))
            {
                yield return mathMember;
            }
        }

        private IEnumerable<object> TimeChildren()
        {
            foreach (var timeMember in GetMembers(typeof(Time)).Where(option => !((MemberUnit)option.unit).member.requiresTarget))
            {
                yield return timeMember;
            }
        }

        private IEnumerable<object> NestingChildren()
        {
            foreach (var nester in options.Where(option => option.UnitIs<IGraphNesterElement>() && ((IGraphNesterElement)option.unit).nest.macro == null)
                     .OrderBy(option => option.label))
            {
                yield return nester;
            }
        }

        private IEnumerable<object> MacroChildren()
        {
            foreach (var macroNester in options.Where(option => option.UnitIs<IGraphNesterElement>() && ((IGraphNesterElement)option.unit).nest.macro != null)
                     .OrderBy(option => option.label))
            {
                yield return macroNester;
            }
        }

        private IEnumerable<object> VariablesChildren()
        {
            yield return VariableKind.Flow;
            yield return VariableKind.Graph;
            yield return VariableKind.Object;
            yield return VariableKind.Scene;
            yield return VariableKind.Application;
            yield return VariableKind.Saved;
        }

        private IEnumerable<object> VariableKindChildren(VariableKind kind)
        {
            foreach (var variable in options.OfType<IUnifiedVariableUnitOption>()
                     .Where(option => option.kind == kind)
                     .OrderBy(option => option.name))
            {
                yield return variable;
            }
        }

        private IEnumerable<object> NamespaceChildren(Namespace @namespace)
        {
            foreach (var childNamespace in GetChildrenNamespaces(@namespace))
            {
                yield return childNamespace;
            }

            foreach (var type in GetNamespaceTypes(@namespace))
            {
                yield return type;
            }
        }

        private IEnumerable<Namespace> GetChildrenNamespaces(Namespace @namespace)
        {
            if (!@namespace.IsGlobal)
            {
                foreach (var childNamespace in typesWithMembers.Where(t => !t.IsEnum)
                         .SelectMany(t => t.Namespace().AndAncestors())
                         .Distinct()
                         .Where(ns => ns.Parent == @namespace)
                         .OrderBy(ns => ns.DisplayName(false)))
                {
                    yield return childNamespace;
                }
            }
        }

        private IEnumerable<Type> GetNamespaceTypes(Namespace @namespace)
        {
            foreach (var type in typesWithMembers.Where(t => t.Namespace() == @namespace && !t.IsEnum)
                     .OrderBy(t => t.DisplayName()))
            {
                yield return type;
            }
        }

        private IEnumerable<object> TypeChildren(Type type)
        {
            foreach (var literal in options.Where(option => option is LiteralOption literalOption && literalOption.literalType == type))
            {
                yield return literal;
            }

            foreach (var expose in options.Where(option => option is ExposeOption exposeOption && exposeOption.exposedType == type))
            {
                yield return expose;
            }

            if (type.IsStruct())
            {
                foreach (var createStruct in options.Where(option => option is CreateStructOption createStructOption && createStructOption.structType == type))
                {
                    yield return createStruct;
                }
            }

            foreach (var member in GetMembers(type))
            {
                yield return member;
            }
        }

        private IEnumerable<IUnitOption> GetMembers(Type type)
        {
            foreach (var member in options.Where(option => option is IMemberUnitOption memberUnitOption && memberUnitOption.targetType == type && option.unit.canDefine)
                     .OrderBy(option => BoltCore.Configuration.groupInheritedMembers && ((MemberUnit)option.unit).member.isPseudoInherited)
                     .ThenBy(option => option.order)
                     .ThenBy(option => option.label))
            {
                yield return member;
            }
        }

        private IEnumerable<object> EnumsChildren()
        {
            foreach (var literal in options.Where(option => option is LiteralOption literalOption && literalOption.literalType.IsEnum)
                     .OrderBy(option => option.label))
            {
                yield return literal;
            }
        }

        private IEnumerable<object> CategoryChildren(UnitCategory category, bool subCategories = true)
        {
            if (category != null && subCategories)
            {
                foreach (var subCategory in options.SelectMany(option => option.category == null ? Enumerable.Empty<UnitCategory>() : option.category.AndAncestors())
                         .Distinct()
                         .Where(c => c.parent == category)
                         .OrderBy(c => c.name))
                {
                    yield return subCategory;
                }
            }

            foreach (var unit in options.Where(option => option.category == category)
                     .Where(option => !option.unitType.HasAttribute<SpecialUnitAttribute>())
                     .OrderBy(option => option.order)
                     .ThenBy(option => option.label))
            {
                yield return unit;
            }

            if (category != null)
            {
                if (category.root.name == "Events")
                {
                    foreach (var eventChild in EventsChildren(category))
                    {
                        yield return eventChild;
                    }
                }
                else if (category.fullName == "Codebase")
                {
                    foreach (var codebaseChild in CodebaseChildren())
                    {
                        yield return codebaseChild;
                    }
                }
                else if (category.fullName == "Variables")
                {
                    foreach (var variableChild in VariablesChildren())
                    {
                        yield return variableChild;
                    }
                }
                else if (category.fullName == "Math")
                {
                    foreach (var mathChild in MathChildren())
                    {
                        yield return mathChild;
                    }
                }
                else if (category.fullName == "Time")
                {
                    foreach (var timeChild in TimeChildren())
                    {
                        yield return timeChild;
                    }
                }
                else if (category.fullName == "Nesting")
                {
                    foreach (var nestingChild in NestingChildren())
                    {
                        yield return nestingChild;
                    }
                }
                else if (category.fullName == "Graphs")
                {
                    foreach (var macroChild in MacroChildren())
                    {
                        yield return macroChild;
                    }
                }
            }
        }

        private IEnumerable<object> EventsChildren(UnitCategory category)
        {
            foreach (var unit in options.Where(option => option.UnitIs<IEventUnit>() && option.category == category)
                     .OrderBy(option => option.order)
                     .ThenBy(option => option.label))
            {
                yield return unit;
            }
        }

        #endregion


        #region Search

        public override bool searchable { get; } = true;

        public override IEnumerable<ISearchResult> SearchResults(string query, CancellationToken cancellation)
        {
            foreach (var typeResult in typesWithMembers.Cancellable(cancellation).OrderableSearchFilter(query, t => t.DisplayName()))
            {
                yield return typeResult;
            }

            foreach (var optionResult in options.Cancellable(cancellation)
                     .OrderableSearchFilter(query, o => o.haystack, o => o.formerHaystack)
                     .WithoutInheritedDuplicates(r => r.result, cancellation))
            {
                yield return optionResult;
            }
        }

        public override string SearchResultLabel(object item, string query)
        {
            if (item is Type type)
            {
                return TypeOption.SearchResultLabel(type, query);
            }
            else if (item is IUnitOption unitOption)
            {
                return unitOption.SearchResultLabel(query);
            }
            else
            {
                return base.SearchResultLabel(item, query);
            }
        }

        #endregion


        #region Favorites

        public override ICollection<object> favorites { get; }

        public override bool CanFavorite(object item)
        {
            return (item as IUnitOption)?.favoritable ?? false;
        }

        public override string FavoritesLabel(object item)
        {
            return SearchResultLabel(item, null);
        }

        public override void OnFavoritesChange()
        {
            BoltFlow.Configuration.Save();
        }

        private class Favorites : ICollection<object>
        {
            public Favorites(UnitOptionTree tree)
            {
                this.tree = tree;
            }

            private UnitOptionTree tree { get; }

            private IEnumerable<IUnitOption> options => tree.options.Where(option => BoltFlow.Configuration.favoriteUnitOptions.Contains(option.favoriteKey));

            public bool IsReadOnly => false;

            public int Count => BoltFlow.Configuration.favoriteUnitOptions.Count;

            public IEnumerator<object> GetEnumerator()
            {
                foreach (var option in options)
                {
                    yield return option;
                }
            }

            IEnumerator IEnumerable.GetEnumerator()
            {
                return GetEnumerator();
            }

            public bool Contains(object item)
            {
                var option = (IUnitOption)item;

                return BoltFlow.Configuration.favoriteUnitOptions.Contains(option.favoriteKey);
            }

            public void Add(object item)
            {
                var option = (IUnitOption)item;

                BoltFlow.Configuration.favoriteUnitOptions.Add(option.favoriteKey);
            }

            public bool Remove(object item)
            {
                var option = (IUnitOption)item;

                return BoltFlow.Configuration.favoriteUnitOptions.Remove(option.favoriteKey);
            }

            public void Clear()
            {
                BoltFlow.Configuration.favoriteUnitOptions.Clear();
            }

            public void CopyTo(object[] array, int arrayIndex)
            {
                if (array == null)
                {
                    throw new ArgumentNullException(nameof(array));
                }

                if (arrayIndex < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(arrayIndex));
                }

                if (array.Length - arrayIndex < Count)
                {
                    throw new ArgumentException();
                }

                var i = 0;

                foreach (var item in this)
                {
                    array[i + arrayIndex] = item;
                    i++;
                }
            }
        }

        #endregion
    }
}