using System.Diagnostics;
using System.Runtime.CompilerServices;
using Jint.Native;
using Jint.Native.Object;

namespace Jint.Runtime.Descriptors;

[DebuggerDisplay("Value: {Value}, Flags: {Flags}")]
public class PropertyDescriptor
{
    public static readonly PropertyDescriptor Undefined = new UndefinedPropertyDescriptor();

    internal PropertyFlag _flags;
    internal JsValue? _value;

    public PropertyDescriptor() : this(PropertyFlag.None)
    {
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    protected PropertyDescriptor(PropertyFlag flags)
    {
        _flags = flags & ~PropertyFlag.NonData;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    protected internal PropertyDescriptor(JsValue? value, PropertyFlag flags) : this(flags)
    {
        if ((_flags & PropertyFlag.CustomJsValue) != PropertyFlag.None)
        {
#pragma warning disable MA0056
            CustomValue = value;
#pragma warning restore MA0056
        }
        _value = value;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public PropertyDescriptor(JsValue? value, bool? writable, bool? enumerable, bool? configurable)
    {
        if ((_flags & PropertyFlag.CustomJsValue) != PropertyFlag.None)
        {
#pragma warning disable MA0056
            CustomValue = value;
#pragma warning restore MA0056
        }
        _value = value;

        if (writable != null)
        {
            Writable = writable.Value;
            WritableSet = true;
        }

        if (enumerable != null)
        {
            Enumerable = enumerable.Value;
            EnumerableSet = true;
        }

        if (configurable != null)
        {
            Configurable = configurable.Value;
            ConfigurableSet = true;
        }
    }

    public PropertyDescriptor(PropertyDescriptor descriptor)
    {
        Value = descriptor.Value;

        Enumerable = descriptor.Enumerable;
        EnumerableSet = descriptor.EnumerableSet;

        Configurable = descriptor.Configurable;
        ConfigurableSet = descriptor.ConfigurableSet;

        Writable = descriptor.Writable;
        WritableSet = descriptor.WritableSet;
    }

    public virtual JsValue? Get => null;
    public virtual JsValue? Set => null;

    public bool Enumerable
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & PropertyFlag.Enumerable) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        set
        {
            _flags |= PropertyFlag.EnumerableSet;
            if (value)
            {
                _flags |= PropertyFlag.Enumerable;
            }
            else
            {
                _flags &= ~(PropertyFlag.Enumerable);
            }
        }
    }

    public bool EnumerableSet
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & (PropertyFlag.EnumerableSet | PropertyFlag.Enumerable)) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private set
        {
            if (value)
            {
                _flags |= PropertyFlag.EnumerableSet;
            }
            else
            {
                _flags &= ~(PropertyFlag.EnumerableSet);
            }
        }
    }

    public bool Writable
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & PropertyFlag.Writable) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        set
        {
            _flags |= PropertyFlag.WritableSet;
            if (value)
            {
                _flags |= PropertyFlag.Writable;
            }
            else
            {
                _flags &= ~(PropertyFlag.Writable);
            }
        }
    }

    public bool WritableSet
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & (PropertyFlag.WritableSet | PropertyFlag.Writable)) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private set
        {
            if (value)
            {
                _flags |= PropertyFlag.WritableSet;
            }
            else
            {
                _flags &= ~(PropertyFlag.WritableSet);
            }
        }
    }

    public bool Configurable
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & PropertyFlag.Configurable) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        set
        {
            _flags |= PropertyFlag.ConfigurableSet;
            if (value)
            {
                _flags |= PropertyFlag.Configurable;
            }
            else
            {
                _flags &= ~(PropertyFlag.Configurable);
            }
        }
    }

    public bool ConfigurableSet
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => (_flags & (PropertyFlag.ConfigurableSet | PropertyFlag.Configurable)) != PropertyFlag.None;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private set
        {
            if (value)
            {
                _flags |= PropertyFlag.ConfigurableSet;
            }
            else
            {
                _flags &= ~(PropertyFlag.ConfigurableSet);
            }
        }
    }

    public JsValue Value
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get
        {
            if ((_flags & PropertyFlag.CustomJsValue) != PropertyFlag.None)
            {
                return CustomValue!;
            }

            return _value!;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        set
        {
            if ((_flags & PropertyFlag.CustomJsValue) != PropertyFlag.None)
            {
                CustomValue = value;
            }
            _value = value;
        }
    }

    protected internal virtual JsValue? CustomValue
    {
        get => null;
        set => Throw.NotImplementedException();
    }

    internal PropertyFlag Flags
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get => _flags;
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-topropertydescriptor
    /// </summary>
    public static PropertyDescriptor ToPropertyDescriptor(Realm realm, JsValue o)
    {
        if (o is not ObjectInstance obj)
        {
            Throw.TypeError(realm);
            return null;
        }

        bool? enumerable = null;
        var hasEnumerable = obj.HasProperty(CommonProperties.Enumerable);
        if (hasEnumerable)
        {
            enumerable = TypeConverter.ToBoolean(obj.Get(CommonProperties.Enumerable));
        }

        bool? configurable = null;
        var hasConfigurable = obj.HasProperty(CommonProperties.Configurable);
        if (hasConfigurable)
        {
            configurable = TypeConverter.ToBoolean(obj.Get(CommonProperties.Configurable));
        }

        JsValue? value = null;
        var hasValue = obj.HasProperty(CommonProperties.Value);
        if (hasValue)
        {
            value = obj.Get(CommonProperties.Value);
        }

        bool? writable = null;
        var hasWritable = obj.HasProperty(CommonProperties.Writable);
        if (hasWritable)
        {
            writable = TypeConverter.ToBoolean(obj.Get(CommonProperties.Writable));
        }

        JsValue? get = null;
        var hasGet = obj.HasProperty(CommonProperties.Get);
        if (hasGet)
        {
            get = obj.Get(CommonProperties.Get);
        }

        JsValue? set = null;
        var hasSet = obj.HasProperty(CommonProperties.Set);
        if (hasSet)
        {
            set = obj.Get(CommonProperties.Set);
        }

        if ((hasValue || hasWritable) && (hasGet || hasSet))
        {
            Throw.TypeError(realm, "Invalid property descriptor. Cannot both specify accessors and a value or writable attribute");
        }

        var desc = hasGet || hasSet
            ? new GetSetPropertyDescriptor(null, null, PropertyFlag.None)
            : new PropertyDescriptor(PropertyFlag.None);

        if (hasEnumerable)
        {
            desc.Enumerable = enumerable!.Value;
            desc.EnumerableSet = true;
        }

        if (hasConfigurable)
        {
            desc.Configurable = configurable!.Value;
            desc.ConfigurableSet = true;
        }

        if (hasValue)
        {
            desc.Value = value!;
        }

        if (hasWritable)
        {
            desc.Writable = TypeConverter.ToBoolean(writable!.Value);
            desc.WritableSet = true;
        }

        if (hasGet)
        {
            if (!get!.IsUndefined() && get!.TryCast<ICallable>() == null)
            {
                Throw.TypeError(realm);
            }

            ((GetSetPropertyDescriptor) desc).SetGet(get!);
        }

        if (hasSet)
        {
            if (!set!.IsUndefined() && set!.TryCast<ICallable>() is null)
            {
                Throw.TypeError(realm);
            }

            ((GetSetPropertyDescriptor) desc).SetSet(set!);
        }

        if ((hasSet || hasGet) && (hasValue || hasWritable))
        {
            Throw.TypeError(realm);
        }

        return desc;
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-frompropertydescriptor
    /// </summary>
    public static JsValue FromPropertyDescriptor(Engine engine, PropertyDescriptor desc, bool strictUndefined = false)
    {
        if (ReferenceEquals(desc, Undefined))
        {
            return JsValue.Undefined;
        }

        var obj = engine.Realm.Intrinsics.Object.Construct(Arguments.Empty);
        var properties = new PropertyDictionary(4, checkExistingKeys: false);

        // TODO should not check for strictUndefined, but needs a bigger cleanup
        // we should have possibility to leave out the properties in property descriptors as newer tests
        // also assert properties to be undefined

        if (desc.IsDataDescriptor())
        {
            properties["value"] = new PropertyDescriptor(desc.Value ?? JsValue.Undefined, PropertyFlag.ConfigurableEnumerableWritable);
            if (desc._flags != PropertyFlag.None || desc.WritableSet)
            {
                properties["writable"] = new PropertyDescriptor(desc.Writable, PropertyFlag.ConfigurableEnumerableWritable);
            }
        }
        else
        {
            properties["get"] = new PropertyDescriptor(desc.Get ?? JsValue.Undefined, PropertyFlag.ConfigurableEnumerableWritable);
            properties["set"] = new PropertyDescriptor(desc.Set ?? JsValue.Undefined, PropertyFlag.ConfigurableEnumerableWritable);
        }

        if (!strictUndefined || desc.EnumerableSet)
        {
            properties["enumerable"] = new PropertyDescriptor(desc.Enumerable, PropertyFlag.ConfigurableEnumerableWritable);
        }

        if (!strictUndefined || desc.ConfigurableSet)
        {
            properties["configurable"] = new PropertyDescriptor(desc.Configurable, PropertyFlag.ConfigurableEnumerableWritable);
        }

        obj.SetProperties(properties);
        return obj;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool IsAccessorDescriptor()
    {
        return Get is not null || Set is not null;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool IsDataDescriptor()
    {
        if ((_flags & PropertyFlag.NonData) != PropertyFlag.None)
        {
            return false;
        }
        return (_flags & (PropertyFlag.WritableSet | PropertyFlag.Writable)) != PropertyFlag.None
               || (_flags & PropertyFlag.CustomJsValue) != PropertyFlag.None && CustomValue is not null
               || _value is not null;
    }

    /// <summary>
    /// http://www.ecma-international.org/ecma-262/5.1/#sec-8.10.3
    /// </summary>
    /// <returns></returns>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool IsGenericDescriptor()
    {
        return !IsDataDescriptor() && !IsAccessorDescriptor();
    }

    private sealed class UndefinedPropertyDescriptor : PropertyDescriptor
    {
        public UndefinedPropertyDescriptor() : base(PropertyFlag.None | PropertyFlag.CustomJsValue)
        {
        }

        protected internal override JsValue? CustomValue
        {
            set => Throw.InvalidOperationException("making changes to undefined property's descriptor is not allowed");
        }
    }

    internal sealed class AllForbiddenDescriptor : PropertyDescriptor
    {
        private static readonly PropertyDescriptor[] _cache;

        public static readonly AllForbiddenDescriptor NumberZero = new AllForbiddenDescriptor(JsNumber.Create(0));
        public static readonly AllForbiddenDescriptor NumberOne = new AllForbiddenDescriptor(JsNumber.Create(1));

        public static readonly AllForbiddenDescriptor BooleanFalse = new AllForbiddenDescriptor(JsBoolean.False);
        public static readonly AllForbiddenDescriptor BooleanTrue = new AllForbiddenDescriptor(JsBoolean.True);

        static AllForbiddenDescriptor()
        {
            _cache = new PropertyDescriptor[10];
            for (int i = 0; i < _cache.Length; ++i)
            {
                _cache[i] = new AllForbiddenDescriptor(JsNumber.Create(i));
            }
        }

        private AllForbiddenDescriptor(JsValue value)
            : base(PropertyFlag.AllForbidden)
        {
            _value = value;
        }

        public static PropertyDescriptor ForNumber(int number)
        {
            var temp = _cache;
            return (uint) number < temp.Length
                ? temp[number]
                : new PropertyDescriptor(number, PropertyFlag.AllForbidden);
        }
    }
}