using System.Globalization;
using System.Runtime.CompilerServices;
using Jint.Native.ArrayBuffer;
using Jint.Native.Number;
using Jint.Native.Object;
using Jint.Native.TypedArray;
using Jint.Runtime;
using Jint.Runtime.Descriptors;

namespace Jint.Native;

public sealed class JsTypedArray : ObjectInstance
{
    internal const uint LengthAuto = uint.MaxValue;

    internal readonly TypedArrayContentType _contentType;
    internal readonly TypedArrayElementType _arrayElementType;
    internal JsArrayBuffer _viewedArrayBuffer;
    internal uint _byteLength;
    internal int _byteOffset;
    private readonly Intrinsics _intrinsics;
    internal uint _arrayLength;

    internal JsTypedArray(
        Engine engine,
        Intrinsics intrinsics,
        TypedArrayElementType type,
        uint length) : base(engine)
    {
        _intrinsics = intrinsics;
        _viewedArrayBuffer = new JsArrayBuffer(engine, []);

        _arrayElementType = type;
        _contentType = type != TypedArrayElementType.BigInt64 && type != TypedArrayElementType.BigUint64
            ? TypedArrayContentType.Number
            : TypedArrayContentType.BigInt;

        _arrayLength = length;
    }

    public JsValue this[int index]
    {
        get => IntegerIndexedElementGet(index);
        set => IntegerIndexedElementSet(index, value);
    }

    public JsValue this[uint index]
    {
        get => IntegerIndexedElementGet(index);
        set => IntegerIndexedElementSet(index, value);
    }

    public uint Length => GetLength();

    internal override uint GetLength()
    {
        var record = IntrinsicTypedArrayPrototype.MakeTypedArrayWithBufferWitnessRecord(this, ArrayBufferOrder.Unordered);
        return record.IsTypedArrayOutOfBounds ? 0 : record.TypedArrayLength;
    }

    public override bool PreventExtensions()
    {
        if (!IsTypedArrayFixedLength)
        {
            return false;
        }

        return base.PreventExtensions();
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-istypedarrayfixedlength
    /// </summary>
    private bool IsTypedArrayFixedLength
    {
        get
        {
            if (_arrayLength == LengthAuto)
            {
                return false;
            }

            var buffer = _viewedArrayBuffer;
            if (!buffer.IsFixedLengthArrayBuffer && !buffer.IsSharedArrayBuffer)
            {
                return false;
            }

            return true;
        }
    }

    internal override bool IsArrayLike => true;

    internal override bool IsIntegerIndexedArray => true;

    /// <summary>
    /// https://tc39.es/ecma262/#sec-allocatetypedarraybuffer
    /// </summary>
    internal void AllocateTypedArrayBuffer(ulong len)
    {
        var elementSize = _arrayElementType.GetElementSize();
        var byteLength = elementSize * len;

        var data = _intrinsics.ArrayBuffer.AllocateArrayBuffer(_intrinsics.ArrayBuffer, byteLength);

        _byteLength = (uint) byteLength;
        _arrayLength = (uint) len;
        _viewedArrayBuffer = data;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal bool HasProperty(long numericIndex)
    {
        return IsValidIntegerIndex(numericIndex);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-hasproperty-p
    /// </summary>
    public override bool HasProperty(JsValue property)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            return IsValidIntegerIndex(numericIndex.Value);
        }

        return base.HasProperty(property);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-getownproperty-p
    /// </summary>
    public override PropertyDescriptor GetOwnProperty(JsValue property)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            var value = IntegerIndexedElementGet(numericIndex.Value);
            if (value.IsUndefined())
            {
                return PropertyDescriptor.Undefined;
            }

            return new PropertyDescriptor(value, PropertyFlag.ConfigurableEnumerableWritable);
        }

        return base.GetOwnProperty(property);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-get-p-receiver
    /// </summary>
    public override JsValue Get(JsValue property, JsValue receiver)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            return IntegerIndexedElementGet(numericIndex.Value);
        }

        return base.Get(property, receiver);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-set-p-v-receiver
    /// </summary>
    public override bool Set(JsValue property, JsValue value, JsValue receiver)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            if (ReferenceEquals(this, receiver))
            {
                IntegerIndexedElementSet(numericIndex.Value, value);
                return true;
            }

            if (!IsValidIntegerIndex(numericIndex.Value))
            {
                return true;
            }
        }

        return base.Set(property, value, receiver);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-defineownproperty-p-desc
    /// </summary>
    public override bool DefineOwnProperty(JsValue property, PropertyDescriptor desc)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            if (!IsValidIntegerIndex(numericIndex.Value))
            {
                return false;
            }

            if (desc is { ConfigurableSet: true, Configurable: false })
            {
                return false;
            }

            if (desc is { EnumerableSet: true, Enumerable: false })
            {
                return false;
            }

            if (desc.IsAccessorDescriptor())
            {
                return false;
            }

            if (desc is { WritableSet: true, Writable: false })
            {
                return false;
            }

            IntegerIndexedElementSet(numericIndex.Value, desc.Value);
            return true;
        }

        return base.DefineOwnProperty(property, desc);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-ownpropertykeys
    /// </summary>
    public override List<JsValue> GetOwnPropertyKeys(Types types = Types.Empty | Types.String | Types.Symbol)
    {
        var taRecord = IntrinsicTypedArrayPrototype.MakeTypedArrayWithBufferWitnessRecord(this, ArrayBufferOrder.SeqCst);
        var keys = new List<JsValue>();
        if (!taRecord.IsTypedArrayOutOfBounds)
        {
            var length = GetLength();
            for (uint i = 0; i < length; ++i)
            {
                keys.Add(JsString.Create(i));
            }
        }

        if (_properties is not null)
        {
            foreach (var pair in _properties)
            {
                keys.Add(pair.Key.Name);
            }
        }

        if (_symbols is not null)
        {
            foreach (var pair in _symbols)
            {
                keys.Add(pair.Key);
            }
        }

        return keys;
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integer-indexed-exotic-objects-delete-p
    /// </summary>
    public override bool Delete(JsValue property)
    {
        var numericIndex = TypeConverter.CanonicalNumericIndexString(property);
        if (numericIndex is not null)
        {
            return !IsValidIntegerIndex(numericIndex.Value);
        }

        return base.Delete(property);
    }

    // helper to prevent floating points
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    private JsValue IntegerIndexedElementGet(int index)
    {
        if (!IsValidIntegerIndex(index))
        {
            return Undefined;
        }

        return DoIntegerIndexedElementGet(index);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integerindexedelementget
    /// </summary>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    private JsValue IntegerIndexedElementGet(double index)
    {
        if (!IsValidIntegerIndex(index))
        {
            return Undefined;
        }

        return DoIntegerIndexedElementGet((int) index);
    }

    private JsValue DoIntegerIndexedElementGet(int index)
    {
        var offset = _byteOffset;
        var elementType = _arrayElementType;
        var elementSize = elementType.GetElementSize();
        var indexedPosition = index * elementSize + offset;
        var value = _viewedArrayBuffer.GetValueFromBuffer(indexedPosition, elementType, isTypedArray: true, ArrayBufferOrder.Unordered);
        if (value.Type == Types.Number)
        {
            return _arrayElementType.FitsInt32()
                ? JsNumber.Create((int) value.DoubleValue)
                : JsNumber.Create(value.DoubleValue);
        }

        return JsBigInt.Create(value.BigInteger);
    }

    // helper tot prevent floating point
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal void IntegerIndexedElementSet(int index, JsValue value)
    {
        TypedArrayValue numValue = _contentType != TypedArrayContentType.BigInt
            ? TypeConverter.ToNumber(value)
            : value.ToBigInteger(_engine);

        if (IsValidIntegerIndex(index))
        {
            DoIntegerIndexedElementSet(index, numValue);
        }
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-integerindexedelementset
    /// </summary>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    private void IntegerIndexedElementSet(double index, JsValue value)
    {
        if (_contentType != TypedArrayContentType.BigInt)
        {
            var numValue = TypeConverter.ToNumber(value);
            if (IsValidIntegerIndex(index))
            {
                DoIntegerIndexedElementSet((int) index, numValue);
            }
        }
        else
        {
            try
            {
                var numValue = TypeConverter.ToBigInt(value);
                if (IsValidIntegerIndex(index))
                {
                    DoIntegerIndexedElementSet((int) index, numValue);
                }
            }
            catch (ParseErrorException ex)
            {
                Throw.SyntaxError(_engine.Realm, ex.Message);
            }
        }
    }

    internal void DoIntegerIndexedElementSet(int index, TypedArrayValue numValue)
    {
        var offset = _byteOffset;
        var elementType = _arrayElementType;
        var elementSize = elementType.GetElementSize();
        var indexedPosition = index * elementSize + offset;
        _viewedArrayBuffer.SetValueInBuffer(indexedPosition, elementType, numValue, true, ArrayBufferOrder.Unordered);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-isvalidintegerindex
    /// </summary>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal bool IsValidIntegerIndex(double index)
    {
        if (_viewedArrayBuffer.IsDetachedBuffer)
        {
            return false;
        }

        if (!TypeConverter.IsIntegralNumber(index))
        {
            return false;
        }

        if (NumberInstance.IsNegativeZero(index))
        {
            return false;
        }

        return IsValidIntegerIndex((int) index);
    }

    /// <summary>
    /// https://tc39.es/ecma262/#sec-isvalidintegerindex
    /// </summary>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal bool IsValidIntegerIndex(int index)
    {
        if (_viewedArrayBuffer.IsDetachedBuffer)
        {
            return false;
        }

        var taRecord = IntrinsicTypedArrayPrototype.MakeTypedArrayWithBufferWitnessRecord(this, ArrayBufferOrder.Unordered);
        if (taRecord.IsTypedArrayOutOfBounds)
        {
            return false;
        }

        var length = taRecord.TypedArrayLength;
        if (index < 0 || index >= length)
        {
            return false;
        }

        return true;
    }

    internal T[] ToNativeArray<T>()
    {
        var conversionType = typeof(T);
        var elementSize = _arrayElementType.GetElementSize();
        var byteOffset = _byteOffset;
        var buffer = _viewedArrayBuffer;

        var array = new T[GetLength()];
        for (var i = 0; i < array.Length; ++i)
        {
            var indexedPosition = i * elementSize + byteOffset;
            var value = buffer.RawBytesToNumeric(_arrayElementType, indexedPosition, BitConverter.IsLittleEndian);
            array[i] = (T) Convert.ChangeType(value, conversionType, CultureInfo.InvariantCulture);
        }

        return array;
    }
}