// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Diagnostics.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Symbols;

namespace Microsoft.CodeAnalysis.CSharp
{
    /// <summary>
    /// A collection of value set factory instances for built-in types.
    /// </summary>
    internal static partial class ValueSetFactory
    {
        internal static readonly IConstantValueSetFactory<byte> ForByte = new NumericValueSetFactory<byte>(ByteTC.Instance);
        internal static readonly IConstantValueSetFactory<sbyte> ForSByte = new NumericValueSetFactory<sbyte>(SByteTC.Instance);
        internal static readonly IConstantValueSetFactory<char> ForChar = new NumericValueSetFactory<char>(CharTC.Instance);
        internal static readonly IConstantValueSetFactory<short> ForShort = new NumericValueSetFactory<short>(ShortTC.Instance);
        internal static readonly IConstantValueSetFactory<ushort> ForUShort = new NumericValueSetFactory<ushort>(UShortTC.Instance);
        internal static readonly IConstantValueSetFactory<int> ForInt = new NumericValueSetFactory<int>(IntTC.DefaultInstance);
        internal static readonly IConstantValueSetFactory<uint> ForUInt = new NumericValueSetFactory<uint>(UIntTC.Instance);
        internal static readonly IConstantValueSetFactory<long> ForLong = new NumericValueSetFactory<long>(LongTC.Instance);
        internal static readonly IConstantValueSetFactory<ulong> ForULong = new NumericValueSetFactory<ulong>(ULongTC.Instance);
        internal static readonly IConstantValueSetFactory<bool> ForBool = BoolValueSetFactory.Instance;
        internal static readonly IConstantValueSetFactory<float> ForFloat = new FloatingValueSetFactory<float>(SingleTC.Instance);
        internal static readonly IConstantValueSetFactory<double> ForDouble = new FloatingValueSetFactory<double>(DoubleTC.Instance);
        internal static readonly IConstantValueSetFactory<string> ForString = new EnumeratedValueSetFactory<string>(StringTC.Instance);
        internal static readonly IConstantValueSetFactory<decimal> ForDecimal = DecimalValueSetFactory.Instance;
        internal static readonly IConstantValueSetFactory<int> ForNint = NintValueSetFactory.Instance;
        internal static readonly IConstantValueSetFactory<uint> ForNuint = NuintValueSetFactory.Instance;
        internal static readonly IConstantValueSetFactory<int> ForLength = NonNegativeIntValueSetFactory.Instance;

        public static IConstantValueSetFactory? ForSpecialType(SpecialType specialType, bool isNative = false)
        {
            return specialType switch
            {
                SpecialType.System_Byte => ForByte,
                SpecialType.System_SByte => ForSByte,
                SpecialType.System_Char => ForChar,
                SpecialType.System_Int16 => ForShort,
                SpecialType.System_UInt16 => ForUShort,
                SpecialType.System_Int32 => ForInt,
                SpecialType.System_UInt32 => ForUInt,
                SpecialType.System_Int64 => ForLong,
                SpecialType.System_UInt64 => ForULong,
                SpecialType.System_Boolean => ForBool,
                SpecialType.System_Single => ForFloat,
                SpecialType.System_Double => ForDouble,
                SpecialType.System_String => ForString,
                SpecialType.System_Decimal => ForDecimal,
                SpecialType.System_IntPtr when isNative => ForNint,
                SpecialType.System_UIntPtr when isNative => ForNuint,
                _ => null,
            };
        }

        public static IConstantValueSetFactory? ForType(TypeSymbol type)
        {
            if (type.IsSpanOrReadOnlySpanChar())
                return ForString;
            type = type.EnumUnderlyingTypeOrSelf();
            return ForSpecialType(type.SpecialType, type.IsNativeIntegerType);
        }

        public static IConstantValueSetFactory? ForInput(BoundDagTemp input)
        {
            if (input.Source is BoundDagPropertyEvaluation { IsLengthOrCount: true })
                return ForLength;
            return ForType(input.Type);
        }

        public static ITypeUnionValueSetFactory? TypeUnionValueSetFactoryForInput(CSharpCompilation compilation, BoundDagTemp input)
        {
            if (DecisionDagBuilder.IsUnionValue(input, out BoundDagTemp? unionInstance))
            {
                var unionType = (NamedTypeSymbol)unionInstance.Type;
                if (unionType.UnionCaseTypesNoUseSiteDiagnostics is not [])
                {
                    return new UnionTypeTypeUnionValueSetFactory(unionType);
                }

                return null;
            }

            if (compilation.IsFeatureEnabled(MessageID.IDS_FeatureClosedClasses)
                && input.Type is (NamedTypeSymbol { IsClosed: true } or TypeParameterSymbol { EffectiveBaseClassNoUseSiteDiagnostics.IsClosed: true }) and var closedClassOrTypeParameter)
            {
                return new ClosedClassTypeUnionValueSetFactory(closedClassOrTypeParameter);
            }

            return null;
        }
    }
}