// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
using System.Collections.Immutable;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis;
using ILLink.RoslynAnalyzer.DataFlow;
using ILLink.Shared.DataFlow;
 
namespace ILLink.RoslynAnalyzer
{
	public static class ISymbolExtensions
	{
		/// <summary>
		/// Returns true if symbol <see paramref="symbol"/> has an attribute with name <see paramref="attributeName"/>.
		/// </summary>
		internal static bool HasAttribute (this ISymbol symbol, string attributeName)
		{
			foreach (var attr in symbol.GetAttributes ())
				if (attr.AttributeClass?.Name == attributeName)
					return true;
 
			return false;
		}
 
		internal static bool TryGetAttribute (this ISymbol member, string attributeName, [NotNullWhen (returnValue: true)] out AttributeData? attribute)
		{
			attribute = null;
			foreach (var attr in member.GetAttributes ()) {
				if (attr.AttributeClass is { } attrClass && attrClass.HasName (attributeName)) {
					attribute = attr;
					return true;
				}
			}
 
			return false;
		}
 
		internal static IEnumerable<AttributeData> GetAttributes (this ISymbol member, string attributeName)
		{
			foreach (var attr in member.GetAttributes ()) {
				if (attr.AttributeClass is { } attrClass && attrClass.HasName (attributeName))
					yield return attr;
			}
		}
 
		/// <summary>
		/// Gets DynamicallyAccessedMemberTypes for any DynamicallyAccessedMembers annotation on the symbol.
		/// This doesn't validate whether the annotation is valid based on the type of the annotated symbol.
		/// Use FlowAnnotations.Get*Annotation when getting annotations that are valid and should participate
		/// in dataflow analysis.
		/// </summary>
		internal static DynamicallyAccessedMemberTypes GetDynamicallyAccessedMemberTypes (this ISymbol symbol)
		{
			if (!TryGetAttribute (symbol, DynamicallyAccessedMembersAnalyzer.DynamicallyAccessedMembersAttribute, out var dynamicallyAccessedMembers))
				return DynamicallyAccessedMemberTypes.None;
 
			return (DynamicallyAccessedMemberTypes) dynamicallyAccessedMembers!.ConstructorArguments[0].Value!;
		}
 
		internal static DynamicallyAccessedMemberTypes GetDynamicallyAccessedMemberTypesOnReturnType (this IMethodSymbol methodSymbol)
		{
			AttributeData? dynamicallyAccessedMembers = null;
			foreach (var returnTypeAttribute in methodSymbol.GetReturnTypeAttributes ())
				if (returnTypeAttribute.AttributeClass is var attrClass && attrClass != null &&
					attrClass.HasName (DynamicallyAccessedMembersAnalyzer.DynamicallyAccessedMembersAttribute)) {
					dynamicallyAccessedMembers = returnTypeAttribute;
					break;
				}
 
			if (dynamicallyAccessedMembers == null)
				return DynamicallyAccessedMemberTypes.None;
 
			return (DynamicallyAccessedMemberTypes) dynamicallyAccessedMembers.ConstructorArguments[0].Value!;
		}
 
		internal static ValueSet<string> GetFeatureGuardAnnotations (this IPropertySymbol propertySymbol)
		{
			HashSet<string> featureSet = new ();
			foreach (var featureGuardAttribute in propertySymbol.GetAttributes (DynamicallyAccessedMembersAnalyzer.FullyQualifiedFeatureGuardAttribute)) {
				if (featureGuardAttribute.ConstructorArguments is [TypedConstant { Value: INamedTypeSymbol featureType }])
					featureSet.Add (featureType.GetDisplayName ());
			}
			return featureSet.Count == 0 ? ValueSet<string>.Empty : new ValueSet<string> (featureSet);
		}
 
		internal static bool TryGetReturnAttribute (this IMethodSymbol member, string attributeName, [NotNullWhen (returnValue: true)] out AttributeData? attribute)
		{
			attribute = null;
			foreach (var attr in member.GetReturnTypeAttributes ()) {
				if (attr.AttributeClass is { } attrClass && attrClass.HasName (attributeName)) {
					attribute = attr;
					return true;
				}
			}
 
			return false;
		}
 
		internal static DynamicallyAccessedMemberTypes GetDynamicallyAccessedMemberTypesOnAssociatedSymbol (this IMethodSymbol methodSymbol) =>
			methodSymbol.AssociatedSymbol is ISymbol associatedSymbol ? GetDynamicallyAccessedMemberTypes (associatedSymbol) : DynamicallyAccessedMemberTypes.None;
 
		internal static bool TryGetOverriddenMember (this ISymbol? symbol, [NotNullWhen (returnValue: true)] out ISymbol? overriddenMember)
		{
			overriddenMember = symbol switch {
				IMethodSymbol method => method.OverriddenMethod,
				IPropertySymbol property => property.OverriddenProperty,
				IEventSymbol @event => @event.OverriddenEvent,
				_ => null,
			};
			return overriddenMember != null;
		}
 
		public static SymbolDisplayFormat ILLinkTypeDisplayFormat { get; } =
			new SymbolDisplayFormat (
				typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypesAndNamespaces,
				genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters
			);
 
		public static SymbolDisplayFormat ILLinkMemberDisplayFormat { get; } =
			new SymbolDisplayFormat (
				typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameOnly,
				genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters,
				memberOptions:
					SymbolDisplayMemberOptions.IncludeParameters |
					SymbolDisplayMemberOptions.IncludeExplicitInterface,
				parameterOptions:
					SymbolDisplayParameterOptions.IncludeType |
					SymbolDisplayParameterOptions.IncludeParamsRefOut
			);
 
		public static string GetDisplayName (this ISymbol symbol)
		{
			var sb = new StringBuilder ();
			switch (symbol) {
			case IFieldSymbol fieldSymbol:
				sb.Append (fieldSymbol.ContainingSymbol.ToDisplayString (ILLinkTypeDisplayFormat));
				sb.Append ('.');
				sb.Append (fieldSymbol.MetadataName);
				break;
 
			case IParameterSymbol parameterSymbol:
				sb.Append (parameterSymbol.Name);
				break;
 
			case IMethodSymbol methodSymbol when methodSymbol.IsStaticConstructor ():
				sb.Append (symbol.ContainingType.ToDisplayString (ILLinkTypeDisplayFormat));
				sb.Append ("..cctor()");
				break;
 
			case IMethodSymbol methodSymbol:
				// Use definition type parameter names, not instance type parameters
				methodSymbol = methodSymbol.OriginalDefinition;
				// Format the declaring type with namespace and containing types.
				if (methodSymbol.ContainingSymbol?.Kind == SymbolKind.NamedType) {
					// If the containing symbol is a method (for example for local functions),
					// don't include the containing type's name. This matches the behavior of
					// CSharpErrorMessageFormat.
					sb.Append (methodSymbol.ContainingType.ToDisplayString (ILLinkTypeDisplayFormat));
					sb.Append ('.');
				}
				// Format parameter types with only type names.
				sb.Append (methodSymbol.ToDisplayString (ILLinkMemberDisplayFormat));
				break;
 
			default:
				sb.Append (symbol.ToDisplayString ());
				break;
			}
 
			return sb.ToString ();
		}
 
		public static bool IsInterface (this ISymbol symbol)
		{
			if (symbol is not INamedTypeSymbol namedTypeSymbol)
				return false;
 
			var typeSymbol = namedTypeSymbol as ITypeSymbol;
			return typeSymbol.TypeKind == TypeKind.Interface;
		}
 
		public static bool IsSubclassOf (this ISymbol symbol, string ns, string type)
		{
			if (symbol is not ITypeSymbol typeSymbol)
				return false;
 
			while (typeSymbol != null) {
				if (typeSymbol.IsTypeOf (ns, type))
					return true;
 
				typeSymbol = typeSymbol.ContainingType;
			}
 
			return false;
		}
 
		public static bool IsConstructor ([NotNullWhen (returnValue: true)] this ISymbol? symbol)
			=> (symbol as IMethodSymbol)?.MethodKind is MethodKind.Constructor or MethodKind.StaticConstructor;
 
		public static bool IsStaticConstructor ([NotNullWhen (returnValue: true)] this ISymbol? symbol)
			=> (symbol as IMethodSymbol)?.MethodKind == MethodKind.StaticConstructor;
 
		public static bool IsEntryPoint (this IMethodSymbol methodSymbol, Compilation compilation)
			=> methodSymbol.Name is WellKnownMemberNames.EntryPointMethodName or WellKnownMemberNames.TopLevelStatementsEntryPointMethodName &&
			   methodSymbol.IsStatic &&
			   (methodSymbol.ReturnsVoid ||
				methodSymbol.ReturnType.SpecialType == SpecialType.System_Int32 ||
				SymbolEqualityComparer.Default.Equals(methodSymbol.ReturnType.OriginalDefinition, compilation.TaskType()) ||
				SymbolEqualityComparer.Default.Equals(methodSymbol.ReturnType.OriginalDefinition, compilation.TaskOfTType()));
 
		public static bool IsUnmanagedCallersOnlyEntryPoint (this IMethodSymbol methodSymbol)
		{
			foreach (var attr in methodSymbol.GetAttributes ()) {
				if (attr.AttributeClass is { } attrClass && attrClass.HasName ("System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute")) {
					foreach (var namedArgument in attr.NamedArguments) {
						if (namedArgument.Key == "EntryPoint")
							return true;
					}
				}
			}
 
			return false;
		}
	}
}