// 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.Generic;
using System.Diagnostics;
using ILLink.RoslynAnalyzer.DataFlow;
using ILLink.Shared.TrimAnalysis;
using Microsoft.CodeAnalysis;
 
namespace ILLink.RoslynAnalyzer.TrimAnalysis
{
	public readonly record struct TrimAnalysisGenericInstantiationPattern
	{
		public ISymbol GenericInstantiation { get; init; }
		public IOperation Operation { get; init; }
		public ISymbol OwningSymbol { get; init; }
		public FeatureContext FeatureContext { get; init; }
 
		public TrimAnalysisGenericInstantiationPattern (
			ISymbol genericInstantiation,
			IOperation operation,
			ISymbol owningSymbol,
			FeatureContext featureContext)
		{
			GenericInstantiation = genericInstantiation;
			Operation = operation;
			OwningSymbol = owningSymbol;
			FeatureContext = featureContext.DeepCopy ();
		}
 
		public TrimAnalysisGenericInstantiationPattern Merge (
			FeatureContextLattice featureContextLattice,
			TrimAnalysisGenericInstantiationPattern other)
		{
			Debug.Assert (Operation == other.Operation);
			Debug.Assert (SymbolEqualityComparer.Default.Equals (GenericInstantiation, other.GenericInstantiation));
			Debug.Assert (SymbolEqualityComparer.Default.Equals (OwningSymbol, other.OwningSymbol));
 
			return new TrimAnalysisGenericInstantiationPattern (
				GenericInstantiation,
				Operation,
				OwningSymbol,
				featureContextLattice.Meet (FeatureContext, other.FeatureContext));
		}
 
		public IEnumerable<Diagnostic> CollectDiagnostics (DataFlowAnalyzerContext context)
		{
			DiagnosticContext diagnosticContext = new (Operation.Syntax.GetLocation ());
			if (context.EnableTrimAnalyzer &&
				!OwningSymbol.IsInRequiresUnreferencedCodeAttributeScope (out _) &&
				!FeatureContext.IsEnabled (RequiresUnreferencedCodeAnalyzer.FullyQualifiedRequiresUnreferencedCodeAttribute)) {
				switch (GenericInstantiation) {
				case INamedTypeSymbol type:
					GenericArgumentDataFlow.ProcessGenericArgumentDataFlow (diagnosticContext, type);
					break;
 
				case IMethodSymbol method:
					GenericArgumentDataFlow.ProcessGenericArgumentDataFlow (diagnosticContext, method);
					break;
 
				case IFieldSymbol field:
					GenericArgumentDataFlow.ProcessGenericArgumentDataFlow (diagnosticContext, field);
					break;
				}
			}
 
			return diagnosticContext.Diagnostics;
		}
	}
}