using System.Collections.Generic;

namespace Microsoft.CodeAnalysis.CSharp;

internal sealed class DefinitelyAssignedWalker : AbstractRegionDataFlowPass
{
	private readonly HashSet<Symbol> _definitelyAssignedOnEntry = new HashSet<Symbol>();

	private readonly HashSet<Symbol> _definitelyAssignedOnExit = new HashSet<Symbol>();

	private DefinitelyAssignedWalker(CSharpCompilation compilation, Symbol member, BoundNode node, BoundNode firstInRegion, BoundNode lastInRegion)
		: base(compilation, member, node, firstInRegion, lastInRegion)
	{
	}

	internal static (HashSet<Symbol> entry, HashSet<Symbol> exit) Analyze(CSharpCompilation compilation, Symbol member, BoundNode node, BoundNode firstInRegion, BoundNode lastInRegion)
	{
		DefinitelyAssignedWalker definitelyAssignedWalker = new DefinitelyAssignedWalker(compilation, member, node, firstInRegion, lastInRegion);
		try
		{
			bool badRegion = false;
			definitelyAssignedWalker.Analyze(ref badRegion, null);
			return badRegion ? (entry: new HashSet<Symbol>(), exit: new HashSet<Symbol>()) : (entry: definitelyAssignedWalker._definitelyAssignedOnEntry, exit: definitelyAssignedWalker._definitelyAssignedOnExit);
		}
		finally
		{
			definitelyAssignedWalker.Free();
		}
	}

	protected override void EnterRegion()
	{
		ProcessRegion(_definitelyAssignedOnEntry);
		base.EnterRegion();
	}

	protected override void LeaveRegion()
	{
		ProcessRegion(_definitelyAssignedOnExit);
		base.LeaveRegion();
	}

	private void ProcessRegion(HashSet<Symbol> definitelyAssigned)
	{
		definitelyAssigned.Clear();
		if (IsConditionalState)
		{
			ProcessState(definitelyAssigned, StateWhenTrue, StateWhenFalse);
		}
		else
		{
			ProcessState(definitelyAssigned, State, null);
		}
	}

	private void ProcessState(HashSet<Symbol> definitelyAssigned, LocalState state1, LocalState? state2opt)
	{
		//IL_005d: Unknown result type (might be due to invalid IL or missing references)
		//IL_0063: Invalid comparison between Unknown and I4
		foreach (int item in ((BitVector)(ref state1.Assigned)).TrueBits())
		{
			if (item < variableBySlot.Count && (!state2opt.HasValue || state2opt.GetValueOrDefault().IsAssigned(item)))
			{
				Symbol symbol = variableBySlot[item].Symbol;
				if ((object)symbol != null && (int)symbol.Kind != 6)
				{
					definitelyAssigned.Add(symbol);
				}
			}
		}
	}
}