namespace Microsoft.Maui.Controls.BindingSourceGen;
using static Microsoft.Maui.Controls.BindingSourceGen.UnsafeAccessorsMethodName;
 
public sealed record Setter(string[] PatternMatchingExpressions, string AssignmentStatement)
{
	public static Setter From(
		IEnumerable<IPathPart> path,
		uint bindingId,
		string sourceVariableName = "source",
		string assignedValueExpression = "value")
	{
		string accessAccumulator = sourceVariableName;
		List<string> patternMatchingExpressions = new();
		bool skipNextConditionalAccess = false;
 
		void AddPatternMatchingExpression(string pattern)
		{
			var tmpVariableName = $"p{patternMatchingExpressions.Count}";
			patternMatchingExpressions.Add($"{accessAccumulator} is {pattern} {tmpVariableName}");
			accessAccumulator = tmpVariableName;
		}
 
		foreach (var part in path)
		{
			var skipConditionalAccess = skipNextConditionalAccess;
			skipNextConditionalAccess = false;
 
			if (part is Cast { TargetType: var targetType })
			{
				AddPatternMatchingExpression(targetType.GlobalName);
 
				// the current `is T` expression makes sure that the value is not null
				// so if a conditional access to a member/indexer follows, we can skip the next null check
				skipNextConditionalAccess = true;
			}
			else if (part is ConditionalAccess { Part: var innerPart })
			{
				if (!skipConditionalAccess)
				{
					AddPatternMatchingExpression("{}");
				}
 
				accessAccumulator = AccessExpressionBuilder.ExtendExpression(accessAccumulator, innerPart, bindingId);
			}
			else
			{
				accessAccumulator = AccessExpressionBuilder.ExtendExpression(accessAccumulator, part, bindingId, part == path.Last());
			}
		}
 
		return new Setter(
			patternMatchingExpressions.ToArray(),
			AssignmentStatement: BuildAssignmentStatement(accessAccumulator, path.Any() ? path.Last() : null, bindingId, assignedValueExpression));
	}
 
	public static string BuildAssignmentStatement(string accessAccumulator, IPathPart? lastPart, uint bindingId, string assignedValueExpression = "value") =>
		lastPart switch
		{
			InaccessibleMemberAccess inaccessibleMemberAccess when inaccessibleMemberAccess.Kind == AccessorKind.Property => $"{CreateUnsafePropertyAccessorSetMethodName(bindingId, inaccessibleMemberAccess.MemberName)}({accessAccumulator}, {assignedValueExpression});",
			_ => $"{accessAccumulator} = {assignedValueExpression};",
		};
}