// 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.

namespace Microsoft.CodeAnalysis.ChangeSignature;

/// <summary>
/// Base type for Parameter information, whether the parameter
/// is preexisting or new.
/// </summary>
internal abstract class Parameter
{
    public abstract bool HasDefaultValue { get; }
    public abstract string Name { get; }
}

internal sealed class ExistingParameter(IParameterSymbol param) : Parameter
{
    public IParameterSymbol Symbol { get; } = param;

    public override bool HasDefaultValue => Symbol.HasExplicitDefaultValue;
    public override string Name => Symbol.Name;
}

internal sealed class AddedParameter : Parameter
{
    public AddedParameter(
        ITypeSymbol type,
        string typeName,
        string name,
        CallSiteKind callSiteKind,
        string callSiteValue = "",
        bool isRequired = true,
        string defaultValue = "",
        bool typeBinds = true)
    {
        Type = type;
        TypeBinds = typeBinds;
        TypeName = typeName;
        Name = name;
        CallSiteValue = callSiteValue;

        IsRequired = isRequired;
        DefaultValue = defaultValue;
        CallSiteKind = callSiteKind;

        // Populate the call site text for the UI
        switch (CallSiteKind)
        {
            case CallSiteKind.Value:
            case CallSiteKind.ValueWithName:
                CallSiteValue = callSiteValue;
                break;
            case CallSiteKind.Todo:
                CallSiteValue = FeaturesResources.ChangeSignature_NewParameterIntroduceTODOVariable;
                break;
            case CallSiteKind.Omitted:
                CallSiteValue = FeaturesResources.ChangeSignature_NewParameterOmitValue;
                break;
            case CallSiteKind.Inferred:
                CallSiteValue = FeaturesResources.ChangeSignature_NewParameterInferValue;
                break;
            default:
                throw ExceptionUtilities.Unreachable();
        }
    }

    public override string Name { get; }
    public override bool HasDefaultValue => !string.IsNullOrWhiteSpace(DefaultValue);

    public ITypeSymbol Type { get; }
    public string TypeName { get; }
    public bool TypeBinds { get; }

    public CallSiteKind CallSiteKind { get; }

    /// <summary>
    /// Display string for the Call Site column in the Change Signature dialog.
    /// </summary>
    public string CallSiteValue { get; }

    /// <summary>
    /// True if required, false if optional with a default value.
    /// </summary>
    public bool IsRequired { get; }

    /// <summary>
    /// Value to use in the declaration of an optional parameter.
    /// E.g. the "3" in M(int x = 3);
    /// </summary>
    public string DefaultValue { get; }

    // For test purposes: to display assert failure details in tests.
    public override string ToString() => $"{Type.ToDisplayString(new SymbolDisplayFormat(genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters))} {Name} ({CallSiteValue})";
}