using System;

namespace Spectre.Console.Cli;

/// <summary>
/// An attribute representing a command argument.
/// </summary>
/// <seealso cref="Attribute" />
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public sealed class CommandArgumentAttribute : Attribute
{
    /// <summary>
    /// Gets the argument position.
    /// </summary>
    /// <value>The argument position.</value>
    public int Position { get; }

    /// <summary>
    /// Gets the value name of the argument.
    /// </summary>
    /// <value>The value name of the argument.</value>
    public string ValueName { get; }

    /// <summary>
    /// Gets a value indicating whether the argument is required.
    /// </summary>
    /// <value>
    ///   <c>true</c> if the argument is required; otherwise, <c>false</c>.
    /// </value>
    public bool IsRequired { get; }

    /// <summary>
    /// Initializes a new instance of the <see cref="CommandArgumentAttribute"/> class.
    /// </summary>
    /// <param name="position">The argument position.</param>
    /// <param name="template">The argument template.</param>
    public CommandArgumentAttribute(int position, string template)
    {
        if (template == null)
        {
            throw new ArgumentNullException(nameof(template));
        }

        // Parse the option template.
        var result = TemplateParser.ParseArgumentTemplate(template);

        // Assign the result.
        Position = position;
        ValueName = result.Value;
        IsRequired = result.Required;
    }
}