using System.Security.Claims;

namespace Shogi.Api.Extensions;

public static class ClaimsExtensions
{
	private static readonly string MsalUsernameClaim = "preferred_username";

	public static string? GetGuestUserId(this ClaimsPrincipal self)
	{
		return self.Claims.FirstOrDefault(c => c.Type == ClaimTypes.NameIdentifier)?.Value;
	}

	public static string? DisplayName(this ClaimsPrincipal self)
	{
		return self.Claims.FirstOrDefault(c => c.Type == ClaimTypes.Name)?.Value;
	}

	public static bool IsMicrosoft(this ClaimsPrincipal self)
	{
		return self.HasClaim(c => c.Type == MsalUsernameClaim);
	}

	public static string? GetMicrosoftUserId(this ClaimsPrincipal self)
	{
		return self.Claims.FirstOrDefault(c => c.Type == MsalUsernameClaim)?.Value;
	}

	/// <summary>
	/// Reads the userId from claims after claims transformation has occurred.
	/// Throws if a shogi userid is not found.
	/// </summary>
	/// <exception cref="InvalidOperationException"></exception>
	public static string GetShogiUserId(this ClaimsPrincipal self)
	{
		var id = self.IsMicrosoft() ? self.GetMicrosoftUserId() : self.GetGuestUserId();
		
		if (string.IsNullOrEmpty(id)) throw new InvalidOperationException("Shogi UserId not found in claims.");

		return id;
	}
}