EnvelopeGenerator/EnvelopeGenerator.API/Extensions/ReceiverClaimExtensions.cs

using DigitalData.Auth.Claims;
using Microsoft.IdentityModel.JsonWebTokens;
using System.Security.Claims;

namespace EnvelopeGenerator.API.Extensions;

/// <summary>
/// Provides helper methods for working with envelope-specific authentication claims.
/// </summary>
public static class ReceiverClaimExtensions
{
    /// <summary>
    /// 
    /// </summary>
    /// <param name="user"></param>
    /// <param name="claimType"></param>
    /// <returns></returns>
    /// <exception cref="InvalidOperationException"></exception>
    private static string GetRequiredClaimValue(this ClaimsPrincipal user, string claimType)
    {
        var value = user.FindFirstValue(claimType);
        if (value is not null)
        {
            return value;
        }

        var identity = user.Identity;
        var principalName = identity?.Name ?? "(anonymous)";
        var authType = identity?.AuthenticationType ?? "(none)";
        var availableClaims = string.Join(", ", user.Claims.Select(c => $"{c.Type}={c.Value}"));
        var message = $"Required claim '{claimType}' is missing for user '{principalName}' (auth: {authType}). Available claims: [{availableClaims}].";
        throw new InvalidOperationException(message);
    }

    private static string GetRequiredClaimValue(this ClaimsPrincipal user, params string[] claimTypes)
    {
        foreach (var claimType in claimTypes.Where(t => !string.IsNullOrWhiteSpace(t)).Distinct())
        {
            var value = user.FindFirstValue(claimType);
            if (!string.IsNullOrWhiteSpace(value))
                return value;
        }

        var identity = user.Identity;
        var principalName = identity?.Name ?? "(anonymous)";
        var authType = identity?.AuthenticationType ?? "(none)";
        var availableClaims = string.Join(", ", user.Claims.Select(c => $"{c.Type}={c.Value}"));
        var message = $"Required claim(s) '{string.Join("', '", claimTypes)}' are missing for user '{principalName}' (auth: {authType}). Available claims: [{availableClaims}].";
        throw new InvalidOperationException(message);
    }

    /// <summary>
    /// Gets the authenticated envelope UUID from the claims.
    /// </summary>
    public static string EnvelopeUuid(this ClaimsPrincipal user)
        => user.GetRequiredClaimValue(EnvelopeClaimNames.EnvelopeUuid);

    /// <summary>
    /// Gets the authenticated receiver signature from the claims.
    /// </summary>
    public static string ReceiverSignature(this ClaimsPrincipal user)
        => user.GetRequiredClaimValue(EnvelopeClaimNames.ReceiverSignature);

    /// <summary>
    /// Gets the authenticated receiver email address from the claims.
    /// </summary>
    public static string ReceiverMail(this ClaimsPrincipal user)
        => user.GetRequiredClaimValue(JwtRegisteredClaimNames.Email);

    /// <summary>
    /// Gets the authenticated envelope identifier from the claims.
    /// </summary>
    public static int EnvelopeId(this ClaimsPrincipal user)
    {
        var envIdStr = user.GetRequiredClaimValue(EnvelopeClaimNames.EnvelopeId);
        if (int.TryParse(envIdStr, out var envId))
            return envId;
        else
            throw new InvalidOperationException($"Claim '{EnvelopeClaimNames.EnvelopeId}' is not a valid integer.");
    }

    /// <summary>
    /// Gets the authenticated receiver identifier from the claims.
    /// </summary>
    /// <param name="user"></param>
    /// <returns></returns>
    /// <exception cref="InvalidOperationException"></exception>
    public static int ReceiverId(this ClaimsPrincipal user)
    {
        var rcvIdStr = user.GetRequiredClaimValue(EnvelopeClaimNames.ReceiverId);
        if (int.TryParse(rcvIdStr, out var rcvId))
            return rcvId;
        else
            throw new InvalidOperationException($"Claim '{EnvelopeClaimNames.ReceiverId}' is not a valid integer.");
    }
}