protected override string BuildChallengeUrl()

in src/JetBrains.Space.AspNetCore.Authentication/SpaceHandler.cs [66:101]
28 lines of code
3 McCabe index (conditional complexity)

    protected override string BuildChallengeUrl(AuthenticationProperties properties, string redirectUri)
    {
        var scopeParameter = properties.GetParameter<ICollection<string>>(OAuthChallengeProperties.ScopeKey);
        var scope = scopeParameter != null ? FormatScope(scopeParameter) : FormatScope();

        var parameters = new Dictionary<string, string?>
        {
            { "client_id", Options.ClientId },
            { "scope", scope },
            { "response_type", "code" },
            { "redirect_uri", redirectUri },
            { "request_credentials", Options.RequestCredentials.ToEnumString() },
            { "access_type", Options.AccessType.ToEnumString() }
        };

        if (Options.UsePkce)
        {
            var bytes = new byte[32];
            CryptoRandom.GetBytes(bytes);
            var codeVerifier = Base64UrlTextEncoder.Encode(bytes);

            // Store this for use during the code redemption.
            properties.Items.Add(OAuthConstants.CodeVerifierKey, codeVerifier);

            using var sha256 = SHA256.Create();
            var challengeBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(codeVerifier));
            var codeChallenge = WebEncoders.Base64UrlEncode(challengeBytes);

            parameters[OAuthConstants.CodeChallengeKey] = codeChallenge;
            parameters[OAuthConstants.CodeChallengeMethodKey] = OAuthConstants.CodeChallengeMethodS256;
        }

        parameters["state"] = Options.StateDataFormat.Protect(properties);

        return QueryHelpers.AddQueryString(Options.AuthorizationEndpoint, parameters);
    }