Web - AI Based Regex Generator

Problem Statement: 

I want to dynamically generate RegEx based on human provided input with simple .Net, C# web application. 

Implementation:

- Create web application using .Net C#, Web API

- As prerequisite need to get the Open AI Service details. If it's not already exists follow this

• Go to Portal.Azure.Com
• Search for Azure OpenAI 
  
  
  
  
  
• Create new Open AI and click to go to Azure AI Foundry
• In Azure AI Foundry, Left side click Home. This is your Open AI API Key to use in code below
• In Azure AI Foundry, Left side click PlayGrounds/Chat, you should be able to setup new Chatbot with new deployment model (For ex: GPT3.5Turbo, GPT5 etc,.). This is your Deployment Model Name to use in code below.
• Click the View Code on Chat, to get the Endpoint details. This is your Chat Completion Endpoint to use in code below.
  
  
  
  
  
  

- In index.cshtml, simply add textbox and post call
  

<h2>Balaji - AI-Powered Regex Validator - POC</h2>

<form method="post">

    <label for="rule">Enter validation rule (human text):</label><br />

    <input type="text" id="rule" name="Rule" value="@Model.Rule" size="50" /><br /><br />

     <button type="submit">Generate Regex</button><br /><br />

     @if (!string.IsNullOrEmpty(Model.GeneratedRegex))

    {

        <div><strong>Generated Regex:</strong> @Model.GeneratedRegex</div>

         <br />

        <label for="inputText">Enter text to validate:</label>

        <br />

        <input type="text" id="inputText" name="InputText" value="@Model.InputText" size="50" />

         <br />

         <br />

        <div id="result">@Model.ValidationResult</div>

    }

</form>

 - In Index.cshtml.cs, add below logic to generate the validation from AI code. 

using Microsoft.AspNetCore.Mvc;

using Microsoft.AspNetCore.Mvc.RazorPages;

using System.Net.Http;

using System.Text;

using System.Text.Json;

using System.Threading.Tasks;

 

namespace POCRegexBuilderAI.Pages

{

    public class IndexModel : PageModel

    {

        [BindProperty]

        public string Rule { get; set; }

        [BindProperty]

        public string InputText { get; set; }

        public string GeneratedRegex { get; set; }

        public string ValidationResult { get; set; }

 

        public async Task<IActionResult> OnPostAsync()

        {

            if (!string.IsNullOrEmpty(Rule))

            {

                // Call OpenAI API to generate regex

                var regex = await GenerateRegexFromRule(Rule);

                GeneratedRegex = regex;

 

                if (!string.IsNullOrEmpty(InputText) && !string.IsNullOrEmpty(regex))

                {

                    try

                    {

                        var isValid = System.Text.RegularExpressions.Regex.IsMatch(InputText, regex);

                        ValidationResult = isValid ? "✅ Valid input" : "❌ Invalid input";

                    }

                    catch

                    {

                        ValidationResult = "⚠️ Invalid regex pattern.";

                    }

                }

            }

             return Page();

        }

        private async Task<string> GenerateRegexFromRule(string rule)

        {

            var apiKey = "1.ReplaceYourOpenAIKey";

            var prompt = $"Convert this rule to regex: {rule}";

            var requestBody = new

            {

                model = "gpt-35-turbo", //2.Replace with your deployment model

                messages = new[]

                {

                new { role = "user", content = prompt }

            }

            };

             using var client = new HttpClient();

            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {apiKey}");

             var chatCompletionUrl = "https://api.openai.com/v1/chat/completions";//3.Replace with your chatmodel endpoint

             var content = new StringContent(JsonSerializer.Serialize(requestBody), Encoding.UTF8, "application/json");

            var response = await client.PostAsync(chatCompletionUrl, content);

            var responseString = await response.Content.ReadAsStringAsync();

 

            using var doc = JsonDocument.Parse(responseString);

            var regex = doc.RootElement.GetProperty("choices")[0].GetProperty("message").GetProperty("content").GetString();

             return regex.Trim();

        }

     }

}

 

- Now simply try with human text ("Zipcode with alphabet numeric with Min 3 and Max 5 character") to convert into Regex to apply in any textbox UI as output. It will show the validation simply as below

Azure AD SAML SSO for Web Application

Requirement:

External vendor having SAML based app registered in their Azure AD and wanted to do SSO from web application.


Prerequisites:

- Create a SAML app in Azure AD and then provide us the Metadata, EntityId details. (This usually would be done by external vendor side, we can mock ourside to test internally)

- Will use SustainSys library for SAML setup in C#. Refer: https://saml2.sustainsys.com/en/v2/

- Web application with .Net Core, C#, Razor

Implementation Steps:

- Create SAML App in Azure AD (For mock test). Go to Entra Id -> Enterprise applications -> Add New Application -> Create Your Own Application -> Provide Some App Name + Choose "Integrate any other application you don't find in the gallery (Non-gallery)"

- Go to your web project, add Sustainsys.Saml2.AspNetCore2 from Nuget. 

- Update the startup to include SAML2 steps, something like below

using Microsoft.AspNetCore.Authentication.Cookies;

using Sustainsys.Saml2;

using Sustainsys.Saml2.AspNetCore2;

using Sustainsys.Saml2.Metadata;

          .....

builder.Services.AddAuthentication(opt =>

{

    // Default scheme that maintains session is cookies.

    opt.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;

 

    // If there's a challenge to sign in, use the Saml2 scheme.

    opt.DefaultChallengeScheme = Saml2Defaults.Scheme;

})

.AddCookie()

.AddSaml2(opt =>

{

    // Set up our EntityId, this is our application.

    opt.SPOptions.EntityId = new EntityId("YourAppName"); //This would be the External AD SAML App's Identifier (Entity ID)

 

    opt.IdentityProviders.Add(

        new IdentityProvider(

            new EntityId("SamlAppIdentiferURL"), //Saml App's Microsoft Entra Identifier

            opt.SPOptions)

        {

            MetadataLocation = "SamlAppMetadataUrl", //Saml App's Meatadata Url

            LoadMetadata = true

        });

});

 

- Now we can initiate the Challenge in code 

var props = new AuthenticationProperties

 {

     RedirectUri = "/"

 };

 return Challenge(props, Saml2Defaults.Scheme); 

//You can set some different default scheme in startup and change in runtime here too

- Read the claims as below

  var authResult = await HttpContext.AuthenticateAsync();

  Properties = authResult.Properties!.Items;

  Claims = authResult.Principal!.Claims;

Read B2C Token from Razor MVC Application

 To Retrieve B2C logged in users token for delegate permissions, follow below steps,

Add below lines in startup,

// Configuration to sign-in users with Azure AD B2C

   services.AddMicrosoftIdentityWebAppAuthentication(Configuration, Constants.AzureAdB2C).

        EnableTokenAcquisitionToCallDownstreamApi(new string[] { "https://graph.microsoft.com/.default" })

       .AddInMemoryTokenCaches();

services.Configure<OpenIdConnectOptions>(OpenIdConnectDefaults.AuthenticationScheme, options =>

{

    options.TokenValidationParameters = new TokenValidationParameters

    {

        ValidAudience = "https://graph.microsoft.com"

    };

    options.SaveTokens = true;

});

 

services.Configure<ConfidentialClientApplicationOptions>(options =>

{

    options.ClientSecret = Configuration["AzureAdB2C:ClientSecret"];

});

 

services.ConfigureApplicationCookie(options =>

{

    options.Cookie.SameSite = SameSiteMode.None;

    options.Cookie.SecurePolicy = CookieSecurePolicy.Always;

});

 

Now retrieve token from Controller with below syntax,

    HttpContext.GetTokenAsync("access_token").Result

    or

    HttpContext.GetTokenAsync("id_token").Result