Program.cs

using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Azure.Storage.Blobs;
using Azure;
using Azure.AI.OpenAI;
using System.Threading.RateLimiting;
using Polly;


using Code_Scanner.HelperClasses;
using Code_Scanner.Activities;

var builder = FunctionsApplication.CreateBuilder(args);
builder.ConfigureFunctionsWebApplication();


builder.Services.AddSingleton<BlobServiceClient>(sp =>
{
    string? connectionString = builder.Configuration["AzureBlobStorageConnectionString"];
    return new BlobServiceClient(connectionString);
});

builder.Services.AddSingleton<AzureOpenAIClient>(sp =>
{
    string endpoint = builder.Configuration["AzureOpenAIEndpoint"]!;
    string apiKey = builder.Configuration["AzureOpenAIKey"]!;

    return new AzureOpenAIClient(new Uri(endpoint), new AzureKeyCredential(apiKey));
});

builder.Services.AddResiliencePipeline("OpenAiPipeline", pipelineBuilder =>
{
    pipelineBuilder
        // 1. EXPONENTIAL BACKOFF (Handles rate-limit errors like HTTP 429)
        .AddRetry(new()
        {
            ShouldHandle = new PredicateBuilder().Handle<RequestFailedException>(ex => ex.Status == 429),
            MaxRetryAttempts = 4,
            BackoffType = DelayBackoffType.Exponential,
            Delay = TimeSpan.FromSeconds(2), // Initial delay
            UseJitter = true // Prevents synchronized retries
        })
        // 2. RATE LIMITING / THROTTLING (Prevents hitting Azure limits proactively)
        .AddRateLimiter(new TokenBucketRateLimiter(new()
        {
            TokenLimit = 10,                // Maximum burst capacity
            QueueLimit = 20,                // How many requests can wait in line
            QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
            ReplenishmentPeriod = TimeSpan.FromSeconds(60), // Refill cadence
            TokensPerPeriod = 10     // Number of tokens refilled
        }));
});

builder.Services.AddScoped<CallOpenAi>();
builder.Services.AddScoped<PromptFA>();
builder.Services.AddSingleton<MasterResultBuilder>();
builder.Services.AddSingleton<DeleteFolder>();
builder.Services.AddScoped<CodeFileFormatBuilder>();

await builder.Build().RunAsync();