Program.cs

using System.Text.Json;
using System.Net.Http.Headers;
using System.Net.Http.Json;

namespace CherryServersTrafficBuyer
{
    internal class Program
    {
        static string? apiKey = Environment.GetEnvironmentVariable("API_KEY");
        static string? projectId = Environment.GetEnvironmentVariable("PROJECT_ID");

        static string? trafficThresholdPercentString = Environment.GetEnvironmentVariable("TRAFFIC_THRESHOLD_PERCENT");
        static int trafficThresholdPercent;

        static string? refreshIntervalMinutesString = Environment.GetEnvironmentVariable("REFRESH_INTERVAL_MINUTES");
        static int refreshIntervalMinutes;

        const string retrieveProjectTrafficUrl = "https://api.cherryservers.com/v1/projects/{projectId}/traffic";
        const string requestMoreTrafficUrl = "https://api.cherryservers.com/v1/traffic/{trafficId}";

        static async Task Main(string[] args)
        {
            #region Validate and parse environment variables
            if (apiKey == null)
            {
                Console.WriteLine("[FATAL]: No API key provided! You must provide an API key with the \"API_KEY\" environment variable!");
                return;
            }

            if (projectId == null)
            {
                Console.WriteLine("[FATAL]: No project ID provided! You must provide a project ID with the \"PROJECT_ID\" environment variable!");
                return;
            }

            if (trafficThresholdPercentString != null)
            {
                try
                {
                    trafficThresholdPercent = Convert.ToInt32(trafficThresholdPercentString);
                }
                catch
                {
                    Console.WriteLine("[ERROR]: Unable to parse \"TRAFFIC_THRESHOLD_PERCENT\" environment variable! Defaulting to 90 percent.");
                    trafficThresholdPercent = 90;
                }
            }
            else
            {
                Console.WriteLine("[INFO]: \"TRAFFIC_THRESHOLD_PERCENT\" environment variable not provided. Defaulting to 90 percent.");
                trafficThresholdPercent = 90;
            }

            if(trafficThresholdPercent < 1 || trafficThresholdPercent > 100)
            {
                Console.WriteLine("[ERROR]: \"TRAFFIC_THRESHOLD_PERCENT\" environment variable not in valid range (expected: 1-100, actual: {0}). Defaulting to 90 percent.", trafficThresholdPercent);
                trafficThresholdPercent = 90;
            }

            if (refreshIntervalMinutesString != null)
            {
                try
                {
                    refreshIntervalMinutes = Convert.ToInt32(refreshIntervalMinutesString);
                }
                catch
                {
                    Console.WriteLine("[ERROR]: Unable to parse \"REFRESH_INTERVAL_MINUTES\" environment variable! Defaulting to 65 minutes.");
                    refreshIntervalMinutes = 65;
                }
            }
            else
            {
                Console.WriteLine("[INFO]: \"REFRESH_INTERVAL_MINUTES\" environment variable not provided. Defaulting to 65 minutes.");
                refreshIntervalMinutes = 65;
            }


            if (refreshIntervalMinutes < 1)
            {
                Console.WriteLine("[ERROR]: \"REFRESH_INTERVAL_MINUTES\" environment variable not in valid range (expected: 1 or greater, actual: {0}). Defaulting to 65 minutes.", refreshIntervalMinutes);
                refreshIntervalMinutes = 65;
            }
            #endregion

            var client = new HttpClient();
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);

            var saveTimer = new PeriodicTimer(TimeSpan.FromMinutes(refreshIntervalMinutes));

            do
            {
                Console.WriteLine("[INFO]: Refreshing...");

                var retrieveProjectTrafficRequest = new HttpRequestMessage(HttpMethod.Get,
                    retrieveProjectTrafficUrl.Replace("{projectId}", projectId));

                var retrieveProjectTrafficResponse = await client.SendAsync(retrieveProjectTrafficRequest);

                string retrieveProjectTrafficResult = await retrieveProjectTrafficResponse.Content.ReadAsStringAsync();

                if (!retrieveProjectTrafficResponse.IsSuccessStatusCode)
                {
                    Console.WriteLine("[ERROR]: Retrieve Project Traffic request failed with code {0}", retrieveProjectTrafficResponse.StatusCode);
                    Console.WriteLine(retrieveProjectTrafficResult);
                    continue;
                }

                var retrieveProjectTrafficResultsObjects = JsonSerializer.Deserialize<RetrieveProjectTrafficResponseObject[]>(retrieveProjectTrafficResult);

                if (retrieveProjectTrafficResultsObjects == null)
                {
                    Console.WriteLine("[ERROR]: Unable to deserialize response from Retrieve Project Traffic endpoint!");
                    continue;
                }

                foreach (var resultsObject in retrieveProjectTrafficResultsObjects)
                {
                    //Check for valid entry
                    if (resultsObject == null || resultsObject.id == null || resultsObject.limited_bytes == null || resultsObject.used_bytes == null || resultsObject.limited_bytes == 0 || resultsObject.used_bytes == 0)
                        continue;

                    double percentUsed = Math.Round(((double)resultsObject.used_bytes / (double)resultsObject.limited_bytes) * 100, 1);

                    Console.WriteLine("[INFO]: ID: {0} is at {1} bytes used out of {2} bytes available ({3}%)",
                        resultsObject.id, resultsObject.used_bytes, resultsObject.limited_bytes, percentUsed);


                    if (percentUsed >= trafficThresholdPercent)
                    {
                        Console.WriteLine("[INFO]: Requesting more traffic...");

                        var requestMoreTrafficRequest = new HttpRequestMessage(HttpMethod.Patch,
                            requestMoreTrafficUrl.Replace("{trafficId}", resultsObject.id));

                        requestMoreTrafficRequest.Content = JsonContent.Create(new
                        {
                            adjust = 1
                        });

                        var requestMoreTrafficResponse = await client.SendAsync(requestMoreTrafficRequest);

                        string requestMoreTrafficResult = await requestMoreTrafficResponse.Content.ReadAsStringAsync();

                        if (requestMoreTrafficResponse.IsSuccessStatusCode)
                            Console.WriteLine("[INFO]: Successfully bought more traffic for ID: {0}", resultsObject.id);
                        else
                        {
                            Console.WriteLine("[ERROR]: Unable to buy more traffic!");
                            Console.WriteLine(requestMoreTrafficResult);
                        }
                    }
                }
            } while (await saveTimer.WaitForNextTickAsync());

            client.Dispose();
        }
    }
}

class RetrieveProjectTrafficResponseObject
{
    public string? id { get; set; }
    public long? used_bytes { get; set; }
    public long? limited_bytes { get; set; }
}