aswi2022bug-thugs-gitlab/ld_client/LDClient/detection/ProcessDetection.cs @ d49f4d79

using System.Diagnostics;
using LDClient.network;
using LDClient.network.data;

namespace LDClient.detection {

    /// <summary>
    /// This class takes care of process detection. When t32mtc (process)
    /// is detected, it means that the debugger is currently being used.
    /// The class keeps track of the current state of a debugger.
    /// </summary>
    public sealed class ProcessDetection : IProcessDetection {

        /// <summary>
        /// Datetime format used when sending payloads to the server.
        /// </summary>
        private const string DatetimeFormat = "yyyy-MM-dd hh:mm:ss";

        /// <summary>
        /// Name of the process the application detects.
        /// </summary>
        private readonly string _processName;
        
        /// <summary>
        /// How often the application check the current status of the process (cunning / not running).
        /// </summary>
        private readonly uint _detectionPeriodMs;
        
        /// <summary>
        /// Instance of InfoFetcher used to fetch information from the debugger
        /// (when the process is detected).
        /// </summary>
        private readonly IInfoFetcher _infoFetcher;
        
        /// <summary>
        /// Instance of API clients used for sending data off to the server.
        /// </summary>
        private readonly IApiClient _apiClient;
        
        /// <summary>
        /// Instance of ProcessUtils which encapsulates common functionality
        /// when it comes to dealing with processes (limited by the needs of this application).
        /// </summary>
        private readonly IProcessUtils _processUtils;

        /// <summary>
        /// Flag indicating whether the process is currently running or not.
        /// </summary>
        private bool _processIsActive;
        
        /// <summary>
        /// Flag if the application failed to retrieve data when the process was detected.
        /// </summary>
        private bool _failedToRetrieveData;
        
        /// <summary>
        /// Last payload that was sent to the server.
        /// </summary>
        private Payload? _lastConnectedPayload;

        /// <summary>
        /// Flag used to stop the thread (process detection).
        /// </summary>
        public bool DetectionRunning = false;
        
        /// <summary>
        /// Creates an instance of this class.
        /// </summary>
        /// <param name="processName">Name of the process the application detects</param>
        /// <param name="detectionPeriodMs">How often the application check the current status of the process (cunning / not running)</param>
        /// <param name="infoFetcher">Instance of InfoFetcher used to fetch information from the debugger</param>
        /// <param name="apiClient">Instance of API clients used for sending data off to the server</param>
        /// <param name="processUtils">Instance of ProcessUtils which encapsulates common functionality when it comes to dealing with processes (limited by the needs of this application)</param>
        public ProcessDetection(string processName, uint detectionPeriodMs, IInfoFetcher infoFetcher,
            IApiClient apiClient, IProcessUtils processUtils) {
            _processName = processName;
            _detectionPeriodMs = detectionPeriodMs;
            _infoFetcher = infoFetcher;
            _apiClient = apiClient;
            _failedToRetrieveData = false;
            _processUtils = processUtils;
        }

        /// <summary>
        /// Retrieves data from the debugger.
        /// </summary>
        /// <returns>True, if the data was fetched successfully. False, otherwise.</returns>
        private async Task<bool> RetrieveDataFromDebugger() {
            // Try to fetch data from the debugger.
            var success = await _infoFetcher.FetchDataAsync();
            
            // If the data was fetched successfully, send a payload off to the server.
            if (success) {
                _lastConnectedPayload = await SendDataToServerAsync(_infoFetcher.HeadSerialNumber,
                    _infoFetcher.BodySerialNumber, DatetimeFormat);
            }
            return success;
        }

        /// <summary>
        /// Sends a payload to the server when a debugger gets disconnected.
        /// </summary>
        private async Task DebuggerDisconnected() {
            // Make sure the debugger was connected in the first place.
            if (_lastConnectedPayload is not null) {
                // Update the status and timestamp of the last payload
                // (the serial numbers remain the same).
                _lastConnectedPayload.Status = ConnectionStatus.Disconnected;
                _lastConnectedPayload.TimeStamp = DateTime.Now.ToString(DatetimeFormat);
                
                // Send the data to the server.
                await _apiClient.SendPayloadAsync(_lastConnectedPayload);
                
                // Clear the last payload.
                _lastConnectedPayload = null;
            }
        }

        /// <summary>
        /// Checks if the t32mtc process is running or not. 
        /// </summary>
        private async Task DetectProcessAsync() {
            // Check if the process is running.
            var processExists = _processUtils.IsProcessRunning(_processName);

            // Check if the process was not running but now it is (flip flop ON). 
            if (processExists && !_processIsActive) {
                Program.DefaultLogger.Info($"Process started: {_processName}");
                if (!_failedToRetrieveData) {
                    _failedToRetrieveData = !await RetrieveDataFromDebugger();
                }
            }
            // Check if the process was running but now it is not (fli flop OFF).
            else if (!processExists && _processIsActive) {
                Program.DefaultLogger.Info($"Process stopped: {_processName}");
                _failedToRetrieveData = false;
                await DebuggerDisconnected();
            }

            // Keep track of the current state of the debugger.
            _processIsActive = processExists;
        }

        /// <summary>
        /// Creates a payload and sends it to the server.
        /// </summary>
        /// <param name="headSerialNumber">serial number of the head of the debugger</param>
        /// <param name="bodySerialNumber">serial number of the body of the debugger</param>
        /// <param name="datetimeFormat">datetime format (timestamp)</param>
        /// <returns>the newly-created payload</returns>
        private async Task<Payload> SendDataToServerAsync(string headSerialNumber, string bodySerialNumber, string datetimeFormat) {
            // Create a new payload. 
            Payload payload = new() {
                UserName = Environment.UserName,
                HostName = Environment.MachineName,
                TimeStamp = DateTime.Now.ToString(datetimeFormat),
                HeadDevice = new DebuggerInfo {
                    SerialNumber = headSerialNumber
                },
                BodyDevice = new DebuggerInfo {
                    SerialNumber = bodySerialNumber
                },
                Status = ConnectionStatus.Connected
            };
            
            // Send it to the server and return it.
            await _apiClient.SendPayloadAsync(payload);
            return payload;
        }

        /// <summary>
        /// Periodically runs process detection. This method is instantiated
        /// as a thread from the main class (Program.cs).
        /// </summary>
        public async void RunPeriodicDetection() {
            Program.DefaultLogger.Info("Process periodic detector has started");
            DetectionRunning = true;
            
            while (DetectionRunning) {
                await DetectProcessAsync();
                Thread.Sleep((int) _detectionPeriodMs);
            }
        }
    }
}