/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <windows.h>
#include <shlwapi.h>
#include <stdio.h>
#include <wchar.h>
#include <shlobj.h>

#include "serviceinstall.h"
#include "maintenanceservice.h"
#include "servicebase.h"
#include "workmonitor.h"
#include "uachelper.h"
#include "updatehelper.h"
#include "registrycertificates.h"

// Link w/ subsystem window so we don't get a console when executing
// this binary through the installer.
#pragma comment(linker, "/SUBSYSTEM:windows")

SERVICE_STATUS gSvcStatus = {0};
SERVICE_STATUS_HANDLE gSvcStatusHandle = nullptr;
HANDLE gWorkDoneEvent = nullptr;
HANDLE gThread = nullptr;
bool gServiceControlStopping = false;

// logs are pretty small, about 20 lines, so 10 seems reasonable.
#define LOGS_TO_KEEP 10

BOOL GetLogDirectoryPath(WCHAR* path);

int wmain(int argc, WCHAR** argv) {
  // If command-line parameter is "install", install the service
  // or upgrade if already installed
  // If command line parameter is "forceinstall", install the service
  // even if it is older than what is already installed.
  // If command-line parameter is "upgrade", upgrade the service
  // but do not install it if it is not already installed.
  // If command line parameter is "uninstall", uninstall the service.
  // Otherwise, the service is probably being started by the SCM.
  bool forceInstall = !lstrcmpi(argv[1], L"forceinstall");
  if (!lstrcmpi(argv[1], L"install") || forceInstall) {
    WCHAR logFilePath[MAX_PATH + 1];
    if (GetLogDirectoryPath(logFilePath) &&
        PathAppendSafe(logFilePath, L"maintenanceservice-install.log")) {
      LogInit(logFilePath);
    }

    SvcInstallAction action = InstallSvc;
    if (forceInstall) {
      action = ForceInstallSvc;
      LOG(("Installing service with force specified..."));
    } else {
      LOG(("Installing service..."));
    }

    bool ret = SvcInstall(action);
    if (!ret) {
      LOG_WARN(("Could not install service.  (%lu)", GetLastError()));
      LogFinish();
      return 1;
    }

    LOG(("The service was installed successfully"));
    LogFinish();
    return 0;
  }

  if (!lstrcmpi(argv[1], L"upgrade")) {
    WCHAR logFilePath[MAX_PATH + 1];
    if (GetLogDirectoryPath(logFilePath) &&
        PathAppendSafe(logFilePath, L"maintenanceservice-install.log")) {
      LogInit(logFilePath);
    }

    LOG(("Upgrading service if installed..."));
    if (!SvcInstall(UpgradeSvc)) {
      LOG_WARN(("Could not upgrade service.  (%lu)", GetLastError()));
      LogFinish();
      return 1;
    }

    LOG(("The service was upgraded successfully"));
    LogFinish();
    return 0;
  }

  if (!lstrcmpi(argv[1], L"uninstall")) {
    WCHAR logFilePath[MAX_PATH + 1];
    if (GetLogDirectoryPath(logFilePath) &&
        PathAppendSafe(logFilePath, L"maintenanceservice-uninstall.log")) {
      LogInit(logFilePath);
    }
    LOG(("Uninstalling service..."));
    if (!SvcUninstall()) {
      LOG_WARN(("Could not uninstall service.  (%lu)", GetLastError()));
      LogFinish();
      return 1;
    }
    LOG(("The service was uninstalled successfully"));
    LogFinish();
    return 0;
  }

  if (!lstrcmpi(argv[1], L"check-cert") && argc > 2) {
    return DoesBinaryMatchAllowedCertificates(argv[2], argv[3], FALSE) ? 0 : 1;
  }

  SERVICE_TABLE_ENTRYW DispatchTable[] = {
      {const_cast<LPWSTR>(SVC_NAME),
       (LPSERVICE_MAIN_FUNCTIONW)SvcMain},  // -Wwritable-strings
      {nullptr, nullptr}};

  // This call returns when the service has stopped.
  // The process should simply terminate when the call returns.
  if (!StartServiceCtrlDispatcherW(DispatchTable)) {
    LOG_WARN(("StartServiceCtrlDispatcher failed.  (%lu)", GetLastError()));
  }

  return 0;
}

/**
 * Obtains the base path where logs should be stored
 *
 * @param  path The out buffer for the backup log path of size MAX_PATH + 1
 * @return TRUE if successful.
 */
BOOL GetLogDirectoryPath(WCHAR* path) {
  if (!GetModuleFileNameW(nullptr, path, MAX_PATH)) {
    return FALSE;
  }

  if (!PathRemoveFileSpecW(path)) {
    return FALSE;
  }

  if (!PathAppendSafe(path, L"logs")) {
    return FALSE;
  }
  CreateDirectoryW(path, nullptr);
  return TRUE;
}

/**
 * Calculated a backup path based on the log number.
 *
 * @param  path      The out buffer to store the log path of size MAX_PATH + 1
 * @param  basePath  The base directory where the calculated path should go
 * @param  logNumber The log number, 0 == updater.log
 * @return TRUE if successful.
 */
BOOL GetBackupLogPath(LPWSTR path, LPCWSTR basePath, int logNumber) {
  WCHAR logName[64] = {L'\0'};
  wcsncpy(path, basePath, sizeof(logName) / sizeof(logName[0]) - 1);
  if (logNumber <= 0) {
    swprintf(logName, sizeof(logName) / sizeof(logName[0]),
             L"maintenanceservice.log");
  } else {
    swprintf(logName, sizeof(logName) / sizeof(logName[0]),
             L"maintenanceservice-%d.log", logNumber);
  }
  return PathAppendSafe(path, logName);
}

/**
 * Moves the old log files out of the way before a new one is written.
 * If you for example keep 3 logs, then this function will do:
 *   updater2.log -> updater3.log
 *   updater1.log -> updater2.log
 *   updater.log -> updater1.log
 * Which clears room for a new updater.log in the basePath directory
 *
 * @param basePath      The base directory path where log files are stored
 * @param numLogsToKeep The number of logs to keep
 */
void BackupOldLogs(LPCWSTR basePath, int numLogsToKeep) {
  WCHAR oldPath[MAX_PATH + 1];
  WCHAR newPath[MAX_PATH + 1];
  for (int i = numLogsToKeep; i >= 1; i--) {
    if (!GetBackupLogPath(oldPath, basePath, i - 1)) {
      continue;
    }

    if (!GetBackupLogPath(newPath, basePath, i)) {
      continue;
    }

    if (!MoveFileExW(oldPath, newPath, MOVEFILE_REPLACE_EXISTING)) {
      continue;
    }
  }
}

/**
 * Ensures the service is shutdown once all work is complete.
 * There is an issue on XP SP2 and below where the service can hang
 * in a stop pending state even though the SCM is notified of a stopped
 * state.  Control *should* be returned to StartServiceCtrlDispatcher from the
 * call to SetServiceStatus on a stopped state in the wmain thread.
 * Sometimes this is not the case though. This thread will terminate the process
 * if it has been 5 seconds after all work is done and the process is still not
 * terminated.  This thread is only started once a stopped state was sent to the
 * SCM. The stop pending hang can be reproduced intermittently even if you set
 * a stopped state dirctly and never set a stop pending state.  It is safe to
 * forcefully terminate the process ourselves since all work is done once we
 * start this thread.
 */
DWORD WINAPI EnsureProcessTerminatedThread(LPVOID) {
  Sleep(5000);
  exit(0);
}

void StartTerminationThread() {
  // If the process does not self terminate like it should, this thread
  // will terminate the process after 5 seconds.
  HANDLE thread = CreateThread(nullptr, 0, EnsureProcessTerminatedThread,
                               nullptr, 0, nullptr);
  if (thread) {
    CloseHandle(thread);
  }
}

/**
 * Main entry point when running as a service.
 */
void WINAPI SvcMain(DWORD argc, LPWSTR* argv) {
  // Setup logging, and backup the old logs
  WCHAR logFilePath[MAX_PATH + 1];
  if (GetLogDirectoryPath(logFilePath)) {
    BackupOldLogs(logFilePath, LOGS_TO_KEEP);
    if (PathAppendSafe(logFilePath, L"maintenanceservice.log")) {
      LogInit(logFilePath);
    }
  }

  // Disable every privilege we don't need. Processes started using
  // CreateProcess will use the same token as this process.
  UACHelper::DisablePrivileges(nullptr);

  // Register the handler function for the service
  gSvcStatusHandle = RegisterServiceCtrlHandlerW(SVC_NAME, SvcCtrlHandler);
  if (!gSvcStatusHandle) {
    LOG_WARN(("RegisterServiceCtrlHandler failed.  (%lu)", GetLastError()));
    ExecuteServiceCommand(argc, argv);
    LogFinish();
    exit(1);
  }

  // These values will be re-used later in calls involving gSvcStatus
  gSvcStatus.dwServiceType = SERVICE_WIN32_OWN_PROCESS;
  gSvcStatus.dwServiceSpecificExitCode = 0;

  // Report initial status to the SCM
  ReportSvcStatus(SERVICE_START_PENDING, NO_ERROR, 3000);

  // This event will be used to tell the SvcCtrlHandler when the work is
  // done for when a stop comamnd is manually issued.
  gWorkDoneEvent = CreateEvent(nullptr, TRUE, FALSE, nullptr);
  if (!gWorkDoneEvent) {
    ReportSvcStatus(SERVICE_STOPPED, 1, 0);
    StartTerminationThread();
    return;
  }

  // Initialization complete and we're about to start working on
  // the actual command.  Report the service state as running to the SCM.
  ReportSvcStatus(SERVICE_RUNNING, NO_ERROR, 0);

  // The service command was executed, stop logging and set an event
  // to indicate the work is done in case someone is waiting on a
  // service stop operation.
  BOOL success = ExecuteServiceCommand(argc, argv);
  LogFinish();

  SetEvent(gWorkDoneEvent);

  // If we aren't already in a stopping state then tell the SCM we're stopped
  // now.  If we are already in a stopping state then the SERVICE_STOPPED state
  // will be set by the SvcCtrlHandler.
  if (!gServiceControlStopping) {
    ReportSvcStatus(SERVICE_STOPPED, success ? NO_ERROR : 1, 0);
    StartTerminationThread();
  }
}

/**
 * Sets the current service status and reports it to the SCM.
 *
 * @param currentState  The current state (see SERVICE_STATUS)
 * @param exitCode      The system error code
 * @param waitHint      Estimated time for pending operation in milliseconds
 */
void ReportSvcStatus(DWORD currentState, DWORD exitCode, DWORD waitHint) {
  static DWORD dwCheckPoint = 1;

  gSvcStatus.dwCurrentState = currentState;
  gSvcStatus.dwWin32ExitCode = exitCode;
  gSvcStatus.dwWaitHint = waitHint;

  if (SERVICE_START_PENDING == currentState ||
      SERVICE_STOP_PENDING == currentState) {
    gSvcStatus.dwControlsAccepted = 0;
  } else {
    gSvcStatus.dwControlsAccepted =
        SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;
  }

  if ((SERVICE_RUNNING == currentState) || (SERVICE_STOPPED == currentState)) {
    gSvcStatus.dwCheckPoint = 0;
  } else {
    gSvcStatus.dwCheckPoint = dwCheckPoint++;
  }

  // Report the status of the service to the SCM.
  SetServiceStatus(gSvcStatusHandle, &gSvcStatus);
}

/**
 * Since the SvcCtrlHandler should only spend at most 30 seconds before
 * returning, this function does the service stop work for the SvcCtrlHandler.
 */
DWORD WINAPI StopServiceAndWaitForCommandThread(LPVOID) {
  do {
    ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 1000);
  } while (WaitForSingleObject(gWorkDoneEvent, 100) == WAIT_TIMEOUT);
  CloseHandle(gWorkDoneEvent);
  gWorkDoneEvent = nullptr;
  ReportSvcStatus(SERVICE_STOPPED, NO_ERROR, 0);
  StartTerminationThread();
  return 0;
}

/**
 * Called by SCM whenever a control code is sent to the service
 * using the ControlService function.
 */
void WINAPI SvcCtrlHandler(DWORD dwCtrl) {
  // After a SERVICE_CONTROL_STOP there should be no more commands sent to
  // the SvcCtrlHandler.
  if (gServiceControlStopping) {
    return;
  }

  // Handle the requested control code.
  switch (dwCtrl) {
    case SERVICE_CONTROL_SHUTDOWN:
    case SERVICE_CONTROL_STOP: {
      gServiceControlStopping = true;
      ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 1000);

      // The SvcCtrlHandler thread should not spend more than 30 seconds in
      // shutdown so we spawn a new thread for stopping the service
      HANDLE thread = CreateThread(
          nullptr, 0, StopServiceAndWaitForCommandThread, nullptr, 0, nullptr);
      if (thread) {
        CloseHandle(thread);
      } else {
        // Couldn't start the thread so just call the stop ourselves.
        // If it happens to take longer than 30 seconds the caller will
        // get an error.
        StopServiceAndWaitForCommandThread(nullptr);
      }
    } break;
    default:
      break;
  }
}