/*
Copyright (©) 2003-2025 Teus Benschop.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/


#include <library/bibledit.h>
#include <config/libraries.h>
#include <filter/url.h>
#include <filter/string.h>
#include <filter/shell.h>
#ifdef HAVE_LIBPROC
#include <libproc.h>
#endif
#ifdef HAVE_EXECINFO
#include <execinfo.h>
#endif
#include <database/logs.h>
#ifdef HAVE_WINDOWS
#include <windows.h>
#endif
#include <config/globals.h>

// Fix for architecture hurd-i386 that does not define MAXPATHLEN.
#ifndef MAXPATHLEN
#define MAXPATHLEN 1024
#endif


static void sigint_handler ([[maybe_unused]] int s)
{
  // When pressing Ctrl-C, the system outputs a "^C".
  // It is cleaner to write a new line after that.
  std::cout << std::endl;
  // Initiate server(s) shutdown.
  bibledit_stop_library ();
}


static std::string backtrace_path ()
{
  return filter_url_create_root_path ({filter_url_temp_dir (), "backtrace.txt"});
}


#ifdef HAVE_EXECINFO
// https://stackoverflow.com/questions/77005/how-to-generate-a-stacktrace-when-my-gcc-c-app-crashes
// To add linker flag -rdynamic is essential.
[[ noreturn ]]
static void sigsegv_handler ([[maybe_unused]] int sig)
{
  // Information.
  std::cout << "Segmentation fault, writing backtrace to " << backtrace_path () << std::endl;
  
  // Get void*'s for all entries on the stack
  void *array[20];
  int size = backtrace (array, 20);

  // Write entries to file (to be logged next time bibledit starts).
  int fd = open (backtrace_path ().c_str (), O_WRONLY|O_CREAT, 0666);
  backtrace_symbols_fd (array, size, fd);
  close (fd);

  exit (1);
}
#endif


#ifdef HAVE_WINDOWS
void my_invalid_parameter_handler(const wchar_t* expression, const wchar_t* function, const wchar_t* file,	unsigned int line, uintptr_t pReserved) {
  std::wstring wexpression(expression);
  std::string sexpression(wexpression.begin(), wexpression.end());
  std::wstring wfunction(function);
  std::string sfunction(wfunction.begin(), wfunction.end());
  std::wstring wfile (file);
  std::string sfile(wfile.begin(), wfile.end());
  Database_Logs::log ("Invalid parameter detected in function " + sfunction + " in file " + sfile + " line " + std::to_string(line) + " expression " + sexpression + ".");
}
#endif


int main ()
{
  // Ctrl-C initiates a clean shutdown sequence, so there's no memory leak.
  signal (SIGINT, sigint_handler);

  
#ifdef HAVE_EXECINFO
  // Handler for logging segmentation fault.
  signal (SIGSEGV, sigsegv_handler);
#endif


#ifdef HAVE_WINDOWS
  // Set our own invalid parameter handler for on Windows.
  _set_invalid_parameter_handler(my_invalid_parameter_handler);
  // Disable the message box for assertions on Windows.
  _CrtSetReportMode(_CRT_ASSERT, 0);
#endif

  
  // Get the executable path and derive the document root from it.
  std::string webroot {};
#ifndef HAVE_WINDOWS
  {
    // The following works on Linux but not on macOS:
    char *linkname = static_cast<char *> (malloc (256));
    memset (linkname, 0, 256); // valgrind uninitialized value(s)
    [[maybe_unused]] auto result = readlink ("/proc/self/exe", linkname, 256);
    webroot = filter_url_dirname (linkname);
    free (linkname);
  }
#endif
#ifdef HAVE_LIBPROC
  {
    // The following works on Linux and on macOS:
    pid_t pid = getpid ();
    char pathbuf [2048];
    int ret = proc_pidpath (pid, pathbuf, sizeof (pathbuf));
    if (ret > 0 ) {
      webroot = filter_url_dirname (pathbuf);
    }
  }
#endif
#ifdef HAVE_WINDOWS
  {
    // Getting the web root on Windows.
    // The following gets the path to the server.exe.
    // char buf[MAX_PATH] = { 0 };
    // DWORD ret = GetModuleFileNameA(nullptr, buf, MAX_PATH);
    // While developing, the .exe runs in folder Debug or Release, and not in the expected folder.
    // Therefore it's better to take the path of the current directory.
    wchar_t buffer[MAX_PATH];
    GetCurrentDirectory (MAX_PATH, buffer);
    char chars[MAX_PATH];
    char def_char = ' ';
    WideCharToMultiByte (CP_ACP, 0, buffer, -1, chars, MAX_PATH, &def_char, nullptr);
    webroot = chars;
  }
#endif
#ifdef HAVE_CLOUD
  // The following is for the Cloud configuration only:
  {
    // Get home folder and working directory.
    std::string home_folder;
    const char * home_env_ptr = getenv ("HOME");
    if (home_env_ptr) home_folder = home_env_ptr;
    std::string workingdirectory;
    char cwd [MAXPATHLEN];
    if (getcwd(cwd, sizeof(cwd)) != nullptr) workingdirectory = cwd;
    // If the web root folder, derived from the binary, is the same as the current directory,
    // it means that the binary is started from a Cloud installation in user space.
    // The web root folder is okay as it is.
    if (webroot != workingdirectory) {
      // If the web root is the home folder, it should be updated,
      // because it is undesirable to have all the data in the home folder.
      // If the web root is the package prefix, it should be updated,
      // because it now runs the binary installed in /usr/bin.
      if ((webroot == home_folder) || (webroot.find (PACKAGE_PREFIX_DIR) == 0)) {
        // Update web root to ~/bibledit or ~/bibledit-cloud.
        webroot = filter_url_create_path ({home_folder, filter_url_basename (PACKAGE_DATA_DIR)});
      }
    }
  }
#endif
  // The $ make install will copy the data files to /usr/share/bibledit.
  // That is the package data directory.
  // Bibledit will copy this to the webroot upon first run for a certain version number.
  // If this directory is empty, it won't copy anything.
  // That would be okay if it runs in a user folder like ~/bibledit or similar.
  // Read the package directory from config.h.
  bibledit_initialize_library (PACKAGE_DATA_DIR, webroot.c_str());
  

  // Start the Bibledit library.
  bibledit_start_library ();
  bibledit_log ("The server started");
  std::cout << "Listening on http://localhost:" << config::logic::http_network_port () << std::endl;
  std::cout << "Press Ctrl-C to quit" << std::endl;

  
  // Log possible backtrace from a previous crash.
  std::string backtrace = filter_url_file_get_contents (backtrace_path ());
  filter_url_unlink (backtrace_path ());
  if (!backtrace.empty ()) {
    Database_Logs::log ("Backtrace of the last segmentation fault:");
    std::vector <std::string> lines = filter::strings::explode (backtrace, '\n');
    for (auto & line : lines) {
      Database_Logs::log (line);
      // Set a flag if the backtrace appears to be caused while sending email.
      if (line.find ("email_send") != std::string::npos) config_globals_has_crashed_while_mailing = true;
    }
  }


  // In Cloud configuration, check the existence of all command line tools that may be needed.
#ifdef HAVE_CLOUD
  filter::shell::check_existence_executables();
#endif

  
  // Keep running till Bibledit stops or gets interrupted.
  while (bibledit_is_running ()) { }

  
  // Shut the library down.
  bibledit_shutdown_library ();

  
  // Done.
  return EXIT_SUCCESS;
}