#ifndef URLADER
# define URLADER "urlader"
#endif
#define URLADER_VERSION "1.0"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <fcntl.h>

#include "lzf_d.c"

#define TAIL_MAGIC "SCHMORPPACK0"

#ifdef _WIN32

   #include <windows.h>
   //#include <winbase.h>
   #include <shlobj.h>
   #include <shlwapi.h>
   #include <wininet.h>

   static DWORD dword;

   #define u_handle HANDLE
   #define u_setenv(name,value) SetEnvironmentVariable (name, value)
   #define u_mkdir(path) !CreateDirectory (path, NULL)
   #define u_chdir(path) !SetCurrentDirectory (path)
   #define u_rename(fr,to) !MoveFile (fr, to)
   #define u_open(path) CreateFile (path, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL)
   #define u_creat(path,exec) CreateFile (path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL)
   #define u_close(handle) CloseHandle (handle)
   #define u_append(path,add) PathAppend (path, add)
   #define u_write(handle,data,len) (WriteFile (handle, data, len, &dword, 0) ? dword : -1)

#else

   #include <sys/mman.h>
   #include <sys/types.h>
   #include <pwd.h>

   #ifdef PATH_MAX
     #define MAX_PATH (PATH_MAX < 4096 ? 4096 : PATH_MAX)
   #else
     #define MAX_PATH 4096
   #endif

   #define u_handle int
   #define u_setenv(name,value) setenv (name, value, 1)
   #define u_mkdir(path) mkdir (path, 0777)
   #define u_chdir(path) chdir (path)
   #define u_rename(fr,to) rename (fr, to)
   #define u_open(path) open (path, O_RDONLY) + 1
   #define u_creat(path,exec) open (path, O_WRONLY | O_CREAT | O_TRUNC, (exec) ? 0777 : 0666) + 1
   #define u_close(handle) close (handle - 1)
   #define u_append(path,add) strcat (strcat (path, "/"), add)
   #define u_write(handle,data,len) write ((handle) - 1, data, len)

#endif

#define u_16(ptr) (((ptr)[0] << 8) | (ptr)[1])
#define u_32(ptr) (((ptr)[0] << 24) | ((ptr)[1] << 16) | ((ptr)[2] << 8) | (ptr)[3])

static u_handle pack_handle;
static char tmppath[MAX_PATH];
static char currdir[MAX_PATH];
static char datadir[MAX_PATH];  // %AppData%/urlader
static char exe_dir[MAX_PATH];  // %AppData%/urlader/EXE_ID
static char execdir[MAX_PATH];  // %AppData%/urlader/EXE_ID/EXE_VER
static char exe_id[MAX_PATH];
static char exe_ver[MAX_PATH];

static int exe_argc;
static const char *exe_argv[32];

static void
fatal (const char *msg)
{
#ifdef _WIN32
  MessageBox (0, msg, URLADER, 0);
#else
  fprintf (stderr, "%s: %s\n", URLADER, msg);
#endif

  _exit (1);
}

static void
tmpdir (const char *dir)
{
  static int cnt;

  for (;;)
    {
//      #ifdef _WIN32
//        sprintf (tmppath, "%s/%x_%x.tmp", dir, (unsigned int)GetCurrentProcessId (), ++cnt);
//      #else
        sprintf (tmppath, "%s/t-%x_%x.tmp", dir, (unsigned int)getpid ()             , ++cnt);
//      #endif

      if (!u_mkdir (tmppath))
        return;
    }
}

static void
systemv (const char *const argv[])
{
#ifdef _WIN32
  _spawnv (P_WAIT, argv [0], argv);
#else
  pid_t pid = fork ();

  if (pid < 0)
    fatal ("fork failure");

  if (!pid)
    {
      execv (argv [0], (void *)argv);
      _exit (124);
    }

  int status;
  waitpid (pid, &status, 0);
#endif
}

static void
deltree (const char *path)
{
  #ifdef _WIN32
    char buf[MAX_PATH * 2 + 64];
    const char *argv[] = { getenv ("COMSPEC"), "/c", "rd", "/s", "/q", buf, 0 };
    sprintf (buf, "\"%s\"", path);
  #else
    const char *argv[] = { "/bin/rm", "-rf", path, 0 };
  #endif
  systemv (argv);
}

static void
execute (void)
{
  exe_argv [exe_argc] = 0;
  systemv (exe_argv);
}

enum
{
  T_NULL, // 5
  T_META, // 1 : exe_id, exe_ver
  T_ARG,  // 2 : arg
  T_ENV,  // 3 : name, value
  T_DIR,  // 4+: path
  T_FILE, // 4+: path, data
  T_NUM
};

enum
{
  F_EXEC = 1,
  F_LZF  = 2,
  F_NULL = 0
};

struct hdr
{
  unsigned char type;
  unsigned char flags;
  unsigned char namelen[2];
  unsigned char datalen[4];
};

struct tail {
  unsigned char max_filesize[4];
  unsigned char size[4];
  char magic[12];
};

static char *pack_base, *pack_end;
static struct hdr *pack_cur;

#define PACK_NAME ((char *)(pack_cur + 1))
#define PACK_DATA (PACK_NAME + u_16 (pack_cur->namelen) + 1)
#define PACK_VALID pack_cur->type

static void
pack_next (void)
{
  unsigned int d = u_32 (pack_cur->datalen);

  pack_cur = (struct hdr *)(PACK_DATA + d);
}

static void
pack_unmap (void)
{
  if (!pack_base)
    return;

#ifdef _WIN32
  UnmapViewOfFile (pack_base);
#else
  munmap (pack_base, pack_end - pack_base);
#endif
}

static int
pack_map (void)
{
#ifdef _WIN32
  BY_HANDLE_FILE_INFORMATION fi;

  if (!GetFileInformationByHandle (pack_handle, &fi))
    return 0;

  if (fi.nFileSizeHigh) // too big
    return 0;

  HANDLE handle = CreateFileMapping (pack_handle, 0, PAGE_READONLY, 0, fi.nFileSizeLow, NULL);

  if (!handle)
    return 0;

  pack_unmap ();

  pack_base = MapViewOfFile (handle, FILE_MAP_READ, 0, 0, fi.nFileSizeLow);

  CloseHandle (handle);

  pack_end  = pack_base + fi.nFileSizeLow;
#else
  off_t len = lseek (pack_handle - 1, 0, SEEK_END);

  pack_unmap ();

  pack_base = mmap (0, len, PROT_READ, MAP_SHARED, pack_handle - 1, 0);
  if (pack_base == (void *)-1)
    pack_base = 0;

  pack_end = pack_base + len;
#endif

  if (!pack_base)
    return 0;

  struct tail *tail;

  tail = (void *)(pack_end - sizeof (*tail));

  if (memcmp (tail->magic, TAIL_MAGIC, sizeof (TAIL_MAGIC) - 1))
    return 0;

  pack_cur = (struct hdr *)(pack_end - u_32 (tail->size));

  return 1;
}

static void
exe_info (void)
{
  if (!pack_map ())
    fatal ("unable to locate packfile in executable - executable corrupted?");

  if (pack_cur->type != T_META)
    fatal ("unable to locate executable metadata - executable corrupted?");

  strcpy (exe_id, PACK_NAME);
}

static void
load (void)
{
  u_mkdir (datadir);

  strcpy (exe_dir, datadir);
  u_append (exe_dir, exe_id);
  u_mkdir (exe_dir);

  if (u_chdir (exe_dir))
    fatal ("unable to change to application data directory");

  u_handle h = u_open ("override");
  if (h)
    {
      u_handle oh = pack_handle;

      pack_handle = h;
      if (!pack_map ())
        {
          pack_handle = oh;
          oh = h;
        }

      u_close (oh);
    }

  if (pack_cur->type != T_META)
    fatal ("unable to locate override metadata");

  strcpy (exe_ver, PACK_DATA);
  pack_next ();

  while (pack_cur->type == T_ARG)
    {
      exe_argv [exe_argc++] = strdup (PACK_NAME);
      pack_next ();
    }

  while (pack_cur->type == T_ENV)
    {
      u_setenv (PACK_NAME, PACK_DATA);
      pack_next ();
    }

  strcpy (execdir, exe_dir);
  u_append (execdir, "i-");
  strcat (execdir, exe_ver);

  if (access (execdir, F_OK))
    {
      // does not exist yet, so unpack and move
      tmpdir (exe_dir);

      if (u_chdir (tmppath))
        fatal ("unable to change to new instance directory");

      for (;;)
        {
          switch (pack_cur->type)
            {
              case T_DIR:
                u_mkdir (PACK_NAME);
                break;

              case T_FILE:
                {
                  u_handle h = u_creat (PACK_NAME, pack_cur->flags & F_EXEC);
                  unsigned int len = u_32 (pack_cur->datalen);

                  if (!h)
                    fatal ("unable to unpack file from packfile - disk full?");

                  if (u_write (h, PACK_DATA, len) != len)
                    fatal ("unable to unpack file from packfile - disk full?");

                  u_close (h);
                }
                break;

              case T_NULL:
                goto done;
            }

          pack_next ();
        }

done:
      if (u_chdir (datadir))
        fatal ("unable to change to data directory");

      if (u_rename (tmppath, execdir))
        deltree (tmppath); // if move fails, delete new, assume other process created it independently

      if (u_chdir (execdir))
        fatal ("unable to change to application instance directory");
    }

  pack_unmap ();
  u_close (pack_handle);

  u_setenv ("URLADER_VERSION", URLADER_VERSION);
  u_setenv ("URLADER_DATADIR", datadir);
  u_setenv ("URLADER_EXECDIR", execdir);
  u_setenv ("URLADER_EXE_ID" , exe_id);
  u_setenv ("URLADER_EXE_DIR", exe_dir);
  u_setenv ("URLADER_EXE_VER", exe_ver);

  // yes, this is overkill
  u_setenv ("SHLIB_PATH"        , execdir); // hpux
  u_setenv ("LIBPATH"           , execdir); // aix
  u_setenv ("LD_LIBRARY_PATH"   , execdir); // most elf systems
  u_setenv ("LD_LIBRARY_PATH_32", execdir); // solaris
  u_setenv ("LD_LIBRARY_PATH_64", execdir); // solaris
  u_setenv ("LD_LIBRARYN32_PATH", execdir); // irix
  u_setenv ("LD_LIBRARY64_PATH" , execdir); // irix
  u_setenv ("DYLD_LIBRARY_PATH" , execdir); // os sucks from apple
}

#ifdef _WIN32

int APIENTRY
WinMain (HINSTANCE hI, HINSTANCE hP, LPSTR argv, int command_show)
{
  if (!GetModuleFileName (hI, tmppath, sizeof (tmppath)))
    fatal ("unable to find executable pack");

  if (!(pack_handle = u_open (tmppath)))
    fatal ("unable to open executable pack");

  exe_info ();

  if (!GetCurrentDirectory (sizeof (currdir), currdir))
    strcpy (currdir, ".");

  if (SHGetFolderPath (0, CSIDL_APPDATA | CSIDL_FLAG_CREATE, NULL, SHGFP_TYPE_CURRENT, datadir) != S_OK)
    fatal ("unable to find application data directory");

  u_mkdir (datadir);
  u_append (datadir, URLADER);

  load ();
  execute ();

  return 0;
}

#else

int
main (int argc, char *argv[])
{
  char *home = getenv ("HOME");

  // we assume fd 0 and 2 are "normal"

  if (!(pack_handle = u_open (argv [0])))
    fatal ("unable to open executable pack");

  exe_info ();

  if (!home)
    {
      struct passwd *pw;

      if ((pw = getpwuid (getuid ())))
        home = pw->pw_dir;
      else
        home = "/tmp";
    }

  if (!getcwd (currdir, sizeof (currdir)))
    strcpy (currdir, ".");

  u_mkdir (home);
  sprintf (datadir, "%s/.%s", home, URLADER);
  u_mkdir (datadir);

  if (gethostname (tmppath, sizeof (tmppath)))
    strcpy (tmppath, "default");

  u_append (datadir, tmppath);

  load ();
  execute ();

  return 0;
}

#endif