//
// fl_open_uri() code for FLTK.
//
// Test with:
//
//    gcc -I/fltk/dir -I/fltk/dir/src -DTEST -o fl_open_uri fl_open_uri.cxx -lfltk
//
// Copyright 2003-2010 by Michael R Sweet
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

//
// Include necessary headers...
//

#include "config_lib.h"
#include <FL/filename.H>
#include <FL/Fl.H>
#include "Fl_System_Driver.H"
#include <stdio.h>
#include <stdlib.h>
#include "flstring.h"

/** \addtogroup filenames
 \{ */

/**
 Opens the specified Uniform Resource Identifier (URI).
 Uses an operating-system dependent program or interface. For URIs
 using the "ftp", "http", or "https" schemes, the system default web
 browser is used to open the URI, while "mailto" and "news" URIs are
 typically opened using the system default mail reader and "file" URIs
 are opened using the file system navigator.

 On success, the (optional) msg buffer is filled with the command that
 was run to open the URI; on Windows, this will always be "open uri".

 On failure, the msg buffer is filled with an English error message.

 \note
 \b Platform \b Specific \b Issues: \b Windows \n
 With "file:" based URIs on Windows, you may encounter issues with
 anchors being ignored. Example: "file:///c:/some/index.html#anchor"
 may open in the browser without the "#anchor" suffix. The behavior
 seems to vary across different Windows versions. Workaround: open a link
 to a separate html file that redirects to the desired "file:" URI.

 \b Example
 \code
 #include <FL/filename.H>
 [..]
 char errmsg[512];
 if ( !fl_open_uri("http://google.com/", errmsg, sizeof(errmsg)) ) {
     char warnmsg[768];
     sprintf(warnmsg, "Error: %s", errmsg);
     fl_alert(warnmsg);
 }
 \endcode

 \param uri The URI to open
 \param msg Optional buffer which contains the command or error message
 \param msglen Length of optional buffer
 \return 1 on success, 0 on failure
 */
int fl_open_uri(const char *uri, char *msg, int msglen) {
  // Supported URI schemes...
  static const char * const schemes[] = {
    "file://",
    "ftp://",
    "http://",
    "https://",
    "mailto:",
    "news://",
    NULL
  };

  // Validate the URI scheme...
  int i;
  for (i = 0; schemes[i]; i ++)
    if (!strncmp(uri, schemes[i], strlen(schemes[i])))
      break;

  if (!schemes[i]) {
    if (msg) {
      char scheme[255];
      if (sscanf(uri, "%254[^:]", scheme) == 1) {
        snprintf(msg, msglen, "URI scheme \"%s\" not supported.", scheme);
      } else {
        snprintf(msg, msglen, "Bad URI \"%s\"", uri);
      }
    }

    return 0;
  }
  return Fl::system_driver()->open_uri(uri, msg, msglen);
}

/** Decodes a URL-encoded string.

 In a Uniform Resource Identifier (URI), all non-ASCII bytes and several others (e.g., '<', '%', ' ')
 are URL-encoded using 3 bytes by "%XY" where XY is the hexadecimal value of the byte. This function
 decodes the URI restoring its original UTF-8 encoded content. Decoding is done in-place.
 */
void fl_decode_uri(char *uri)
{
  char *last = uri + strlen(uri);
  while (uri < last-2) {
    if (*uri == '%') {
      int h;
      if ( sscanf(uri+1, "%2X", &h) != 1 ) break;
      *uri = h;
      memmove(uri+1, uri+3, last - (uri+2));
      last -= 2;
    }
    uri++;
  }
}

/**   @} */


#if defined(FL_CFG_SYS_POSIX) && !defined(FL_DOXYGEN)
// code shared by the Mac OS and USE_X11 platforms
#  include "drivers/Posix/Fl_Posix_System_Driver.H"
#  include <unistd.h>
#  include <sys/wait.h>
#  include <signal.h>
#  include <fcntl.h>
#  include <errno.h>

// Run the specified program, returning 1 on success and 0 on failure
int Fl_Posix_System_Driver::run_program(const char *program, char **argv, char *msg, int msglen) {
  pid_t pid;                            // Process ID of first child
  int status;                           // Exit status from first child
  sigset_t set, oldset;                 // Signal masks


  // Block SIGCHLD while we run the program...
  //
  // Note that I only use the POSIX signal APIs, however older operating
  // systems may either not support POSIX signals or have side effects.
  // IRIX, for example, provides three separate and incompatible signal
  // APIs, so it is possible that an application setting a signal handler
  // via signal() or sigset() will not have its SIGCHLD signals blocked...

  sigemptyset(&set);
  sigaddset(&set, SIGCHLD);
  sigprocmask(SIG_BLOCK, &set, &oldset);

  // Create child processes that actually run the program for us...
  if ((pid = fork()) == 0) {
    // First child comes here, fork a second child and exit...
    if (!fork()) {
      // Second child comes here, redirect stdin/out/err to /dev/null...
      close(0);
      ::open("/dev/null", O_RDONLY);

      close(1);
      ::open("/dev/null", O_WRONLY);

      close(2);
      ::open("/dev/null", O_WRONLY);

      // Detach from the current process group...
      setsid();

      // Run the program...
      execv(program, argv);
      _exit(0);
    } else {
      // First child gets here, exit immediately...
      _exit(0);
    }
  } else if (pid < 0) {
    // Restore signal handling...
    sigprocmask(SIG_SETMASK, &oldset, NULL);

    // Return indicating failure...
    return 0;
  }

  // Wait for the first child to exit...
  while (waitpid(pid, &status, 0) < 0) {
    if (errno != EINTR) {
      // Someone else grabbed the child status...
      if (msg) snprintf(msg, msglen, "waitpid(%ld) failed: %s", (long)pid,
                        strerror(errno));

      // Restore signal handling...
      sigprocmask(SIG_SETMASK, &oldset, NULL);

      // Return indicating failure...
      return 0;
    }
  }

  // Restore signal handling...
  sigprocmask(SIG_SETMASK, &oldset, NULL);

  // Return indicating success...
  return 1;
}
#endif // FL_CFG_SYS_POSIX


#ifdef TEST
//
// Test code...
//

// Open the URI on the command-line...
int main(int argc, char **argv) {
  char msg[1024];


  if (argc != 2) {
    puts("Usage: fl_open_uri URI");
    return 1;
  }

  if (!fl_open_uri(argv[1], msg, sizeof(msg))) {
    puts(msg);
    return 1;
  } else return 0;
}
#endif // TEST