/***************************************************************************
 *            main.c
 *
 *  Mon Apr 18 15:19:04 2005
 *  Copyright  2005  Benjamin Ducke
 ****************************************************************************/

/*
 *  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 2 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 Library 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.
 */


/* TODO:

   for 1.04:                    

   EASY STUFF:


   - tried to install GeneralStatistics w/o first installing RasterTools or anything else: attempts to install, fails because
   of missing raster tools headers! Even though line 379 in reg_deps.c should check for this case !!!

   - include $GISBASE/lib in linker path for compilation of extensions [NOT FIXED: see lines preceeding INSTALL action case: 693
   -L is added to command line, but problems still exist]
   MAYBE EXPORT LD_LIBRARY_PATH ??? (only add $GISBASE/lib if it does not already exist)

   - version number in HTML documentation index seems to not get updated when installing a newer version of an extension

   - remember to update version number in globals.h


   for 1.2 (GRASS 6.4 ?):
   - make GRASS store its ./configure command line options in a file in the GISBASE/etc directory, so that
   it will be possible for GEM to automatically configure extensions according to the system setup
   [this means that configure file needs to be kept in sync with GEM; --configure option can be used
   to overwrite this behaviour]
   - configure script should not fail but disable options and create config.msgs the
   contents of this should be displayed and deleted afterwards
   - check if it works with this Mac version of GRASS, as well: http://openosx.com/grass/
   - before release: any problems expected with native Win32-Kompilation?:
   - location for tmp-files?
   - a simple wrapper g.install with GRASS style parameters. Should start an xterm and ask for su pwd,
   if necessary
   - action to check dependencies of installed extensions
   - instead of aborting on each failed dependency: build list of all failed
   dependencies before aborting
   - mechanism to recursively download and install missing deps from a
   provided list of URLs
   - instead of calling external tar, switch to tarlib and zlib
   - action --validate for checking an extension archive/dir
   - add link to HTML help index into each extension's submenu in GIS Manager
   - g.install with a real custom-made GUI
   [VARIABLE GUI must be set appropriately in run_post() for post script]        
   this should be an independent Tcl/Tk GUI: install/uninstall/query extensions
   - extension database on the internet that can be queried and used with either gem
   or g.install
   - entries for QGIS
   - simplified scheme for installing just a single module
   - new scheme for registering menu entries in GIS Manager with stable hooks in menu.tcl


   NEED HELP
   - GRASS' make install installs all files BENEATH top level dir with UID
   set to benni !!! Is this intentional?
   - provide gem6x as link in /usr/local/bin as part of grass 6.x base install
   - description.html should not contain </body> or </html> as Rules.Make seems
   to append those ?
   - source install copies files COPYING README REQUIREMENTS.html to somewhere (but where?)
   -> into <extension>/src but where else ?     
   - menu.tcl in GRASS 6.0.0 has "all options 1", but 6.1 will have "all options $tmenu".
   How to cater for such things? Maybe in the future there should always be an
   Xtns menu provided by GIS Manager and always delimited by reliable tags
   - d.m window is a bit to small horizontally

   CAVEATS:
   - does not allow installation of different versions of the same extension within
   the same GRASS bin tree
   - does not have a real upgrading mechanism: option --upgrade has been disabled for now
   - restore cannot fix partially corrupted entries in HTML and TCL files
   - Links to other extension's modules will only work if those extensions are installed

   DOCS:

   - skeleton contains GPL as default license. Creators of new extensions
   need to be aware of this!

   - menu.tcl will be backed up as menu.tcl.gem.bak

   - HTML docs: users must prefix references to GRASS modules outside the Extension with
   "../../html/" !!!    
   - description files: things inside "<" and ">" will be filtered out as HTML tags, even
   if they are none!
   - make clear that there are some files which will be rendered both as text and HTML
   and therefore need things like <br> while others DO NOT (which ones?)!

   - configure script should not fail but disable options and create 'config.msgs'
   - deletes config.msg after display

   - State clearly that it is recommended to uninstall an older
   extension version before installing a new one. STATE CLEARLY that --upgrade is rather
   another version of --force than a real updating mechanism (RENAME to --newer)
   - document all env vars that gem sets
   - STATE CLEARLY, that users should not meddle with stuff in index.html, menu.tcl,
   gem-entries/ and docs/extensions/ !!!
   - provide a unix man page, ASCII and HTML documentation (write HTML and convert)
   - files in the skeleton should always be present, even if they do not containing
   information
   - make it clear, that uninstall and postinstall are run with su privileges! thus,
   author must make sure, that only objects in the GRASS install tree are affected
   - user may specify either file name or extension name for uninstall action
   - user may list installed extensions by using -q w/o filename. Explain
   what is meant by type (e.g. 'src')
   - uninstallation works only by extension name, NOT file name !
   - compiling extensions on a GRASS install with all but the most basic options
   disabled should give very portable binaries! (statically linked binaries?)

   BUGS:
   - remove cva, install again: WARNING: list item 'cva' exists in index.html (?)
   - superfluous warning upon uninstall of extension w/o "entries-gisman"
   - due to bad command line parsing, listing installed extensions only works like this:
   ./gem65 --grass=/usr/local/grass-6.5.svn -q
   NOT like this:
   ./gem65 -q --grass=/usr/local/grass-6.5.svn


 */

#include <getopt.h>
#include <fcntl.h>

#define LOCAL
#include "globals.h"


void show_help(void)
{
    fprintf(stdout, "Usage: gem65 [OPTION] [ACTION] [FILE|DIR]\n");
    fprintf(stdout, "Install a GRASS extension from FILE or DIR.\n");
    fprintf(stdout, "Manage (installed) GRASS extension(s).\n");
    fprintf(stdout, "\nPossible ACTIONs are:\n");
    fprintf(stdout, "  -i, --install=EXT\tinstall a GRASS extension\n");
    fprintf(stdout,
	    "  -u, --uninstall=EXT\tremove an extension from GRASS\n");
    fprintf(stdout,
	    "  -q, --query=EXT\tdisplay information about extension/list installed\n");
    fprintf(stdout,
	    "  -d, --details=EXT\tdisplay additional details about an extension\n");
    fprintf(stdout,
	    "  -c, --clean=EXT\tclean extension's source code directories\n");
    fprintf(stdout,
	    "  -t, --test=EXT\tconfigure and compile extension, but don't install\n");
    fprintf(stdout,
	    "  -l, --license=EXT\tshow copyright information for an extension\n");
    fprintf(stdout,
	    "  -r, --restore\t\trecreate HTML links and GIS Manager entries\n");
    fprintf(stdout, "  -h, --help\t\tdisplay this help and exit\n");
    fprintf(stdout,
	    "  -V, --version\t\toutput version information and exit\n\n");
    fprintf(stdout, "\nPossible OPTIONs are:\n");
    fprintf(stdout, "  -g, --grass=PATH\tpath to GRASS installation dir\n");
    fprintf(stdout,
	    "  -b, --binary=NAME\tno compilation: use binary files for system NAME\n");
    fprintf(stdout,
	    "  -f, --force\t\tforce action, regardless of dependencies\n");
    fprintf(stdout,
	    "  -v, --verbose\t\tdisplay detailed status information\n");
    fprintf(stdout, "  -s, --skip-config\tskip configure script\n");
    fprintf(stdout,
	    "  -x, --config-opts=OPTS\tpass OPTS to configure script\n");
    fprintf(stdout,
	    "  -o, --options=OPTS\toptions to pass to the C compiler/linker\n");
    fprintf(stdout,
	    "  -C, --config-cmd=CMD\tDefine custom 'configure' command (default=configure)\n");
    fprintf(stdout,
	    "  -m, --make-cmd=CMD\tDefine custom 'make' command (default=make)\n");
    fprintf(stdout,
	    "\nWhen run from within a GRASS session, locations of libs, header files\n");
    fprintf(stdout,
	    "and installation target dir will be assumed to match those of the active\n");
    fprintf(stdout, "GRASS version. ");
    fprintf(stdout,
	    "Option -g can be used to override these or install extensions\nfrom outside");
    fprintf(stdout, "of a GRASS session.\n");
    fprintf(stdout,
	    "Per default, extensions will be compiled from source and then installed.\n");
    fprintf(stdout,
	    "If the exension package contains binaries for the user's platform, they can\n");
    fprintf(stdout, "be installed instead using the -b option. ");
    fprintf(stdout,
	    "For installation from source code, a C compiler and make tools are needed.\n");
    fprintf(stdout, "\nExample:\n");
    fprintf(stdout,
	    "\tgem65 -b macosx --grass=/usr/local/grass-6.5.0 -i myExtension\n");
    fprintf(stdout,
	    "Installs the MacOS X binaries for 'myExtension' in /usr/local/grass-6.5.0.\n");
    exit(0);
}


void show_details(char *package)
{
    int error;
    char tmp[MAXSTR];

    sprintf(tmp, "%s", basename(package));
    error = chdir(tmp);
    if (error < 0) {
	print_error(ERR_NO_ACCESS_EXT,
		    "extension '%s' not accessible: (%s)\n", package,
		    strerror(errno));
    }

    dump_ascii("info", "Detailed information");


    /* run post action script */
    system("sh post");

    exit(0);
}


void show_license(char *package)
{
    int error;
    char tmp[MAXSTR];

    sprintf(tmp, "%s", basename(package));
    error = chdir(tmp);
    if (error < 0) {
	print_error(ERR_NO_ACCESS_EXT,
		    "extension '%s' not accessible: (%s)\n", package,
		    strerror(errno));
    }

    dump_ascii("license", "Detailed information");

    /* run post action script */
    system("sh post");

    exit(0);
}


void show_version(void)
{
    fprintf(stdout, "gem65 (GRASS extensions manager) %.2f\n", PROGVERSION);
    fprintf(stdout, "Written by Benjamin Ducke\n");
    fprintf(stdout, "\nCopyright (C) 2005 Benjamin Ducke\n");
    fprintf(stdout,
	    "This is free software; see the source for copying conditions.  There is NO\n");
    fprintf(stdout,
	    "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n");
    exit(0);
}


/* determine options to pass to extension's configure script */
/* TODO: check, if system configuration meets a set of requirements */
/* THIS FUNCTION IS CURRENTLY NOT USED */
void get_configure_options(char *gisbase)
{

    FILE *fp;
    char str[MAXSTR];

    if (strcmp(CONFIG_OPTS, "")) {
	/* if user has specified config options on the GEM command line: override anything else */
	return;
    }

    /* check if GISBASE/etc/config.system exists and if so, read options from it */
    sprintf(str, "%s/etc/config.system", gisbase);
    fp = fopen(str, "r");
    if (fp == NULL) {
	print_warning
	    ("could not open %s for read access. Using default configure options.\n",
	     str);
	return;
    }

    /* config.system may also contain nothing, only comments and/or whitespace */
    if (nc_fgets_nb(str, MAXSTR, fp) != NULL) {
	strcpy(CONFIG_OPTS, str);
    }
}


int main(int argc, char *argv[])
{
    char *gisbase;
    char *grass_version;
    char *grass_major;
    char *grass_minor;
    char *grass_revision;
    char *tmp;
    char *url;
    char *filepart;
    char version_file[MAXSTR];
    char package[MAXSTR];
    char orgname[MAXSTR];
    char pkg_name[MAXSTR];
    char *bins;
    int pkg_major, pkg_minor, pkg_revision;
    FILE *f;
    int fd;

    char pkg_short_name[MAXSTR];
    char invocation[MAXSTR];

    char coptions[MAXSTR];

    int major, minor, revision;
    int option;
    int action;
    int valid;

    struct stat buf;
    struct stat buf2;
    int error;
    int is_directory = 0;
    DIR *dir;
    struct dirent *dir_entry;
    int dir_found;

    int option_index = 0;
    static struct option long_options[] = {
	{"install", 1, NULL, 'i'},
	{"uninstall", 1, NULL, 'u'},
	{"query", 2, NULL, 'q'},
	{"details", 1, NULL, 'd'},
	{"clean", 1, NULL, 'c'},
	{"test", 1, NULL, 't'},
	{"license", 1, NULL, 'l'},
	{"restore", 0, NULL, 'r'},
	{"help", 0, NULL, 'h'},
	{"version", 0, NULL, 'V'},

	{"grass", 1, NULL, 'g'},
	{"options", 1, NULL, 'o'},
	{"binary", 1, NULL, 'b'},
	{"force", 0, NULL, 'f'},
	{"verbose", 0, NULL, 'v'},
	{"skip-config", 0, NULL, 's'},
	{"config-opts", 1, NULL, 'x'},

	{"config-cmd", 1, NULL, 'C'},
	{"make-cmd", 1, NULL, 'm'},

	{0, 0, 0, 0}
    };


    /* set global variables to defaults */
    VERBOSE = 0;
    TMPCLEAN = 0;
    TMPDBCLEAN = 0;
    FORCE = 0;
    UPGRADE = 0;
    ERROR = 0;
    WARNINGS = 0;
    SKIP_CFG = 0;

    strcpy(GISMAN_CMD, "");
    strcpy(GISMAN2_CMD, "");
    strcpy(QGIS_CMD, "");
    strcpy(UNINSTALL_CMD, "");
    strcpy(HTML_CMD, "");

    strcpy(TMPDIR, "");
    strcpy(TMPDB, "");
    strcpy(TMP_GISMAN, "");
    strcpy(TMP_DESCR, "");
    strcpy(TMP_INFO, "");
    strcpy(TMP_DEPS, "");
    strcpy(TMP_BUGS, "");
    strcpy(TMP_AUTHORS, "");
    strcpy(TMP_HTML, "");
    strcpy(TMP_NULL, "");

    strcpy(CONFIG_OPTS, "");

    strcpy(CONFIG_CMD, "configure");
    strcpy(MAKE_CMD, "make");

    getcwd(CWD, MAXSTR);

    /* reset terminal colors */
    fprintf(stdout, "\033[0m");

    tmp = malloc(sizeof(char) * MAXSTR);
    strncpy(invocation, argv[0], MAXSTR);
    invocation[MAXSTR-1] = '\0';

    /* all output should be unbuffered */
    setvbuf(stdout, (char *)NULL, _IONBF, 0);

    /* if run with no arguments: show help */
    if (argc == 1) {
	/* show usage info and exit */
	show_help();
	exit(0);
    }

    atexit(&exit_msg);		/* show a message after program termination */

    valid = 0;
    bins = NULL;
    gisbase = NULL;

    opterr = 0;
    option =
	getopt_long(argc, argv, ":i:u:q:d:c:C:t:l:m:o:x:rhVg:b:fvs",
		    long_options, &option_index);
    while (option != -1) {

	if (option == '?') {
	    print_error(ERR_INVOCATION,
			"unknown option or action specified.\n");
	}


	/* check for missing arguments */
	if (option == ':') {
	    if ((optopt == 'i') || (optopt == 'u') || (optopt == 'd') ||
		(optopt == 'c') || (optopt == 't') || (optopt == 'l') ||
		(optopt == 'r')) {
		print_error(ERR_INVOCATION,
			    "missing file or directory name.\n");
	    }
	    if (optopt == 'g') {
		print_error(ERR_INVOCATION, "missing path to GRASS 6.\n");
	    }
	    if (optopt == 'b') {
		print_error(ERR_INVOCATION,
			    "missing name of binary architecture.\n");
	    }
	    if (optopt == 'b') {
		print_error(ERR_INVOCATION, "missing configure options.\n");
	    }
	    if (optopt == 'q') {
		/* '-q' w/o filename is list action */
		action = LIST;
		valid++;
		break;
	    }
	}

	if ((option == 'i') || (option == 'u') || (option == 'q') ||
	    (option == 'd') || (option == 'c') || (option == 't') ||
	    (option == 'l') || (option == 'r') || (option == 'h') ||
	    (option == 'V')) {
	    /* got a valid action specifier */
	    valid++;
	    /* set action accordingly */
	    switch (option) {
	    case 'i':
		if (action != BIN_INSTALL) {
		    action = INSTALL;
		}
		break;
	    case 'u':
		action = UNINSTALL;
		break;
	    case 'q':
		action = QUERY;
		break;
	    case 'd':
		action = DETAILS;
		break;
	    case 'c':
		action = CLEAN;
		break;
	    case 't':
		action = TEST_INSTALL;
		break;
	    case 'l':
		action = LICENSE;
		break;
	    case 'r':
		action = RESTORE;
		break;
	    case 'h':
		action = HELP;
		break;
	    case 'V':
		action = VERSION;
		break;
	    }
	    if (optarg != NULL) {
		/* save package name as given on command line */
		strcpy(package, optarg);
		/* orgname will always preserve the commandline option */
		strcpy(orgname, optarg);
	    }
	}

	/* set options */
	if (option == 'g') {
	    gisbase = malloc(sizeof(char) * (strlen(optarg) + 1));
	    strcpy(gisbase, optarg);
	}
	if (option == 'b') {
	    bins = malloc(sizeof(char) * (strlen(optarg) + 1));
	    strcpy(bins, optarg);
	    action = BIN_INSTALL;
	}
	if (option == 'x') {
	    /* configure script options */
	    strcpy(&CONFIG_OPTS[0], optarg);
	}

	if (option == 'f') {
	    FORCE = 1;
	}
	if (option == 'v') {
	    VERBOSE = 1;
	}

	if (option == 's') {
	    SKIP_CFG = 1;
	}
	if (option == 'o') {
	    /* GEM_C_OPTS gets passed to the C compiler via the GRASS/GEM Makefiles:
	       <EXT>/src/include/Make/Grass.make.in:
	       CFLAGS      =  $(INC) $(COMPILE_FLAGS) $(USE_TERMIO) $(GEM_C_OPTS)
	     */
	    strcat(coptions, optarg);
	}
	/* define a custom configure command */
	if (option == 'C') {
	    strcpy(CONFIG_CMD, optarg);
	}
	/* define a custom make command */
	if (option == 'm') {
	    strcpy(MAKE_CMD, optarg);
	}
	/* get next option from command line */
	option =
	    getopt_long(argc, argv, ":i:u:q:d:c:t:l:o:x:rhVg:b:fvs",
			long_options, &option_index);
    }


    if (valid < 1) {
	print_error(ERR_INVOCATION, "please specify a valid action.\n");
    }
    if (valid > 1) {
	print_error(ERR_INVOCATION, "please specify only one action.\n");
    }

    /* export compiler options for use by Makefiles */
    sprintf(GEM_C_OPTS, "GEM_C_OPTS=%s", coptions);
    putenv(GEM_C_OPTS);

    /* these actions can be done without any extension checking */
    if (action == HELP) {
	/* show usage info and exit */
	show_help();
	exit(0);
    }

    if (action == VERSION) {
	/* show version info and exit */
	show_version();
	exit(0);
    }

    if (!VERBOSE) {
	/* set temp file to pipe output to for silent operation */
	/* TODO: Do not hardcode temp paths */
	strcpy(TMP_NULL, "/tmp/grass.extension.log.XXXXXX");	/* TMP_NULL is a global variable */
	mkstemp(TMP_NULL);
	fd = open(TMP_NULL, O_CREAT, 0777);
	if (fd == -1) {
	    print_error(ERR_TMPFILE, "could not create temp file: %s",
			strerror(errno));
	    exit(ERR_TMPFILE);
	}
    }


    /* these actions need a valid GRASS path but no extensions */
    if (action == RESTORE) {
	/* figure out path to GRASS installation */
	/* GIS base not given? */
	if (gisbase == NULL) {
	    /* try to read from GRASS environment */
	    gisbase = getenv("GISBASE");
	    if (gisbase == NULL) {
		/* still NULL? Abort! */
		print_error(ERR_INVOCATION,
			    "GISBASE environment variable not set and path to GRASS not given.\n");
	    }
	}

	if (VERBOSE) {
	    fprintf(stdout, "Path to GRASS is %s.\n", gisbase);
	}

	restore(gisbase, grass_version);
	exit(0);
    }

    if (action == LIST) {
	/* figure out path to GRASS installation */
	/* GIS base not given? */
	if (gisbase == NULL) {
	    /* try to read from GRASS environment */
	    gisbase = getenv("GISBASE");
	    if (gisbase == NULL) {
		/* still NULL? Abort! */
		print_error(ERR_INVOCATION,
			    "GISBASE environment variable not set and path to GRASS not given.\n");
	    }
	}

	if (VERBOSE) {
	    fprintf(stdout, "Path to GRASS is %s.\n", gisbase);
	}
	list_extensions(gisbase);
	exit(0);
    }

    /* check if extension is stored in a remote URL */
    if ((strstr(package, "http://")) || (strstr(package, "ftp://"))) {
	wget_extension(package);	/* download into current dir using wget */
	/* cut off the path specification */
	url = malloc(sizeof(char) * MAXSTR);
	strcpy(url, package);
	filepart = strrchr(url, '/');
	filepart++;
	strcpy(package, filepart);
	free(url);
    }

    if (VERBOSE) {
	fprintf(stdout, "Extension location is '%s'.\n", package);
    }

    if (action != UNINSTALL) {
	error = stat(package, &buf);
	if (error < 0) {
	    print_error(ERR_NO_ACCESS_EXT,
			"extension FILE or DIR '%s' invalid: %s\n", package,
			strerror(errno));
	}
	if (S_ISDIR(buf.st_mode)) {
	    is_directory = 1;
	    if (VERBOSE) {
		fprintf(stdout, "Extension files stored in a directory.\n");
	    }
	}
	else {
	    if (VERBOSE) {
		fprintf(stdout,
			"Extension files stored in a package file.\n");
	    }
	    /* DECOMPRESS INTO TEMP DIR, CHANGE NAME OF package TO THAT DIR */
	    unpack_extension(package);
	    /* find name of directory containing extension files */
	    /* very primitive: just picks the first directory */
	    dir = opendir(TMPDIR);
	    dir_entry = readdir(dir);
	    dir_found = 0;
	    while (dir_entry != NULL) {
		if ((strcmp(dir_entry->d_name, ".")) &&
		    (strcmp(dir_entry->d_name, ".."))
		    ) {
		    /* check if it is a directory */
		    sprintf(tmp, "%s/%s", TMPDIR, dir_entry->d_name);
		    stat(tmp, &buf2);
		    if (S_ISDIR(buf2.st_mode)) {
			dir_found = 1;
			break;
		    }
		}
		dir_entry = readdir(dir);
	    }
	    strcpy(package, tmp);

	    if (dir_found == 0) {
		print_error(ERR_UNPACK_EXT,
			    "no top-level directory found in extension package.\n");
	    }
	}
    }

    /* copy package name into this maliciously named variable */
    /* (sorry about the mess ...) */
    /* This name will be used for all registration actions and */
    /* for creating files and directories that store extension */
    /* information for uninstall and restore actions */
    /* For uninstall, we take the last argument as package, NOT */
    /* file name */
    if (action == UNINSTALL) {
	strcpy(pkg_short_name, package);
    }
    else {
	get_package_name(package, pkg_short_name);
    }

    /* export relevant VARS for use by post script */
    if (valid > 0) {
	/* export all relevant env vars for the post script */
	if (gisbase == NULL) {
	    /* try to read from GRASS environment */
	    gisbase = getenv("GISBASE");
	}
	run_post(package, action, bins, gisbase);
    }

    if (VERBOSE) {
	fprintf(stdout, "Extension will be installed from '%s'\n", package);
    }

    /* CHECK PACKAGE FOR VALIDITY */
    if (action != UNINSTALL) {
	check_extension(package, pkg_name, &pkg_major, &pkg_minor,
			&pkg_revision);
    }

    /* these actions can be done without GRASS checking */
    if (action == QUERY) {
	query_extension(package, pkg_name, pkg_major, pkg_minor, pkg_revision,
			pkg_short_name, invocation, orgname);
	exit(0);
    }

    if (action == DETAILS) {
	show_details(package);
	exit(0);
    }

    if (action == LICENSE) {
	show_license(package);
	exit(0);
    }

    if (action == CLEAN) {
	source_clean(package);
	exit(0);
    }


    /* The following checks need to be done for all other actions! */

    /* figure out path to GRASS installation */
    /* GIS base not given? */
    if (gisbase == NULL) {
	/* try to read from GRASS environment */
	gisbase = getenv("GISBASE");
	if (gisbase == NULL) {
	    /* still NULL? Abort! */
	    print_error(ERR_INVOCATION,
			"GISBASE environment variable not set and path to GRASS not given.\n");
	}
    }

    if (VERBOSE) {
	fprintf(stdout, "Path to GRASS is %s.\n", gisbase);
    }

    /* figure out GRASS version */
    grass_version = getenv("GRASS_VERSION");
    if (grass_version == NULL) {
	/* GRASS version can be read from gisbase/etc/VERSIONNUMBER */
	sprintf(version_file, "%s/etc/VERSIONNUMBER", gisbase);
	f = fopen(version_file, "r");
	if (f == NULL) {
	    /* still NULL? Abort! */
	    print_error(ERR_VERSION,
			"Could not read GRASS version. Did you specify the right path?\n");
	}
	else {
	    grass_version = malloc(sizeof(char) * 16);
	    error = fscanf(f, "%s", grass_version);
	    fclose(f);
	    if (error < 1) {
		print_error(ERR_VERSION,
			    "Could not read GRASS version. Did you specify the right path?\n");
	    }
	}
    }

    if (grass_version != NULL) {
	/* extract major and minor version numbers */
	tmp = strdup(grass_version);

	grass_major = strtok(tmp, ".");
	grass_minor = strtok(NULL, ".");
	grass_revision = strtok(NULL, ".");

	major = strtol(grass_major, NULL, 10);
	minor = strtol(grass_minor, NULL, 10);
	revision = strtol(grass_revision, NULL, 10);

	grass_version = malloc(sizeof(char) * MAXSTR);
	sprintf(grass_version, "%i.%i.%i", major, minor, revision);
	if (VERBOSE) {
	    fprintf(stdout, "GRASS version is %s.\n", grass_version);
	}

	if (major < 6) {
	    print_error(ERR_VERSION,
			"extensions only work with GRASS version 6 and above.\n");
	}
    }

    /* for GDAL compatibility and           
       for the sake of people using Lorenzo Moretti's GRASS for MacOS, we always export the following
       compiler options */
    sprintf(coptions, "-L%s/lib -I/usr/local/grasslib/include/ ", gisbase);

    /* these actions can only be done after everything has been checked */
    if (action == INSTALL) {
	source_install(package, gisbase, pkg_short_name, pkg_major, pkg_minor,
		       pkg_revision, grass_version);
	exit(0);
    }

    if (action == UNINSTALL) {
	uninstall(package, pkg_short_name, gisbase, grass_version);
	exit(0);
    }

    if (action == TEST_INSTALL) {
	test_install(package, gisbase, pkg_short_name, pkg_major, pkg_minor,
		     pkg_revision, grass_version);
	exit(0);
    }

    if (action == BIN_INSTALL) {
	if (binaries_exist(package, bins)) {
	    bin_install(package, gisbase, bins, pkg_short_name, pkg_major,
			pkg_minor, pkg_revision, grass_version);
	    exit(0);
	}
	else {
	    print_error(ERR_MISSING_BINS, "no binaries for system '%s'\n",
			bins);
	}
    }

    exit(0);
}