#!/usr/bin/env python

# Copyright (c) 2002-2005 ActiveState Corp.

# See LICENSE.txt for license details.

# Author:

#   Trent Mick (TrentM@ActiveState.com)

# Home:

#   http://trentm.com/projects/which/

r"""Find the full path to commands.

which(command, path=None, verbose=0, exts=None)

    Return the full path to the first match of the given command on the

    path.

whichall(command, path=None, verbose=0, exts=None)

    Return a list of full paths to all matches of the given command on

    the path.

whichgen(command, path=None, verbose=0, exts=None)

    Return a generator which will yield full paths to all matches of the

    given command on the path.

By default the PATH environment variable is searched (as well as, on

Windows, the AppPaths key in the registry), but a specific 'path' list

to search may be specified as well.  On Windows, the PATHEXT environment

variable is applied as appropriate.

If "verbose" is true then a tuple of the form

    (<fullpath>, <matched-where-description>)

is returned for each match. The latter element is a textual description

of where the match was found. For example:

    from PATH element 0

    from HKLM\SOFTWARE\...\perl.exe

"""

_cmdlnUsage = """

    Show the full path of commands.

    Usage:

        which [<options>...] [<command-name>...]

    Options:

        -h, --help      Print this help and exit.

        -V, --version   Print the version info and exit.

        -a, --all       Print *all* matching paths.

        -v, --verbose   Print out how matches were located and

                        show near misses on stderr.

        -q, --quiet     Just print out matches. I.e., do not print out

                        near misses.

        -p <altpath>, --path=<altpath>

                        An alternative path (list of directories) may

                        be specified for searching.

        -e <exts>, --exts=<exts>

                        Specify a list of extensions to consider instead

                        of the usual list (';'-separate list, Windows

                        only).

    Show the full path to the program that would be run for each given

    command name, if any. Which, like GNU's which, returns the number of

    failed arguments, or -1 when no <command-name> was given.

    Near misses include duplicates, non-regular files and (on Un*x)

    files without executable access.

"""

__revision__ = "$Id$"

__version_info__ = (1, 1, 0)

__version__ = '.'.join(map(str, __version_info__))

import os

import sys

import getopt

import stat

#---- exceptions

class WhichError(Exception):

    pass

#---- internal support stuff

def _getRegisteredExecutable(exeName):

    """Windows allow application paths to be registered in the registry."""

    registered = None

    if sys.platform.startswith('win'):

        if os.path.splitext(exeName)[1].lower() != '.exe':

            exeName += '.exe'

        import _winreg

        try:

            key = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\" +\

                  exeName

            value = _winreg.QueryValue(_winreg.HKEY_LOCAL_MACHINE, key)

            registered = (value, "from HKLM\\"+key)

        except _winreg.error:

            pass

        if registered and not os.path.exists(registered[0]):

            registered = None

    return registered

def _samefile(fname1, fname2):

    if sys.platform.startswith('win'):

        return ( os.path.normpath(os.path.normcase(fname1)) ==\

            os.path.normpath(os.path.normcase(fname2)) )

    else:

        return os.path.samefile(fname1, fname2)

def _cull(potential, matches, verbose=0):

    """Cull inappropriate matches. Possible reasons:

        - a duplicate of a previous match

        - not a disk file

        - not executable (non-Windows)

    If 'potential' is approved it is returned and added to 'matches'.

    Otherwise, None is returned.

    """

    for match in matches:  # don't yield duplicates

        if _samefile(potential[0], match[0]):

            if verbose:

                sys.stderr.write("duplicate: %s (%s)\n" % potential)

            return None

    else:

        if not stat.S_ISREG(os.stat(potential[0]).st_mode):

            if verbose:

                sys.stderr.write("not a regular file: %s (%s)\n" % potential)

        elif not os.access(potential[0], os.X_OK):

            if verbose:

                sys.stderr.write("no executable access: %s (%s)\n"\

                                 % potential)

        else:

            matches.append(potential)

            return potential

#---- module API

def whichgen(command, path=None, verbose=0, exts=None):

    """Return a generator of full paths to the given command.

    "command" is a the name of the executable to search for.

    "path" is an optional alternate path list to search. The default it

        to use the PATH environment variable.

    "verbose", if true, will cause a 2-tuple to be returned for each

        match. The second element is a textual description of where the

        match was found.

    "exts" optionally allows one to specify a list of extensions to use

        instead of the standard list for this system. This can

        effectively be used as an optimization to, for example, avoid

        stat's of "foo.vbs" when searching for "foo" and you know it is

        not a VisualBasic script but ".vbs" is on PATHEXT. This option

        is only supported on Windows.

    This method returns a generator which yields either full paths to

    the given command or, if verbose, tuples of the form (

    command>, <where path found>).

    """

    matches = []

    if path is None:

        usingGivenPath = 0

        path = os.environ.get("PATH", "").split(os.pathsep)

        if sys.platform.startswith("win"):

            path.insert(0, os.curdir)  # implied by Windows shell

    else:

        usingGivenPath = 1

    # Windows has the concept of a list of extensions (PATHEXT env var).

    if sys.platform.startswith("win"):

        if exts is None:

            exts = os.environ.get("PATHEXT", "").split(os.pathsep)

            # If '.exe' is not in exts then obviously this is Win9x and

            # or a bogus PATHEXT, then use a reasonable default.

            for ext in exts:

                if ext.lower() == ".exe":

                    break

            else:

                exts = ['.COM', '.EXE', '.BAT']

        elif not isinstance(exts, list):

            raise TypeError("'exts' argument must be a list or None")

    else:

        if exts is not None:

            raise WhichError("'exts' argument is not supported on "\

                             "platform '%s'" % sys.platform)

        exts = []

    # File name cannot have path separators because PATH lookup does not

    # work that way.

    if os.sep in command or os.altsep and os.altsep in command:

        pass

    else:

        for i in range(len(path)):

            dirName = path[i]

            # On windows the dirName *could* be quoted, drop the quotes

            if sys.platform.startswith("win") and len(dirName) >= 2\

               and dirName[0] == '"' and dirName[-1] == '"':

                dirName = dirName[1:-1]

            for ext in ['']+exts:

                absName = os.path.abspath(

                    os.path.normpath(os.path.join(dirName, command+ext)))

                if os.path.isfile(absName):

                    if usingGivenPath:

                        fromWhere = "from given path element %d" % i

                    elif not sys.platform.startswith("win"):

                        fromWhere = "from PATH element %d" % i

                    elif i == 0:

                        fromWhere = "from current directory"

                    else:

                        fromWhere = "from PATH element %d" % (i-1)

                    match = _cull((absName, fromWhere), matches, verbose)

                    if match:

                        if verbose:

                            yield match

                        else:

                            yield match[0]

        match = _getRegisteredExecutable(command)

        if match is not None:

            match = _cull(match, matches, verbose)

            if match:

                if verbose:

                    yield match

                else:

                    yield match[0]

def which(command, path=None, verbose=0, exts=None):

    """Return the full path to the first match of the given command on

    the path.

    "command" is a the name of the executable to search for.

    "path" is an optional alternate path list to search. The default it

        to use the PATH environment variable.

    "verbose", if true, will cause a 2-tuple to be returned. The second

        element is a textual description of where the match was found.

    "exts" optionally allows one to specify a list of extensions to use

        instead of the standard list for this system. This can

        effectively be used as an optimization to, for example, avoid

        stat's of "foo.vbs" when searching for "foo" and you know it is

        not a VisualBasic script but ".vbs" is on PATHEXT. This option

        is only supported on Windows.

    If no match is found for the command, a WhichError is raised.

    """

    try:

        match = whichgen(command, path, verbose, exts).next()

    except StopIteration:

        raise WhichError("Could not find '%s' on the path." % command)

    return match

def whichall(command, path=None, verbose=0, exts=None):

    """Return a list of full paths to all matches of the given command

    on the path.  

    "command" is a the name of the executable to search for.

    "path" is an optional alternate path list to search. The default it

        to use the PATH environment variable.

    "verbose", if true, will cause a 2-tuple to be returned for each

        match. The second element is a textual description of where the

        match was found.

    "exts" optionally allows one to specify a list of extensions to use

        instead of the standard list for this system. This can

        effectively be used as an optimization to, for example, avoid

        stat's of "foo.vbs" when searching for "foo" and you know it is

        not a VisualBasic script but ".vbs" is on PATHEXT. This option

        is only supported on Windows.

    """

    return list( whichgen(command, path, verbose, exts) )

#---- mainline

def main(argv):

    all = 0

    verbose = 0

    altpath = None

    exts = None

    try:

        optlist, args = getopt.getopt(argv[1:], 'haVvqp:e:',

            ['help', 'all', 'version', 'verbose', 'quiet', 'path=', 'exts='])

    except getopt.GetoptError, msg:

        sys.stderr.write("which: error: %s. Your invocation was: %s\n"\

                         % (msg, argv))

        sys.stderr.write("Try 'which --help'.\n")

        return 1

    for opt, optarg in optlist:

        if opt in ('-h', '--help'):

            print _cmdlnUsage

            return 0

        elif opt in ('-V', '--version'):

            print "which %s" % __version__

            return 0

        elif opt in ('-a', '--all'):

            all = 1

        elif opt in ('-v', '--verbose'):

            verbose = 1

        elif opt in ('-q', '--quiet'):

            verbose = 0

        elif opt in ('-p', '--path'):

            if optarg:

                altpath = optarg.split(os.pathsep)

            else:

                altpath = []

        elif opt in ('-e', '--exts'):

            if optarg:

                exts = optarg.split(os.pathsep)

            else:

                exts = []

    if len(args) == 0:

        return -1

    failures = 0

    for arg in args:

        #print "debug: search for %r" % arg

        nmatches = 0

        for match in whichgen(arg, path=altpath, verbose=verbose, exts=exts):

            if verbose:

                print "%s (%s)" % match

            else:

                print match

            nmatches += 1

            if not all:

                break

        if not nmatches:

            failures += 1

    return failures

if __name__ == "__main__":

    sys.exit( main(sys.argv) )