"""A generic class to build line-oriented command interpreters.

Interpreters constructed with this class obey the following conventions:

1. End of file on input is processed as the command 'EOF'.

2. A command is parsed out of each line by collecting the prefix composed

   of characters in the identchars member.

3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method

   is passed a single argument consisting of the remainder of the line.

4. Typing an empty line repeats the last command.  (Actually, it calls the

   method `emptyline', which may be overridden in a subclass.)

5. There is a predefined `help' method.  Given an argument `topic', it

   calls the command `help_topic'.  With no arguments, it lists all topics

   with defined help_ functions, broken into up to three topics; documented

   commands, miscellaneous help topics, and undocumented commands.

6. The command '?' is a synonym for `help'.  The command '!' is a synonym

   for `shell', if a do_shell method exists.

7. If completion is enabled, completing commands will be done automatically,

   and completing of commands args is done by calling complete_foo() with

   arguments text, line, begidx, endidx.  text is string we are matching

   against, all returned matches must begin with it.  line is the current

   input line (lstripped), begidx and endidx are the beginning and end

   indexes of the text being matched, which could be used to provide

   different completion depending upon which position the argument is in.

The `default' method may be overridden to intercept commands for which there

is no do_ method.

The `completedefault' method may be overridden to intercept completions for

commands that have no complete_ method.

The data member `self.ruler' sets the character used to draw separator lines

in the help messages.  If empty, no ruler line is drawn.  It defaults to "=".

If the value of `self.intro' is nonempty when the cmdloop method is called,

it is printed out on interpreter startup.  This value may be overridden

via an optional argument to the cmdloop() method.

The data members `self.doc_header', `self.misc_header', and

`self.undoc_header' set the headers used for the help function's

listings of documented functions, miscellaneous topics, and undocumented

functions respectively.

These interpreters use raw_input; thus, if the readline module is loaded,

they automatically support Emacs-like command history and editing features.

"""

import string

__all__ = ["Cmd"]

PROMPT = '(Cmd) '

IDENTCHARS = string.ascii_letters + string.digits + '_'

class Cmd:

    """A simple framework for writing line-oriented command interpreters.

    These are often useful for test harnesses, administrative tools, and

    prototypes that will later be wrapped in a more sophisticated interface.

    A Cmd instance or subclass instance is a line-oriented interpreter

    framework.  There is no good reason to instantiate Cmd itself; rather,

    it's useful as a superclass of an interpreter class you define yourself

    in order to inherit Cmd's methods and encapsulate action methods.

    """

    prompt = PROMPT

    identchars = IDENTCHARS

    ruler = '='

    lastcmd = ''

    intro = None

    doc_leader = ""

    doc_header = "Documented commands (type help <topic>):"

    misc_header = "Miscellaneous help topics:"

    undoc_header = "Undocumented commands:"

    nohelp = "*** No help on %s"

    use_rawinput = 1

    def __init__(self, completekey='tab', stdin=None, stdout=None):

        """Instantiate a line-oriented interpreter framework.

        The optional argument 'completekey' is the readline name of a

        completion key; it defaults to the Tab key. If completekey is

        not None and the readline module is available, command completion

        is done automatically. The optional arguments stdin and stdout

        specify alternate input and output file objects; if not specified,

        sys.stdin and sys.stdout are used.

        """

        import sys

        if stdin is not None:

            self.stdin = stdin

        else:

            self.stdin = sys.stdin

        if stdout is not None:

            self.stdout = stdout

        else:

            self.stdout = sys.stdout

        self.cmdqueue = []

        self.completekey = completekey

    def cmdloop(self, intro=None):

        """Repeatedly issue a prompt, accept input, parse an initial prefix

        off the received input, and dispatch to action methods, passing them

        the remainder of the line as argument.

        """

        self.preloop()

        if self.use_rawinput and self.completekey:

            try:

                import readline

                self.old_completer = readline.get_completer()

                readline.set_completer(self.complete)

                readline.parse_and_bind(self.completekey+": complete")

            except ImportError:

                pass

        try:

            if intro is not None:

                self.intro = intro

            if self.intro:

                self.stdout.write(str(self.intro)+"\n")

            stop = None

            while not stop:

                if self.cmdqueue:

                    line = self.cmdqueue.pop(0)

                else:

                    if self.use_rawinput:

                        try:

                            line = raw_input(self.prompt)

                        except EOFError:

                            line = 'EOF'

                    else:

                        self.stdout.write(self.prompt)

                        self.stdout.flush()

                        line = self.stdin.readline()

                        if not len(line):

                            line = 'EOF'

                        else:

                            line = line[:-1] # chop \n

                line = self.precmd(line)

                stop = self.onecmd(line)

                stop = self.postcmd(stop, line)

            self.postloop()

        finally:

            if self.use_rawinput and self.completekey:

                try:

                    import readline

                    readline.set_completer(self.old_completer)

                except ImportError:

                    pass

    def precmd(self, line):

        """Hook method executed just before the command line is

        interpreted, but after the input prompt is generated and issued.

        """

        return line

    def postcmd(self, stop, line):

        """Hook method executed just after a command dispatch is finished."""

        return stop

    def preloop(self):

        """Hook method executed once when the cmdloop() method is called."""

        pass

    def postloop(self):

        """Hook method executed once when the cmdloop() method is about to

        return.

        """

        pass

    def parseline(self, line):

        """Parse the line into a command name and a string containing

        the arguments.  Returns a tuple containing (command, args, line).

        'command' and 'args' may be None if the line couldn't be parsed.

        """

        line = line.strip()

        if not line:

            return None, None, line

        elif line[0] == '?':

            line = 'help ' + line[1:]

        elif line[0] == '!':

            if hasattr(self, 'do_shell'):

                line = 'shell ' + line[1:]

            else:

                return None, None, line

        i, n = 0, len(line)

        while i < n and line[i] in self.identchars: i = i+1

        cmd, arg = line[:i], line[i:].strip()

        return cmd, arg, line

    def onecmd(self, line):

        """Interpret the argument as though it had been typed in response

        to the prompt.

        This may be overridden, but should not normally need to be;

        see the precmd() and postcmd() methods for useful execution hooks.

        The return value is a flag indicating whether interpretation of

        commands by the interpreter should stop.

        """

        cmd, arg, line = self.parseline(line)

        if not line:

            return self.emptyline()

        if cmd is None:

            return self.default(line)

        self.lastcmd = line

        if cmd == '':

            return self.default(line)

        else:

            try:

                func = getattr(self, 'do_' + cmd)

            except AttributeError:

                return self.default(line)

            return func(arg)

    def emptyline(self):

        """Called when an empty line is entered in response to the prompt.

        If this method is not overridden, it repeats the last nonempty

        command entered.

        """

        if self.lastcmd:

            return self.onecmd(self.lastcmd)

    def default(self, line):

        """Called on an input line when the command prefix is not recognized.

        If this method is not overridden, it prints an error message and

        returns.

        """

        self.stdout.write('*** Unknown syntax: %s\n'%line)

    def completedefault(self, *ignored):

        """Method called to complete an input line when no command-specific

        complete_*() method is available.

        By default, it returns an empty list.

        """

        return []

    def completenames(self, text, *ignored):

        dotext = 'do_'+text

        return [a[3:] for a in self.get_names() if a.startswith(dotext)]

    def complete(self, text, state):

        """Return the next possible completion for 'text'.

        If a command has not been entered, then complete against command list.

        Otherwise try to call complete_<command> to get list of completions.

        """

        if state == 0:

            import readline

            origline = readline.get_line_buffer()

            line = origline.lstrip()

            stripped = len(origline) - len(line)

            begidx = readline.get_begidx() - stripped

            endidx = readline.get_endidx() - stripped

            if begidx>0:

                cmd, args, foo = self.parseline(line)

                if cmd == '':

                    compfunc = self.completedefault

                else:

                    try:

                        compfunc = getattr(self, 'complete_' + cmd)

                    except AttributeError:

                        compfunc = self.completedefault

            else:

                compfunc = self.completenames

            self.completion_matches = compfunc(text, line, begidx, endidx)

        try:

            return self.completion_matches[state]

        except IndexError:

            return None

    def get_names(self):

        # Inheritance says we have to look in class and

        # base classes; order is not important.

        names = []

        classes = [self.__class__]

        while classes:

            aclass = classes.pop(0)

            if aclass.__bases__:

                classes = classes + list(aclass.__bases__)

            names = names + dir(aclass)

        return names

    def complete_help(self, *args):

        return self.completenames(*args)

    def do_help(self, arg):

        if arg:

            # XXX check arg syntax

            try:

                func = getattr(self, 'help_' + arg)

            except AttributeError:

                try:

                    doc=getattr(self, 'do_' + arg).__doc__

                    if doc:

                        self.stdout.write("%s\n"%str(doc))

                        return

                except AttributeError:

                    pass

                self.stdout.write("%s\n"%str(self.nohelp % (arg,)))

                return

            func()

        else:

            names = self.get_names()

            cmds_doc = []

            cmds_undoc = []

            help = {}

            for name in names:

                if name[:5] == 'help_':

                    help[name[5:]]=1

            names.sort()

            # There can be duplicates if routines overridden

            prevname = ''

            for name in names:

                if name[:3] == 'do_':

                    if name == prevname:

                        continue

                    prevname = name

                    cmd=name[3:]

                    if cmd in help:

                        cmds_doc.append(cmd)

                        del help[cmd]

                    elif getattr(self, name).__doc__:

                        cmds_doc.append(cmd)

                    else:

                        cmds_undoc.append(cmd)

            self.stdout.write("%s\n"%str(self.doc_leader))

            self.print_topics(self.doc_header,   cmds_doc,   15,80)

            self.print_topics(self.misc_header,  help.keys(),15,80)

            self.print_topics(self.undoc_header, cmds_undoc, 15,80)

    def print_topics(self, header, cmds, cmdlen, maxcol):

        if cmds:

            self.stdout.write("%s\n"%str(header))

            if self.ruler:

                self.stdout.write("%s\n"%str(self.ruler * len(header)))

            self.columnize(cmds, maxcol-1)

            self.stdout.write("\n")

    def columnize(self, list, displaywidth=80):

        """Display a list of strings as a compact set of columns.

        Each column is only as wide as necessary.

        Columns are separated by two spaces (one was not legible enough).

        """

        if not list:

            self.stdout.write("<empty>\n")

            return

        nonstrings = [i for i in range(len(list))

                        if not isinstance(list[i], str)]

        if nonstrings:

            raise TypeError, ("list[i] not a string for i in %s" %

                              ", ".join(map(str, nonstrings)))

        size = len(list)

        if size == 1:

            self.stdout.write('%s\n'%str(list[0]))

            return

        # Try every row count from 1 upwards

        for nrows in range(1, len(list)):

            ncols = (size+nrows-1) // nrows

            colwidths = []

            totwidth = -2

            for col in range(ncols):

                colwidth = 0

                for row in range(nrows):

                    i = row + nrows*col

                    if i >= size:

                        break

                    x = list[i]

                    colwidth = max(colwidth, len(x))

                colwidths.append(colwidth)

                totwidth += colwidth + 2

                if totwidth > displaywidth:

                    break

            if totwidth <= displaywidth:

                break

        else:

            nrows = len(list)

            ncols = 1

            colwidths = [0]

        for row in range(nrows):

            texts = []

            for col in range(ncols):

                i = row + nrows*col

                if i >= size:

                    x = ""

                else:

                    x = list[i]

                texts.append(x)

            while texts and not texts[-1]:

                del texts[-1]

            for col in range(len(texts)):

                texts[col] = texts[col].ljust(colwidths[col])

            self.stdout.write("%s\n"%str("  ".join(texts)))