"""Python part of the warnings subsystem."""

# Note: function level imports should *not* be used

# in this module as it may cause import lock deadlock.

# See bug 683658.

import sys, types

import linecache

__all__ = ["warn", "showwarning", "formatwarning", "filterwarnings",

           "resetwarnings"]

# filters contains a sequence of filter 5-tuples

# The components of the 5-tuple are:

# - an action: error, ignore, always, default, module, or once

# - a compiled regex that must match the warning message

# - a class representing the warning category

# - a compiled regex that must match the module that is being warned

# - a line number for the line being warning, or 0 to mean any line

# If either if the compiled regexs are None, match anything.

filters = []

defaultaction = "default"

onceregistry = {}

def warn(message, category=None, stacklevel=1):

    """Issue a warning, or maybe ignore it or raise an exception."""

    # Check if message is already a Warning object

    if isinstance(message, Warning):

        category = message.__class__

    # Check category argument

    if category is None:

        category = UserWarning

    assert issubclass(category, Warning)

    # Get context information

    try:

        caller = sys._getframe(stacklevel)

    except ValueError:

        globals = sys.__dict__

        lineno = 1

    else:

        globals = caller.f_globals

        lineno = caller.f_lineno

    if '__name__' in globals:

        module = globals['__name__']

    else:

        module = "<string>"

    filename = globals.get('__file__')

    if filename:

        fnl = filename.lower()

        if fnl.endswith((".pyc", ".pyo")):

            filename = filename[:-1]

    else:

        if module == "__main__":

            try:

                filename = sys.argv[0]

            except AttributeError:

                # embedded interpreters don't have sys.argv, see bug #839151

                filename = '__main__'

        if not filename:

            filename = module

    registry = globals.setdefault("__warningregistry__", {})

    warn_explicit(message, category, filename, lineno, module, registry,

                  globals)

def warn_explicit(message, category, filename, lineno,

                  module=None, registry=None, module_globals=None):

    if module is None:

        module = filename or "<unknown>"

        if module[-3:].lower() == ".py":

            module = module[:-3] # XXX What about leading pathname?

    if registry is None:

        registry = {}

    if isinstance(message, Warning):

        text = str(message)

        category = message.__class__

    else:

        text = message

        message = category(message)

    key = (text, category, lineno)

    # Quick test for common case

    if registry.get(key):

        return

    # Search the filters

    for item in filters:

        action, msg, cat, mod, ln = item

        if ((msg is None or msg.match(text)) and

            issubclass(category, cat) and

            (mod is None or mod.match(module)) and

            (ln == 0 or lineno == ln)):

            break

    else:

        action = defaultaction

    # Early exit actions

    if action == "ignore":

        registry[key] = 1

        return

    # Prime the linecache for formatting, in case the

    # "file" is actually in a zipfile or something.

    linecache.getlines(filename, module_globals)

    if action == "error":

        raise message

    # Other actions

    if action == "once":

        registry[key] = 1

        oncekey = (text, category)

        if onceregistry.get(oncekey):

            return

        onceregistry[oncekey] = 1

    elif action == "always":

        pass

    elif action == "module":

        registry[key] = 1

        altkey = (text, category, 0)

        if registry.get(altkey):

            return

        registry[altkey] = 1

    elif action == "default":

        registry[key] = 1

    else:

        # Unrecognized actions are errors

        raise RuntimeError(

              "Unrecognized action (%r) in warnings.filters:\n %s" %

              (action, item))

    # Print message and context

    showwarning(message, category, filename, lineno)

def showwarning(message, category, filename, lineno, file=None):

    """Hook to write a warning to a file; replace if you like."""

    if file is None:

        file = sys.stderr

    try:

        file.write(formatwarning(message, category, filename, lineno))

    except IOError:

        pass # the file (probably stderr) is invalid - this warning gets lost.

def formatwarning(message, category, filename, lineno):

    """Function to format a warning the standard way."""

    s =  "%s:%s: %s: %s\n" % (filename, lineno, category.__name__, message)

    line = linecache.getline(filename, lineno).strip()

    if line:

        s = s + "  " + line + "\n"

    return s

def filterwarnings(action, message="", category=Warning, module="", lineno=0,

                   append=0):

    """Insert an entry into the list of warnings filters (at the front).

    Use assertions to check that all arguments have the right type."""

    import re

    assert action in ("error", "ignore", "always", "default", "module",

                      "once"), "invalid action: %r" % (action,)

    assert isinstance(message, basestring), "message must be a string"

    assert isinstance(category, (type, types.ClassType)), \

           "category must be a class"

    assert issubclass(category, Warning), "category must be a Warning subclass"

    assert isinstance(module, basestring), "module must be a string"

    assert isinstance(lineno, int) and lineno >= 0, \

           "lineno must be an int >= 0"

    item = (action, re.compile(message, re.I), category,

            re.compile(module), lineno)

    if append:

        filters.append(item)

    else:

        filters.insert(0, item)

def simplefilter(action, category=Warning, lineno=0, append=0):

    """Insert a simple entry into the list of warnings filters (at the front).

    A simple filter matches all modules and messages.

    """

    assert action in ("error", "ignore", "always", "default", "module",

                      "once"), "invalid action: %r" % (action,)

    assert isinstance(lineno, int) and lineno >= 0, \

           "lineno must be an int >= 0"

    item = (action, None, category, None, lineno)

    if append:

        filters.append(item)

    else:

        filters.insert(0, item)

def resetwarnings():

    """Clear the list of warning filters, so that no filters are active."""

    filters[:] = []

class _OptionError(Exception):

    """Exception used by option processing helpers."""

    pass

# Helper to process -W options passed via sys.warnoptions

def _processoptions(args):

    for arg in args:

        try:

            _setoption(arg)

        except _OptionError, msg:

            print >>sys.stderr, "Invalid -W option ignored:", msg

# Helper for _processoptions()

def _setoption(arg):

    import re

    parts = arg.split(':')

    if len(parts) > 5:

        raise _OptionError("too many fields (max 5): %r" % (arg,))

    while len(parts) < 5:

        parts.append('')

    action, message, category, module, lineno = [s.strip()

                                                 for s in parts]

    action = _getaction(action)

    message = re.escape(message)

    category = _getcategory(category)

    module = re.escape(module)

    if module:

        module = module + '$'

    if lineno:

        try:

            lineno = int(lineno)

            if lineno < 0:

                raise ValueError

        except (ValueError, OverflowError):

            raise _OptionError("invalid lineno %r" % (lineno,))

    else:

        lineno = 0

    filterwarnings(action, message, category, module, lineno)

# Helper for _setoption()

def _getaction(action):

    if not action:

        return "default"

    if action == "all": return "always" # Alias

    for a in ('default', 'always', 'ignore', 'module', 'once', 'error'):

        if a.startswith(action):

            return a

    raise _OptionError("invalid action: %r" % (action,))

# Helper for _setoption()

def _getcategory(category):

    import re

    if not category:

        return Warning

    if re.match("^[a-zA-Z0-9_]+$", category):

        try:

            cat = eval(category)

        except NameError:

            raise _OptionError("unknown warning category: %r" % (category,))

    else:

        i = category.rfind(".")

        module = category[:i]

        klass = category[i+1:]

        try:

            m = __import__(module, None, None, [klass])

        except ImportError:

            raise _OptionError("invalid module name: %r" % (module,))

        try:

            cat = getattr(m, klass)

        except AttributeError:

            raise _OptionError("unknown warning category: %r" % (category,))

    if not issubclass(cat, Warning):

        raise _OptionError("invalid warning category: %r" % (category,))

    return cat

# Module initialization

_processoptions(sys.warnoptions)

simplefilter("ignore", category=PendingDeprecationWarning, append=1)

simplefilter("ignore", category=ImportWarning, append=1)