# logtoprocess.py - send ui.log() data to a subprocess

#

# Copyright 2016 Facebook, Inc.

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

"""send ui.log() data to a subprocess (EXPERIMENTAL)

This extension lets you specify a shell command per ui.log() event,

sending all remaining arguments to as environment variables to that command.

Each positional argument to the method results in a `MSG[N]` key in the

environment, starting at 1 (so `MSG1`, `MSG2`, etc.). Each keyword argument

is set as a `OPT_UPPERCASE_KEY` variable (so the key is uppercased, and

prefixed with `OPT_`). The original event name is passed in the `EVENT`

environment variable, and the process ID of mercurial is given in `HGPID`.

So given a call `ui.log('foo', 'bar', 'baz', spam='eggs'), a script configured

for the `foo` event can expect an environment with `MSG1=bar`, `MSG2=baz`, and

`OPT_SPAM=eggs`.

Scripts are configured in the `[logtoprocess]` section, each key an event name.

For example::

  [logtoprocess]

  commandexception = echo "$MSG2$MSG3" > /var/log/mercurial_exceptions.log

would log the warning message and traceback of any failed command dispatch.

Scripts are run asynchronously as detached daemon processes; mercurial will

not ensure that they exit cleanly.

"""

from __future__ import absolute_import

import itertools

import os

from mercurial.utils import (

    procutil,

)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for

# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should

# be specifying the version(s) of Mercurial they are tested with, or

# leave the attribute unspecified.

testedwith = 'ships-with-hg-core'

def uisetup(ui):

    class logtoprocessui(ui.__class__):

        def log(self, event, *msg, **opts):

            """Map log events to external commands

            Arguments are passed on as environment variables.

            """

            script = self.config('logtoprocess', event)

            if script:

                if msg:

                    # try to format the log message given the remaining

                    # arguments

                    try:

                        # Format the message as blackbox does

                        formatted = msg[0] % msg[1:]

                    except (TypeError, KeyError):

                        # Failed to apply the arguments, ignore

                        formatted = msg[0]

                    messages = (formatted,) + msg[1:]

                else:

                    messages = msg

                # positional arguments are listed as MSG[N] keys in the

                # environment

                msgpairs = (

                    ('MSG{0:d}'.format(i), str(m))

                    for i, m in enumerate(messages, 1))

                # keyword arguments get prefixed with OPT_ and uppercased

                optpairs = (

                    ('OPT_{0}'.format(key.upper()), str(value))

                    for key, value in opts.iteritems())

                env = dict(itertools.chain(procutil.shellenviron().items(),

                                           msgpairs, optpairs),

                           EVENT=event, HGPID=str(os.getpid()))

            return super(logtoprocessui, self).log(event, *msg, **opts)

    # Replace the class for this instance and all clones created from it:

    ui.__class__ = logtoprocessui