# pager.py - display output using a pager

#

# Copyright 2008 David Soria Parra <dsp@php.net>

#

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

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

#

# To load the extension, add it to your configuration file:

#

#   [extension]

#   pager =

#

# Run "hg help pager" to get info on configuration.

'''browse command output with an external pager

To set the pager that should be used, set the application variable::

  [pager]

  pager = less -FRSX

If no pager is set, the pager extensions uses the environment variable

$PAGER. If neither pager.pager, nor $PAGER is set, no pager is used.

You can disable the pager for certain commands by adding them to the

pager.ignore list::

  [pager]

  ignore = version, help, update

You can also enable the pager only for certain commands using

pager.attend. Below is the default list of commands to be paged::

  [pager]

  attend = annotate, cat, diff, export, glog, log, qdiff

Setting pager.attend to an empty value will cause all commands to be

paged.

If pager.attend is present, pager.ignore will be ignored.

To ignore global commands like :hg:`version` or :hg:`help`, you have

to specify them in your user configuration file.

The --pager=... option can also be used to control when the pager is

used. Use a boolean value like yes, no, on, off, or use auto for

normal behavior.

'''

import atexit, sys, os, signal, subprocess

from mercurial import commands, dispatch, util, extensions

from mercurial.i18n import _

def _runpager(p):

    pager = subprocess.Popen(p, shell=True, bufsize=-1,

                             close_fds=util.closefds, stdin=subprocess.PIPE,

                             stdout=sys.stdout, stderr=sys.stderr)

    stdout = os.dup(sys.stdout.fileno())

    stderr = os.dup(sys.stderr.fileno())

    os.dup2(pager.stdin.fileno(), sys.stdout.fileno())

    if util.isatty(sys.stderr):

        os.dup2(pager.stdin.fileno(), sys.stderr.fileno())

    @atexit.register

    def killpager():

        pager.stdin.close()

        os.dup2(stdout, sys.stdout.fileno())

        os.dup2(stderr, sys.stderr.fileno())

        pager.wait()

def uisetup(ui):

    if ui.plain() or '--debugger' in sys.argv or not util.isatty(sys.stdout):

        return

    def pagecmd(orig, ui, options, cmd, cmdfunc):

        p = ui.config("pager", "pager", os.environ.get("PAGER"))

        if p:

            attend = ui.configlist('pager', 'attend', attended)

            auto = options['pager'] == 'auto'

            always = util.parsebool(options['pager'])

            if (always or auto and

                (cmd in attend or

                 (cmd not in ui.configlist('pager', 'ignore') and not attend))):

                ui.setconfig('ui', 'formatted', ui.formatted())

                ui.setconfig('ui', 'interactive', False)

                try:

                    signal.signal(signal.SIGPIPE, signal.SIG_DFL)

                except ValueError:

                    pass

                _runpager(p)

        return orig(ui, options, cmd, cmdfunc)

    extensions.wrapfunction(dispatch, '_runcommand', pagecmd)

def extsetup(ui):

    commands.globalopts.append(

        ('', 'pager', 'auto',

         _("when to paginate (boolean, always, auto, or never)"),

         _('TYPE')))

attended = ['annotate', 'cat', 'diff', 'export', 'glog', 'log', 'qdiff']