# 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 -FRX

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.

Lastly, you can enable and disable paging for individual commands with

the attend-<command> option. This setting takes precedence over

existing attend and ignore options and defaults::

  [pager]

  attend-cat = false

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, errno, shlex

from mercurial import commands, dispatch, util, extensions, cmdutil

from mercurial.i18n import _

testedwith = 'internal'

def _pagerfork(ui, p):

    if not util.safehasattr(os, 'fork'):

        sys.stdout = util.popen(p, 'wb')

        if ui._isatty(sys.stderr):

            sys.stderr = sys.stdout

        return

    fdin, fdout = os.pipe()

    pid = os.fork()

    if pid == 0:

        os.close(fdin)

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

        if ui._isatty(sys.stderr):

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

        os.close(fdout)

        return

    os.dup2(fdin, sys.stdin.fileno())

    os.close(fdin)

    os.close(fdout)

    try:

        os.execvp('/bin/sh', ['/bin/sh', '-c', p])

    except OSError, e:

        if e.errno == errno.ENOENT:

            # no /bin/sh, try executing the pager directly

            args = shlex.split(p)

            os.execvp(args[0], args)

        else:

            raise

def _pagersubprocess(ui, 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 ui._isatty(sys.stderr):

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

    @atexit.register

    def killpager():

        if util.safehasattr(signal, "SIGINT"):

            signal.signal(signal.SIGINT, signal.SIG_IGN)

        pager.stdin.close()

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

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

        pager.wait()

def _runpager(ui, p):

    # The subprocess module shipped with Python <= 2.4 is buggy (issue3533).

    # The compat version is buggy on Windows (issue3225), but has been shipping

    # with hg for a long time.  Preserve existing functionality.

    if sys.version_info >= (2, 5):

        _pagersubprocess(ui, p)

    else:

        _pagerfork(ui, p)

def uisetup(ui):

    if '--debugger' in sys.argv or not ui.formatted():

        return

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

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

        usepager = False

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

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

        if not p:

            pass

        elif always:

            usepager = True

        elif not auto:

            usepager = False

        else:

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

            ignore = ui.configlist('pager', 'ignore')

            cmds, _ = cmdutil.findcmd(cmd, commands.table)

            for cmd in cmds:

                var = 'attend-%s' % cmd

                if ui.config('pager', var):

                    usepager = ui.configbool('pager', var)

                    break

                if (cmd in attend or

                     (cmd not in ignore and not attend)):

                    usepager = True

                    break

        setattr(ui, 'pageractive', usepager)

        if usepager:

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

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

            if util.safehasattr(signal, "SIGPIPE"):

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

            _runpager(ui, p)

        return orig(ui, options, cmd, cmdfunc)

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']