# keyword.py - keyword expansion for mercurial
# $Id$

'''keyword expansion hack against the grain of a DSCM

This extension lets you expand RCS/CVS-like keywords in a Mercurial
repository.

There are many good reasons why this is not needed in a distributed
SCM, still it may be useful in very small projects based on single
files (like LaTeX packages), that are mostly addressed to an audience
not running a version control system.

For in-depth discussion refer to
<http://www.selenic.com/mercurial/wiki/index.cgi/KeywordPlan>.

Keywords are only expanded in local repositories and not logged by
Mercurial internally. The mechanism can be regarded as a convenience
for the current user and may be turned off anytime.

Substitution takes place on every commit and update of the working
repository.

Keyword expansion is based on Mercurial's changeset template mappings.
The extension provides an additional UTC-date filter.

The user has the choice either to create his own keywords and their
expansions or to use the CVS-like default ones.

Default $keywords$ and their $keyword: substition $ are:
    Revision: changeset id
    Author:   username
    Date:     %Y/%m/%d %H:%M:%S [UTC]
    RCSFile:  basename,v
    Source:   /path/to/basename,v
    Id:       basename,v csetid %Y/%m/%d %H:%M:%S username
    Header:   /path/to/basename,v csetid %Y/%m/%d %H:%M:%S username

Expansions spanning more than one line are truncated to their first line.
Incremental expansion (like CVS' $Log$) is not supported.

Simple setup in hgrc:

    # enable extension
    keyword = /full/path/to/keyword.py
    # or, if script in hgext folder:
    # hgext.keyword =
    
    # filename patterns for expansion are configured in this section
    # files matching patterns with value 'ignore' are ignored
    [keyword]
    **.py =
    x* = ignore
    ...
    # in case you prefer your own keyword maps over the cvs-like defaults:
    [keywordmaps]
    HGdate = {date|rfc822date}
    lastlog = {desc} ## same as {desc|firstline} in this context
    checked in by = {author}
    ...
'''

from mercurial.i18n import gettext as _
# above line for backwards compatibility; can be changed to
#   from mercurial.i18n import _
# some day
from mercurial import context, filelog, revlog
from mercurial import commands, cmdutil, templater, util
from mercurial.node import bin
import os.path, re, sys, time

deftemplates = {
        'Revision': '{node|short}',
        'Author': '{author|user}',
        'Date': '{date|utcdate}',
        'RCSFile': '{file|basename},v',
        'Source': '{root}/{file},v',
        'Id': '{file|basename},v {node|short} {date|utcdate} {author|user}',
        'Header': '{root}/{file},v {node|short} {date|utcdate} {author|user}',
        }

def utcdate(date):
    '''Returns hgdate in cvs-like UTC format.'''
    return time.strftime('%Y/%m/%d %H:%M:%S', time.gmtime(date[0]))

def getmodulename():
    '''Makes sure pretxncommit-hook can import keyword module
    regardless of where its located.'''
    for k, v in sys.modules.iteritems():
        if v is None:
            continue
        if not hasattr(v, '__file__'):
            continue
        if v.__file__.startswith(__file__):
            return k
    else:
        sys.path.insert(0, os.path.abspath(os.path.dirname(__file__)))
        return os.path.splitext(os.path.basename(__file__))[0]

def kwfmatches(ui, repo, files):
    '''Selects candidates for keyword substitution
    configured in keyword section in hgrc.'''
    inc, exc = [], []
    for pat, opt in ui.configitems('keyword'):
        if opt != 'ignore':
            inc.append(pat)
        else:
            exc.append(pat)
    if not inc:
        ui.debug(_('keyword: no filename globs for substitution\n'))
        return []
    kwfmatcher = util.matcher(repo.root, inc=inc, exc=['.hg*']+exc)[1]
    return [f for f in files if kwfmatcher(f)]


class kwtemplater(object):
    '''
    Sets up keyword templates, corresponding keyword regex, and
    provides keyword expansion function.
    '''
    def __init__(self, ui, repo):
        self.ui = ui
        self.repo = repo
        self.templates = dict(ui.configitems('keywordmaps')) or deftemplates
        self.re_kw = re.compile(r'\$(%s)[^$]*?\$' %
                '|'.join(re.escape(k) for k in self.templates.keys()))
        templater.common_filters['utcdate'] = utcdate
        self.t = cmdutil.changeset_templater(ui, repo, False, '', False)
            

    def expand(self, mobj, path, node):
        '''Expands keyword with corresponding template.'''
        kw = mobj.group(1)
        template = templater.parsestring(self.templates[kw], quoted=False)
        self.t.use_template(template)
        self.ui.pushbuffer()
        self.t.show(changenode=node, root=self.repo.root, file=path)
        kwsub = templater.firstline(self.ui.popbuffer())
        return '$%s: %s $' % (kw, kwsub)


def reposetup(ui, repo):
    '''Sets up repo, and filelog especially, as kwrepo and kwfilelog
    for keyword substitution.  This is done for local repos only.'''

    if not repo.local():
        return


    class kwrepo(repo.__class__):
        def file(self, f):
            if f[0] == '/':
                f = f[1:]
            return filelog.filelog(self.sopener, f, self, self.revlogversion)

    class kwfilelog(filelog.filelog):
        '''
        Superclass over filelog to customize it's read, add, cmp methods.
        Keywords are "stored" unexpanded, and expanded on reading.
        '''
        def __init__(self, opener, path, repo,
                     defversion=revlog.REVLOG_DEFAULT_VERSION):
            super(kwfilelog, self).__init__(opener, path, defversion)
            self._repo = repo
            self._path = path
            # only init kwtemplater if needed
            if not isinstance(repo, int) and kwfmatches(ui, repo, [path]):
                self.kwt = kwtemplater(ui, repo)
            else:
                self.kwt = None

        def iskwcandidate(self, data):
            '''Decides whether to act on keywords.'''
            return self.kwt is not None and not util.binary(data)

        def read(self, node):
            '''Substitutes keywords when reading filelog.'''
            data = super(kwfilelog, self).read(node)
            if self.iskwcandidate(data):
                c = context.filectx(self._repo, self._path,
                                    fileid=node, filelog=self)
                return self.kwt.re_kw.sub(lambda m:
                        self.kwt.expand(m, self._path, c.node()), data)
            return data

        def add(self, text, meta, tr, link, p1=None, p2=None):
            '''Removes keyword substitutions when adding to filelog.'''
            if self.iskwcandidate(text):
                text = self.kwt.re_kw.sub(r'$\1$', text)
            return super(kwfilelog, self).add(text,
                            meta, tr, link, p1=p1, p2=p2)

        def cmp(self, node, text):
            '''Removes keyword substitutions for comparison.'''
            if self.iskwcandidate(text):
                text = self.kwt.re_kw.sub(r'$\1$', text)
            return super(kwfilelog, self).cmp(node, text)

    filelog.filelog = kwfilelog
    repo.__class__ = kwrepo
    # configure pretxncommit hook
    ui.setconfig('hooks', 'pretxncommit.keyword',
            'python:%s.pretxnkw' % getmodulename())


def pretxnkw(ui, repo, hooktype, **args):
    '''pretxncommit hook that collects candidates for keyword expansion
    on commit and expands keywords in working dir.'''

    cmd, sysargs, globalopts, cmdopts = commands.parse(ui, sys.argv[1:])[1:]
    if repr(cmd).split()[1] in ('tag', 'import_'):
        return

    files, match, anypats = cmdutil.matchpats(repo, sysargs, cmdopts)
    modified, added = repo.status(files=files, match=match)[:2]
    candidates = kwfmatches(ui, repo, modified+added)
    if not candidates:
        return

    kwt = kwtemplater(ui, repo)
    node = bin(args['node'])
    for f in candidates:
        data = repo.wfile(f).read()
        if not util.binary(data):
            data, kwct = kwt.re_kw.subn(lambda m: kwt.expand(m, f, node), data)
            if kwct:
                ui.debug(_('overwriting %s expanding keywords\n' % f))
                repo.wfile(f, 'w').write(data)