# keyword.py - keyword expansion for Mercurial
# $Id$
# 
# Keyword expansion hack against the grain of a DSCM
# 
# 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>.
#
# Keyword expansion is based on Mercurial's changeset template mappings.
# The extension provides an additional UTC-date filter ({date|utcdate}).
#
# 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}
#     ...

'''keyword expansion in local repositories

This extension expands RCS/CVS-like or self-customized keywords in
the text files selected by your configuration.

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.

Configuration is done in the [keyword] and [keywordmaps] sections of
hgrc files.
'''
 
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 and weeds out candidates for keyword substitution
    by patterns configured in [keyword] section in hgrc.'''
    inc, exc = [], ['.hg*']
    for pat, opt in ui.configitems('keyword'):
        if opt != 'ignore':
            inc.append(pat)
        else:
            exc.append(pat)
    if not inc:
        return []
    kwfmatcher = util.matcher(repo.root, inc=inc, exc=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 using 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)