# $Hg$

from mercurial.i18n import _
from mercurial import util
import re

def expandkw(ui, repo, rev, cid, candidates, update=False):
    '''Important: returns False on success, True on failure.'''

    # name of keyword encode filter:
    kwencodefilter = 'hgkwencode'

    # update only needs string search for encoded keyword
    # as hgkwencode always runs before
    kwstr = '%sHg$' % '$'

    # pretxncommit looks for both encoded and decoded keywords
    kwpat = r'[$]Hg(: %s,v [a-z0-9]{12} [^$]+? )?\$'

    def wwritekw(ui, repo, f, text):
        '''Writes text with kwupdates keywords to f in working directory.'''
        ui.note(_('expanding keywords in %s\n' % f))
        # backup file, at least when commiting (?)
        repo.wfile(f, 'w').write(text)

    # only check files that have hgkwencode assigned as encode filter
    files = []
    # python2.4: files = set()
    for pat, cmd in repo.ui.configitems('encode'):
        if cmd.endswith(kwencodefilter):
            mf = util.matcher(repo.root, '', [pat], [], [])[1]
            for candidate in candidates:
                if mf(candidate) and candidate not in files:
                    files.append(candidate)
                # python2.4:
                # if mf(candidate): files.add(candidate)

    if not files: # nothing to do
        return False

    user, date = repo.changelog.read(rev)[1:3]
    user = util.shortuser(user)
    date = util.datestr(date=date, format=util.defaultdateformats[2])
                                               # %Y-%m-%d %H:%M

    # collect filenames that were changed by hg update
    kwupdates = []

    for f in files:

        text = repo.wfile(f).read()
        if not util.binary(text):

            # TODO for update:
            # walk back through file history onto last add/modify
            # like "hg log -l1 f"
            kw = '%sHg: %s,v %s %s %s $' % ('$', f, cid, date, user)

            if update and text.find(kwstr) > -1:
                text = text.replace(kwstr, kw)
                wwritekw(ui, repo, f, text)
                kwupdates.append(f)
            
            elif not update:
                re_kw = re.compile(kwpat % f)
                text, kwct = re_kw.subn(kw, text)
                if kwct:
                    wwritekw(ui, repo, f, text)

    if kwupdates:
        # cheat hg to believe that updated files were not modified
        repo.dirstate.update(kwupdates, 'n')