# hgweb/hgweb_mod.py - Web interface for a repository.
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import os, mimetypes, re, mimetools, cStringIO
from mercurial.node import *
from mercurial import mdiff, ui, hg, util, archival, patch, hook
from mercurial import revlog, templater
from common import ErrorResponse, get_mtime, style_map, paritygen, get_contact
from request import wsgirequest
import webcommands, protocol

shortcuts = {
    'cl': [('cmd', ['changelog']), ('rev', None)],
    'sl': [('cmd', ['shortlog']), ('rev', None)],
    'cs': [('cmd', ['changeset']), ('node', None)],
    'f': [('cmd', ['file']), ('filenode', None)],
    'fl': [('cmd', ['filelog']), ('filenode', None)],
    'fd': [('cmd', ['filediff']), ('node', None)],
    'fa': [('cmd', ['annotate']), ('filenode', None)],
    'mf': [('cmd', ['manifest']), ('manifest', None)],
    'ca': [('cmd', ['archive']), ('node', None)],
    'tags': [('cmd', ['tags'])],
    'tip': [('cmd', ['changeset']), ('node', ['tip'])],
    'static': [('cmd', ['static']), ('file', None)]
}

def _up(p):
    if p[0] != "/":
        p = "/" + p
    if p[-1] == "/":
        p = p[:-1]
    up = os.path.dirname(p)
    if up == "/":
        return "/"
    return up + "/"

def revnavgen(pos, pagelen, limit, nodefunc):
    def seq(factor, limit=None):
        if limit:
            yield limit
            if limit >= 20 and limit <= 40:
                yield 50
        else:
            yield 1 * factor
            yield 3 * factor
        for f in seq(factor * 10):
            yield f

    def nav(**map):
        l = []
        last = 0
        for f in seq(1, pagelen):
            if f < pagelen or f <= last:
                continue
            if f > limit:
                break
            last = f
            if pos + f < limit:
                l.append(("+%d" % f, hex(nodefunc(pos + f).node())))
            if pos - f >= 0:
                l.insert(0, ("-%d" % f, hex(nodefunc(pos - f).node())))

        try:
            yield {"label": "(0)", "node": hex(nodefunc('0').node())}

            for label, node in l:
                yield {"label": label, "node": node}

            yield {"label": "tip", "node": "tip"}
        except hg.RepoError:
            pass

    return nav

class hgweb(object):
    def __init__(self, repo, name=None):
        if isinstance(repo, str):
            parentui = ui.ui(report_untrusted=False, interactive=False)
            self.repo = hg.repository(parentui, repo)
        else:
            self.repo = repo

        hook.redirect(True)
        self.mtime = -1
        self.reponame = name
        self.archives = 'zip', 'gz', 'bz2'
        self.stripecount = 1
        # a repo owner may set web.templates in .hg/hgrc to get any file
        # readable by the user running the CGI script
        self.templatepath = self.config("web", "templates",
                                        templater.templatepath(),
                                        untrusted=False)

    # The CGI scripts are often run by a user different from the repo owner.
    # Trust the settings from the .hg/hgrc files by default.
    def config(self, section, name, default=None, untrusted=True):
        return self.repo.ui.config(section, name, default,
                                   untrusted=untrusted)

    def configbool(self, section, name, default=False, untrusted=True):
        return self.repo.ui.configbool(section, name, default,
                                       untrusted=untrusted)

    def configlist(self, section, name, default=None, untrusted=True):
        return self.repo.ui.configlist(section, name, default,
                                       untrusted=untrusted)

    def refresh(self):
        mtime = get_mtime(self.repo.root)
        if mtime != self.mtime:
            self.mtime = mtime
            self.repo = hg.repository(self.repo.ui, self.repo.root)
            self.maxchanges = int(self.config("web", "maxchanges", 10))
            self.stripecount = int(self.config("web", "stripes", 1))
            self.maxshortchanges = int(self.config("web", "maxshortchanges", 60))
            self.maxfiles = int(self.config("web", "maxfiles", 10))
            self.allowpull = self.configbool("web", "allowpull", True)
            self.encoding = self.config("web", "encoding", util._encoding)

    def run(self):
        if not os.environ.get('GATEWAY_INTERFACE', '').startswith("CGI/1."):
            raise RuntimeError("This function is only intended to be called while running as a CGI script.")
        import mercurial.hgweb.wsgicgi as wsgicgi
        wsgicgi.launch(self)

    def __call__(self, env, respond):
        req = wsgirequest(env, respond)
        self.run_wsgi(req)
        return req

    def run_wsgi(self, req):

        self.refresh()

        # expand form shortcuts

        for k in shortcuts.iterkeys():
            if k in req.form:
                for name, value in shortcuts[k]:
                    if value is None:
                        value = req.form[k]
                    req.form[name] = value
                del req.form[k]

        # work with CGI variables to create coherent structure
        # use SCRIPT_NAME, PATH_INFO and QUERY_STRING as well as our REPO_NAME

        req.url = req.env['SCRIPT_NAME']
        if not req.url.endswith('/'):
            req.url += '/'
        if req.env.has_key('REPO_NAME'):
            req.url += req.env['REPO_NAME'] + '/'

        if req.env.get('PATH_INFO'):
            parts = req.env.get('PATH_INFO').strip('/').split('/')
            repo_parts = req.env.get('REPO_NAME', '').split('/')
            if parts[:len(repo_parts)] == repo_parts:
                parts = parts[len(repo_parts):]
            query = '/'.join(parts)
        else:
            query = req.env['QUERY_STRING'].split('&', 1)[0]
            query = query.split(';', 1)[0]

        # translate user-visible url structure to internal structure

        args = query.split('/', 2)
        if 'cmd' not in req.form and args and args[0]:

            cmd = args.pop(0)
            style = cmd.rfind('-')
            if style != -1:
                req.form['style'] = [cmd[:style]]
                cmd = cmd[style+1:]

            # avoid accepting e.g. style parameter as command
            if hasattr(webcommands, cmd) or hasattr(protocol, cmd):
                req.form['cmd'] = [cmd]

            if args and args[0]:
                node = args.pop(0)
                req.form['node'] = [node]
            if args:
                req.form['file'] = args

            if cmd == 'static':
                req.form['file'] = req.form['node']
            elif cmd == 'archive':
                fn = req.form['node'][0]
                for type_, spec in self.archive_specs.iteritems():
                    ext = spec[2]
                    if fn.endswith(ext):
                        req.form['node'] = [fn[:-len(ext)]]
                        req.form['type'] = [type_]

        # actually process the request

        try:

            cmd = req.form.get('cmd', [''])[0]
            if hasattr(protocol, cmd):
                method = getattr(protocol, cmd)
                method(self, req)
            else:

                tmpl = self.templater(req)
                if cmd == '':
                    req.form['cmd'] = [tmpl.cache['default']]
                    cmd = req.form['cmd'][0]

                if cmd == 'file' and 'raw' in req.form['style']:
                    webcommands.rawfile(self, req, tmpl)
                else:
                    getattr(webcommands, cmd)(self, req, tmpl)

                del tmpl

        except revlog.LookupError, err:
            req.respond(404, tmpl(
                        'error', error='revision not found: %s' % err.name))
        except (hg.RepoError, revlog.RevlogError), inst:
            req.respond('500 Internal Server Error',
                        tmpl('error', error=str(inst)))
        except ErrorResponse, inst:
            req.respond(inst.code, tmpl('error', error=inst.message))
        except AttributeError:
            req.respond(400, tmpl('error', error='No such method: ' + cmd))

    def templater(self, req):

        # determine scheme, port and server name
        # this is needed to create absolute urls

        proto = req.env.get('wsgi.url_scheme')
        if proto == 'https':
            proto = 'https'
            default_port = "443"
        else:
            proto = 'http'
            default_port = "80"

        port = req.env["SERVER_PORT"]
        port = port != default_port and (":" + port) or ""
        urlbase = '%s://%s%s' % (proto, req.env['SERVER_NAME'], port)
        staticurl = self.config("web", "staticurl") or req.url + 'static/'
        if not staticurl.endswith('/'):
            staticurl += '/'

        # some functions for the templater

        def header(**map):
            header_file = cStringIO.StringIO(
                ''.join(tmpl("header", encoding=self.encoding, **map)))
            msg = mimetools.Message(header_file, 0)
            req.header(msg.items())
            yield header_file.read()

        def footer(**map):
            yield tmpl("footer", **map)

        def motd(**map):
            yield self.config("web", "motd", "")

        def sessionvars(**map):
            fields = []
            if req.form.has_key('style'):
                style = req.form['style'][0]
                if style != self.config('web', 'style', ''):
                    fields.append(('style', style))

            separator = req.url[-1] == '?' and ';' or '?'
            for name, value in fields:
                yield dict(name=name, value=value, separator=separator)
                separator = ';'

        # figure out which style to use

        style = self.config("web", "style", "")
        if req.form.has_key('style'):
            style = req.form['style'][0]
        mapfile = style_map(self.templatepath, style)

        if not self.reponame:
            self.reponame = (self.config("web", "name")
                             or req.env.get('REPO_NAME')
                             or req.url.strip('/') or self.repo.root)

        # create the templater

        tmpl = templater.templater(mapfile, templater.common_filters,
                                   defaults={"url": req.url,
                                             "staticurl": staticurl,
                                             "urlbase": urlbase,
                                             "repo": self.reponame,
                                             "header": header,
                                             "footer": footer,
                                             "motd": motd,
                                             "sessionvars": sessionvars
                                            })
        return tmpl

    def archivelist(self, nodeid):
        allowed = self.configlist("web", "allow_archive")
        for i, spec in self.archive_specs.iteritems():
            if i in allowed or self.configbool("web", "allow" + i):
                yield {"type" : i, "extension" : spec[2], "node" : nodeid}

    def listfilediffs(self, tmpl, files, changeset):
        for f in files[:self.maxfiles]:
            yield tmpl("filedifflink", node=hex(changeset), file=f)
        if len(files) > self.maxfiles:
            yield tmpl("fileellipses")

    def siblings(self, siblings=[], hiderev=None, **args):
        siblings = [s for s in siblings if s.node() != nullid]
        if len(siblings) == 1 and siblings[0].rev() == hiderev:
            return
        for s in siblings:
            d = {'node': hex(s.node()), 'rev': s.rev()}
            if hasattr(s, 'path'):
                d['file'] = s.path()
            d.update(args)
            yield d

    def renamelink(self, fl, node):
        r = fl.renamed(node)
        if r:
            return [dict(file=r[0], node=hex(r[1]))]
        return []

    def nodetagsdict(self, node):
        return [{"name": i} for i in self.repo.nodetags(node)]

    def nodebranchdict(self, ctx):
        branches = []
        branch = ctx.branch()
        # If this is an empty repo, ctx.node() == nullid,
        # ctx.branch() == 'default', but branchtags() is
        # an empty dict. Using dict.get avoids a traceback.
        if self.repo.branchtags().get(branch) == ctx.node():
            branches.append({"name": branch})
        return branches

    def showtag(self, tmpl, t1, node=nullid, **args):
        for t in self.repo.nodetags(node):
            yield tmpl(t1, tag=t, **args)

    def diff(self, tmpl, node1, node2, files):
        def filterfiles(filters, files):
            l = [x for x in files if x in filters]

            for t in filters:
                if t and t[-1] != os.sep:
                    t += os.sep
                l += [x for x in files if x.startswith(t)]
            return l

        parity = paritygen(self.stripecount)
        def diffblock(diff, f, fn):
            yield tmpl("diffblock",
                       lines=prettyprintlines(diff),
                       parity=parity.next(),
                       file=f,
                       filenode=hex(fn or nullid))

        def prettyprintlines(diff):
            for l in diff.splitlines(1):
                if l.startswith('+'):
                    yield tmpl("difflineplus", line=l)
                elif l.startswith('-'):
                    yield tmpl("difflineminus", line=l)
                elif l.startswith('@'):
                    yield tmpl("difflineat", line=l)
                else:
                    yield tmpl("diffline", line=l)

        r = self.repo
        c1 = r.changectx(node1)
        c2 = r.changectx(node2)
        date1 = util.datestr(c1.date())
        date2 = util.datestr(c2.date())

        modified, added, removed, deleted, unknown = r.status(node1, node2)[:5]
        if files:
            modified, added, removed = map(lambda x: filterfiles(files, x),
                                           (modified, added, removed))

        diffopts = patch.diffopts(self.repo.ui, untrusted=True)
        for f in modified:
            to = c1.filectx(f).data()
            tn = c2.filectx(f).data()
            yield diffblock(mdiff.unidiff(to, date1, tn, date2, f, f,
                                          opts=diffopts), f, tn)
        for f in added:
            to = None
            tn = c2.filectx(f).data()
            yield diffblock(mdiff.unidiff(to, date1, tn, date2, f, f,
                                          opts=diffopts), f, tn)
        for f in removed:
            to = c1.filectx(f).data()
            tn = None
            yield diffblock(mdiff.unidiff(to, date1, tn, date2, f, f,
                                          opts=diffopts), f, tn)

    def changelog(self, tmpl, ctx, shortlog=False):
        def changelist(limit=0,**map):
            cl = self.repo.changelog
            l = [] # build a list in forward order for efficiency
            for i in xrange(start, end):
                ctx = self.repo.changectx(i)
                n = ctx.node()

                l.insert(0, {"parity": parity.next(),
                             "author": ctx.user(),
                             "parent": self.siblings(ctx.parents(), i - 1),
                             "child": self.siblings(ctx.children(), i + 1),
                             "changelogtag": self.showtag("changelogtag",n),
                             "desc": ctx.description(),
                             "date": ctx.date(),
                             "files": self.listfilediffs(tmpl, ctx.files(), n),
                             "rev": i,
                             "node": hex(n),
                             "tags": self.nodetagsdict(n),
                             "branches": self.nodebranchdict(ctx)})

            if limit > 0:
                l = l[:limit]

            for e in l:
                yield e

        maxchanges = shortlog and self.maxshortchanges or self.maxchanges
        cl = self.repo.changelog
        count = cl.count()
        pos = ctx.rev()
        start = max(0, pos - maxchanges + 1)
        end = min(count, start + maxchanges)
        pos = end - 1
        parity = paritygen(self.stripecount, offset=start-end)

        changenav = revnavgen(pos, maxchanges, count, self.repo.changectx)

        return tmpl(shortlog and 'shortlog' or 'changelog',
                    changenav=changenav,
                    node=hex(cl.tip()),
                    rev=pos, changesets=count,
                    entries=lambda **x: changelist(limit=0,**x),
                    latestentry=lambda **x: changelist(limit=1,**x),
                    archives=self.archivelist("tip"))

    def search(self, tmpl, query):

        def changelist(**map):
            cl = self.repo.changelog
            count = 0
            qw = query.lower().split()

            def revgen():
                for i in xrange(cl.count() - 1, 0, -100):
                    l = []
                    for j in xrange(max(0, i - 100), i):
                        ctx = self.repo.changectx(j)
                        l.append(ctx)
                    l.reverse()
                    for e in l:
                        yield e

            for ctx in revgen():
                miss = 0
                for q in qw:
                    if not (q in ctx.user().lower() or
                            q in ctx.description().lower() or
                            q in " ".join(ctx.files()).lower()):
                        miss = 1
                        break
                if miss:
                    continue

                count += 1
                n = ctx.node()

                yield tmpl('searchentry',
                           parity=parity.next(),
                           author=ctx.user(),
                           parent=self.siblings(ctx.parents()),
                           child=self.siblings(ctx.children()),
                           changelogtag=self.showtag("changelogtag",n),
                           desc=ctx.description(),
                           date=ctx.date(),
                           files=self.listfilediffs(tmpl, ctx.files(), n),
                           rev=ctx.rev(),
                           node=hex(n),
                           tags=self.nodetagsdict(n),
                           branches=self.nodebranchdict(ctx))

                if count >= self.maxchanges:
                    break

        cl = self.repo.changelog
        parity = paritygen(self.stripecount)

        return tmpl('search',
                    query=query,
                    node=hex(cl.tip()),
                    entries=changelist,
                    archives=self.archivelist("tip"))

    def changeset(self, tmpl, ctx):
        n = ctx.node()
        parents = ctx.parents()
        p1 = parents[0].node()

        files = []
        parity = paritygen(self.stripecount)
        for f in ctx.files():
            files.append(tmpl("filenodelink",
                              node=hex(n), file=f,
                              parity=parity.next()))

        def diff(**map):
            yield self.diff(tmpl, p1, n, None)

        return tmpl('changeset',
                    diff=diff,
                    rev=ctx.rev(),
                    node=hex(n),
                    parent=self.siblings(parents),
                    child=self.siblings(ctx.children()),
                    changesettag=self.showtag("changesettag",n),
                    author=ctx.user(),
                    desc=ctx.description(),
                    date=ctx.date(),
                    files=files,
                    archives=self.archivelist(hex(n)),
                    tags=self.nodetagsdict(n),
                    branches=self.nodebranchdict(ctx))

    def filelog(self, tmpl, fctx):
        f = fctx.path()
        fl = fctx.filelog()
        count = fl.count()
        pagelen = self.maxshortchanges
        pos = fctx.filerev()
        start = max(0, pos - pagelen + 1)
        end = min(count, start + pagelen)
        pos = end - 1
        parity = paritygen(self.stripecount, offset=start-end)

        def entries(limit=0, **map):
            l = []

            for i in xrange(start, end):
                ctx = fctx.filectx(i)
                n = fl.node(i)

                l.insert(0, {"parity": parity.next(),
                             "filerev": i,
                             "file": f,
                             "node": hex(ctx.node()),
                             "author": ctx.user(),
                             "date": ctx.date(),
                             "rename": self.renamelink(fl, n),
                             "parent": self.siblings(fctx.parents()),
                             "child": self.siblings(fctx.children()),
                             "desc": ctx.description()})

            if limit > 0:
                l = l[:limit]

            for e in l:
                yield e

        nodefunc = lambda x: fctx.filectx(fileid=x)
        nav = revnavgen(pos, pagelen, count, nodefunc)
        return tmpl("filelog", file=f, node=hex(fctx.node()), nav=nav,
                    entries=lambda **x: entries(limit=0, **x),
                    latestentry=lambda **x: entries(limit=1, **x))

    def filerevision(self, tmpl, fctx):
        f = fctx.path()
        text = fctx.data()
        fl = fctx.filelog()
        n = fctx.filenode()
        parity = paritygen(self.stripecount)

        mt = mimetypes.guess_type(f)[0]
        rawtext = text
        if util.binary(text):
            mt = mt or 'application/octet-stream'
            text = "(binary:%s)" % mt
        mt = mt or 'text/plain'

        def lines():
            for l, t in enumerate(text.splitlines(1)):
                yield {"line": t,
                       "linenumber": "% 6d" % (l + 1),
                       "parity": parity.next()}

        return tmpl("filerevision",
                    file=f,
                    path=_up(f),
                    text=lines(),
                    raw=rawtext,
                    mimetype=mt,
                    rev=fctx.rev(),
                    node=hex(fctx.node()),
                    author=fctx.user(),
                    date=fctx.date(),
                    desc=fctx.description(),
                    parent=self.siblings(fctx.parents()),
                    child=self.siblings(fctx.children()),
                    rename=self.renamelink(fl, n),
                    permissions=fctx.manifest().flags(f))

    def fileannotate(self, tmpl, fctx):
        f = fctx.path()
        n = fctx.filenode()
        fl = fctx.filelog()
        parity = paritygen(self.stripecount)

        def annotate(**map):
            last = None
            for f, l in fctx.annotate(follow=True):
                fnode = f.filenode()
                name = self.repo.ui.shortuser(f.user())

                if last != fnode:
                    last = fnode

                yield {"parity": parity.next(),
                       "node": hex(f.node()),
                       "rev": f.rev(),
                       "author": name,
                       "file": f.path(),
                       "line": l}

        return tmpl("fileannotate",
                    file=f,
                    annotate=annotate,
                    path=_up(f),
                    rev=fctx.rev(),
                    node=hex(fctx.node()),
                    author=fctx.user(),
                    date=fctx.date(),
                    desc=fctx.description(),
                    rename=self.renamelink(fl, n),
                    parent=self.siblings(fctx.parents()),
                    child=self.siblings(fctx.children()),
                    permissions=fctx.manifest().flags(f))

    def manifest(self, tmpl, ctx, path):
        mf = ctx.manifest()
        node = ctx.node()

        files = {}
        parity = paritygen(self.stripecount)

        if path and path[-1] != "/":
            path += "/"
        l = len(path)
        abspath = "/" + path

        for f, n in mf.items():
            if f[:l] != path:
                continue
            remain = f[l:]
            if "/" in remain:
                short = remain[:remain.index("/") + 1] # bleah
                files[short] = (f, None)
            else:
                short = os.path.basename(remain)
                files[short] = (f, n)

        if not files:
            raise ErrorResponse(404, 'Path not found: ' + path)

        def filelist(**map):
            fl = files.keys()
            fl.sort()
            for f in fl:
                full, fnode = files[f]
                if not fnode:
                    continue

                fctx = ctx.filectx(full)
                yield {"file": full,
                       "parity": parity.next(),
                       "basename": f,
                       "date": fctx.changectx().date(),
                       "size": fctx.size(),
                       "permissions": mf.flags(full)}

        def dirlist(**map):
            fl = files.keys()
            fl.sort()
            for f in fl:
                full, fnode = files[f]
                if fnode:
                    continue

                yield {"parity": parity.next(),
                       "path": "%s%s" % (abspath, f),
                       "basename": f[:-1]}

        return tmpl("manifest",
                    rev=ctx.rev(),
                    node=hex(node),
                    path=abspath,
                    up=_up(abspath),
                    upparity=parity.next(),
                    fentries=filelist,
                    dentries=dirlist,
                    archives=self.archivelist(hex(node)),
                    tags=self.nodetagsdict(node),
                    branches=self.nodebranchdict(ctx))

    def tags(self, tmpl):
        i = self.repo.tagslist()
        i.reverse()
        parity = paritygen(self.stripecount)

        def entries(notip=False,limit=0, **map):
            count = 0
            for k, n in i:
                if notip and k == "tip":
                    continue
                if limit > 0 and count >= limit:
                    continue
                count = count + 1
                yield {"parity": parity.next(),
                       "tag": k,
                       "date": self.repo.changectx(n).date(),
                       "node": hex(n)}

        return tmpl("tags",
                    node=hex(self.repo.changelog.tip()),
                    entries=lambda **x: entries(False,0, **x),
                    entriesnotip=lambda **x: entries(True,0, **x),
                    latestentry=lambda **x: entries(True,1, **x))

    def summary(self, tmpl):
        i = self.repo.tagslist()
        i.reverse()

        def tagentries(**map):
            parity = paritygen(self.stripecount)
            count = 0
            for k, n in i:
                if k == "tip": # skip tip
                    continue;

                count += 1
                if count > 10: # limit to 10 tags
                    break;

                yield tmpl("tagentry",
                           parity=parity.next(),
                           tag=k,
                           node=hex(n),
                           date=self.repo.changectx(n).date())


        def branches(**map):
            parity = paritygen(self.stripecount)

            b = self.repo.branchtags()
            l = [(-self.repo.changelog.rev(n), n, t) for t, n in b.items()]
            l.sort()

            for r,n,t in l:
                ctx = self.repo.changectx(n)

                yield {'parity': parity.next(),
                       'branch': t,
                       'node': hex(n),
                       'date': ctx.date()}

        def changelist(**map):
            parity = paritygen(self.stripecount, offset=start-end)
            l = [] # build a list in forward order for efficiency
            for i in xrange(start, end):
                ctx = self.repo.changectx(i)
                n = ctx.node()
                hn = hex(n)

                l.insert(0, tmpl(
                   'shortlogentry',
                    parity=parity.next(),
                    author=ctx.user(),
                    desc=ctx.description(),
                    date=ctx.date(),
                    rev=i,
                    node=hn,
                    tags=self.nodetagsdict(n),
                    branches=self.nodebranchdict(ctx)))

            yield l

        cl = self.repo.changelog
        count = cl.count()
        start = max(0, count - self.maxchanges)
        end = min(count, start + self.maxchanges)

        return tmpl("summary",
                    desc=self.config("web", "description", "unknown"),
                    owner=get_contact(self.config) or "unknown",
                    lastchange=cl.read(cl.tip())[2],
                    tags=tagentries,
                    branches=branches,
                    shortlog=changelist,
                    node=hex(cl.tip()),
                    archives=self.archivelist("tip"))

    def filediff(self, tmpl, fctx):
        n = fctx.node()
        path = fctx.path()
        parents = fctx.parents()
        p1 = parents and parents[0].node() or nullid

        def diff(**map):
            yield self.diff(tmpl, p1, n, [path])

        return tmpl("filediff",
                    file=path,
                    node=hex(n),
                    rev=fctx.rev(),
                    parent=self.siblings(parents),
                    child=self.siblings(fctx.children()),
                    diff=diff)

    archive_specs = {
        'bz2': ('application/x-tar', 'tbz2', '.tar.bz2', None),
        'gz': ('application/x-tar', 'tgz', '.tar.gz', None),
        'zip': ('application/zip', 'zip', '.zip', None),
        }

    def archive(self, tmpl, req, key, type_):
        reponame = re.sub(r"\W+", "-", os.path.basename(self.reponame))
        cnode = self.repo.lookup(key)
        arch_version = key
        if cnode == key or key == 'tip':
            arch_version = short(cnode)
        name = "%s-%s" % (reponame, arch_version)
        mimetype, artype, extension, encoding = self.archive_specs[type_]
        headers = [('Content-type', mimetype),
                   ('Content-disposition', 'attachment; filename=%s%s' %
                    (name, extension))]
        if encoding:
            headers.append(('Content-encoding', encoding))
        req.header(headers)
        archival.archive(self.repo, req, cnode, artype, prefix=name)

    # add tags to things
    # tags -> list of changesets corresponding to tags
    # find tag, changeset, file

    def cleanpath(self, path):
        path = path.lstrip('/')
        return util.canonpath(self.repo.root, '', path)

    def changectx(self, req):
        if req.form.has_key('node'):
            changeid = req.form['node'][0]
        elif req.form.has_key('manifest'):
            changeid = req.form['manifest'][0]
        else:
            changeid = self.repo.changelog.count() - 1

        try:
            ctx = self.repo.changectx(changeid)
        except hg.RepoError:
            man = self.repo.manifest
            mn = man.lookup(changeid)
            ctx = self.repo.changectx(man.linkrev(mn))

        return ctx

    def filectx(self, req):
        path = self.cleanpath(req.form['file'][0])
        if req.form.has_key('node'):
            changeid = req.form['node'][0]
        else:
            changeid = req.form['filenode'][0]
        try:
            ctx = self.repo.changectx(changeid)
            fctx = ctx.filectx(path)
        except hg.RepoError:
            fctx = self.repo.filectx(path, fileid=changeid)

        return fctx

    def check_perm(self, req, op, default):
        '''check permission for operation based on user auth.
        return true if op allowed, else false.
        default is policy to use if no config given.'''

        user = req.env.get('REMOTE_USER')

        deny = self.configlist('web', 'deny_' + op)
        if deny and (not user or deny == ['*'] or user in deny):
            return False

        allow = self.configlist('web', 'allow_' + op)
        return (allow and (allow == ['*'] or user in allow)) or default