import os
import logging
from mercurial import ui, config, hg
from mercurial.error import RepoError
log = logging.getLogger(__name__)


def get_repo_slug(request):
    path_info = request.environ.get('PATH_INFO')
    uri_lst = path_info.split('/')   
    repo_name = uri_lst[1]
    return repo_name

def is_mercurial(environ):
    """
    Returns True if request's target is mercurial server - header
    ``HTTP_ACCEPT`` of such request would start with ``application/mercurial``.
    """
    http_accept = environ.get('HTTP_ACCEPT')
    if http_accept and http_accept.startswith('application/mercurial'):
        return True
    return False

def check_repo_dir(paths):
    repos_path = paths[0][1].split('/')
    if repos_path[-1] in ['*', '**']:
        repos_path = repos_path[:-1]
    if repos_path[0] != '/':
        repos_path[0] = '/'
    if not os.path.isdir(os.path.join(*repos_path)):
        raise Exception('Not a valid repository in %s' % paths[0][1])

def check_repo(repo_name, base_path):

    repo_path = os.path.join(base_path, repo_name)

    try:
        r = hg.repository(ui.ui(), repo_path)
        hg.verify(r)
        #here we hnow that repo exists it was verified
        log.info('%s repo is already created', repo_name)
        return False
        #raise Exception('Repo exists')
    except RepoError:
        log.info('%s repo is free for creation', repo_name)
        #it means that there is no valid repo there...
        return True
                
def make_ui(path='hgwebdir.config', checkpaths=True):        
    """
    A funcion that will read python rc files and make an ui from read options
    
    @param path: path to mercurial config file
    """
    if not os.path.isfile(path):
        log.warning('Unable to read config file %s' % path)
        return False
    #propagated from mercurial documentation
    sections = [
                'alias',
                'auth',
                'decode/encode',
                'defaults',
                'diff',
                'email',
                'extensions',
                'format',
                'merge-patterns',
                'merge-tools',
                'hooks',
                'http_proxy',
                'smtp',
                'patch',
                'paths',
                'profiling',
                'server',
                'trusted',
                'ui',
                'web',
                ]

    baseui = ui.ui()
    cfg = config.config()
    cfg.read(path)
    if checkpaths:check_repo_dir(cfg.items('paths'))

    for section in sections:
        for k, v in cfg.items(section):
            baseui.setconfig(section, k, v)
    
    return baseui

def invalidate_cache(name, *args):
    """Invalidates given name cache"""
    
    from beaker.cache import region_invalidate
    log.info('INVALIDATING CACHE FOR %s', name)
    
    """propagate our arguments to make sure invalidation works. First
    argument has to be the name of cached func name give to cache decorator
    without that the invalidation would not work"""
    tmp = [name]
    tmp.extend(args)
    args = tuple(tmp)
    
    if name == 'cached_repo_list':
        from pylons_app.lib.base import _get_repos_cached
        region_invalidate(_get_repos_cached, None, *args)
        
    if name == 'full_changelog':
        from pylons_app.lib.base import _full_changelog_cached
        region_invalidate(_full_changelog_cached, None, *args)
        
from vcs.backends.base import BaseChangeset
from vcs.utils.lazy import LazyProperty
class EmptyChangeset(BaseChangeset):
    
    revision = -1

    @LazyProperty
    def raw_id(self):
        """
        Returns raw string identifing this changeset, useful for web
        representation.
        """
        return '0' * 12