#!/usr/bin/env python
# encoding: utf-8
# middleware to handle mercurial api calls
# Copyright (C) 2009-2010 Marcin Kuzminski <marcin@python-works.com>
 
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2
# of the License or (at your opinion) any later version of the license.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA  02110-1301, USA.

"""
Created on 2010-04-28

@author: marcink
SimpleHG middleware for handling mercurial protocol request (push/clone etc.)
It's implemented with basic auth function
"""
from datetime import datetime
from itertools import chain
from mercurial.hgweb import hgweb
from mercurial.hgweb.request import wsgiapplication
from paste.auth.basic import AuthBasicAuthenticator
from paste.httpheaders import REMOTE_USER, AUTH_TYPE
from pylons_app.lib.auth import authfunc, HasPermissionAnyMiddleware
from pylons_app.lib.utils import is_mercurial, make_ui, invalidate_cache
from pylons_app.model import meta
from pylons_app.model.db import UserLog, User
from webob.exc import HTTPNotFound, HTTPForbidden
import logging
import os
import traceback
log = logging.getLogger(__name__)

class SimpleHg(object):

    def __init__(self, application, config):
        self.application = application
        self.config = config
        #authenticate this mercurial request using 
        realm = '%s %s' % (self.config['hg_app_name'], 'mercurial repository')
        self.authenticate = AuthBasicAuthenticator(realm, authfunc)
        
    def __call__(self, environ, start_response):
        if not is_mercurial(environ):
            return self.application(environ, start_response)
        else:
            #===================================================================
            # AUTHENTICATE THIS MERCURIAL REQUEST
            #===================================================================
            username = REMOTE_USER(environ)
            if not username:
                result = self.authenticate(environ)
                if isinstance(result, str):
                    AUTH_TYPE.update(environ, 'basic')
                    REMOTE_USER.update(environ, result)
                else:
                    return result.wsgi_application(environ, start_response)
            
            try:
                repo_name = '/'.join(environ['PATH_INFO'].split('/')[1:])
            except Exception as e:
                log.error(traceback.format_exc())
                return HTTPNotFound()(environ, start_response)
            
            #===================================================================
            # CHECK PERMISSIONS FOR THIS REQUEST
            #===================================================================
            action = self.__get_action(environ)
            if action:
                username = self.__get_environ_user(environ)
                try:
                    sa = meta.Session
                    user = sa.query(User)\
                        .filter(User.username == username).one()
                except:
                    return HTTPNotFound()(environ, start_response)
                #check permissions for this repository
                if action == 'pull':
                    if not HasPermissionAnyMiddleware('repository.read',
                                                      'repository.write',
                                                      'repository.admin')\
                                                        (user, repo_name):
                        return HTTPForbidden()(environ, start_response)
                if action == 'push':
                    if not HasPermissionAnyMiddleware('repository.write',
                                                      'repository.admin')\
                                                        (user, repo_name):
                        return HTTPForbidden()(environ, start_response)
                
                #log action    
                self.__log_user_action(user, action, repo_name)            
            
            #===================================================================
            # MERCURIAL REQUEST HANDLING
            #===================================================================
            environ['PATH_INFO'] = '/'#since we wrap into hgweb, reset the path
            self.baseui = make_ui(self.config['hg_app_repo_conf'])
            self.basepath = self.config['base_path']
            self.repo_path = os.path.join(self.basepath, repo_name)
            try:
                app = wsgiapplication(self.__make_app)
            except Exception:
                log.error(traceback.format_exc())
                return HTTPNotFound()(environ, start_response)
            
            
            #invalidate cache on push
            if action == 'push':
                self.__invalidate_cache(repo_name)
                
            messages = ['thanks for using hg app !']
            return self.msg_wrapper(app, environ, start_response, messages)            


    def msg_wrapper(self, app, environ, start_response, messages):
        """
        Wrapper for custom messages that come out of mercurial respond messages
        is a list of messages that the user will see at the end of response 
        from merurial protocol actions that involves remote answers
        @param app:
        @param environ:
        @param start_response:
        """
        def custom_messages(msg_list):
            for msg in msg_list:
                yield msg + '\n'
        org_response = app(environ, start_response)
        return chain(org_response, custom_messages(messages))

    def __make_app(self):
        hgserve = hgweb(self.repo_path)
        return  self.__load_web_settings(hgserve)
    
    def __get_environ_user(self, environ):
        return environ.get('REMOTE_USER')
        
    def __get_action(self, environ):
        """
        Maps mercurial request commands into a pull or push command.
        @param environ:
        """
        mapping = {'changegroup': 'pull',
                   'changegroupsubset': 'pull',
                   'stream_out': 'pull',
                   'listkeys': 'pull',
                   'unbundle': 'push',
                   'pushkey': 'push', }
        
        for qry in environ['QUERY_STRING'].split('&'):
            if qry.startswith('cmd'):
                cmd = qry.split('=')[-1]
                if mapping.has_key(cmd):
                    return mapping[cmd]
    
    def __log_user_action(self, user, action, repo):
        sa = meta.Session
        try:
            user_log = UserLog()
            user_log.user_id = user.user_id
            user_log.action = action
            user_log.repository = repo.replace('/', '')
            user_log.action_date = datetime.now()
            sa.add(user_log)
            sa.commit()
            log.info('Adding user %s, action %s on %s',
                                            user.username, action, repo)
        except Exception as e:
            sa.rollback()
            log.error('could not log user action:%s', str(e))
    
    def __invalidate_cache(self, repo_name):
        """we know that some change was made to repositories and we should
        invalidate the cache to see the changes right away but only for
        push requests"""
        invalidate_cache('cached_repo_list')
        invalidate_cache('full_changelog', repo_name)
           
                   
    def __load_web_settings(self, hgserve):
        repoui = make_ui(os.path.join(self.repo_path, '.hg', 'hgrc'), False)
        #set the global ui for hgserve
        hgserve.repo.ui = self.baseui
        
        if repoui:
            #set the repository based config
            hgserve.repo.ui = repoui
            
        return hgserve