#!/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 itertools import chain
from mercurial.error import RepoError
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 rhodecode.lib.auth import authfunc, HasPermissionAnyMiddleware
from rhodecode.lib.utils import is_mercurial, make_ui, invalidate_cache, \
    check_repo_fast, ui_sections
from rhodecode.model.user import UserModel
from webob.exc import HTTPNotFound, HTTPForbidden, HTTPInternalServerError
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 
        self.authenticate = AuthBasicAuthenticator('', authfunc)
        self.ipaddr = '0.0.0.0'
        self.repository = None
        self.username = None
        self.action = None
        
    def __call__(self, environ, start_response):
        if not is_mercurial(environ):
            return self.application(environ, start_response)
        
        proxy_key = 'HTTP_X_REAL_IP'
        def_key = 'REMOTE_ADDR'
        self.ipaddr = environ.get(proxy_key, environ.get(def_key, '0.0.0.0'))
        
        #===================================================================
        # AUTHENTICATE THIS MERCURIAL REQUEST
        #===================================================================
        username = REMOTE_USER(environ)
        
        if not username:
            self.authenticate.realm = self.config['rhodecode_realm']
            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)
            
        #=======================================================================
        # GET REPOSITORY
        #=======================================================================
        try:
            repo_name = '/'.join(environ['PATH_INFO'].split('/')[1:])
            if repo_name.endswith('/'):
                repo_name = repo_name.rstrip('/')
            self.repository = repo_name
        except:
            log.error(traceback.format_exc())
            return HTTPInternalServerError()(environ, start_response)

        #===================================================================
        # CHECK PERMISSIONS FOR THIS REQUEST
        #===================================================================
        self.action = self.__get_action(environ)
        if self.action:
            username = self.__get_environ_user(environ)
            try:
                user = self.__get_user(username)
                self.username = user.username
            except:
                log.error(traceback.format_exc())
                return HTTPInternalServerError()(environ, start_response)

            #check permissions for this repository
            if self.action == 'push':
                if not HasPermissionAnyMiddleware('repository.write',
                                                  'repository.admin')\
                                                    (user, repo_name):
                    return HTTPForbidden()(environ, start_response)

            else:
                #any other action need at least read permission
                if not HasPermissionAnyMiddleware('repository.read',
                                                  'repository.write',
                                                  'repository.admin')\
                                                    (user, repo_name):
                    return HTTPForbidden()(environ, start_response)
                
        self.extras = {'ip':self.ipaddr,
                       'username':self.username,
                       'action':self.action,
                       'repository':self.repository}

        #===================================================================
        # MERCURIAL REQUEST HANDLING
        #===================================================================
        environ['PATH_INFO'] = '/'#since we wrap into hgweb, reset the path
        self.baseui = make_ui('db')
        self.basepath = self.config['base_path']
        self.repo_path = os.path.join(self.basepath, repo_name)

        #quick check if that dir exists...
        if check_repo_fast(repo_name, self.basepath):
            return HTTPNotFound()(environ, start_response)
        try:
            app = wsgiapplication(self.__make_app)
        except RepoError, e:
            if str(e).find('not found') != -1:
                return HTTPNotFound()(environ, start_response)
        except Exception:
            log.error(traceback.format_exc())
            return HTTPInternalServerError()(environ, start_response)

        #invalidate cache on push
        if self.action == 'push':
            self.__invalidate_cache(repo_name)
            messages = []
            messages.append('thank you for using rhodecode')

            return self.msg_wrapper(app, environ, start_response, messages)
        else:
            return app(environ, start_response)


    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(str(self.repo_path), baseui=self.baseui)
        return  self.__load_web_settings(hgserve, self.extras)

    def __get_environ_user(self, environ):
        return environ.get('REMOTE_USER')

    def __get_user(self, username):
        return UserModel().get_by_username(username, cache=True)

    def __get_action(self, environ):
        """
        Maps mercurial request commands into a clone,pull or push command.
        This should always return a valid command string
        :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]
                else:
                    return cmd

    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, extras={}):
        #set the global ui for hgserve instance passed
        hgserve.repo.ui = self.baseui

        hgrc = os.path.join(self.repo_path, '.hg', 'hgrc')
    
        #inject some additional parameters that will be available in ui
        #for hooks
        for k, v in extras.items():
            hgserve.repo.ui.setconfig('rhodecode_extras', k, v)
        
        repoui = make_ui('file', hgrc, False)

        if repoui:
            #overwrite our ui instance with the section from hgrc file
            for section in ui_sections:
                for k, v in repoui.configitems(section):
                    hgserve.repo.ui.setconfig(section, k, v)
            
        return hgserve