# Copyright (C) 2009, Tutorius.org
#
# 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; either version 2 of the License, or
# (at your option) any later version.
#
# 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 St, Fifth Floor, Boston, MA  02110-1301  USA

import urllib
import urllib2
from xml.dom import minidom
from apilib.restful_lib import Connection
from array import array

class StoreProxy(object):
    """
    Implements a communication channel with the Tutorius Store, where tutorials
    are shared from around the world. This proxy is meant to offer a one-stop
    shop to implement all the requests that could be made to the Store.
    """

    def __init__(self, base_url):
    
        # Base Urls for the api
        self.base_url = base_url
        self.remora_api = "api/1.4"
        self.tutorius_api = "TutoriusApi"
        self.bandwagon_api = "api/1.4/sharing"

        self.api_auth_key = None

        # Prepares the connection with the api
        self.conn = Connection(self.base_url)

        # Setup the helper
        self.helper = StoreProxyHelper()
    
    def get_categories(self):
        """
        Returns all the categories registered in the store. Categories are used to
        classify tutorials according to a theme. (e.g. Mathematics, History, etc...)
        
        @return The list of category names stored on the server.
        """

        request_url = "/%s/categories" % (self.tutorius_api)
        
        response = self.conn.request_get(request_url)

        if self.helper.iserror(response):
            return None
        
        xml_response = minidom.parseString(response['body'])

        xml_categories = xml_response.getElementsByTagName('category')

        categories = list()

        # Loop through the categories and create the list to be returned
        for xml_category in xml_categories:
            category = {}
            
            category['id'] = xml_category.getElementsByTagName('id')[0].firstChild.nodeValue
            category['name'] = xml_category.getElementsByTagName('name')[0].firstChild.nodeValue

            categories.append(category)

        return categories
    
    def search(self, keywords, category='all', page=1, numResults=10, sortBy='name'):
        """
        Returns a list of tutorials that correspond to the given search criteria.
        
        @param keywords The keywords to search for
        @param page The page in the result set from which to return results. This is
                            used to allow applications to fetch results one set at a time.
        @param numResults The max number of results that can be returned in a page
        @param sortBy The field on which to sort the results
        @return A list of tutorial meta-data that corresponds to the query
        """
        request_url = "/%s/search/%s/%s/%d/%d/%s" % (self.tutorius_api, keywords, category, page, numResults, sortBy)
        
        response = self.conn.request_get(request_url)

        if (self.helper.iserror(response)):
            return None

        xml_response = minidom.parseString(response['body'])

        xml_tutorials = xml_response.getElementsByTagName('tutorial')

        tutorials = list()

        for xml_tutorial in xml_tutorials:
            tutorial = self.helper.parse_tutorial(xml_tutorial)
            tutorials.append(tutorial)

        return tutorials
    
    def get_tutorials(self, category='all', page=1, numResults=10, sortBy='name'):
        """
        Returns the list of tutorials that correspond to the given search criteria.
        
        @param category The category in which to restrict the search.
        @param page The page in the result set from which to return results. This is
                            used to allow applications to fetch results one set at a time.
        @param numResults The max number of results that can be returned in a page
        @param sortBy The field on which to sort the results
        @return A list of tutorial meta-data that corresponds to the query
        """
        
        request_url = "/%s/tutorials/%s/%d/%d/%s" % (self.tutorius_api, category, page, numResults, sortBy)
        
        response = self.conn.request_get(request_url)

        if (self.helper.iserror(response)):
            return None

        xml_response = minidom.parseString(response['body'])

        xml_tutorials = xml_response.getElementsByTagName('tutorial')

        tutorials = list()

        for xml_tutorial in xml_tutorials:
            tutorial = self.helper.parse_tutorial(xml_tutorial)
            tutorials.append(tutorial)

        return tutorials

    def list(self, type='recommended', numResults=3):
        """
        Returns a list of tutorials corresponding to the type specified.
        Type examples: 'Most downloaded', 'recommended', etc.

        @param type The type of list (Most downloaded, recommended, etc.)
        @return A list of tutorials
        """
        request_url = "/%s/list/%s/tutorial/%s" % (self.remora_api, type, numResults)

        response = self.conn.request_get(request_url)

        if (self.helper.iserror(response)):
            return None

        xml_response = minidom.parseString(response['body'])

        xml_tutorials = xml_response.getElementsByTagName('addon')

        tutorials = list()

        for xml_tutorial in xml_tutorials:
            tutorial = self.helper.parse_tutorial(xml_tutorial)
            tutorials.append(tutorial)

        return tutorials

    
    def get_latest_version(self, tutorial_id_list):
        """
        Returns the latest version number on the server, for each tutorial ID
        in the list.
        
        @param tutorial_id_list The list of tutorial IDs from which we want to
                                known the latest version number.
        @return A dictionary having the tutorial ID as the key and the version
                as the value.
        """
        
        versions = {}
        
        for tutorial_id in tutorial_id_list:
            
            request_url = "/%s/addon/%s/" % (self.remora_api, tutorial_id)
            
            response = self.conn.request_get(request_url)
            
            if (self.helper.iserror(response)):
                return None
            
            xml = minidom.parseString(response['body'])
            
            versionnode = xml.getElementsByTagName("version")[0]
            
            version = versionnode.firstChild.nodeValue
            
            versions[tutorial_id] = version
        
        return versions
    
    def download_tutorial(self, tutorial_id, version=None):
        """
        Fetches the tutorial file from the server and returns the
        
        @param tutorial_id The tutorial that we want to get
        @param version The version number that we want to download. If None,
                        the latest version will be downloaded.
        @return The downloaded file itself (an in-memory representation of the file,
                not a path to it on the disk)
        
        TODO : We should decide if we're saving to disk or in mem.
        """
        request_url = "/%s/addon/%s/" % (self.remora_api, tutorial_id)
        
        response = self.conn.request_get(request_url)

        if (self.helper.iserror(response)):
            return None
        
        xml = minidom.parseString(response['body'])
        
        installnode = xml.getElementsByTagName("install")[0]
        installurl = installnode.firstChild.nodeValue
        
        fp = urllib.urlopen(installurl)
        
        return fp
    
    def login(self, username, password):
        """
        Logs in the user on the store and saves the login status in the proxy
        state. After a successful logon, the operation requiring a login will
        be successful.
        
        @param username
        @param password
        @return True if the login was successful, False otherwise
        """
        request_url = "/%s/auth/" % (self.tutorius_api)
        
        params = {'username': username, 'password': password}
        
        response = self.conn.request_post(request_url, params)

        if (self.helper.iserror(response)):
            return False
        
        xml_response = minidom.parseString(response['body'])
        
        keynode = xml_response.getElementsByTagName("token")[0]
        
        key = keynode.getAttribute('value')
        
        self.api_auth_key = key
        
        return True
    
    def close_session(self):
        """
        Ends the user's session on the server and changes the state of the proxy
        to disallow the calls to the store that requires to be logged in.
        
        @return True if the user was disconnected, False otherwise
        """
        request_url = "/%s/auth/%s" % (self.tutorius_api, self.api_auth_key)
        
        headers = { 'X-API-Auth' : self.api_auth_key }
        
        response = self.conn.request_delete(request_url, None, headers)

        if (self.helper.iserror(response)):
            return False
        
        self.api_auth_key = None
        
        return True
    
    def get_session_id(self):
        """
        Gives the current session ID cached in the Store Proxy, or returns
        None is the user is not logged yet.
        
        @return The current session's ID, or None if the user is not logged
        """
        return self.api_auth_key
    
    def rate(self, value, tutorial_store_id):
        """
        Sends a rating for the given tutorial.
        
        This function requires the user to be logged in.
        
        @param value The value of the rating. It must be an integer with a value
                    from 1 to 5.
        @param tutorial_store_id The ID of the tutorial that was rated
        @return True if the rating was sent to the Store, False otherwise.
        """
        request_url = "/%s/review/%s" % (self.tutorius_api, tutorial_store_id)
        
        params = {'title': 'from api', 'body': 'from api', 'rating': value}
        headers = { 'X-API-Auth' : self.api_auth_key }
        
        response = self.conn.request_post(request_url, params, None, None, headers)

        if self.helper.iserror(response):
            return False
        
        return True
    
    def publish(self, tutorial, tutorial_info=None, tutorial_store_id = None):
        """
        Sends a tutorial to the store.
        
        This function requires the user to be logged in.
        
        @param tutorial The tutorial file to be sent. Note that this is the
                        content itself and not the path to the file.
        @param tutorial_info An array containing the tutorial information
        @return True if the tutorial was sent correctly, False otherwise.
        """
        
        # This is in the case we have to re-publish a tutorial
        if tutorial_store_id is not None:
            request_url = "/%s/publish/%s" % (self.tutorius_api, tutorial_store_id)
            headers = { 'X-API-Auth' : self.api_auth_key }
            
            response = self.conn.request_post(request_url, None, None, None, headers)
            if self.helper.iserror(response):
                return -1

            return tutorial_store_id

        # Otherwise, we want to publish a new tutorial
        if tutorial_info == None:
            return -1

        request_url = "/%s/publish/" % (self.tutorius_api)

        headers = { 'X-API-Auth' : self.api_auth_key }

        response = self.conn.request_post(request_url, tutorial_info, tutorial, tutorial_info['filename'], headers)
        
        if self.helper.iserror(response):
            return -1
        
        xml_response = minidom.parseString(response['body'])
        
        id_node = xml_response.getElementsByTagName("id")[0].firstChild
        
        id = id_node.nodeValue
        
        return id

    def unpublish(self, tutorial_store_id):
        """
        Removes a tutorial from the server. The user in the current session
        needs to be the creator for it to be unpublished. This will remove
        the file from the server and from all its collections and categories.
        
        This function requires the user to be logged in.
        
        @param tutorial_store_id The ID of the tutorial to be removed
        @return True if the tutorial was properly removed from the server
        """
        request_url = "/%s/publish/%s" % (self.tutorius_api, tutorial_store_id)

        headers = { 'X-API-Auth' : self.api_auth_key }
        response = self.conn.request_delete(request_url, None, headers)

        if self.helper.iserror(response):
            return False
        
        return True
    
    def update_published_tutorial(self, tutorial_id, tutorial, tutorial_info):
        """
        Sends the new content for the tutorial with the given ID.
        
        This function requires the user to be logged in.
        
        @param tutorial_id The ID of the tutorial to be updated
        @param tutorial The bundled tutorial file content (not a path!)
        @return True if the tutorial was sent and updated, False otherwise
        """
        request_url = "/%s/update/%s" % (self.tutorius_api, tutorial_id)

        headers = { 'X-API-Auth' : self.api_auth_key }

        response = self.conn.request_post(request_url, tutorial_info, tutorial, tutorial_info['filename'], headers)

        if self.helper.iserror(response):
            return False    

        return True        

    
    def register_new_user(self, user_info):
        """
        Creates a new user from the given user information.
        
        @param user_info A structure containing all the data required to do a login.
        @return True if the new account was created, false otherwise
        """
        request_url = "/%s/registerNewUser" % (self.tutorius_api)
        
        params = {'nickname': user_info['nickname'], 'password': user_info['password'], 'email': user_info['email']}

        response = self.conn.request_post(request_url, params)
        
        if self.helper.iserror(response):
            return False
        
        return True


class StoreProxyHelper(object):
    """
    Implements helper methods for the Store, more specifically
    methods to handle xml responses and errors
    """
    def iserror(self, response):
        """
        Check if the response received from the server is an error
        
        @param response The XML response from the server
        @return True if the response is an error
        """
        # first look for HTTP errors
        http_status = response['headers']['status']

        if http_status in ['400', '401', '403', '500' ]:
            return True

        # Now check if the response is valid XML
        try:
            minidom.parseString(response['body'])
        except Exception, e:
            return True

        # The response is valid XML, parse it and look for 
        # an error in xml format
        xml_response = minidom.parseString(response['body'])

        errors = xml_response.getElementsByTagName('error')
        
        if (len(errors) > 0):
            return True
        
        return False

    def parse_tutorial(self, xml_tutorial):
        """
        Parse a tutorial's XML metadata and returns a dictionnary
        containing the metadata

        @param xml_tutorial The tutorial metadata in XML format
        @return A dictionnary containing the metadata
        """
        tutorial = {}
        
        params = [
            'id',
            'name',
            'summary',
            'version',
            'description',
            'author',
            'rating'
        ]
        
        for param in params:
            xml_node = xml_tutorial.getElementsByTagName(param)[0].firstChild
            
            if xml_node != None:
                tutorial[param] = xml_node.nodeValue
            else:
                tutorial[param] = ''

        return tutorial