Python Entrouvert

import os

import json

class TenantSettingBaseMiddleware(object):

    '''Base middleware classe for loading settings based on tenants

       Child classes MUST override the load_tenant_settings() method.

    '''

    def __init__(self, *args, **kwargs):

        self.tenants_settings = {}

    def get_tenant_settings(self, wrapped, tenant):

        '''Get last loaded settings for tenant, try to update it by loading

           settings again is last loading time is less recent thant settings data

           store. Compare with last modification time is done in the

           load_tenant_settings() method.

        '''

        tenant_settings, last_time = self.tenants_settings.get(tenant.schema_name, (None,None))

        if tenant_settings is None:

            tenant_settings = UserSettingsHolder(wrapped)

        tenant_settings, last_time = self.load_tenant_settings(wrapped, tenant, tenant_settings, last_time)

        self.tenants_settings[tenant.schema_name] = tenant_settings, last_time

        return tenant_settings

    def load_tenant_settings(self, wrapped, tenant, tenant_settings, last_time):

        '''Load tenant settings into tenant_settings object, eventually skip if

           last_time is more recent than last update time for settings and return

           the new value for tenant_settings and last_time'''

        raise NotImplemented

    def process_request(self, request):

        if not hasattr(request, '_old_settings_wrapped'):

            request._old_settings_wrapped = []

        request._old_settings_wrapped.append(settings._wrapped)

        settings._wrapped = self.get_tenant_settings(settings._wrapped, request.tenant)

    def process_response(self, request, response):

        if hasattr(request, '_old_settings_wrapped') and request._old_settings_wrapped:

            settings._wrapped = request._old_settings_wrapped.pop()

        return response

class FileBasedTenantSettingBaseMiddleware(TenantSettingBaseMiddleware):

    FILENAME = None

    def load_tenant_settings(self, wrapped, tenant, tenant_settings, last_time):

        path = os.path.join(settings.TENANT_BASE, tenant.schema_name, self.FILENAME)

        try:

            new_time = os.stat(path).st_mtime

        except OSError:

            # file was removed

            if not last_time is None:

                return UserSettingsHolder(wrapped), None

        else:

            if last_time is None or new_time >= last_time:

                # file is new

                tenant_settings = UserSettingsHolder(wrapped)

                self.load_file(tenant_settings, path)

                return tenant_settings, new_time

        # nothing has changed

        return tenant_settings, last_time

class JSONSettingsMiddleware(FileBasedTenantSettingBaseMiddleware):

    '''Load settings from a JSON file whose path is given by:

            os.path.join(settings.TENANT_BASE % schema_name, 'settings.json')

       The JSON file must be a dictionnary whose key/value will override

       current settings.

    '''

    FILENAME = 'settings.json'

    def load_file(sef, tenant_settings, path):

        with file(path) as f:

            json_settings = json.load(f)

            for key in json_settings:

                setattr(tenant_settings, key, json_settings[key])

class DictAdapter(dict):

    '''Give dict interface to plain objects'''

    def __init__(self, wrapped):

        self.wrapped = wrapped

    def __setitem__(self, key, value):

        setattr(self.wrapped, key, value)

    def __getitem__(self, key):

        try:

            return getattr(self.wrapped, key)

        except AttributeError:

            raise KeyError

class PythonSettingsMiddleware(JSONSettingsMiddleware):

    '''Load settings from a file whose path is given by:

            os.path.join(settings.TENANT_BASE % schema_name, 'settings.py')

       The file is executed in the same context as the classic settings file

       using execfile.

    '''

    FILENAME = 'settings.py'

    def load_file(self, tenant_settings, path):

        execfile(path, DictAdapter(tenant_settings))