from passlib.context import CryptContext
from pyramid.settings import aslist


password_context = CryptContext()


def crypt_context_settings_to_string(settings, prefix='passlib.'):
    ''' returns a passlib context setting as a INI-formatted content
    
    :param dict settings: settings for the crypt context
    :param str prefix: prefix of the settings keys
    :rtype: (str) config string in INI format for CryptContext.load()
    
    This looks at first like a dump hack, but the parsing of all possible
    context settings is quite a task. Since passlib has a context parser 
    included, this seems the most reliable way to do it.
    '''
    as_list_keys = {'schemes', 'deprecated'}
    config_lines = ['[passlib]']
    for ini_key, value in settings.items():
        if ini_key.startswith(prefix):
            context_key = ini_key.replace(prefix, '')            
            # the pyramid .ini format is different on lists 
            # than the .ini format used by passlib.
            if context_key in as_list_keys and ',' not in value:
                value = ','.join(aslist(value))
            config_lines.append(f'{context_key} = {value}')
    return '\n'.join(config_lines)
    

def includeme(config):
    ''' initializing authentication, authorization and password hash settings

    Activate this setup using ``config.include('ordr2.security')``.
    '''
    settings = config.get_settings()

    # configure the passlib context manager for hashing user passwords
    config_str = crypt_context_settings_to_string(settings, prefix='passlib.')
    password_context.load(config_str)