PARAM_NEXT = 'next'
PARAMETER_METHOD = 'method'

PARAMETER_CURRENT_PAGE = 'current_page'
PARAMETER_PAGINATOR = 'paginator'

PARAMETER_PREV_LINK = 'prev_page_link'
PARAMETER_NEXT_LINK = 'next_page_link'


class DispatcherMixin:
    """
    This class contains a dispather method that can run a method specified by
    'method' request parameter.
    """

    def __init__(self):
        self.user = None

    def dispatch_method(self, *args, **kwargs):
        request = args[0]

        self.user = request.user

        method_name = None
        if PARAMETER_METHOD in request.GET:
            method_name = request.GET[PARAMETER_METHOD]
        elif PARAMETER_METHOD in request.POST:
            method_name = request.POST[PARAMETER_METHOD]

        if method_name:
            return getattr(self, method_name)(*args, **kwargs)


class PaginatedMixin:
    def get_page_context(self, paginator, page):
        """
        Get pagination context variables
        """

        params = {}

        params[PARAMETER_PAGINATOR] = paginator
        current_page = paginator.page(int(page))
        params[PARAMETER_CURRENT_PAGE] = current_page
        if current_page.has_previous():
            params[PARAMETER_PREV_LINK] = paginator.get_page_url(
                    current_page.previous_page_number())
        if current_page.has_next():
            params[PARAMETER_NEXT_LINK] = paginator.get_page_url(
                    current_page.next_page_number())

        return params