# coding=utf-8
class Diagnostic(object):
    """
    Base class for the diagnostics. Provides a common interface for them and also
    has a mechanism that allows diagnostic retrieval by name.

    :param data_manager: data manager that will be used to store and retrieve the necessary data
    :type data_manager: DataManager
    """

    def __init__(self, data_manager):
        self.data_manager = data_manager
        self.required_vars = []
        self.generated_vars = []
        self.can_run_multiple_instances = True

    @staticmethod
    def register(cls, alias):
        """
        Register a new diagnostic using the given alias. It must be call using the derived class.
        :param cls: diagnostic class to register
        :type cls: Diagnostic
        :param alias: alias for the diagnostic
        :type alias: str
        """
        try:
            Diagnostic._diag_list[alias] = cls
        except AttributeError:
            Diagnostic._diag_list = dict()
            Diagnostic._diag_list[alias] = cls

    # noinspection PyProtectedMember
    @staticmethod
    def get_diagnostic(name):
        """
        Return the class for a diagnostic given its name

        :param name: diagnostic alias
        :type name: str
        :return: the selected Diagnostic class, None if name can not be found
        :rtype: Diagnostic
        """
        try:
            if name in Diagnostic._diag_list.keys():
                return Diagnostic._diag_list[name]
        except AttributeError:
            pass
        return None

    def compute(self):
        """
        Calculates the diagnostic and stores the output

        Must be implemented by derived classes
        """
        raise NotImplementedError("Class must override compute method")

    @classmethod
    def generate_jobs(cls, diags, options):
        """
        Generate the instances of the diagnostics that will be run by the manager

        Must be implemented by derived classes.

        :param diags: diagnostics manager
        :type diags: Diags
        :param options: list of strings containing the options passed to the diagnostic
        :type options: list[str]
        :return:
        """
        raise NotImplementedError("Class must override generate_jobs class method")

    def __str__(self):
        """
        Must be implemented by derived classes
        :return:
        """
        return 'Developer must override base class __str__ method'