import logger
from sage.all import sage_eval, PolynomialRing, QQ

class PFOperator:
    """
    A class representing a Picard-Fuchs operator in a single variable z.
    """
    def _operator_from_string(self, operator_string):
        z_names = ['z%d' % i for i in range(self.no_variables)]
        theta_names = ['theta%d' % i for i in range(self.no_variables)]
        self.ring = PolynomialRing(QQ, z_names + theta_names)
        self.z_gens = self.ring.gens()[:self.no_variables]
        self.theta_gens = self.ring.gens()[self.no_variables:]

        try:
            operator = sage_eval(operator_string, locals=self.ring.gens_dict())
        except Exception as e:
            raise ValueError("Invalid operator string: %s" % e)
        return self.ring(operator)

    def __init__(self, operator_string, no_variables=1):
        self.no_variables = no_variables
        self.operator = self._operator_from_string(operator_string)