#!/usr/bin/env python3

from abc import ABC, abstractmethod
import logging
import random

from type.rate import Rate

import data


logger = logging.getLogger(__name__)


class ReturnsAndExpenses(ABC):
    @abstractmethod
    def get_annual_inflation_rate(self, year: int) -> Rate:
        pass

    @abstractmethod
    def get_annual_social_security_increase_rate(self, year: int) -> Rate:
        pass

    @abstractmethod
    def get_annual_investment_return_rate(self, year: int) -> Rate:
        pass


class ConstantValueRaE(ReturnsAndExpenses):
    def __init__(
            self,
            *,
            inflation_rate = Rate(0.0),
            social_security_increase_rate = Rate(0.0),
            investment_return_rate = Rate(0.0),
    ):
        super().__init__()
        self.inflation_rate = inflation_rate
        self.social_security_increase_rate = social_security_increase_rate
        self.investment_return_rate = investment_return_rate

    def get_annual_inflation_rate(self, year: int) -> Rate:
        return self.inflation_rate

    def get_annual_social_security_increase_rate(self, year: int) -> Rate:
        return self.social_security_increase_rate

    def get_annual_investment_return_rate(self, year: int) -> Rate:
        return self.investment_return_rate

    def __repr__(self):
        return f'Constant rates: inflation={self.inflation_rate}, ss={self.social_security_increase_rate}, roi={self.investment_return_rate}'


class HistoricalRaE(ReturnsAndExpenses):
    def __init__(self):
        super().__init__()
        #self.years = range(1928, 2020)
        self.years = [1929, 1930, 1931, 1932, 1933,
                      1939,
                      1946, 1947,
                      1956, 1957,
                      1964, 1965, 1966, 1969,
                      1973, 1974, 1977, 1978,
                      1981, 1984, 1987, 1990,
                      2000, 2001, 2002, 2007, 2007]
        self.year = None

    def get_annual_inflation_rate(self, year: int) -> Rate:
        #self.year = random.randrange(1928, 2020)
        self.year = random.choice(self.years)
        rois_and_inflation = data.ROIs_AND_INFLATION[self.year]
        inflation = rois_and_inflation.inflation
        logger.debug(f'HistoricalRaE: inflation is {inflation} (replay={self.year})')
        return inflation

    def get_annual_social_security_increase_rate(self, year: int) -> Rate:
        rois_and_inflation = data.ROIs_AND_INFLATION[self.year]
        ss = rois_and_inflation.inflation
        if ss > 0:
            ss -= 1.0
            ss /= 2
            ss += 1.0
        logger.debug(f'HistoricalRaE: social security increase rate is {ss} (replay={self.year})')
        return ss

    def get_annual_investment_return_rate(self, year: int) -> Rate:
        rois_and_inflation = data.ROIs_AND_INFLATION[self.year]
        roi = (
            rois_and_inflation.snp_500_return * 0.50 +
            rois_and_inflation.us_10y_bond_return * 0.50
        )
        logger.debug(f'HistoricalRaE: investment return 50/50 is {roi} (replay={self.year})')
        return Rate(roi)

    def __repr__(self):
        return f'historical reply of inflation/returns in {self.years}'


class GaussianRae(ReturnsAndExpenses):
    def __init__(self):
        self.inflation = None
        self.mean_inflation = 1.04         # Historical = 3.5% inflation
        self.stdev_inflation = 0.028       # Historical = 2.8% inflation stdev
        self.mean_roi = 1.060              # Historical = 8.5% 30s/70b; 9.1% 50s/50s; 9.7% 70s/30b
        self.stdev_roi = 0.093             # Historical = 6.7% 30s/70b; 9.3% 50s/50b; 12.2% 70s/30b
        self.ss_discount = 0.02

    def get_annual_inflation_rate(self, year: int) -> Rate:
        self.inflation = random.gauss(self.mean_inflation, self.stdev_inflation)
        return Rate(multiplier=self.inflation)

    def get_annual_social_security_increase_rate(self, year: int) -> Rate:
        return Rate(multiplier=self.inflation - self.ss_discount)

    def get_annual_investment_return_rate(self, year: int) -> Rate:
        return Rate(multiplier=random.gauss(self.mean_roi, self.stdev_roi))

    def __repr__(self):
        return f'Random Gaussian: (μinflation={Rate(self.mean_inflation).__repr__(relative=True)}, σ={Rate(self.stdev_inflation)}); (μroi={Rate(self.mean_roi).__repr__(relative=True)}, σ={Rate(self.stdev_roi)})'