"""
Diagnostics for estimated gwr models
"""
__author__ = "Taylor Oshan tayoshan@gmail.com"

import numpy as np
from scipy import linalg
from pysal.model.spglm.family import Gaussian, Poisson, Binomial


def get_AICc(gwr):
    """
    Get AICc value
    
    Gaussian: p61, (2.33), Fotheringham, Brunsdon and Charlton (2002)
    
    GWGLM: AICc=AIC+2k(k+1)/(n-k-1), Nakaya et al. (2005): p2704, (36)

    """
    n = gwr.n
    k = gwr.tr_S
    #sigma2 = gwr.sigma2
    if isinstance(gwr.family, Gaussian):
        aicc = -2.0 * gwr.llf + 2.0 * n * (k + 1.0) / (
            n - k - 2.0)  #equivalent to below but
        #can't control denominator of sigma without altering GLM familt code
        #aicc = n*np.log(sigma2) + n*np.log(2.0*np.pi) + n*(n+k)/(n-k-2.0)
    elif isinstance(gwr.family, (Poisson, Binomial)):
        aicc = get_AIC(gwr) + 2.0 * k * (k + 1.0) / (n - k - 1.0)
    return aicc


def get_AIC(gwr):
    """
    Get AIC calue

    Gaussian: p96, (4.22), Fotheringham, Brunsdon and Charlton (2002)

    GWGLM:  AIC(G)=D(G) + 2K(G), where D and K denote the deviance and the effective
    number of parameters in the model with bandwidth G, respectively.
    
    """
    k = gwr.tr_S
    #deviance = -2*log-likelihood
    y = gwr.y
    mu = gwr.mu
    if isinstance(gwr.family, Gaussian):
        aic = -2.0 * gwr.llf + 2.0 * (k + 1)
    elif isinstance(gwr.family, (Poisson, Binomial)):
        aic = np.sum(gwr.family.resid_dev(y, mu)**2) + 2.0 * k
    return aic


def get_BIC(gwr):
    """
    Get BIC value

    Gaussian: p61 (2.34), Fotheringham, Brunsdon and Charlton (2002)
    BIC = -2log(L)+klog(n)

    GWGLM: BIC = dev + tr_S * log(n)

    """
    n = gwr.n  # (scalar) number of observations
    k = gwr.tr_S
    y = gwr.y
    mu = gwr.mu
    if isinstance(gwr.family, Gaussian):
        bic = -2.0 * gwr.llf + (k + 1) * np.log(n)
    elif isinstance(gwr.family, (Poisson, Binomial)):
        bic = np.sum(gwr.family.resid_dev(y, mu)**2) + k * np.log(n)
    return bic


def get_CV(gwr):
    """
    Get CV value

    Gaussian only

    Methods: p60, (2.31) or p212 (9.4)
    Fotheringham, A. S., Brunsdon, C., & Charlton, M. (2002).
    Geographically weighted regression: the analysis of spatially varying relationships.
    Modification: sum of residual squared is divided by n according to GWR4 results

    """
    aa = gwr.resid_response.reshape((-1, 1)) / (1.0 - gwr.influ)
    cv = np.sum(aa**2) / gwr.n
    return cv


def corr(cov):
    invsd = np.diag(1 / np.sqrt(np.diag(cov)))
    cors = np.dot(np.dot(invsd, cov), invsd)
    return cors
