# Nonparametric signficance tests to consider
# From https://jmyao17.github.io/Statistics/Nonparametric_Statistical_Significance_Tests.html:
"""

==> The Mann-Whitney U test (for two independent samples)
  The Mann-Whitney U test is a nonparametric statistical significance test for 
  determining whether two independent samples were drawn from a population with 
  the same distribution.

  More specifically, the test determines whether it is equally likely that any 
  randomly selected observation from one sample will be greater or less than a 
  sample in the other distribution. 
  
  If violated, it suggests differing distributions.
    -Fail to Reject H0: Sample distributions are equal.
    -Reject H0: Sample distributions are not equal.

==> Wilcoxon Signed-Rank Test (for two paired samples/ one sample)
  NOTE: each sample must have the same number of data points.
  The samples are related or matched in some way or represent two measurements 
  of the same technique. 
  
  More specifically, each sample is independent, but 
  comes from the same population. The Wilcoxon signed ranks test is a 
  nonparametric statistical procedure for comparing two samples that are 
  paired, or related. The parametric equivalent to the Wilcoxon signed ranks 
  test goes by names such as the Student t-test, t-test for matched pairs, 
  t-test for paired samples, or t-test for dependent samples.

  The default assumption for the test, the null hypothesis, is that the 
  two samples have the same distribution.
    Fail to Reject H0: Sample distributions are equal.
    Reject H0: Sample distributions are not equal.

  For the test to be effective, it requires at least 20 observations 
  in each data sample.

"""

import matplotlib.pyplot as plt
import numpy as np
from scipy.stats import mannwhitneyu
# from scipy.stats import wilcoxon


def makehist(dffire, dfnofire, nd, imgfile):
    axesn = dfnofire.hist(layout=(7, 13), figsize=(20, 10),
                          bins=120, alpha=0.5, color='blue')
    dffire.hist(ax=axesn.ravel()[:nd + 1], layout=(7, 13),
             figsize=(20, 10), bins=12, alpha=0.5, color='red')
    plt.tight_layout()
    plt.savefig(imgfile)
    plt.close()


def siglis(dffire, dfnofire, var, sigval, ndays):
    low = 0.05
    high = 0.95
    sigvals = np.empty(ndays+1)
    for day in range(0, ndays+1, 1):
        print(f'DAY: {day - 90}')
        fire = dffire[day]
        nofire = dfnofire[day]
        fireavg = fire.mean()
        nofireavg = nofire.mean()
        print(f'  -{var} FIRE/IMMED [Mean: {fireavg}]')
        print(f'  -{var} NOFIRE/HLD [Mean: {nofireavg}]')
        stat, p = mannwhitneyu(fire, nofire, alternative='less')
        # Wilcoxin only works if the number of samples are the same.
        #stat, p = wilcoxon(fire, nofire, alternative='less')
        # print(f'  -STAT: {stat}')
        if p < low:
            print(f'  -Fire/Immed Sig << Nofire/Hold; P: {p}')
            sigvals[day] = sigval
        elif p > high:
            print(f'  -Fire/Immed Sig >> Nofire/Hold; P: {p}')
            sigvals[day] = sigval
        else:
            print(f'  -Fire/Immed NonSIG Nofire/Hold; P: {p}')
            sigvals[day] = -1*sigval

    return sigvals


def sigesi(dffire, dfnofire, var, sigval, ndays):
    low = 0.05
    high = 0.95
    sigvals = np.empty(ndays)
    for day in range(0, ndays, 1):
        print(f'DAY: {day*7 - 84}')
        fire = dffire[day]
        nofire = dfnofire[day]
        fireavg = fire.mean()
        nofireavg = nofire.mean()
        print(f'  -{var} FIRE/IMMED [Mean: {fireavg}]')
        print(f'  -{var} NOFIRE/HLD [Mean: {nofireavg}]')
        stat, p = mannwhitneyu(fire, nofire, alternative='less')
        # Wilcoxin only works if the number of samples are the same.
        #stat, p = wilcoxon(fire, nofire, alternative='less')
        # print(f'  -STAT: {stat}')
        if p < low:
            print(f'  -Fire/Immed Sig << Nofire/Hold; P: {p}')
            sigvals[day] = sigval
        elif p > high:
            print(f'  -Fire/Immed Sig >> Nofire/Hold; P: {p}')
            sigvals[day] = sigval
        else:
            print(f'  -Fire/Immed NonSIG Nofire/Hold; P: {p}')
            if sigval > 0:
                sigvals[day] = -1*sigval
            else:
                sigvals[day] = 4*sigval

    return sigvals