import numpy as np


class NetworkBase(object):
    def __init__(self, ntw, pointpattern,nsteps=10,
                 permutations=99, threshold=0.5,
                 distribution='poisson',
                 lowerbound=None,upperbound=None):

        self.ntw = ntw
        self.pointpattern = pointpattern
        self.nsteps = nsteps
        self.permutations = permutations
        self.threshold = threshold

        self.distribution = distribution
        self.validatedistribution()

        self.sim = np.empty((permutations, nsteps))
        self.npts = self.pointpattern.npoints

        self.lowerbound = lowerbound
        self.upperbound = upperbound

        #Compute Statistic
        self.computeobserved()
        self.computepermutations()

        #Compute the envelope vectors
        self.computeenvelope()

    def validatedistribution(self):
        valid_distributions = ['uniform', 'poisson']
        assert(self.distribution in valid_distributions),"Disstribution not in {}".format(valid_distributions)

    def computeenvelope(self):
        upper = 1.0 - self.threshold / 2.0
        lower = self.threshold / 2.0

        self.upperenvelope = np.nanmax(self.sim, axis=0) * upper
        self.lowerenvelope = np.nanmin(self.sim, axis=0) * lower

    def setbounds(self, nearest):
        if self.lowerbound == None:
            self.lowerbound = 0
        if self.upperbound == None:
            self.upperbound = np.nanmax(nearest)

class NetworkG(NetworkBase):
    """
    Compute a network constrained G statistic

    Attributes
    ==========

    """

    def computeobserved(self):
        nearest = np.nanmin(self.ntw.allneighbordistances(self.pointpattern), axis=1)
        self.setbounds(nearest)
        observedx, observedy = gfunction(nearest,self.lowerbound,self.upperbound,
                                     nsteps=self.nsteps)
        self.observed = observedy
        self.xaxis = observedx

    def computepermutations(self):
        for p in range(self.permutations):
            sim = self.ntw.simulate_observations(self.npts,
                                                 distribution=self.distribution)
            nearest = np.nanmin(self.ntw.allneighbordistances(sim), axis=1)

            simx, simy = gfunction(nearest,
                                   self.lowerbound,
                                   self.upperbound,
                                   nsteps=self.nsteps)
            self.sim[p] = simy


class NetworkK(NetworkBase):
    """
    Network constrained K Function
    """

    def computeobserved(self):
        nearest = self.ntw.allneighbordistances(self.pointpattern)
        self.setbounds(nearest)

        self.lam = self.npts / np.sum(np.array(list(self.ntw.edge_lengths.values())))
        observedx, observedy = kfunction(nearest,
                                         self.upperbound,
                                         self.lam,
                                         nsteps = self.nsteps)
        self.observed = observedy
        self.xaxis = observedx

    def computepermutations(self):
        for p in range(self.permutations):
            sim = self.ntw.simulate_observations(self.npts,
                                                 distribution=self.distribution)
            nearest = self.ntw.allneighbordistances(sim)

            simx, simy = kfunction(nearest,
                                   self.upperbound,
                                   self.lam,
                                   nsteps=self.nsteps)
            self.sim[p] = simy

class NetworkF(NetworkBase):
     """
     Network constrained F Function

     This requires the capability to compute a distance matrix between two
     point patterns.  In this case one will be observed and one will be simulated
     """

     def computeobserved(self):
         self.fsim = self.ntw.simulate_observations(self.npts)
         #Nearest neighbor distances from the simulated to the observed
         nearest = np.nanmin(self.ntw.allneighbordistances(self.fsim, self.pointpattern), axis=1)
         self.setbounds(nearest)
         #Generate a random distribution of points
         observedx, observedy = ffunction(nearest, self.lowerbound, self.upperbound,
                                          nsteps=self.nsteps, npts=self.npts)
         self.observed = observedy
         self.xaxis = observedx

     def computepermutations(self):
         for p in range(self.permutations):
             sim = self.ntw.simulate_observations(self.npts,
                                                  distribution=self.distribution)
             nearest = np.nanmin(self.ntw.allneighbordistances(sim, self.fsim), axis=1)
             simx, simy = ffunction(nearest, self.lowerbound, self.upperbound,
                                    self.npts, nsteps=self.nsteps)
             self.sim[p] = simy

def kfunction(nearest, upperbound, intensity, nsteps=10):
    nobs = len(nearest)
    x = np.linspace(0, upperbound, nsteps)
    y = np.empty(len(x))

    for i, s in enumerate(x):
        y[i] = len(nearest[nearest <= s])
    y *= (intensity ** -1)
    return x, y

def ffunction(nearest, lowerbound, upperbound, npts, nsteps = 10):
    nobs = len(nearest)
    x = np.linspace(lowerbound, upperbound, nsteps)
    nearest = np.sort(nearest)
    y = np.empty(len(x))
    for i,r in enumerate(x):
        cnt = len(nearest[nearest <= r])
        if cnt > 0:
            g = cnt / float(npts)
        else:
            g = 0
        y[i] = g
    return x, y

def gfunction(nearest, lowerbound, upperbound, nsteps = 10):
    """
    Compute a G-Function

    Parameters
    ----------
    nearest         ndarray A vector of nearest neighbor distances
    nsteps          int The number of distance bands
    permutations    int The number of permutations to perform
    threshold       int Upper and lower significance threshold
    envelope        bool Return results of all permutations
    poisson         bool Use a poisson distribution to
                         determine the number of points
    """
    nobs = len(nearest)
    x = np.linspace(lowerbound, upperbound, nsteps)
    nearest = np.sort(nearest)

    y = np.empty(len(x))
    for i,r in enumerate(x):
        cnt = len(nearest[nearest <= r])
        if cnt > 0:
            g = cnt / float(nobs)
        else:
            g = 0
        y[i] = g
    return x, y
