#!/usr/bin/env python

import os, sys
from .svm import *
from .svm import __all__ as svm_all
from .commonutil import *
from .commonutil import __all__ as common_all

try:
    import numpy as np
    import scipy
    from scipy import sparse
except:
    scipy = None


if sys.version_info[0] < 3:
    range = xrange
    from itertools import izip as zip
    _cstr = lambda s: s.encode("utf-8") if isinstance(s,unicode) else str(s)
else:
    _cstr = lambda s: bytes(s, "utf-8")

__all__ = ['svm_load_model', 'svm_predict', 'svm_save_model', 'svm_train'] + svm_all + common_all


def svm_load_model(model_file_name):
    """
    svm_load_model(model_file_name) -> model

    Load a LIBSVM model from model_file_name and return.
    """
    model = libsvm.svm_load_model(_cstr(model_file_name))
    if not model:
        print("can't open model file %s" % model_file_name)
        return None
    model = toPyModel(model)
    return model

def svm_save_model(model_file_name, model):
    """
    svm_save_model(model_file_name, model) -> None

    Save a LIBSVM model to the file model_file_name.
    """
    libsvm.svm_save_model(_cstr(model_file_name), model)

def svm_train(arg1, arg2=None, arg3=None):
    """
    svm_train(y, x [, options]) -> model | ACC | MSE

    y: a list/tuple/ndarray of l true labels (type must be int/double).

    x: 1. a list/tuple of l training instances. Feature vector of
          each training instance is a list/tuple or dictionary.

       2. an l * n numpy ndarray or scipy spmatrix (n: number of features).

    svm_train(prob [, options]) -> model | ACC | MSE
    svm_train(prob, param) -> model | ACC| MSE

    Train an SVM model from data (y, x) or an svm_problem prob using
    'options' or an svm_parameter param.
    If '-v' is specified in 'options' (i.e., cross validation)
    either accuracy (ACC) or mean-squared error (MSE) is returned.
    options:
        -s svm_type : set type of SVM (default 0)
            0 -- C-SVC        (multi-class classification)
            1 -- nu-SVC        (multi-class classification)
            2 -- one-class SVM
            3 -- epsilon-SVR    (regression)
            4 -- nu-SVR        (regression)
        -t kernel_type : set type of kernel function (default 2)
            0 -- linear: u'*v
            1 -- polynomial: (gamma*u'*v + coef0)^degree
            2 -- radial basis function: exp(-gamma*|u-v|^2)
            3 -- sigmoid: tanh(gamma*u'*v + coef0)
            4 -- precomputed kernel (kernel values in training_set_file)
        -d degree : set degree in kernel function (default 3)
        -g gamma : set gamma in kernel function (default 1/num_features)
        -r coef0 : set coef0 in kernel function (default 0)
        -c cost : set the parameter C of C-SVC, epsilon-SVR, and nu-SVR (default 1)
        -n nu : set the parameter nu of nu-SVC, one-class SVM, and nu-SVR (default 0.5)
        -p epsilon : set the epsilon in loss function of epsilon-SVR (default 0.1)
        -m cachesize : set cache memory size in MB (default 100)
        -e epsilon : set tolerance of termination criterion (default 0.001)
        -h shrinking : whether to use the shrinking heuristics, 0 or 1 (default 1)
        -b probability_estimates : whether to train a model for probability estimates, 0 or 1 (default 0)
        -wi weight : set the parameter C of class i to weight*C, for C-SVC (default 1)
        -v n: n-fold cross validation mode
        -q : quiet mode (no outputs)
    """
    prob, param = None, None
    if isinstance(arg1, (list, tuple)) or (scipy and isinstance(arg1, np.ndarray)):
        assert isinstance(arg2, (list, tuple)) or (scipy and isinstance(arg2, (np.ndarray, sparse.spmatrix)))
        y, x, options = arg1, arg2, arg3
        param = svm_parameter(options)
        prob = svm_problem(y, x, isKernel=(param.kernel_type == PRECOMPUTED))
    elif isinstance(arg1, svm_problem):
        prob = arg1
        if isinstance(arg2, svm_parameter):
            param = arg2
        else:
            param = svm_parameter(arg2)
    if prob == None or param == None:
        raise TypeError("Wrong types for the arguments")

    if param.kernel_type == PRECOMPUTED:
        for i in range(prob.l):
            xi = prob.x[i]
            idx, val = xi[0].index, xi[0].value
            if idx != 0:
                raise ValueError('Wrong input format: first column must be 0:sample_serial_number')
            if val <= 0 or val > prob.n:
                raise ValueError('Wrong input format: sample_serial_number out of range')

    if param.gamma == 0 and prob.n > 0:
        param.gamma = 1.0 / prob.n
    libsvm.svm_set_print_string_function(param.print_func)
    err_msg = libsvm.svm_check_parameter(prob, param)
    if err_msg:
        raise ValueError('Error: %s' % err_msg)

    if param.cross_validation:
        l, nr_fold = prob.l, param.nr_fold
        target = (c_double * l)()
        libsvm.svm_cross_validation(prob, param, nr_fold, target)
        ACC, MSE, SCC = evaluations(prob.y[:l], target[:l])
        if param.svm_type in [EPSILON_SVR, NU_SVR]:
            print("Cross Validation Mean squared error = %g" % MSE)
            print("Cross Validation Squared correlation coefficient = %g" % SCC)
            return MSE
        else:
            print("Cross Validation Accuracy = %g%%" % ACC)
            return ACC
    else:
        m = libsvm.svm_train(prob, param)
        m = toPyModel(m)

        # If prob is destroyed, data including SVs pointed by m can remain.
        m.x_space = prob.x_space
        return m

def svm_predict(y, x, m, options=""):
    """
    svm_predict(y, x, m [, options]) -> (p_labels, p_acc, p_vals)

    y: a list/tuple/ndarray of l true labels (type must be int/double).
       It is used for calculating the accuracy. Use [] if true labels are
       unavailable.

    x: 1. a list/tuple of l training instances. Feature vector of
          each training instance is a list/tuple or dictionary.

       2. an l * n numpy ndarray or scipy spmatrix (n: number of features).

    Predict data (y, x) with the SVM model m.
    options:
        -b probability_estimates: whether to predict probability estimates,
            0 or 1 (default 0).
        -q : quiet mode (no outputs).

    The return tuple contains
    p_labels: a list of predicted labels
    p_acc: a tuple including  accuracy (for classification), mean-squared
           error, and squared correlation coefficient (for regression).
    p_vals: a list of decision values or probability estimates (if '-b 1'
            is specified). If k is the number of classes, for decision values,
            each element includes results of predicting k(k-1)/2 binary-class
            SVMs. For probabilities, each element contains k values indicating
            the probability that the testing instance is in each class.
            Note that the order of classes here is the same as 'model.label'
            field in the model structure.
    """

    def info(s):
        print(s)

    if scipy and isinstance(x, np.ndarray):
        x = np.ascontiguousarray(x) # enforce row-major
    elif sparse and isinstance(x, sparse.spmatrix):
        x = x.tocsr()
    elif not isinstance(x, (list, tuple)):
        raise TypeError("type of x: {0} is not supported!".format(type(x)))

    if (not isinstance(y, (list, tuple))) and (not (scipy and isinstance(y, np.ndarray))):
        raise TypeError("type of y: {0} is not supported!".format(type(y)))

    predict_probability = 0
    argv = options.split()
    i = 0
    while i < len(argv):
        if argv[i] == '-b':
            i += 1
            predict_probability = int(argv[i])
        elif argv[i] == '-q':
            info = print_null
        else:
            raise ValueError("Wrong options")
        i+=1

    svm_type = m.get_svm_type()
    is_prob_model = m.is_probability_model()
    nr_class = m.get_nr_class()
    pred_labels = []
    pred_values = []

    if scipy and isinstance(x, sparse.spmatrix):
        nr_instance = x.shape[0]
    else:
        nr_instance = len(x)

    if predict_probability:
        if not is_prob_model:
            raise ValueError("Model does not support probabiliy estimates")

        if svm_type in [NU_SVR, EPSILON_SVR]:
            info("Prob. model for test data: target value = predicted value + z,\n"
            "z: Laplace distribution e^(-|z|/sigma)/(2sigma),sigma=%g" % m.get_svr_probability());
            nr_class = 0

        prob_estimates = (c_double * nr_class)()
        for i in range(nr_instance):
            if scipy and isinstance(x, sparse.spmatrix):
                indslice = slice(x.indptr[i], x.indptr[i+1])
                xi, idx = gen_svm_nodearray((x.indices[indslice], x.data[indslice]), isKernel=(m.param.kernel_type == PRECOMPUTED))
            else:
                xi, idx = gen_svm_nodearray(x[i], isKernel=(m.param.kernel_type == PRECOMPUTED))
            label = libsvm.svm_predict_probability(m, xi, prob_estimates)
            values = prob_estimates[:nr_class]
            pred_labels += [label]
            pred_values += [values]
    else:
        if is_prob_model:
            info("Model supports probability estimates, but disabled in predicton.")
        if svm_type in (ONE_CLASS, EPSILON_SVR, NU_SVC):
            nr_classifier = 1
        else:
            nr_classifier = nr_class*(nr_class-1)//2
        dec_values = (c_double * nr_classifier)()
        for i in range(nr_instance):
            if scipy and isinstance(x, sparse.spmatrix):
                indslice = slice(x.indptr[i], x.indptr[i+1])
                xi, idx = gen_svm_nodearray((x.indices[indslice], x.data[indslice]), isKernel=(m.param.kernel_type == PRECOMPUTED))
            else:
                xi, idx = gen_svm_nodearray(x[i], isKernel=(m.param.kernel_type == PRECOMPUTED))
            label = libsvm.svm_predict_values(m, xi, dec_values)
            if(nr_class == 1):
                values = [1]
            else:
                values = dec_values[:nr_classifier]
            pred_labels += [label]
            pred_values += [values]

    if len(y) == 0:
        y = [0] * nr_instance
    ACC, MSE, SCC = evaluations(y, pred_labels)

    if svm_type in [EPSILON_SVR, NU_SVR]:
        info("Mean squared error = %g (regression)" % MSE)
        info("Squared correlation coefficient = %g (regression)" % SCC)
    else:
        info("Accuracy = %g%% (%d/%d) (classification)" % (ACC, int(round(nr_instance*ACC/100)), nr_instance))

    return pred_labels, (ACC, MSE, SCC), pred_values
