# -*- coding: utf-8 -*-
from numpy import sum, asarray, arange, exp
from .go_benchmark import Benchmark


class JennrichSampson(Benchmark):
    r"""
    Jennrich-Sampson objective function.

    This class defines the Jennrich-Sampson [1]_ global optimization problem. This
    is a multimodal minimization problem defined as follows:

    .. math::

        f_{\text{JennrichSampson}}(x) = \sum_{i=1}^{10} \left [2 + 2i
        - (e^{ix_1} + e^{ix_2}) \right ]^2


    with :math:`x_i \in [-1, 1]` for :math:`i = 1, 2`.

    *Global optimum*: :math:`f(x) = 124.3621824` for
    :math:`x = [0.257825, 0.257825]`.

    .. [1] Jamil, M. & Yang, X.-S. A Literature Survey of Benchmark Functions
    For Global Optimization Problems Int. Journal of Mathematical Modelling
    and Numerical Optimisation, 2013, 4, 150-194.
    """

    def __init__(self, dimensions=2):
        Benchmark.__init__(self, dimensions)

        self._bounds = list(zip([-1.0] * self.N, [1.0] * self.N))

        self.global_optimum = [[0.257825, 0.257825]]
        self.custom_bounds = [(-1, 0.34), (-1, 0.34)]
        self.fglob = 124.3621824

    def fun(self, x, *args):
        self.nfev += 1

        i = arange(1, 11)
        return sum((2 + 2 * i - (exp(i * x[0]) + exp(i * x[1]))) ** 2)


class Judge(Benchmark):
    r"""
    Judge objective function.

    This class defines the Judge [1]_ global optimization problem. This
    is a multimodal minimization problem defined as follows:

    .. math::

        f_{\text{Judge}}(x) = \sum_{i=1}^{20}
        \left [ \left (x_1 + A_i x_2 + B x_2^2 \right ) - C_i \right ]^2


    Where, in this exercise:

    .. math::

        \begin{cases}
        C = [4.284, 4.149, 3.877, 0.533, 2.211, 2.389, 2.145,
        3.231, 1.998, 1.379, 2.106, 1.428, 1.011, 2.179, 2.858, 1.388, 1.651,
        1.593, 1.046, 2.152] \\
        A = [0.286, 0.973, 0.384, 0.276, 0.973, 0.543, 0.957, 0.948, 0.543,
             0.797, 0.936, 0.889, 0.006, 0.828, 0.399, 0.617, 0.939, 0.784,
             0.072, 0.889] \\
        B = [0.645, 0.585, 0.310, 0.058, 0.455, 0.779, 0.259, 0.202, 0.028,
             0.099, 0.142, 0.296, 0.175, 0.180, 0.842, 0.039, 0.103, 0.620,
             0.158, 0.704]
        \end{cases}


    with :math:`x_i \in [-10, 10]` for :math:`i = 1, 2`.

    *Global optimum*: :math:`f(x_i) = 16.0817307` for
    :math:`\mathbf{x} = [0.86479, 1.2357]`.

    .. [1] Gavana, A. Global Optimization Benchmarks and AMPGO retrieved 2015
    """

    def __init__(self, dimensions=2):
        Benchmark.__init__(self, dimensions)

        self._bounds = list(zip([-10.0] * self.N, [10.0] * self.N))

        self.global_optimum = [[0.86479, 1.2357]]
        self.custom_bounds = [(-2.0, 2.0), (-2.0, 2.0)]
        self.fglob = 16.0817307
        self.c = asarray([4.284, 4.149, 3.877, 0.533, 2.211, 2.389, 2.145,
                          3.231, 1.998, 1.379, 2.106, 1.428, 1.011, 2.179,
                          2.858, 1.388, 1.651, 1.593, 1.046, 2.152])

        self.a = asarray([0.286, 0.973, 0.384, 0.276, 0.973, 0.543, 0.957,
                          0.948, 0.543, 0.797, 0.936, 0.889, 0.006, 0.828,
                          0.399, 0.617, 0.939, 0.784, 0.072, 0.889])

        self.b = asarray([0.645, 0.585, 0.310, 0.058, 0.455, 0.779, 0.259,
                          0.202, 0.028, 0.099, 0.142, 0.296, 0.175, 0.180,
                          0.842, 0.039, 0.103, 0.620, 0.158, 0.704])

    def fun(self, x, *args):
        self.nfev += 1

        return sum(((x[0] + x[1] * self.a + (x[1] ** 2.0) * self.b) - self.c)
                    ** 2.0)