"""
Tests for structural time series models

Author: Chad Fulton
License: Simplified-BSD
"""
from __future__ import division, absolute_import, print_function

from statsmodels.compat import PY3

import warnings

import numpy as np
from numpy.testing import assert_equal, assert_allclose
import pandas as pd
import pytest

from statsmodels.datasets import macrodata
from statsmodels.tools.sm_exceptions import SpecificationWarning
from statsmodels.tsa.statespace import structural
from statsmodels.tsa.statespace.structural import UnobservedComponents
from statsmodels.tsa.statespace.tests.results import results_structural

dta = macrodata.load_pandas().data
dta.index = pd.date_range(start='1959-01-01', end='2009-07-01', freq='QS')


def run_ucm(name):
    true = getattr(results_structural, name)

    for model in true['models']:
        kwargs = model.copy()
        kwargs.update(true['kwargs'])

        # Make a copy of the data
        values = dta.copy()

        freq = kwargs.pop('freq', None)
        if freq is not None:
            values.index = pd.date_range(start='1959-01-01', periods=len(dta),
                                         freq=freq)

        # Test pandas exog
        if 'exog' in kwargs:
            # Default value here is pd.Series object
            exog = np.log(values['realgdp'])

            # Also allow a check with a 1-dim numpy array
            if kwargs['exog'] == 'numpy':
                exog = exog.values.squeeze()

            kwargs['exog'] = exog

        # Create the model
        mod = UnobservedComponents(values['unemp'], **kwargs)

        # Smoke test for starting parameters, untransform, transform
        # Also test that transform and untransform are inverses
        mod.start_params
        roundtrip = mod.transform_params(
            mod.untransform_params(mod.start_params))
        assert_allclose(mod.start_params, roundtrip)

        # Fit the model at the true parameters
        res_true = mod.filter(true['params'])

        # Check that the cycle bounds were computed correctly
        freqstr = freq[0] if freq is not None else values.index.freqstr[0]
        if 'cycle_period_bounds' in kwargs:
            cycle_period_bounds = kwargs['cycle_period_bounds']
        elif freqstr == 'A':
            cycle_period_bounds = (1.5, 12)
        elif freqstr == 'Q':
            cycle_period_bounds = (1.5*4, 12*4)
        elif freqstr == 'M':
            cycle_period_bounds = (1.5*12, 12*12)
        else:
            # If we have no information on data frequency, require the
            # cycle frequency to be between 0 and pi
            cycle_period_bounds = (2, np.inf)

        # Test that the cycle frequency bound is correct
        assert_equal(mod.cycle_frequency_bound,
                     (2*np.pi / cycle_period_bounds[1],
                      2*np.pi / cycle_period_bounds[0]))

        # Test that the likelihood is correct
        rtol = true.get('rtol', 1e-7)
        atol = true.get('atol', 0)
        assert_allclose(res_true.llf, true['llf'], rtol=rtol, atol=atol)

        # Optional smoke test for plot_components
        try:
            import matplotlib.pyplot as plt
            try:
                from pandas.plotting import register_matplotlib_converters
                register_matplotlib_converters()
            except ImportError:
                pass
            fig = plt.figure()
            res_true.plot_components(fig=fig)
        except ImportError:
            pass

        # Now fit the model via MLE
        with warnings.catch_warnings(record=True):
            res = mod.fit(disp=-1)
            # If we found a higher likelihood, no problem; otherwise check
            # that we're very close to that found by R
            if res.llf <= true['llf']:
                assert_allclose(res.llf, true['llf'], rtol=1e-4)

            # Smoke test for summary
            res.summary()


def test_irregular(close_figures):
    run_ucm('irregular')


def test_fixed_intercept(close_figures):
    # Clear warnings
    structural.__warningregistry__ = {}
    warning = SpecificationWarning if PY3 else None
    match = 'Specified model does not contain' if PY3 else None
    with pytest.warns(warning, match=match):
        run_ucm('fixed_intercept')


def test_deterministic_constant(close_figures):
    run_ucm('deterministic_constant')


def test_random_walk(close_figures):
    run_ucm('random_walk')


def test_local_level(close_figures):
    run_ucm('local_level')


def test_fixed_slope(close_figures):
    warning = SpecificationWarning if PY3 else None
    match = 'irregular component added' if PY3 else None
    with pytest.warns(warning, match=match):
        run_ucm('fixed_slope')


def test_fixed_slope_warn(close_figures):
    # Clear warnings
    structural.__warningregistry__ = {}

    warning = SpecificationWarning if PY3 else None
    match = 'irregular component added' if PY3 else None
    with pytest.warns(warning, match=match):
        run_ucm('fixed_slope')


def test_deterministic_trend(close_figures):
    run_ucm('deterministic_trend')


def test_random_walk_with_drift(close_figures):
    run_ucm('random_walk_with_drift')


def test_local_linear_deterministic_trend(close_figures):
    run_ucm('local_linear_deterministic_trend')


def test_local_linear_trend(close_figures):
    run_ucm('local_linear_trend')


def test_smooth_trend(close_figures):
    run_ucm('smooth_trend')


def test_random_trend(close_figures):
    run_ucm('random_trend')


def test_cycle(close_figures):
    run_ucm('cycle')


def test_seasonal(close_figures):
    run_ucm('seasonal')


def test_freq_seasonal(close_figures):
    run_ucm('freq_seasonal')


def test_reg(close_figures):
    run_ucm('reg')


def test_rtrend_ar1(close_figures):
    run_ucm('rtrend_ar1')


@pytest.mark.slow
def test_lltrend_cycle_seasonal_reg_ar1(close_figures):
    run_ucm('lltrend_cycle_seasonal_reg_ar1')


def test_mle_reg():
    endog = np.arange(100)*1.0
    exog = endog*2
    # Make the fit not-quite-perfect
    endog[::2] += 0.01
    endog[1::2] -= 0.01

    with warnings.catch_warnings(record=True):
        mod1 = UnobservedComponents(endog, irregular=True,
                                    exog=exog, mle_regression=False)
        res1 = mod1.fit(disp=-1)

        mod2 = UnobservedComponents(endog, irregular=True,
                                    exog=exog, mle_regression=True)
        res2 = mod2.fit(disp=-1)

    assert_allclose(res1.regression_coefficients.filtered[0, -1],
                    0.5,
                    atol=1e-5)
    assert_allclose(res2.params[1], 0.5, atol=1e-5)


def test_specifications():
    # Clear warnings
    structural.__warningregistry__ = {}

    endog = [1, 2]

    # Test that when nothing specified, a warning is issued and the model that
    # is fit is one with irregular=True and nothing else.
    warning = SpecificationWarning if PY3 else None
    match = 'irregular component added' if PY3 else None
    with pytest.warns(warning, match=match):
        mod = UnobservedComponents(endog)
        assert_equal(mod.trend_specification, 'irregular')

    # Test an invalid string trend specification
    with pytest.raises(ValueError):
        UnobservedComponents(endog, 'invalid spec')

    # Test that if a trend component is specified without a level component,
    # a warning is issued and a deterministic level component is added
    warning = SpecificationWarning if PY3 else None
    match = 'Trend component specified without' if PY3 else None
    with pytest.warns(warning, match=match):
        mod = UnobservedComponents(endog, trend=True, irregular=True)
        assert_equal(mod.trend_specification, 'deterministic trend')

    # Test that if a string specification is provided, a warning is issued if
    # the boolean attributes are also specified
    trend_attributes = ['irregular', 'trend', 'stochastic_level',
                        'stochastic_trend']
    for attribute in trend_attributes:
        kwargs = {attribute: True}

        warning = SpecificationWarning if PY3 else None
        match = 'may be overridden when the trend' if PY3 else None
        with pytest.warns(warning, match=match):
            UnobservedComponents(endog, 'deterministic trend', **kwargs)

    # Test that a seasonal with period less than two is invalid
    with pytest.raises(ValueError):
        UnobservedComponents(endog, seasonal=1)


def test_start_params():
    # Test that the behavior is correct for multiple exogenous and / or
    # autoregressive components

    # Parameters
    nobs = int(1e4)
    beta = np.r_[10, -2]
    phi = np.r_[0.5, 0.1]

    # Generate data
    np.random.seed(1234)
    exog = np.c_[np.ones(nobs), np.arange(nobs)*1.0]
    eps = np.random.normal(size=nobs)
    endog = np.zeros(nobs+2)
    for t in range(1, nobs):
        endog[t+1] = phi[0] * endog[t] + phi[1] * endog[t-1] + eps[t]
    endog = endog[2:]
    endog += np.dot(exog, beta)

    # Now just test that the starting parameters are approximately what they
    # ought to be (could make this arbitrarily precise by increasing nobs,
    # but that would slow down the test for no real gain)
    mod = UnobservedComponents(endog, exog=exog, autoregressive=2)
    assert_allclose(mod.start_params, [1., 0.5, 0.1, 10, -2], atol=1e-1)


def test_forecast():
    endog = np.arange(50) + 10
    exog = np.arange(50)

    mod = UnobservedComponents(endog, exog=exog, level='dconstant', seasonal=4)
    res = mod.smooth([1e-15, 0, 1])

    actual = res.forecast(10, exog=np.arange(50, 60)[:, np.newaxis])
    desired = np.arange(50, 60) + 10
    assert_allclose(actual, desired)


def test_misc_exog():
    # Tests for missing data
    nobs = 20
    k_endog = 1
    np.random.seed(1208)
    endog = np.random.normal(size=(nobs, k_endog))
    endog[:4, 0] = np.nan
    exog1 = np.random.normal(size=(nobs, 1))
    exog2 = np.random.normal(size=(nobs, 2))

    index = pd.date_range('1970-01-01', freq='QS', periods=nobs)
    endog_pd = pd.DataFrame(endog, index=index)
    exog1_pd = pd.Series(exog1.squeeze(), index=index)
    exog2_pd = pd.DataFrame(exog2, index=index)

    models = [
        UnobservedComponents(endog, 'llevel', exog=exog1),
        UnobservedComponents(endog, 'llevel', exog=exog2),
        UnobservedComponents(endog, 'llevel', exog=exog2),
        UnobservedComponents(endog_pd, 'llevel', exog=exog1_pd),
        UnobservedComponents(endog_pd, 'llevel', exog=exog2_pd),
        UnobservedComponents(endog_pd, 'llevel', exog=exog2_pd),
    ]

    for mod in models:
        # Smoke tests
        mod.start_params
        res = mod.fit(disp=False)
        res.summary()
        res.predict()
        res.predict(dynamic=True)
        res.get_prediction()

        oos_exog = np.random.normal(size=(1, mod.k_exog))
        res.forecast(steps=1, exog=oos_exog)
        res.get_forecast(steps=1, exog=oos_exog)

        # Smoke tests for invalid exog
        oos_exog = np.random.normal(size=(1))
        with pytest.raises(ValueError):
            res.forecast(steps=1, exog=oos_exog)

        oos_exog = np.random.normal(size=(2, mod.k_exog))
        with pytest.raises(ValueError):
            res.forecast(steps=1, exog=oos_exog)

        oos_exog = np.random.normal(size=(1, mod.k_exog + 1))
        with pytest.raises(ValueError):
            res.forecast(steps=1, exog=oos_exog)

    # Test invalid model specifications
    with pytest.raises(ValueError):
        UnobservedComponents(endog, 'llevel', exog=np.zeros((10, 4)))


def test_predict_custom_index():
    np.random.seed(328423)
    endog = pd.DataFrame(np.random.normal(size=50))
    mod = structural.UnobservedComponents(endog, 'llevel')
    res = mod.smooth(mod.start_params)
    out = res.predict(start=1, end=1, index=['a'])
    assert_equal(out.index.equals(pd.Index(['a'])), True)


def test_matrices_somewhat_complicated_model():
    values = dta.copy()

    model = UnobservedComponents(values['unemp'],
                                 level='lltrend',
                                 freq_seasonal=[{'period': 4},
                                                {'period': 9, 'harmonics': 3}],
                                 cycle=True,
                                 cycle_period_bounds=[2, 30],
                                 damped_cycle=True,
                                 stochastic_freq_seasonal=[True, False],
                                 stochastic_cycle=True
                                 )
    # Selected parameters
    params = [1,  # irregular_var
              3, 4,  # lltrend parameters:  level_var, trend_var
              5,   # freq_seasonal parameters: freq_seasonal_var_0
              # cycle parameters: cycle_var, cycle_freq, cycle_damp
              6, 2*np.pi/30., .9
              ]
    model.update(params)

    # Check scalar properties
    assert_equal(model.k_states, 2 + 4 + 6 + 2)
    assert_equal(model.k_state_cov, 2 + 1 + 0 + 1)
    assert_equal(model.loglikelihood_burn, 2 + 4 + 6 + 2)
    assert_allclose(model.ssm.k_posdef, 2 + 4 + 0 + 2)
    assert_equal(model.k_params, len(params))

    # Check the statespace model matrices against hand-constructed answers
    # We group the terms by the component
    expected_design = np.r_[[1, 0],
                            [1, 0, 1, 0],
                            [1, 0, 1, 0, 1, 0],
                            [1, 0]].reshape(1, 14)
    assert_allclose(model.ssm.design[:, :, 0], expected_design)

    expected_transition = __direct_sum([
        np.array([[1, 1],
                  [0, 1]]),
        np.array([[0, 1, 0, 0],
                  [-1, 0, 0, 0],
                  [0, 0, -1,  0],
                  [0, 0,  0, -1]]),
        np.array([[np.cos(2*np.pi*1/9.), np.sin(2*np.pi*1/9.), 0, 0, 0, 0],
                  [-np.sin(2*np.pi*1/9.), np.cos(2*np.pi*1/9.), 0, 0, 0, 0],
                  [0, 0,  np.cos(2*np.pi*2/9.), np.sin(2*np.pi*2/9.), 0, 0],
                  [0, 0, -np.sin(2*np.pi*2/9.), np.cos(2*np.pi*2/9.), 0, 0],
                  [0, 0, 0, 0,  np.cos(2*np.pi/3.), np.sin(2*np.pi/3.)],
                  [0, 0, 0, 0, -np.sin(2*np.pi/3.), np.cos(2*np.pi/3.)]]),
        np.array([[.9*np.cos(2*np.pi/30.), .9*np.sin(2*np.pi/30.)],
                 [-.9*np.sin(2*np.pi/30.), .9*np.cos(2*np.pi/30.)]])
    ])
    assert_allclose(
        model.ssm.transition[:, :, 0], expected_transition, atol=1e-7)

    # Since the second seasonal term is not stochastic,
    # the dimensionality of the state disturbance is 14 - 6 = 8
    expected_selection = np.zeros((14, 14 - 6))
    expected_selection[0:2, 0:2] = np.eye(2)
    expected_selection[2:6, 2:6] = np.eye(4)
    expected_selection[-2:, -2:] = np.eye(2)
    assert_allclose(model.ssm.selection[:, :, 0], expected_selection)

    expected_state_cov = __direct_sum([
        np.diag(params[1:3]),
        np.eye(4)*params[3],
        np.eye(2)*params[4]
    ])
    assert_allclose(model.ssm.state_cov[:, :, 0], expected_state_cov)


def __direct_sum(square_matrices):
    """Compute the matrix direct sum of an iterable of square numpy 2-d arrays
    """
    new_shape = np.sum([m.shape for m in square_matrices], axis=0)
    new_array = np.zeros(new_shape)
    offset = 0
    for m in square_matrices:
        rows, cols = m.shape
        assert rows == cols
        new_array[offset:offset + rows, offset:offset + rows] = m
        offset += rows
    return new_array
