import statsmodels.base.model as base
from statsmodels.base import data
import statsmodels.base.wrapper as wrap
from statsmodels.tsa.base import datetools
from numpy import arange, asarray
from pandas import Index
from pandas import datetools as pandas_datetools
import datetime

_freq_to_pandas = datetools._freq_to_pandas

_tsa_doc = """
    %(model)s

    Parameters
    ----------
    %(params)s
    dates : array-like of datetime, optional
        An array-like object of datetime objects. If a pandas object is given
        for endog or exog, it is assumed to have a DateIndex.
    freq : str, optional
        The frequency of the time-series. A Pandas offset or 'B', 'D', 'W',
        'M', 'A', or 'Q'. This is optional if dates are given.
    %(extra_params)s
    %(extra_sections)s
"""

_model_doc = "Timeseries model base class"

_generic_params = base._model_params_doc
_missing_param_doc = base._missing_param_doc

class TimeSeriesModel(base.LikelihoodModel):

    __doc__ = _tsa_doc % {"model" : _model_doc, "params" : _generic_params,
                          "extra_params" : _missing_param_doc,
                          "extra_sections" : ""}

    def __init__(self, endog, exog=None, dates=None, freq=None, missing='none'):
        super(TimeSeriesModel, self).__init__(endog, exog, missing=missing)
        self._init_dates(dates, freq)

    def _init_dates(self, dates, freq):
        if dates is None:
            dates = self.data.row_labels

        if dates is not None:
            if (not isinstance(dates[0], datetime.datetime) and
                    isinstance(self.data, data.PandasData)):
                raise ValueError("Given a pandas object and the index does "
                                 "not contain dates")
            if not freq:
                try:
                    freq = datetools._infer_freq(dates)
                except:
                    raise ValueError("Frequency inference failed. Use `freq` "
                            "keyword.")
            dates = Index(dates)
        self.data.dates = dates
        if freq:
            try: #NOTE: Can drop this once we move to pandas >= 0.8.x
                _freq_to_pandas[freq]
            except:
                raise ValueError("freq %s not understood" % freq)
        self.data.freq = freq

    def _get_exog_names(self):
        return self.data.xnames

    def _set_exog_names(self, vals):
        if not isinstance(vals, list):
            vals = [vals]
        self.data.xnames = vals

    #overwrite with writable property for (V)AR models
    exog_names = property(_get_exog_names, _set_exog_names)

    def _get_dates_loc(self, dates, date):
        if hasattr(dates, 'indexMap'): # 0.7.x
            date = dates.indexMap[date]
        else:
            date = dates.get_loc(date)
            try: # pandas 0.8.0 returns a boolean array
                len(date)
                from numpy import where
                date = where(date)[0].item()
            except TypeError: # this is expected behavior
                pass
        return date

    def _str_to_date(self, date):
        """
        Takes a string and returns a datetime object
        """
        return datetools.date_parser(date)

    def _set_predict_start_date(self, start):
        dates = self.data.dates
        if dates is None:
            return
        if start > len(dates):
            raise ValueError("Start must be <= len(endog)")
        if start == len(dates):
            self.data.predict_start = datetools._date_from_idx(dates[-1],
                                                    start, self.data.freq)
        elif start < len(dates):
            self.data.predict_start = dates[start]
        else:
            raise ValueError("Start must be <= len(dates)")

    def _get_predict_start(self, start):
        """
        Returns the index of the given start date. Subclasses should define
        default behavior for start = None. That isn't handled here.

        Start can be a string or an integer if self.data.dates is None.
        """
        dates = self.data.dates
        if isinstance(start, str):
            if dates is None:
                raise ValueError("Got a string for start and dates is None")
            dtstart = self._str_to_date(start)
            self.data.predict_start = dtstart
            try:
                start = self._get_dates_loc(dates, dtstart)
            except KeyError:
                raise ValueError("Start must be in dates. Got %s | %s" %
                        (str(start), str(dtstart)))

        self._set_predict_start_date(start)
        return start


    def _get_predict_end(self, end):
        """
        See _get_predict_start for more information. Subclasses do not
        need to define anything for this.
        """

        out_of_sample = 0 # will be overwritten if needed
        if end is None: # use data for ARIMA - endog changes
            end = len(self.data.endog) - 1

        dates = self.data.dates
        freq = self.data.freq

        if isinstance(end, str):
            if dates is None:
                raise ValueError("Got a string for end and dates is None")
            try:
                dtend = self._str_to_date(end)
                self.data.predict_end = dtend
                end = self._get_dates_loc(dates, dtend)
            except KeyError, err: # end is greater than dates[-1]...probably
                if dtend > self.data.dates[-1]:
                    end = len(self.data.endog) - 1
                    freq = self.data.freq
                    out_of_sample = datetools._idx_from_dates(dates[-1], dtend,
                                            freq)
                else:
                    if freq is None:
                        raise ValueError("There is no frequency for these "
                                         "dates and date %s is not in dates "
                                         "index. Try giving a date that is in "
                                         "the dates index or use an integer."
                                         % dtend)
                    else: #pragma: no cover
                        raise err # should never get here
            self._make_predict_dates() # attaches self.data.predict_dates

        elif isinstance(end, int) and dates is not None:
            try:
                self.data.predict_end = dates[end]
            except IndexError, err:
                nobs = len(self.data.endog) - 1 # as an index
                out_of_sample = end - nobs
                end = nobs
                if freq is not None:
                    self.data.predict_end = datetools._date_from_idx(dates[-1],
                            out_of_sample, freq)
                elif out_of_sample <= 0: # have no frequency but are in sample
                    #TODO: what error to catch here to make sure dates is
                    #on the index?
                    try:
                        self.data.predict_end = self._get_dates_loc(dates,
                                                end)
                    except KeyError:
                        raise
                else:
                    self.data.predict_end = end + out_of_sample
                    self.data.predict_start = self._get_dates_loc(dates,
                                                self.data.predict_start)

            self._make_predict_dates()

        elif isinstance(end, int):
            nobs = len(self.data.endog) - 1 # is an index
            if end > nobs:
                out_of_sample = end - nobs
                end = nobs

        elif freq is None: # should have a date with freq = None
            raise ValueError("When freq is None, you must give an integer "
                             "index for end.")

        return end, out_of_sample

    def _make_predict_dates(self):
        data = self.data
        dtstart = data.predict_start
        dtend = data.predict_end
        freq = data.freq

        if freq is not None:
            pandas_freq = _freq_to_pandas[freq]
            try:
                from pandas import DatetimeIndex
                dates = DatetimeIndex(start=dtstart, end=dtend,
                                        freq=pandas_freq)
            except ImportError, err:
                from pandas import DateRange
                dates = DateRange(dtstart, dtend, offset = pandas_freq).values
        # handle
        elif freq is None and (isinstance(dtstart, int) and
                               isinstance(dtend, int)):
            from pandas import Index
            dates = Index(range(dtstart, dtend+1))
        # if freq is None and dtstart and dtend aren't integers, we're
        # in sample
        else:
            dates = self.data.dates
            start = self._get_dates_loc(dates, dtstart)
            end = self._get_dates_loc(dates, dtend)
            dates = dates[start:end+1] # is this index inclusive?
        self.data.predict_dates = dates

class TimeSeriesModelResults(base.LikelihoodModelResults):
    def __init__(self, model, params, normalized_cov_params, scale=1.):
        self.data = model.data
        super(TimeSeriesModelResults,
                self).__init__(model, params, normalized_cov_params, scale)

class TimeSeriesResultsWrapper(wrap.ResultsWrapper):
    _attrs = {}
    _wrap_attrs = wrap.union_dicts(base.LikelihoodResultsWrapper._wrap_attrs,
                                    _attrs)
    _methods = {'predict' : 'dates'}
    _wrap_methods = wrap.union_dicts(base.LikelihoodResultsWrapper._wrap_methods,
                                     _methods)
wrap.populate_wrapper(TimeSeriesResultsWrapper,
                      TimeSeriesModelResults)

if __name__ == "__main__":
    import statsmodels.api as sm
    import datetime
    import pandas

    data = sm.datasets.macrodata.load()

    #make a DataFrame
    #TODO: attach a DataFrame to some of the datasets, for quicker use
    dates = [str(int(x[0])) +':'+ str(int(x[1])) \
             for x in data.data[['year','quarter']]]

    df = pandas.DataFrame(data.data[['realgdp','realinv','realcons']], index=dates)
    ex_mod = TimeSeriesModel(df)
    #ts_series = pandas.TimeSeries()


