# Last Change: Mon Aug 20 08:00 PM 2007 J
from __future__ import division, print_function, absolute_import

import re
import datetime
from collections import OrderedDict

import numpy as np

from scipy._lib.six import next
import csv
import ctypes

"""A module to read arff files."""

__all__ = ['MetaData', 'loadarff', 'ArffError', 'ParseArffError']

# An Arff file is basically two parts:
#   - header
#   - data
#
# A header has each of its components starting by @META where META is one of
# the keyword (attribute of relation, for now).

# TODO:
#   - both integer and reals are treated as numeric -> the integer info
#    is lost!
#   - Replace ValueError by ParseError or something

# We know can handle the following:
#   - numeric and nominal attributes
#   - missing values for numeric attributes

r_meta = re.compile(r'^\s*@')
# Match a comment
r_comment = re.compile(r'^%')
# Match an empty line
r_empty = re.compile(r'^\s+$')
# Match a header line, that is a line which starts by @ + a word
r_headerline = re.compile(r'^\s*@\S*')
r_datameta = re.compile(r'^@[Dd][Aa][Tt][Aa]')
r_relation = re.compile(r'^@[Rr][Ee][Ll][Aa][Tt][Ii][Oo][Nn]\s*(\S*)')
r_attribute = re.compile(r'^\s*@[Aa][Tt][Tt][Rr][Ii][Bb][Uu][Tt][Ee]\s*(..*$)')

r_nominal = re.compile('{(.+)}')
r_date = re.compile(r"[Dd][Aa][Tt][Ee]\s+[\"']?(.+?)[\"']?$")

# To get attributes name enclosed with ''
r_comattrval = re.compile(r"'(..+)'\s+(..+$)")
# To get normal attributes
r_wcomattrval = re.compile(r"(\S+)\s+(..+$)")

# ------------------------
# Module defined exception
# ------------------------


class ArffError(IOError):
    pass


class ParseArffError(ArffError):
    pass


# ----------
# Attributes
# ----------
class Attribute(object):

    type_name = None

    def __init__(self, name):
        self.name = name
        self.range = None
        self.dtype = np.object_

    @classmethod
    def parse_attribute(cls, name, attr_string):
        """
        Parse the attribute line if it knows how. Returns the parsed
        attribute, or None.
        """
        return None

    def parse_data(self, data_str):
        """
        Parse a value of this type.
        """
        return None

    def __str__(self):
        """
        Parse a value of this type.
        """
        return self.name + ',' + self.type_name


class NominalAttribute(Attribute):

    type_name = 'nominal'

    def __init__(self, name, values):
        super().__init__(name)
        self.values = values
        self.range = values
        self.dtype = (np.string_, max(len(i) for i in values))

    @staticmethod
    def _get_nom_val(atrv):
        """Given a string containing a nominal type, returns a tuple of the
        possible values.

        A nominal type is defined as something framed between braces ({}).

        Parameters
        ----------
        atrv : str
           Nominal type definition

        Returns
        -------
        poss_vals : tuple
           possible values

        Examples
        --------
        >>> get_nom_val("{floup, bouga, fl, ratata}")
        ('floup', 'bouga', 'fl', 'ratata')
        """
        m = r_nominal.match(atrv)
        if m:
            attrs, _ = split_data_line(m.group(1))
            return tuple(attrs)
        else:
            raise ValueError("This does not look like a nominal string")

    @classmethod
    def parse_attribute(cls, name, attr_string):
        """
        Parse the attribute line if it knows how. Returns the parsed
        attribute, or None.

        For nominal attributes, the attribute string would be like '{<attr_1>,
         <attr2>, <attr_3>}'.
        """
        if attr_string[0] == '{':
            values = cls._get_nom_val(attr_string)
            return cls(name, values)
        else:
            return None

    def parse_data(self, data_str):
        """
        Parse a value of this type.
        """
        if data_str in self.values:
            return data_str
        elif data_str == '?':
            return data_str
        else:
            raise ValueError("%s value not in %s" % (str(data_str),
                                                     str(self.values)))

    def __str__(self):
        msg = self.name + ",{"
        for i in range(len(self.values)-1):
            msg += self.values[i] + ","
        msg += self.values[-1]
        msg += "}"
        return msg


class NumericAttribute(Attribute):

    def __init__(self, name):
        super().__init__(name)
        self.type_name = 'numeric'
        self.dtype = np.float_

    @classmethod
    def parse_attribute(cls, name, attr_string):
        """
        Parse the attribute line if it knows how. Returns the parsed
        attribute, or None.

        For numeric attributes, the attribute string would be like
        'numeric' or 'int' or 'real'.
        """

        attr_string = attr_string.lower().strip()

        if(attr_string[:len('numeric')] == 'numeric' or
           attr_string[:len('int')] == 'int' or
           attr_string[:len('real')] == 'real'):
            return cls(name)
        else:
            return None

    def parse_data(self, data_str):
        """
        Parse a value of this type.

        Parameters
        ----------
        data_str : str
           string to convert

        Returns
        -------
        f : float
           where float can be nan

        Examples
        --------
        >>> atr = NumericAttribute('atr')
        >>> atr.parse_data('1')
        1.0
        >>> atr.parse_data('1\\n')
        1.0
        >>> atr.parse_data('?\\n')
        nan
        """
        if '?' in data_str:
            return np.nan
        else:
            return float(data_str)

    def _basic_stats(self, data):
        nbfac = data.size * 1. / (data.size - 1)
        return (np.nanmin(data), np.nanmax(data),
                np.mean(data), np.std(data) * nbfac)


class StringAttribute(Attribute):

    def __init__(self, name):
        super().__init__(name)
        self.type_name = 'string'

    @classmethod
    def parse_attribute(cls, name, attr_string):
        """
        Parse the attribute line if it knows how. Returns the parsed
        attribute, or None.

        For string attributes, the attribute string would be like
        'string'.
        """

        attr_string = attr_string.lower().strip()

        if attr_string[:len('string')] == 'string':
            return cls(name)
        else:
            return None


class DateAttribute(Attribute):

    def __init__(self, name, date_format, datetime_unit):
        super().__init__(name)
        self.date_format = date_format
        self.datetime_unit = datetime_unit
        self.type_name = 'date'
        self.range = date_format
        self.dtype = np.datetime64(0, self.datetime_unit)

    @staticmethod
    def _get_date_format(atrv):
        m = r_date.match(atrv)
        if m:
            pattern = m.group(1).strip()
            # convert time pattern from Java's SimpleDateFormat to C's format
            datetime_unit = None
            if "yyyy" in pattern:
                pattern = pattern.replace("yyyy", "%Y")
                datetime_unit = "Y"
            elif "yy":
                pattern = pattern.replace("yy", "%y")
                datetime_unit = "Y"
            if "MM" in pattern:
                pattern = pattern.replace("MM", "%m")
                datetime_unit = "M"
            if "dd" in pattern:
                pattern = pattern.replace("dd", "%d")
                datetime_unit = "D"
            if "HH" in pattern:
                pattern = pattern.replace("HH", "%H")
                datetime_unit = "h"
            if "mm" in pattern:
                pattern = pattern.replace("mm", "%M")
                datetime_unit = "m"
            if "ss" in pattern:
                pattern = pattern.replace("ss", "%S")
                datetime_unit = "s"
            if "z" in pattern or "Z" in pattern:
                raise ValueError("Date type attributes with time zone not "
                                 "supported, yet")

            if datetime_unit is None:
                raise ValueError("Invalid or unsupported date format")

            return pattern, datetime_unit
        else:
            raise ValueError("Invalid or no date format")

    @classmethod
    def parse_attribute(cls, name, attr_string):
        """
        Parse the attribute line if it knows how. Returns the parsed
        attribute, or None.

        For date attributes, the attribute string would be like
        'date <format>'.
        """

        attr_string_lower = attr_string.lower().strip()

        if attr_string_lower[:len('date')] == 'date':
            date_format, datetime_unit = cls._get_date_format(attr_string)
            return cls(name, date_format, datetime_unit)
        else:
            return None

    def parse_data(self, data_str):
        """
        Parse a value of this type.
        """
        date_str = data_str.strip().strip("'").strip('"')
        if date_str == '?':
            return np.datetime64('NaT', self.datetime_unit)
        else:
            dt = datetime.datetime.strptime(date_str, self.date_format)
            return np.datetime64(dt).astype(
                "datetime64[%s]" % self.datetime_unit)

    def __str__(self):
        return super(DateAttribute, self).__str__() + ',' + self.date_format


class RelationalAttribute(Attribute):

    def __init__(self, name):
        super().__init__(name)