"""
Defines intervals for holding components.

:copyright: 2015 Agile Geoscience
:license: Apache 2.0
"""
import operator
import warnings
from functools import total_ordering

try:
    from functools import partialmethod
except:  # Python 2
    from utils import partialmethod

from .component import Component
from .position import Position
from . import utils


class IntervalError(Exception):
    """
    Generic error class.
    """
    pass


@total_ordering
class Interval:
    """
    Used to represent a lithologic or stratigraphic interval, or single point,
    such as a sample location.

    Initialize with a top (and optional base) and a description and/or
    an ordered list of components.

    Args:
        top (float): Required top depth. Required.
        base (float): Base depth. Optional.
        description (str): Textual description.
        lexicon (dict): A lexicon. See documentation. Optional unless you only
            provide descriptions, because it's needed to extract components.
        max_component (int): The number of components to extract. Default 1.
        abbreviations (bool): Whether to parse for abbreviations.

    TODO:
        Seems like I should be able to instantiate like this:

            ``Interval({'top': 0, 'components':[Component({'age': 'Neogene'})``s

        I can get around it for now like this:

            ``Interval(**{'top': 0, 'components':[Component({'age': 'Neogene'})``

        Question: should Interval itself cope with only being handed 'top' and
        either fill in down to the next or optionally create a point?
    """
    def __init__(self, top, base=None,
                 description='',
                 lexicon=None,
                 data=None,
                 components=None,
                 max_component=1,
                 abbreviations=False):

        if not isinstance(top, Position):
            top = Position(middle=top)

        if base is not None:
            if not isinstance(base, Position):
                base = Position(middle=base)

        self.top = top
        if base is not None:
            self.base = base
        else:
            self.base = top

        self.description = str(description)

        self.data = data or {}

        if components:
            self.components = list(components)
        else:
            self.components = []

        if self.description and (not self.components):
            if lexicon:
                comps = self._parse_description(self.description,
                                            lexicon,
                                            max_component=max_component,
                                            abbreviations=abbreviations
                                           )
                self.components = comps
            else:
                with warnings.catch_warnings():
                    w = "You must provide a lexicon to generate "
                    w += "components from descriptions."
                    warnings.warn(w)
                self.components = []

    def __setattr__(self, name, value):
        # If we were passed top or base, make sure it's a position.
        if name in ['top', 'base']:
            if not isinstance(value, Position):
                value = Position(middle=value)
        # Must now use the parent's setattr, or we go in circles.
        super(Interval, self).__setattr__(name, value)
        return

    def __str__(self):
        return self.__dict__.__str__()

    def __repr__(self):
        s = str(self)
        return "Interval({0})".format(s)

    def __add__(self, other):
        """
        TODO:
            If adding components, should take account of 'amount', if present.
            Or 'proportion'? ...Could be specified by lexicon??
        """
        if isinstance(other, self.__class__):
            return self.union(other)

        elif isinstance(other, Component):
            top = self.top.z
            base = self.base.z
            d = self.description + ' with ' + other.summary()
            c = self.components + [other]
            data = self._combine_data(other)

            return Interval(top, base, description=d, data=data, components=c)

        else:
            m = "You can only add components or intervals."
            raise IntervalError(m)

    def __eq__(self, other):
        """
        Must supply __eq__ and one other rich comparison for
        the total_ordering function to provide the others.
        """
        if isinstance(other, self.__class__):
            return self.top == other.top

    def __lt__(self, other):
        if isinstance(other, self.__class__):
            if self.order == 'elevation':
                return self.top < other.top
            return self.top > other.top

    def __bool__(self):
        if (not self.components) and (not self.data):
            return False
        else:
            return True

    def _repr_html_(self):
        """
        Jupyter Notebook magic repr function.
        """
        items = ['top', 'primary', 'summary', 'description', 'data', 'base']
        rows = ''
        row = '<tr>{row1}<td><strong>{e}</strong></td><td>{v}</td></tr>'
        style = 'width:2em; background-color:#DDDDDD'
        extra = '<td style="{}" rowspan="{}"></td>'
        for i, e in enumerate(items):
            row1 = extra.format(style, len(items)) if not i else ''
            v = getattr(self, e)
            v = v._repr_html_() if (v and (e == 'primary')) else v
            v = self.summary() if e == 'summary' else v
            v = utils.dict_repr_html(self.data) if e == 'data' else v
            v = v.z if e in ['top', 'base'] else v
            rows += row.format(row1=row1, e=e, v=v)

        html = '<table>{}</table>'.format(rows)
        return html

    @property
    def primary(self):
        """
        Convenience function returning the first component.

        Returns:
            Component. The first one in the list of components.
        """
        if self.components:
            return self.components[0]
        else:
            return None

    @property
    def middle(self):
        """
        Returns the middle of the interval.

        Returns:
            Float: The middle.
        """
        return (self.base.z + self.top.z) / 2

    @property
    def thickness(self):
        """
        Returns the thickness of the interval.

        Returns:
            Float: The thickness.
        """
        return abs(self.base.z - self.top.z)

    @property
    def min_thickness(self):
        """
        Returns the minimum possible thickness of the interval, given the
        uncertainty in its top and base Positions.

        Returns:
            Float: The minimum thickness.
        """
        return abs(self.base.upper - self.top.lower)

    @property
    def max_thickness(self):
        """
        Returns the maximum possible thickness of the interval, given the
        uncertainty in its top and base Positions.

        Returns:
            Float: The maximum thickness.
        """
        return abs(self.base.lower - self.top.upper)

    @property
    def kind(self):
        """
        The type of Interval: a 'point' (where base = top),
        or an 'interval', where thickness > 0.

        Returns:
            str: Either 'point' or 'interval'.
        """
        if self.thickness == 0:
            return 'point'
        return 'interval'

    @property
    def order(self):
        """
        Gives the order of this interval, based on relative values of
        top & base.
        """
        if self.top.z > self.base.z:
            return 'elevation'
        else:
            return 'depth'

    def summary(self, fmt=None, initial=False):
        """
        Returns a summary of the interval.

        Args:
            fmt (str): A format string. Optional.
            initial (bool): Whether to capitalize the first letter.

        Returns:
            str: An English-language summary.

        TODO:
            Allow formatting of the entire string, not just the rock.
        """
        s = [c.summary(fmt=fmt, initial=initial)
             for c in self.components]
        summary = " with ".join(s)
        if summary:
            return "{0:.2f} {1} of {2}".format(self.thickness, self.top.units, summary)
        elif self.description:
            return "{0:.2f} {1} of {2}".format(self.thickness, self.top.units, self.description)
        else:
            return None

    def invert(self, copy=False):
        """
        Inverts the interval. If it was depth-ordered (positive numbers
        increasing downwards.), it will now be elevation-ordered, and
        vice versa.

        Args:
            copy (bool): Whether to make a copy or not. Default: False.
        """
        if copy:
            d = self.__dict__.copy()
            del(d['top'])
            del(d['base'])
            self.base.invert()
            self.top.invert()
            return Interval(top=self.base, base=self.top, **d)
        else:
            self.base.invert()
            self.top.invert()
            old_base = self.base
            self.base = self.top
            self.top = old_base
            return

    def copy(self):
        """
        Returns a shallow copy of the interval.

        """
        return Interval(**self.__dict__.copy())

    def relationship(self, other):
        """
        Returns the relationship style. Completely deterministic.

        """
        o = {'depth': operator.lt, 'elevation': operator.gt}[self.order]
        top_inside = o(self.top.z, other.top.z) and o(other.top.z, self.base.z)
        base_inside = o(self.top.z, other.base.z) and o(other.base.z, self.base.z)
        above_below = o(other.top.z, self.top.z) and o(self.base.z, other.base.z)

        if top_inside and base_inside:
            return 'contains'
        elif above_below:
            return 'containedby'
        elif top_inside or base_inside:
            return 'partially'
        elif (self.top.z == other.base.z) or (self.base.z == other.top.z):
            return 'touches'
        else:
            return None

    def _overlaps(self, other, rel='any'):
        """
        Checks to see if and how two intervals overlap.

        """
        overlaps = ['partially', 'contains', 'containedby']
        acceptable = overlaps + ['touches', 'any']
        if rel not in acceptable:
            m = 'rel must be one of {}'.format(', '.join(acceptable))
            raise IntervalError(m)

        r = self.relationship(other)
        if r:
            if (r == rel) or ((rel == 'any') and (r in overlaps)):
                return True
        return False

    # Curry _overlaps() into some convenient functions.
    any_overlaps = partialmethod(_overlaps, rel='any')
    partially_overlaps = partialmethod(_overlaps, rel='partially')
    completely_contains = partialmethod(_overlaps, rel='contains')
    is_contained_by = partialmethod(_overlaps, rel='containedby')
    touches = partialmethod(_overlaps, rel='touches')

    def spans(self, d):
        """
        Determines if depth d is within this interval.

        Args:
            d (float): Level or 'depth' to evaluate.

        Returns:
            bool. Whether the depth is in the interval.
        """
        o = {'depth': operator.le, 'elevation': operator.ge}[self.order]
        return (o(d, self.base.z) and o(self.top.z, d))

    def split_at(self, d):
        """
        Splits an interval.

        Args:
            d (float): Level or 'depth' to split at.

        Returns:
            tuple. The two intervals that result from the split.
        """
        if not self.spans(d):
            m = 'd = {} must be within interval {}'.format(d, self)
            raise IntervalError(m)

        int1, int2 = self.copy(), self.copy()

        int1.base = d
        int2.top = d

        return int1, int2  # upper, lower

    def _explode(self, other):
        """
        Private function. 'Explodes' an interval with another interval.
        Note that `self` must at least partially overlap `other`.

        Args:
            other (Interval): The other Interval.

        Returns:
            tuple. Three Intervals: upper, middle, lower; `middle` has the
                properties of the lowermost Interval.
        """
        if not self.order == other.order:
            m = 'self and other must have the same wayupness'
            raise IntervalError(m)

        uppermost = max(self, other).copy()
        lowermost = min(self, other).copy()  # Only based on tops.

        if self.partially_overlaps(other):
            upper, _ = uppermost.split_at(lowermost.top.z)
            middle, lower = lowermost.split_at(uppermost.base.z)
        else:
            upper_temp, lower = uppermost.split_at(lowermost.base.z)
            upper, _ = upper_temp.split_at(lowermost.top.z)
            middle = lowermost

        return upper, middle, lower  # middle has lowermost's properties

    def _combine_data(self, other):
        """
        Combines data only.

        Args:
            other (Interval): The other Interval.

        Returns:
            dict. The blended data.
        """
        self_data = getattr(self, 'data', None)
        other_data = getattr(other, 'data', None)

        if (self_data is None) and (other_data is None):
            return {}
        elif (self_data is not None) and (other_data is None):
            return self_data
        elif (self_data is None) and (other_data is not None):
            return other_data
        else:
            data = {}
            for k, v in other_data.items():
                if k in self_data:
                    v = utils.list_and_add(self_data[k], v)
                data[k] = v
            return data

    def _blend_descriptions(self, other):
        """
        Private method. Computes the description for combining two intervals.
        Make sure that the intervals are already adjusted to the correct
        thicknesses.

        Args:
            other (Interval): The other Interval.

        Returns:
            str. The blended description.
        """
        thin, thick = sorted([self, other], key=lambda k: k.thickness)
        total = thin.thickness + thick.thickness
        prop = 100 * thick.thickness / total

        if self.components == other.components:
            return self.description.strip(' .,')

        d1 = thick.description.strip(' .,') or thick.summary()
        d2 = thin.description.strip(' .,') or thin.summary()
        if d1:
            d = '{:.1f}% {} with {:.1f}% {}'.format(prop, d1, 100-prop, d2)
        else:
            d = ''

        return d

    def _combine(self, old_self, other, blend=True):
        """
        Private method. Combines data, components, and descriptions but
        nothing else.

        Args:
            old_self (Interval): You have to pass the instance explicitly.
            other (Interval): The other Interval.
            blend (bool): Whether to blend or not.

        Returns:
            Interval. The combined description.
        """
        if blend:
            self.components = old_self.components.copy()
            for c in other.components:
                if c not in self.components:
                    self.components.append(c)
            self.description = old_self._blend_descriptions(other)
            self.data = old_self._combine_data(other)
        else:
            self.components = other.components
            self.description = other.description
            self.data = other.data

        return self

    def intersect(self, other, blend=True):
        """
        Perform the intersection binary operation. self must at least
        partially overlap with other or an IntervalError is raised.

        If blend is False, you are essentially replacing self with other.

        Args:
            other (Interval): The other Interval.
            blend (bool): Whether to blend or not.

        Returns:
            Interval. The intersection of the Interval with the one provided.
        """
        if not self.any_overlaps(other):
            m = 'self must at least partially overlap other'
            raise IntervalError(m)

        _, intersection, _ = self._explode(other)

        return intersection._combine(self, other, blend=blend)

    def merge(self, other, blend=True):
        """
        Perform the merge binary operation. self must at least
        partially overlap with other or an IntervalError is raised.

        If blend is False, you are essentially replacing self with other.

        Args:
            other (Interval): The other Interval.
            blend (bool): Whether to blend or not.

        Returns:
            Striplog. The merge of the Interval with the one provided.
        """
        if not self.any_overlaps(other):
            m = 'self must at least partially overlap other'
            raise IntervalError(m)

        upper, middle, lower = self._explode(other)

        if self.top.z == upper.top.z:
            self_is_uppermost = True
        else:
            self_is_uppermost = False

        middle = middle._combine(self, other, blend=blend)

        if self.partially_overlaps(other) and (not blend):
            # Then we'll only have two pieces:
            if self_is_uppermost:
                result = [upper, other]
            else:
                result = [other, lower]
        else:
            result = [lower, middle, upper]

        from .striplog import Striplog  # Import here to avoid circular ref
        if self.order == 'depth':
            return Striplog(result[::-1])
        else:
            return Striplog(result)

    def union(self, other, blend=True):
        """
        Perform the union binary operation. self must at least touch other or
        an IntervalError is raised.

        If blend is False, you are essentially replacing self with other.

        Args:
            other (Interval): The other Interval.
            blend (bool): Whether to blend or not.

        Returns:
            Interval. The union of the Interval with the one provided.
        """
        if not (self.touches(other) or self.any_overlaps(other)):
            # m = 'self must at least touch or partially overlap other'
            # raise IntervalError(m)
            return self, other

        if self.order == 'elevation':
            top = max(self.top.z, other.top.z)
            bot = min(self.base.z, other.base.z)
        else:
            top = min(self.top.z, other.top.z)
            bot = max(self.base.z, other.base.z)

        result = self.copy()
        result.top = top
        result.base = bot

        return result._combine(self, other, blend=blend)

    def difference(self, other):
        """
        Perform the difference binary operation.

        Args:
            other (Interval): The other Interval.

        Returns:
            Interval. One or two Intervals.
        """
        if self.touches(other) or (not self.any_overlaps(other)):
            return self
        elif self.completely_contains(other):
            upper, _, lower = self._explode(other)
            return upper, lower
        else:
            if self > other:
                return self.split_at(other.top.z)[0]
            elif self < other:
                return self.split_at(other.base.z)[1]
            else:  # They are equal
                return None

    @staticmethod
    def _parse_description(description, lexicon,
                            max_component=1,
                            abbreviations=False):
        """
        Turns a description into a lists of components. The items in the
        list are in the order they were found in the description, which is
        usually order of importance.

        Args:
            lexicon (Lexicon): The translation between words and their meaning.
            max_component (int): The most components to return. Default 1.
            abbreviations (bool): Whether to expand abreviations or not.
                Default False.

        Returns:
            List. A list of Components extracted from the description text.
        """

        if abbreviations:
            text = lexicon.expand_abbreviations(description)
        else:
            text = description

        components = []
        for p, part in enumerate(lexicon.split_description(text)):
            if p == max_component:
                break
            components.append(Component.from_text(part, lexicon))

        return components
