# -*- coding: utf-8 -*-

# Copyright (c) 2021, Brandon Nielsen
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license.  See the LICENSE file for details.

from aniso8601 import compat
from aniso8601.builders import TupleBuilder
from aniso8601.builders.python import PythonTimeBuilder
from aniso8601.date import parse_date
from aniso8601.decimalfraction import normalize
from aniso8601.exceptions import ISOFormatError
from aniso8601.resolution import DurationResolution
from aniso8601.time import parse_time


def get_duration_resolution(isodurationstr):
    # Valid string formats are:
    #
    # PnYnMnDTnHnMnS (or any reduced precision equivalent)
    # PnW
    # P<date>T<time>
    isodurationtuple = parse_duration(isodurationstr, builder=TupleBuilder)

    if isodurationtuple.TnS is not None:
        return DurationResolution.Seconds

    if isodurationtuple.TnM is not None:
        return DurationResolution.Minutes

    if isodurationtuple.TnH is not None:
        return DurationResolution.Hours

    if isodurationtuple.PnD is not None:
        return DurationResolution.Days

    if isodurationtuple.PnW is not None:
        return DurationResolution.Weeks

    if isodurationtuple.PnM is not None:
        return DurationResolution.Months

    return DurationResolution.Years


def parse_duration(isodurationstr, builder=PythonTimeBuilder):
    # Given a string representing an ISO 8601 duration, return a
    # a duration built by the given builder. Valid formats are:
    #
    # PnYnMnDTnHnMnS (or any reduced precision equivalent)
    # PnW
    # P<date>T<time>

    if compat.is_string(isodurationstr) is False:
        raise ValueError("Duration must be string.")

    if len(isodurationstr) == 0:
        raise ISOFormatError(
            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
        )

    if isodurationstr[0] != "P":
        raise ISOFormatError("ISO 8601 duration must start with a P.")

    # If Y, M, D, H, S, or W are in the string,
    # assume it is a specified duration
    if _has_any_component(isodurationstr, ["Y", "M", "D", "H", "S", "W"]) is True:
        parseresult = _parse_duration_prescribed(isodurationstr)
        return builder.build_duration(**parseresult)

    if isodurationstr.find("T") != -1:
        parseresult = _parse_duration_combined(isodurationstr)
        return builder.build_duration(**parseresult)

    raise ISOFormatError(
        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
    )


def _parse_duration_prescribed(isodurationstr):
    # durationstr can be of the form PnYnMnDTnHnMnS or PnW

    # Make sure the end character is valid
    # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
    if isodurationstr[-1] not in ["Y", "M", "D", "H", "S", "W"]:
        raise ISOFormatError("ISO 8601 duration must end with a valid " "character.")

    # Make sure only the lowest order element has decimal precision
    durationstr = normalize(isodurationstr)

    if durationstr.count(".") > 1:
        raise ISOFormatError(
            "ISO 8601 allows only lowest order element to " "have a decimal fraction."
        )

    seperatoridx = durationstr.find(".")

    if seperatoridx != -1:
        remaining = durationstr[seperatoridx + 1 : -1]

        # There should only ever be 1 letter after a decimal if there is more
        # then one, the string is invalid
        if remaining.isdigit() is False:
            raise ISOFormatError(
                "ISO 8601 duration must end with " "a single valid character."
            )

    # Do not allow W in combination with other designators
    # https://bitbucket.org/nielsenb/aniso8601/issues/2/week-designators-should-not-be-combinable
    if (
        durationstr.find("W") != -1
        and _has_any_component(durationstr, ["Y", "M", "D", "H", "S"]) is True
    ):
        raise ISOFormatError(
            "ISO 8601 week designators may not be combined "
            "with other time designators."
        )

    # Parse the elements of the duration
    if durationstr.find("T") == -1:
        return _parse_duration_prescribed_notime(durationstr)

    return _parse_duration_prescribed_time(durationstr)


def _parse_duration_prescribed_notime(isodurationstr):
    # durationstr can be of the form PnYnMnD or PnW

    durationstr = normalize(isodurationstr)

    yearstr = None
    monthstr = None
    daystr = None
    weekstr = None

    weekidx = durationstr.find("W")
    yearidx = durationstr.find("Y")
    monthidx = durationstr.find("M")
    dayidx = durationstr.find("D")

    if weekidx != -1:
        weekstr = durationstr[1:-1]
    elif yearidx != -1 and monthidx != -1 and dayidx != -1:
        yearstr = durationstr[1:yearidx]
        monthstr = durationstr[yearidx + 1 : monthidx]
        daystr = durationstr[monthidx + 1 : -1]
    elif yearidx != -1 and monthidx != -1:
        yearstr = durationstr[1:yearidx]
        monthstr = durationstr[yearidx + 1 : monthidx]
    elif yearidx != -1 and dayidx != -1:
        yearstr = durationstr[1:yearidx]
        daystr = durationstr[yearidx + 1 : dayidx]
    elif monthidx != -1 and dayidx != -1:
        monthstr = durationstr[1:monthidx]
        daystr = durationstr[monthidx + 1 : -1]
    elif yearidx != -1:
        yearstr = durationstr[1:-1]
    elif monthidx != -1:
        monthstr = durationstr[1:-1]
    elif dayidx != -1:
        daystr = durationstr[1:-1]
    else:
        raise ISOFormatError(
            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
        )

    for componentstr in [yearstr, monthstr, daystr, weekstr]:
        if componentstr is not None:
            if "." in componentstr:
                intstr, fractionalstr = componentstr.split(".", 1)

                if intstr.isdigit() is False:
                    raise ISOFormatError(
                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
                    )
            else:
                if componentstr.isdigit() is False:
                    raise ISOFormatError(
                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
                    )

    return {"PnY": yearstr, "PnM": monthstr, "PnW": weekstr, "PnD": daystr}


def _parse_duration_prescribed_time(isodurationstr):
    # durationstr can be of the form PnYnMnDTnHnMnS

    timeidx = isodurationstr.find("T")

    datestr = isodurationstr[:timeidx]
    timestr = normalize(isodurationstr[timeidx + 1 :])

    hourstr = None
    minutestr = None
    secondstr = None

    houridx = timestr.find("H")
    minuteidx = timestr.find("M")
    secondidx = timestr.find("S")

    if houridx != -1 and minuteidx != -1 and secondidx != -1:
        hourstr = timestr[0:houridx]
        minutestr = timestr[houridx + 1 : minuteidx]
        secondstr = timestr[minuteidx + 1 : -1]
    elif houridx != -1 and minuteidx != -1:
        hourstr = timestr[0:houridx]
        minutestr = timestr[houridx + 1 : minuteidx]
    elif houridx != -1 and secondidx != -1:
        hourstr = timestr[0:houridx]
        secondstr = timestr[houridx + 1 : -1]
    elif minuteidx != -1 and secondidx != -1:
        minutestr = timestr[0:minuteidx]
        secondstr = timestr[minuteidx + 1 : -1]
    elif houridx != -1:
        hourstr = timestr[0:-1]
    elif minuteidx != -1:
        minutestr = timestr[0:-1]
    elif secondidx != -1:
        secondstr = timestr[0:-1]
    else:
        raise ISOFormatError(
            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
        )

    for componentstr in [hourstr, minutestr, secondstr]:
        if componentstr is not None:
            if "." in componentstr:
                intstr, fractionalstr = componentstr.split(".", 1)

                if intstr.isdigit() is False:
                    raise ISOFormatError(
                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
                    )
            else:
                if componentstr.isdigit() is False:
                    raise ISOFormatError(
                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
                    )

    # Parse any date components
    durationdict = {"PnY": None, "PnM": None, "PnW": None, "PnD": None}

    if len(datestr) > 1:
        durationdict = _parse_duration_prescribed_notime(datestr)

    durationdict.update({"TnH": hourstr, "TnM": minutestr, "TnS": secondstr})

    return durationdict


def _parse_duration_combined(durationstr):
    # Period of the form P<date>T<time>

    # Split the string in to its component parts
    datepart, timepart = durationstr[1:].split("T", 1)  # We skip the 'P'

    datevalue = parse_date(datepart, builder=TupleBuilder)
    timevalue = parse_time(timepart, builder=TupleBuilder)

    return {
        "PnY": datevalue.YYYY,
        "PnM": datevalue.MM,
        "PnD": datevalue.DD,
        "TnH": timevalue.hh,
        "TnM": timevalue.mm,
        "TnS": timevalue.ss,
    }


def _has_any_component(durationstr, components):
    # Given a duration string, and a list of components, returns True
    # if any of the listed components are present, False otherwise.
    #
    # For instance:
    # durationstr = 'P1Y'
    # components = ['Y', 'M']
    #
    # returns True
    #
    # durationstr = 'P1Y'
    # components = ['M', 'D']
    #
    # returns False

    for component in components:
        if durationstr.find(component) != -1:
            return True

    return False