import re

import datetime

from datetime import timedelta

#----------------------------------------------------------

# Functions for parsing the header of a note file and modifying

# the JSON to incorporate these structured fields

#----------------------------------------------------------

def parse_m_d_y(s):

    # I (Josh) added this to catch a date that had a typo in it

    s = s.replace(".", '')

    re_m_d_y = r"([0-9]{1,2})[/-]([0-9]{1,2})[/-]([0-9]{4})|([0-9]{1,2})[/-]([0-9]{1,2})[/-]([0-9]{2})"

    match = re.search(re_m_d_y, s)   

    if match:

        groups = list(match.groups())

        if groups[0] == None:

            groups = groups[3:]

            if int(groups[2]) - 17 >= 0:

                groups[2] = '19' + groups[2]

            else:

                groups[2] = '20' + groups[2]

        else:

            groups = groups[:3]

        return datetime.date(int(groups[2]),int(groups[0]),int(groups[1]))

    else:

        return None

def parse_m_y(s):

    re_m_y = "([0-9]{1,2})/([0-9]{4})|([0-9]{1,2})/([0-9]{2})"

    match = re.search(re_m_y, s)   

    if match:

        groups = list(match.groups())

        if groups[0] == None:

            groups = groups[2:]

            if int(groups[1]) - 17 >= 0:

                groups[1] = str(19) + groups[1]

            else:

                groups[1] = str(20) + groups[1]

        else:

            groups = groups[:2]

        return datetime.date(int(groups[1]),int(groups[0]), 1)

    else:

        return None

def parse_date(s):

    date = parse_m_d_y(s)

    if not date:

        date = parse_m_y(s)

    if not date:

        return None

    return date

def format_date(s):

    if type(s) in [type(""), type(u'')]:

        date = parse_date(s)

    else:

        date = s

    return date.strftime("%m/%d/%Y 00:00")

#----------------------------------------------------------

# Functions for extracting sentences from text

#----------------------------------------------------------

'''

description

    given an index in a string i, extracts the sentence [a, b] where b >= i

    this means if s[i] = '.', then this will return the preceeding sentence

input

    s: a string

    i: the index of the string that should be contained in the output sentence

    index: if true, then the indicies [a, b) that define the sentence are returned

        otherwise, the string s[a:b] is returned (default FALSE)

output

    if index = TRUE

        a tuple (a, b)

    else

        a string s[a, b)

'''

def get_sentence(s, i, index = False):

    #A new line must end a sentence and no ne gives a fuck about '\r'

    s = s.replace("\r", "")

    s = s.replace("\n", ". ")#TODO: more careful way of achieving this effect

    a = i-1

    #find the end of the previous sentence

    while a > 0 and not is_sentence_end(s, a-1):

        a -= 1

    b = i

    #find end of sentence

    while b < len(s) and not is_sentence_end(s, b):

        b += 1

    #return tuple or string based on index variable

    if index:

        return (a, b+1)

    else:

        return s[a : b+1]

'''

description

    uses get_sentence to tokenize string into sentences

input

    s: string

output

    a list of sentences

'''

def split_sentences(s):

    s = s.replace("\r","").replace("\n", ". ")

    i = 0

    result = []

    while i < len(s):

        a, i_new = get_sentence(s, i, True)

        result += [s[i:i_new].strip(" ")]

        i = i_new

    return result

'''

description

    helper function to help identify if '.' in a string indicates if a sentence ends

input

    s: a string

    i: the index of the '.'

output

    boolean of if that '.' indicates an end of a sentence

'''

def is_sentence_end(s, i):

    if i == 0: #if period starts string, not end of sentence

        return False

    elif i >= len(s)-1: #if period ends string, must be end of sentence

        return True

    elif unicode(s[i]) in [u'!',u'?']: #these are unambiguous

        return True

    elif unicode(s[i]) != u'.': #if its not a period it can't end a sentence

        return False

    else: #this is the case that it is a period 

        before = unicode(s[i-1])

        after = unicode(s[i+1])

        if not before.isnumeric(): #e.g. "...and he stopped. 5 is a nice number"

            return True

        elif after.isnumeric(): #e.g. "I have 5.2 liters"

            return False

        else: #e.g. "I have work until 5.I need a friend"

            return True

    #TODO: include cases for Mr. , Mrs. or any arbitary list of abreviations