#!/usr/bin/env python

from __future__ import print_function

import sys
import csv
from functools import total_ordering
from datetime import datetime
from operator import attrgetter

"""Read CSV and make HTML for the conference page.

Handles sorting dates, TBD dates, dates in the past, and more.
No guarantees that this is bug free :)

Author: Christopher Kenna (2012)

"""

@total_ordering
class ConferenceDate(object):
    TBD_STR = 'tbd'
    TBD_VAL = 'tbd'

    def __init__(self, date):
        if isinstance(date, datetime):
            self.dt = date
        else:
            self.dt = self.date_from_str(date)

    @classmethod
    def date_from_str(cls, date_str):
        try:
            return datetime.strptime(date_str, '%m/%d/%Y')
        except ValueError:
            if cls.TBD_STR == date_str.lower():
                return cls.TBD_VAL
            die('bad date: {0}'.format(date_str))

    @classmethod
    def get_timespan(cls, start, end):
        ret = []
        if start is end:
            ret.append(cls.html_date(start))
        elif (not start.is_tbd() and not end.is_tbd() and 
              start.dt.month == end.dt.month):
            ret.append(start.dt.strftime('%b. {0}'.format(start.dt.day)))
            ret.append('–')
            ret.append(end.dt.strftime('{0}, %Y'.format(end.dt.day)))
        else:
            ret.extend([cls.html_date(start), '&endash;',
                cls.html_date(end)])
        return ' '.join(ret)

    @classmethod
    def html_date(cls, d):
        if d.is_tbd():
            return 'TBD'
        # using string format to get '2' and not '02'
        return d.dt.strftime('%b. {0}, %Y'.format(d.dt.day))

    def __eq__(self, other):
        a_is_tbd, b_is_tbd = self.is_tbd(), other.is_tbd()
        if a_is_tbd and b_is_tbd:
            return True
        elif a_is_tbd or b_is_tbd:
            return False
        else:
            return self.dt == other.dt

    def __lt__(self, other):
        a_is_tbd, b_is_tbd = self.is_tbd(), other.is_tbd()
        if not a_is_tbd and not b_is_tbd:
            return self.dt < other.dt
        if not a_is_tbd and b_is_tbd:
            return True
        else:
            # (a_is_tbd and not b_is_tbd) or (a_is_tbd and b_is_tbd)
            return False

    def is_tbd(self):
        return ConferenceDate.TBD_VAL == self.dt

    def in_past(self):
        return self < ConferenceDate(datetime.now())

    def in_past_style(self):
        return 'color: red' if self.in_past() else None


@total_ordering
class Conference(object):
    def __init__(self, name, url, location, deadline, start, end=None):
        self.name = name
        self.url = url
        self.location = location
        self.deadline = ConferenceDate(deadline)
        self.start = ConferenceDate(start)
        self.end = self.start if end is None else ConferenceDate(end)

        if self.end < self.start:
            die('start before end for {0}'.format(self.name))

    @classmethod
    def make_td(cls, contents, style=None):
        _style = ''
        if style is not None:
            _style = ' style="{0}"'.format(style)
        return '<td{0}>{1}</td>'.format(_style, contents)

    def __eq__(self, other):
        cmps = ('deadline', 'name', 'url', 'location', 'start', 'end')
        for s in cmps:
            ag = attrgetter(s)
            if ag(self) != ag(other):
                return False
        return True

    def __lt__(self, other):
        cmps = ('deadline', 'name', 'url', 'location', 'start', 'end')
        for s in cmps:
            ag = attrgetter(s)
            a, b = ag(self), ag(other)
            if a < b:
                return True
            elif a > b:
                return False
        return False

    def html(self):
        s = ['<tr>']
        s.append(self.make_td(ConferenceDate.html_date(self.deadline),
            style=self.deadline.in_past_style()))
        s.append(self.make_td('<a href="{0}">{1}</a>'.format(
            self.url, self.name)))
        s.append(self.make_td(self.location))
        s.append(self.make_td(ConferenceDate.get_timespan(self.start, self.end)))
        s.append('</tr>')
        return ''.join(s)


def die(msg, e=None):
    print(msg, file=sys.stderr)
    sys.exit(1)


def load_conferences(in_f):
    c = []
    r = csv.reader(open(in_f, 'r'))
    for row in r:
        try:
            c.append(Conference(*row))
        except TypeError as e:
            print('error on {0}'.format(row), file=sys.stderr)
            die('error message: {0}'.format(e.message))
    return c


def main():
    if len(sys.argv) < 2:
        die('usage: {0} <CSV file>'.format(sys.argv[0]))

    in_f = sys.argv[1]
    conferences = load_conferences(in_f)
    for c in sorted(conferences):
        print(c.html())


if __name__ == '__main__':
    main()