#!/usr/bin/env python3

import os
import sys
import glob

from debian import deb822
from xml.dom.minidom import Document
from dateutil.parser import parse as date_parse


def main(basedir):
    e = []
    error = False
    num = 0

    doc = Document()
    events = doc.createElement('data')
    doc.appendChild(events)

    filenames = glob.glob(os.path.join(basedir, '*'))

    for filename in sorted(filenames):
        if e:
            print(file=sys.stderr)
        print("Reading events from {}".format(filename), end='', file=sys.stderr)
        with open(filename) as f:
            input = f.read().split('\n')

        e = []
        para_num = 0
        for para in deb822.Deb822.iter_paragraphs(input, use_apt_pkg=False):
            if 'Title' not in para:
                title = "para {}".format(para_num)
                e.append("Start-Date should be before End-Date for {}".format(
                         title))
            else:
                title = para['Title']
            dates = {}
            for header in ('Date', 'Start-Date', 'End-Date'):
                if header not in para:
                    continue
                try:
                    dates[header] = date_parse(para[header])
                except (TypeError, ValueError):
                    e.append("Invalid date header {} for {}".format(
                        header, title,
                    ))
            if 'Start-Date' in para and 'End-Date' in para:
                if 'Start-Date' in dates and 'End-Date' in dates:
                    if dates['Start-Date'] > dates['End-Date']:
                        e.append("Start-Date is after End-Date for {}".format(
                                 title))
            elif 'Start-Date' in para or 'End-Date' in para:
                e.append("Missing Start-Date or End-Date for {}".format(
                         title))
            elif 'Date' not in para:
                e.append("Missing date or date range for {}".format(title))
            events.appendChild(create_event(doc, para))
            sys.stderr.write('.')
            num += 1
            para_num += 1
        print(file=sys.stderr)
        if e:
            for error in e:
                print(error, file=sys.stderr)
            error = True

    if error:
        return 1
    print("Writing {} events".format(num), file=sys.stderr)

    print('<!-- Generated from {}/* - do not edit -->'.format(basedir))
    print(events.toprettyxml(indent='  '))


def create_event(doc, para):
    entry = doc.createElement('entry')
    entry.setAttribute('title', para['Title'])

    if 'Start-Date' in para:
        entry.setAttribute('isDuration', 'true')
        entry.setAttribute('start', para['Start-Date'])
        entry.setAttribute('end', para['End-Date'])
    else:
        entry.setAttribute('start', para['Date'])

    if 'Source' in para:
        text = doc.createTextNode(
            '<a href="{}" target="debian-timeline-source">Source</a>'
            .format(para['Source']))
        entry.appendChild(text)

    return entry


if __name__ == '__main__':
    sys.exit(main(sys.argv[1]))