#!/usr/bin/env python3

from bs4 import BeautifulSoup
from datetime import datetime, timezone
from markdownify import MarkdownConverter
from os import utime
from pathlib import Path
from re import search, sub
from sys import stderr
from urllib.parse import unquote
from yaml import CDumper, dump
import requests

BASE_URL = 'https://kontakt-bamberg.de'

GALLERIES_PATH = '/galerien'
GALLERIES_URL = f'{BASE_URL}{GALLERIES_PATH}'

TARGET_DIR = Path(__file__).resolve().parent.parent / 'content' / 'galerie'

DATE_PATTERN = r'([DFMS]\w+, \d{1,2}. [ADFJMNOS]\w+ \d{4})'
DATE_RANGE_SEPARATOR_PATTERN = r'bis\s+<.+>'
DATE_RANGE_PATTERN = f'{DATE_RANGE_SEPARATOR_PATTERN}{DATE_PATTERN}'

MONTH_NAMES = ('Januar', 'Februar', 'März', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember')
MONTHS = {month: str(i+1).zfill(2) for i, month in enumerate(MONTH_NAMES)}

def convert_date(date):
    components = date.split()
    return f'{components[3]}-{MONTHS[components[2]]}-{components[1].rstrip(".").zfill(2)}'

def minify_whitespace(soup):
    if hasattr(soup, 'contents'):
        for child in soup.contents:
            minify_whitespace(child)
    else:
        soup.replace_with(sub(r'\s+', ' ', soup))

def parse_http_datetime(dt):
    return datetime.strptime(dt.replace('GMT', '+0000'), '%a, %d %b %Y %H:%M:%S %z')

def download_image(url, target):
    name = unquote(url.rsplit('/', 1)[-1])
    image = target / name

    if image.exists():
        r = requests.head(url)
        r.raise_for_status()

        last_modified = parse_http_datetime(r.headers['last-modified'])
        mtime = datetime.fromtimestamp(image.stat().st_mtime, tz=timezone.utc)
        if last_modified <= mtime:
            return

    r = requests.get(url)
    r.raise_for_status()

    image.write_bytes(r.content)

    last_modified = parse_http_datetime(r.headers['last-modified'])
    timestamp = last_modified.timestamp()
    utime(image, times=(timestamp, timestamp))

    print(f"downloaded image '{name}' (last modified: {last_modified.strftime('%a, %d %b %Y %H:%M:%S %Z')})", file=stderr)

def download_gallery(path):
    slug = unquote(path.removeprefix(f'{GALLERIES_PATH}/'))

    target = TARGET_DIR / slug
    target.mkdir(parents=True, exist_ok=True)

    r = requests.get(f'{BASE_URL}{path}')
    r.raise_for_status()

    date = search(DATE_RANGE_PATTERN, r.text)
    if date is None:
        date = search(DATE_PATTERN, r.text)
    date = convert_date(date[1])

    soup = BeautifulSoup(r.text, 'html.parser')
    minify_whitespace(soup)

    title = str(soup.find(id='page-title').string)

    md = MarkdownConverter()
    content = '\n\n'.join(md.convert_soup(p) for p in soup.select('.field-type-text-with-summary > .field-items > .field-item > p'))

    index = target / 'index.md'
    index.write_text(f'''---
slug: "{slug}"
title: {dump(title, Dumper=CDumper).rstrip()}
date: {date}
---

{content}
''')

    picture = soup.find(class_='picture')
    preview = search('https?://kontakt-bamberg.de[-./\w]+', picture.get('style'))
    download_image(preview[0], target)

    for a in soup.select('.field-name-field-pictures > .field-items > .field-item > a'):
        href = a.get('href')
        try:
            download_image(href, target)
        except Exception as e:
            print(f"downloading image '{href}' has failed: {str(e)}", file=stderr)

if __name__ == '__main__':
    r = requests.get(GALLERIES_URL)
    r.raise_for_status()

    soup = BeautifulSoup(r.text, 'html.parser')
    for a in soup.select('.views-field-field-picture > .field-content > a'):
        href = a.get('href')
        try:
            download_gallery(href)
        except Exception as e:
            print(f"downloading gallery at '{href}' has failed: {str(e)}", file=stderr)