"""Download a catalog-linked datasheet, retaining its source URL and SHA256."""
import argparse
from datetime import datetime, timezone
import hashlib
from html.parser import HTMLParser
import json
from pathlib import Path
from urllib.parse import urljoin, urlsplit

import fitz
import requests
from bs4 import BeautifulSoup

ROOT = Path(__file__).resolve().parents[1]


class Links(HTMLParser):
    def __init__(self):
        super().__init__()
        self.pdfs = []

    def handle_starttag(self, tag, attrs):
        for key, value in attrs:
            if key in {'src', 'href', 'data'} and value and urlsplit(value).path.lower().endswith('.pdf'):
                self.pdfs.append(value.split('#')[0])


def main():
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument('name')
    ap.add_argument('url')
    ap.add_argument('--html', action='store_true')
    ap.add_argument('--out-dir', type=Path, default=ROOT/'datasheets/fans')
    args = ap.parse_args()
    if not all(c.isalnum() or c in '-_.' for c in args.name):
        raise ValueError('Filename must be a simple part name')
    output = args.out_dir.resolve()
    output.mkdir(parents=True, exist_ok=True)
    session = requests.Session()
    session.trust_env = False
    response = session.get(args.url, timeout=25)
    response.raise_for_status()
    page = response
    if args.html:
        soup = BeautifulSoup(response.text, 'html.parser')
        path = output/(args.name+'.html')
        path.write_bytes(response.content)
        text = soup.get_text('\n', strip=True)
        path.with_suffix('.txt').write_text(text, encoding='utf-8')
        images = []
        for tag in soup.find_all('img', src=True):
            if any(key in tag['src'] for key in ['pwm_02_en', 'sensor_01_en', 'sensor_02_en']):
                image_url = urljoin(response.url, tag['src'])
                image = session.get(image_url, timeout=20)
                image.raise_for_status()
                image_path = output/Path(urlsplit(image_url).path).name
                image_path.write_bytes(image.content)
                images.append({'url': image_url, 'file': image_path.name,
                               'sha256': hashlib.sha256(image.content).hexdigest()})
        metadata = {'retrieved_at_utc': datetime.now(timezone.utc).isoformat(),
                    'requested_url': args.url, 'source_page_url': response.url,
                    'sha256': hashlib.sha256(response.content).hexdigest(), 'images': images}
        path.with_suffix('.json').write_text(json.dumps(metadata, indent=2)+'\n', encoding='utf-8')
        print(json.dumps(metadata, indent=2))
        return
    if not response.content.startswith(b'%PDF'):
        parser = Links()
        parser.feed(response.text)
        urls = list(dict.fromkeys(urljoin(response.url, p) for p in parser.pdfs))
        if len(urls) != 1:
            raise ValueError(f'Expected a unique linked PDF; found {urls}')
        (output/(args.name+'-source.html')).write_text(response.text, encoding='utf-8')
        response = session.get(urls[0], timeout=25)
        response.raise_for_status()
    if not response.content.startswith(b'%PDF'):
        raise ValueError('Response is not a PDF')
    document = fitz.open(stream=response.content, filetype='pdf')
    pdf = output/(args.name+'.pdf')
    pdf.write_bytes(response.content)
    text = '\n'.join(f'\n--- PDF PAGE {p.number+1} ---\n'+p.get_text() for p in document)
    pdf.with_suffix('.txt').write_text(text, encoding='utf-8')
    metadata = {'retrieved_at_utc': datetime.now(timezone.utc).isoformat(), 'requested_url': args.url,
                'source_page_url': page.url, 'pdf_url': response.url, 'pages': len(document),
                'sha256': hashlib.sha256(response.content).hexdigest(), 'bytes': len(response.content)}
    pdf.with_suffix('.json').write_text(json.dumps(metadata, indent=2)+'\n', encoding='utf-8')
    print(json.dumps(metadata, indent=2))
    print(text[:1600])


if __name__ == '__main__':
    main()