"""Fetch frozen published photometry directly from its origin; no site mirror."""
from pathlib import Path
import argparse
import hashlib
import json
import urllib.parse
import urllib.request

parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('--manifest', type=Path, default=Path(__file__).with_name('observation-sources.json'))
parser.add_argument('--output', type=Path, required=True)
arguments = parser.parse_args()
manifest = json.loads(arguments.manifest.read_text())
user_agent = 'SandboxPhysics-Public-Tutorial/1.0'
assert manifest['ua'] == user_agent
arguments.output.mkdir(parents=True, exist_ok=True)
receipt = {'scope': 'Actual anonymous HTTP origin fetches or separately identified verified cache; no production SandboxPhysics delivery claimed.',
           'userAgent': user_agent, 'files': []}
for item in manifest['files']:
    name = item['name']
    if Path(name).name != name:
        raise ValueError('Non-flat scientific filename')
    url = urllib.parse.urlsplit(item['url'])
    if url.scheme != 'https' or url.hostname != 'ogle.astrouw.edu.pl' or not url.path.startswith('/cont/4_main/epl/blg390/'):
        raise ValueError('Only the five frozen published project files may be fetched')
    destination = arguments.output / name
    if destination.exists():
        data = destination.read_bytes()
        mode = 'verified local cache; no HTTP'
        status = None
    else:
        request = urllib.request.Request(item['url'], headers={'User-Agent': user_agent})
        with urllib.request.urlopen(request, timeout=30) as response:
            if response.status != 200 or response.headers.get_content_type() != item['mediaType']:
                raise ValueError('Unexpected scientific response status or MIME type')
            data = response.read(item['bytes'] + 1)
            status = response.status
            mode = 'anonymous origin HTTP'
    if len(data) != item['bytes'] or hashlib.sha256(data).hexdigest() != item['sha256']:
        raise ValueError('Origin data changed; refuse silently updated scientific input: ' + name)
    if not destination.exists():
        destination.write_bytes(data)
    receipt['files'].append({'name': name, 'url': item['url'], 'mode': mode, 'status': status,
                             'bytes': len(data), 'sha256': item['sha256']})
(arguments.output / 'download-receipt.json').write_text(json.dumps(receipt, indent=2) + '\n')
print('PASS:', len(receipt['files']), 'frozen files verified;', ', '.join(sorted(set(item['mode'] for item in receipt['files']))))