#!/usr/bin/env python3
import http.client
import json
import string
import sys
import xml.etree.ElementTree


if len(sys.argv[1:]) != 3:
	print('Usage: ia-verify-file ITEM FILENAME SHA1', file = sys.stderr)
	print('Verifies that FILENAME is present in ITEM (on all servers) and has hash SHA1', file = sys.stderr)
	sys.exit(1)
item, filename, sha1 = sys.argv[1:]

if len(item) > 100 or item[0] not in (string.ascii_letters + string.digits) or item[1:].strip(string.ascii_letters + string.digits + '_-.') != '':
	print('Invalid identifier', file = sys.stderr)
	sys.exit(1)

# Fetch https://archive.org/metadata/ITEM to get the two servers that store the item
conn = http.client.HTTPSConnection('archive.org', timeout = 30)
conn.request('GET', f'/metadata/{item}')
r = conn.getresponse()
if r.status != 200:
	print(f'Error fetching item metadata: {r.status} {r.reason}', file = sys.stderr)
	sys.exit(1)
o = json.loads(r.read())
if not o:
	print(f'Empty item metadata returned (item might not exist)', file = sys.stderr)
	sys.exit(1)
if 'workable_servers' not in o or 'dir' not in o:
	print(f'Malformed metadata returned: {o!r}', file = sys.stderr)
	sys.exit(1)

if len(o['workable_servers']) < 2:
	print(f'Not enough servers: {o["workable_servers"]!r}', file = sys.stderr)
	sys.exit(1)

# Fetch _files.xml from each server and compare hash
for server in o['workable_servers']:
	conn = http.client.HTTPSConnection(server, timeout = 30)
	conn.request('GET', f'{o["dir"]}/{item}_files.xml')
	r = conn.getresponse()
	if r.status != 200:
		print(f'Error fetching item files from {server}: {r.status} {r.reason}', file = sys.stderr)
		sys.exit(1)
	root = xml.etree.ElementTree.fromstring(r.read().decode('utf-8'))
	if root.tag != 'files' or not all(c.tag == 'file' for c in root):
		print(f'Invalid XML received from {server}', file = sys.stderr)
		sys.exit(1)
	for file in root:
		if file.attrib['name'] == filename:
			for c in file:
				if c.tag == 'sha1':
					if c.text != sha1:
						print(f'SHA-1 mismatch on {server}: expected {sha1}, found {c.text}', file = sys.stderr)
						sys.exit(1)
					break
			else:
				print(f'No SHA-1 found on {server}', file = sys.stderr)
				sys.exit(1)
			break
	else:
		print(f'File not found on {server}', file = sys.stderr)
		sys.exit(1)