#!/usr/bin/env python3

from pathlib import Path
from typing import List, Optional
import hashlib
import json
import textwrap
import urllib
from html.parser import HTMLParser
from packaging import version
import requests

EXTENSIONS_HOST_URL = "https://extdist.wmflabs.org/dist/extensions/"

EXTENSIONS = {
    "ldap_authentication2": "LDAPAuthentication2",
    "ldap_authorization": "LDAPAuthorization",
    # "ldap_auth_remoteuser": "Auth_remoteuser",
    "ldap_groups": "LDAPGroups",
    "ldap_provider": "LDAPProvider",
    "ldap_userinfo": "LDAPUserInfo",
    "pluggable_auth": "PluggableAuth",
}

def sha256sum_of_url(url: str) -> str:
    """Compute checksum without saving the file"""
    checksum = hashlib.sha256()
    for chunk in requests.get(url, stream=True).iter_content():
        checksum.update(chunk)
    return checksum.hexdigest()


def generate_ext_source(asset_url: str, src_filename: str) -> None:
    with open(f"conf/{src_filename}", "w", encoding="utf-8") as output:
        output.write(textwrap.dedent(f"""\
            SOURCE_URL={asset_url}
            SOURCE_SUM={sha256sum_of_url(asset_url)}
            SOURCE_SUM_PRG=sha256sum
            SOURCE_FORMAT=tar.gz
            SOURCE_IN_SUBDIR=false
            SOURCE_FILENAME=
            SOURCE_EXTRACT=true
        """))


def get_all_extensions() -> List[str]:
    """Get all available extensions."""
    with urllib.request.urlopen(EXTENSIONS_HOST_URL) as page:
        webpage = page.read().decode("utf-8")

    class MyHTMLParser(HTMLParser):
        links = []
        def handle_starttag(self, tag, attrs):
            if tag == "a":
                for name, value in attrs:
                    if name == "href":
                        self.links.append(value)

    parser = MyHTMLParser()
    parser.feed(webpage)
    return parser.links

def find_valid_ext(all_exts: List[str], name: str, max_version: version.Version) -> Optional[str]:
    def version_of(ext):
        try:
            return version.parse(ext.split("-")[1].replace("_", ".").replace("REL", ""))
        except version.InvalidVersion:
            print(f"Invalid version (this might be normal): {ext}")
            return version.parse("0.0")

    found_exts = [
        ext for ext in all_exts
        if ext.startswith(name) and version_of(ext) <= max_version 
    ]
    return max(found_exts, key=version_of) if found_exts else None


def main():
    print('Updating extensions source files...')
    with open("manifest.json", "r", encoding="utf-8") as file:
        manifest = json.load(file)
    mediawiki_version = version.Version(manifest["version"].split("~")[0])

    all_extensions = get_all_extensions()

    for file, name in EXTENSIONS.items():
        print(f'Updating source file for {name}')
        ext = find_valid_ext(all_extensions, name, mediawiki_version)
        if ext is None:
            print(f'ERROR: Could not find an upstream link for extension {name}')
        else:
            new_url = EXTENSIONS_HOST_URL + ext
            generate_ext_source(new_url, file + ".src")


if __name__ == "__main__":
    main()