#!/usr/bin/env python

import sys
from types import FrameType
from typing import IO, Any, Callable, Generator, Optional
import xmlrpc.client
from dataclasses import dataclass
import re
import json
from urllib.parse import urljoin, urlparse, urlunparse
from pathlib import Path
from html.parser import HTMLParser
import logging
import html
import os
from os.path import (
    normpath,
)  # fast path computation, instead of accessing real files like pathlib
from contextlib import contextmanager
import sqlite3
from concurrent.futures import ThreadPoolExecutor, as_completed
import signal
import tomllib
from copy import deepcopy

import requests
import click
from tqdm import tqdm
from requests.adapters import HTTPAdapter, Retry

LOG_FORMAT = "%(asctime)s %(levelname)s: %(message)s (%(filename)s:%(lineno)d)"
logger = logging.getLogger("shadowmire")


USER_AGENT = "Shadowmire (https://github.com/taoky/shadowmire)"

# Note that it's suggested to use only 3 workers for PyPI.
WORKERS = int(os.environ.get("SHADOWMIRE_WORKERS", "3"))

# https://github.com/pypa/bandersnatch/blob/a05af547f8d1958217ef0dc0028890b1839e6116/src/bandersnatch_filter_plugins/prerelease_name.py#L18C1-L23C6
PRERELEASE_PATTERNS = (
    re.compile(r".+rc\d+$"),
    re.compile(r".+a(lpha)?\d+$"),
    re.compile(r".+b(eta)?\d+$"),
    re.compile(r".+dev\d+$"),
)


class PackageNotFoundError(Exception):
    pass


class ExitProgramException(Exception):
    pass


def exit_handler(signum: int, frame: Optional[FrameType]) -> None:
    raise ExitProgramException


signal.signal(signal.SIGTERM, exit_handler)


class LocalVersionKV:
    """
    A key-value database wrapper over sqlite3.

    As it would have consistency issue if it's writing while downstream is downloading the database.
    An extra "jsonpath" is used, to store kv results when necessary.
    """

    def __init__(self, dbpath: Path, jsonpath: Path) -> None:
        self.conn = sqlite3.connect(dbpath)
        self.jsonpath = jsonpath
        cur = self.conn.cursor()
        cur.execute(
            "CREATE TABLE IF NOT EXISTS local(key TEXT PRIMARY KEY, value INT NOT NULL)"
        )
        self.conn.commit()

    def get(self, key: str) -> Optional[int]:
        cur = self.conn.cursor()
        res = cur.execute("SELECT value FROM local WHERE key = ?", (key,))
        row = res.fetchone()
        return row[0] if row else None

    INSERT_SQL = "INSERT INTO local (key, value) VALUES (?, ?) ON CONFLICT(key) DO UPDATE SET value=excluded.value"

    def set(self, key: str, value: int) -> None:
        cur = self.conn.cursor()
        cur.execute(self.INSERT_SQL, (key, value))
        self.conn.commit()

    def batch_set(self, d: dict[str, int]) -> None:
        cur = self.conn.cursor()
        kvs = list(d.items())
        cur.executemany(self.INSERT_SQL, kvs)
        self.conn.commit()

    def remove(self, key: str) -> None:
        cur = self.conn.cursor()
        cur.execute("DELETE FROM local WHERE key = ?", (key,))
        self.conn.commit()

    def nuke(self, commit: bool = True) -> None:
        cur = self.conn.cursor()
        cur.execute("DELETE FROM local")
        if commit:
            self.conn.commit()

    def keys(self, skip_invalid: bool = True) -> list[str]:
        cur = self.conn.cursor()
        if skip_invalid:
            res = cur.execute("SELECT key FROM local WHERE value != -1")
        else:
            res = cur.execute("SELECT key FROM local")
        rows = res.fetchall()
        return [row[0] for row in rows]

    def dump(self, skip_invalid: bool = True) -> dict[str, int]:
        cur = self.conn.cursor()
        if skip_invalid:
            res = cur.execute("SELECT key, value FROM local WHERE value != -1")
        else:
            res = cur.execute("SELECT key, value FROM local")
        rows = res.fetchall()
        return {row[0]: row[1] for row in rows}

    def dump_json(self, skip_invalid: bool = True) -> None:
        res = self.dump(skip_invalid)
        with overwrite(self.jsonpath) as f:
            json.dump(res, f, indent=2)


@contextmanager
def overwrite(
    file_path: Path, mode: str = "w", tmp_suffix: str = ".tmp"
) -> Generator[IO[Any], None, None]:
    tmp_path = file_path.parent / (file_path.name + tmp_suffix)
    try:
        with open(tmp_path, mode) as tmp_file:
            yield tmp_file
        tmp_path.rename(file_path)
    except Exception:
        # well, just keep the tmp_path in error case.
        raise


def normalize(name: str) -> str:
    """
    See https://peps.python.org/pep-0503/#normalized-names
    """
    return re.sub(r"[-_.]+", "-", name).lower()


def remove_dir_with_files(directory: Path) -> None:
    """
    Remove dir in a safer (non-recursive) way, which means that the directory should have no child directories.
    """
    if not directory.exists():
        return
    assert directory.is_dir()
    for item in directory.iterdir():
        item.unlink()
    directory.rmdir()
    logger.info("Removed dir %s", directory)


def get_package_urls_from_index_html(html_path: Path) -> list[str]:
    """
    Get all <a> href (fragments removed) from given simple/<package>/index.html contents
    """

    class ATagHTMLParser(HTMLParser):
        def __init__(self) -> None:
            super().__init__()
            self.hrefs: list[Optional[str]] = []

        def handle_starttag(
            self, tag: str, attrs: list[tuple[str, str | None]]
        ) -> None:
            if tag == "a":
                for attr in attrs:
                    if attr[0] == "href":
                        self.hrefs.append(attr[1])

    p = ATagHTMLParser()
    with open(html_path) as f:
        p.feed(f.read())

    ret = []
    for href in p.hrefs:
        if href:
            parsed_url = urlparse(href)
            clean_url = urlunparse(parsed_url._replace(fragment=""))
            ret.append(clean_url)
    return ret


def get_package_urls_from_index_json(json_path: Path) -> list[str]:
    """
    Get all urls from given simple/<package>/index.v1_json contents
    """
    with open(json_path) as f:
        contents_dict = json.load(f)
    urls = [i["url"] for i in contents_dict["files"]]
    return urls


def get_package_urls_size_from_index_json(json_path: Path) -> list[tuple[str, int]]:
    """
    Get all urls and size from given simple/<package>/index.v1_json contents

    If size is not available, returns size as -1
    """
    with open(json_path) as f:
        contents_dict = json.load(f)
    ret = [(i["url"], i.get("size", -1)) for i in contents_dict["files"]]
    return ret


def get_existing_hrefs(package_simple_path: Path) -> Optional[list[str]]:
    """
    There exists packages that have no release files, so when it encounters errors it would return None,
    otherwise empty list or list with hrefs.

    Priority: index.v1_json -> index.html
    """
    if not package_simple_path.exists():
        return None
    json_file = package_simple_path / "index.v1_json"
    html_file = package_simple_path / "index.html"
    if json_file.exists():
        return get_package_urls_from_index_json(json_file)
    if html_file.exists():
        return get_package_urls_from_index_html(html_file)
    return None


class CustomXMLRPCTransport(xmlrpc.client.Transport):
    """
    Set user-agent for xmlrpc.client
    """

    user_agent = USER_AGENT


def create_requests_session() -> requests.Session:
    s = requests.Session()
    retries = Retry(total=3, backoff_factor=0.1)
    s.mount("http://", HTTPAdapter(max_retries=retries))
    s.mount("https://", HTTPAdapter(max_retries=retries))
    s.headers.update({"User-Agent": USER_AGENT})
    return s


class PyPI:
    """
    Upstream which implements full PyPI APIs
    """

    host = "https://pypi.org"
    # Let's assume that only sha256 exists...
    digest_name = "sha256"

    def __init__(self) -> None:
        self.xmlrpc_client = xmlrpc.client.ServerProxy(
            urljoin(self.host, "pypi"), transport=CustomXMLRPCTransport()
        )
        self.session = create_requests_session()

    def list_packages_with_serial(self, do_normalize: bool = True) -> dict[str, int]:
        logger.info(
            "Calling list_packages_with_serial() RPC, this requires some time..."
        )
        ret: dict[str, int] = self.xmlrpc_client.list_packages_with_serial()  # type: ignore
        if do_normalize:
            for key in list(ret.keys()):
                normalized_key = normalize(key)
                if normalized_key == key:
                    continue
                ret[normalized_key] = ret[key]
                del ret[key]
        return ret

    def get_package_metadata(self, package_name: str) -> dict:
        req = self.session.get(urljoin(self.host, f"pypi/{package_name}/json"))
        if req.status_code == 404:
            raise PackageNotFoundError
        return req.json()  # type: ignore

    @staticmethod
    def get_release_files_from_meta(package_meta: dict) -> list[dict]:
        release_files = []
        for release in package_meta["releases"].values():
            release_files.extend(release)
        release_files.sort(key=lambda x: x["filename"])
        return release_files

    @staticmethod
    def file_url_to_local_url(url: str) -> str:
        parsed = urlparse(url)
        assert parsed.path.startswith("/packages")
        prefix = "../.."
        return prefix + parsed.path

    # Func modified from bandersnatch
    @classmethod
    def generate_html_simple_page(cls, package_meta: dict) -> str:
        package_rawname = package_meta["info"]["name"]
        simple_page_content = (
            "<!DOCTYPE html>\n"
            "<html>\n"
            "  <head>\n"
            '    <meta name="pypi:repository-version" content="{0}">\n'
            "    <title>Links for {1}</title>\n"
            "  </head>\n"
            "  <body>\n"
            "    <h1>Links for {1}</h1>\n"
        ).format("1.0", package_rawname)

        release_files = cls.get_release_files_from_meta(package_meta)

        def gen_html_file_tags(release: dict) -> str:
            file_tags = ""

            # data-requires-python: requires_python
            if "requires_python" in release and release["requires_python"] is not None:
                file_tags += (
                    f' data-requires-python="{html.escape(release["requires_python"])}"'
                )

            # data-yanked: yanked_reason
            if "yanked" in release and release["yanked"]:
                if "yanked_reason" in release and release["yanked_reason"]:
                    file_tags += (
                        f' data-yanked="{html.escape(release["yanked_reason"])}"'
                    )
                else:
                    file_tags += ' data-yanked=""'

            return file_tags

        simple_page_content += "\n".join(
            [
                '    <a href="{}#{}={}"{}>{}</a><br/>'.format(
                    cls.file_url_to_local_url(r["url"]),
                    cls.digest_name,
                    r["digests"][cls.digest_name],
                    gen_html_file_tags(r),
                    r["filename"],
                )
                for r in release_files
            ]
        )

        simple_page_content += (
            f"\n  </body>\n</html>\n<!--SERIAL {package_meta['last_serial']}-->"
        )

        return simple_page_content

    # Func modified from bandersnatch
    @classmethod
    def generate_json_simple_page(cls, package_meta: dict) -> str:
        package_json: dict[str, Any] = {
            "files": [],
            "meta": {
                "api-version": "1.1",
                "_last-serial": str(package_meta["last_serial"]),
            },
            "name": package_meta["info"]["name"],
            # (bandsnatch) TODO: Just sorting by default sort - Maybe specify order in future PEP
            "versions": sorted(package_meta["releases"].keys()),
        }

        release_files = cls.get_release_files_from_meta(package_meta)

        # Add release files into the JSON dict
        for r in release_files:
            package_json["files"].append(
                {
                    "filename": r["filename"],
                    "hashes": {
                        cls.digest_name: r["digests"][cls.digest_name],
                    },
                    "requires-python": r.get("requires_python", ""),
                    "size": r["size"],
                    "upload-time": r.get("upload_time_iso_8601", ""),
                    "url": cls.file_url_to_local_url(r["url"]),
                    "yanked": r.get("yanked", False),
                }
            )

        return json.dumps(package_json)


# (normalized_name as key, value)
ShadowmirePackageItem = tuple[str, int]


@dataclass
class Plan:
    remove: list[str]
    update: list[str]


def match_patterns(
    s: str, ps: list[re.Pattern[str]] | tuple[re.Pattern[str], ...]
) -> bool:
    for p in ps:
        if p.match(s):
            return True
    return False


class SyncBase:
    def __init__(
        self, basedir: Path, local_db: LocalVersionKV, sync_packages: bool = False
    ) -> None:
        self.basedir = basedir
        self.local_db = local_db
        self.simple_dir = basedir / "simple"
        self.packages_dir = basedir / "packages"
        self.jsonmeta_dir = basedir / "json"
        # create the dirs, if not exist
        self.simple_dir.mkdir(parents=True, exist_ok=True)
        self.packages_dir.mkdir(parents=True, exist_ok=True)
        self.jsonmeta_dir.mkdir(parents=True, exist_ok=True)
        self.sync_packages = sync_packages

    def filter_remote_with_excludes(
        self, remote: dict[str, int], excludes: list[re.Pattern[str]]
    ) -> dict[str, int]:
        if not excludes:
            return remote
        res = {}
        for k, v in remote.items():
            matched = match_patterns(k, excludes)
            if not matched:
                res[k] = v
        return res

    def determine_sync_plan(
        self, local: dict[str, int], excludes: list[re.Pattern[str]]
    ) -> Plan:
        """
        local should NOT skip invalid (-1) serials
        """
        remote = self.fetch_remote_versions()
        remote = self.filter_remote_with_excludes(remote, excludes)
        with open(self.basedir / "remote_excluded.json", "w") as f:
            json.dump(remote, f)

        to_remove = []
        to_update = []
        local_keys = set(local.keys())
        remote_keys = set(remote.keys())
        for i in local_keys - remote_keys:
            to_remove.append(i)
            local_keys.remove(i)
        for i in remote_keys - local_keys:
            to_update.append(i)
        for i in local_keys:
            local_serial = local[i]
            remote_serial = remote[i]
            if local_serial != remote_serial:
                if local_serial == -1:
                    logger.info("skip %s, as it's marked as not exist at upstream", i)
                    to_remove.append(i)
                else:
                    to_update.append(i)
        output = Plan(remove=to_remove, update=to_update)
        return output

    def fetch_remote_versions(self) -> dict[str, int]:
        raise NotImplementedError

    def check_and_update(
        self,
        package_names: list[str],
        prerelease_excludes: list[re.Pattern[str]],
        compare_size: bool,
    ) -> bool:
        to_update = []
        for package_name in tqdm(package_names, desc="Checking consistency"):
            package_jsonmeta_path = self.jsonmeta_dir / package_name
            if not package_jsonmeta_path.exists():
                logger.info("add %s as it does not have json API file", package_name)
                to_update.append(package_name)
                continue
            package_simple_path = self.simple_dir / package_name
            html_simple = package_simple_path / "index.html"
            htmlv1_simple = package_simple_path / "index.v1_html"
            json_simple = package_simple_path / "index.v1_json"
            if not (
                html_simple.exists() and json_simple.exists() and htmlv1_simple.exists()
            ):
                logger.info(
                    "add %s as it does not have index.html, index.v1_html or index.v1_json",
                    package_name,
                )
                to_update.append(package_name)
                continue
            if not html_simple.is_symlink():
                html_simple.unlink()
                html_simple.symlink_to("index.v1_html")
            hrefs_html = get_package_urls_from_index_html(html_simple)
            hrefsize_json = get_package_urls_size_from_index_json(json_simple)
            if (
                hrefs_html is None
                or hrefsize_json is None
                or hrefs_html != [i[0] for i in hrefsize_json]
            ):
                # something unexpected happens...
                logger.info("add %s as its indexes are not consistent", package_name)
                to_update.append(package_name)
                continue

            # OK, check if all hrefs have corresponding files
            if self.sync_packages:
                should_update = False
                for href, size in hrefsize_json:
                    dest = Path(normpath(package_simple_path / href))
                    if not dest.exists():
                        logger.info("add %s as it's missing packages", package_name)
                        should_update = True
                        break
                    if compare_size and size != -1:
                        dest_size = dest.stat().st_size
                        if dest_size != size:
                            logger.info(
                                "add %s as its local size %s != %s",
                                package_name,
                                dest_size,
                                size,
                            )
                            should_update = True
                            break
                if should_update:
                    to_update.append(package_name)
        logger.info("%s packages to update in check_and_update()", len(to_update))
        return self.parallel_update(to_update, prerelease_excludes)

    def parallel_update(
        self, package_names: list, prerelease_excludes: list[re.Pattern[str]]
    ) -> bool:
        success = True
        with ThreadPoolExecutor(max_workers=WORKERS) as executor:
            futures = {
                executor.submit(
                    self.do_update, package_name, prerelease_excludes, False
                ): (
                    idx,
                    package_name,
                )
                for idx, package_name in enumerate(package_names)
            }
            try:
                for future in tqdm(
                    as_completed(futures), total=len(package_names), desc="Updating"
                ):
                    idx, package_name = futures[future]
                    try:
                        serial = future.result()
                        if serial:
                            self.local_db.set(package_name, serial)
                    except Exception as e:
                        if isinstance(e, (ExitProgramException, KeyboardInterrupt)):
                            raise
                        logger.warning(
                            "%s generated an exception", package_name, exc_info=True
                        )
                        success = False
                    if idx % 100 == 0:
                        logger.info("dumping local db...")
                        self.local_db.dump_json()
            except (ExitProgramException, KeyboardInterrupt):
                logger.info("Get ExitProgramException or KeyboardInterrupt, exiting...")
                for future in futures:
                    future.cancel()
                sys.exit(1)
        return success

    def do_sync_plan(
        self, plan: Plan, prerelease_excludes: list[re.Pattern[str]]
    ) -> bool:
        to_remove = plan.remove
        to_update = plan.update

        for package_name in to_remove:
            self.do_remove(package_name)

        return self.parallel_update(to_update, prerelease_excludes)

    def do_remove(
        self, package_name: str, use_db: bool = True, remove_packages: bool = True
    ) -> None:
        metajson_path = self.jsonmeta_dir / package_name
        package_simple_dir = self.simple_dir / package_name
        if metajson_path.exists() or package_simple_dir.exists():
            # To make this less noisy...
            logger.info("Removing package %s", package_name)
        packages_to_remove = get_existing_hrefs(package_simple_dir)
        if remove_packages and packages_to_remove:
            paths_to_remove = [package_simple_dir / p for p in packages_to_remove]
            for p in paths_to_remove:
                if p.exists():
                    p.unlink()
                    logger.info("Removed file %s", p)
        remove_dir_with_files(package_simple_dir)
        metajson_path = self.jsonmeta_dir / package_name
        metajson_path.unlink(missing_ok=True)
        if use_db:
            old_serial = self.local_db.get(package_name)
            if old_serial != -1:
                self.local_db.remove(package_name)

    def do_update(
        self,
        package_name: str,
        prerelease_excludes: list[re.Pattern[str]],
        use_db: bool = True,
    ) -> Optional[int]:
        raise NotImplementedError

    def write_meta_to_simple(self, package_simple_path: Path, meta: dict) -> None:
        simple_html_contents = PyPI.generate_html_simple_page(meta)
        simple_json_contents = PyPI.generate_json_simple_page(meta)
        for html_filename in ("index.v1_html",):
            html_path = package_simple_path / html_filename
            with overwrite(html_path) as f:
                f.write(simple_html_contents)
        for json_filename in ("index.v1_json",):
            json_path = package_simple_path / json_filename
            with overwrite(json_path) as f:
                f.write(simple_json_contents)
        index_html_path = package_simple_path / "index.html"
        if not index_html_path.is_symlink():
            if index_html_path.exists():
                index_html_path.unlink()
            index_html_path.symlink_to("index.v1_html")

    def finalize(self) -> None:
        local_names = self.local_db.keys()
        # generate index.html at basedir
        index_path = self.basedir / "simple" / "index.html"
        # modified from bandersnatch
        with overwrite(index_path) as f:
            f.write("<!DOCTYPE html>\n")
            f.write("<html>\n")
            f.write("  <head>\n")
            f.write('    <meta name="pypi:repository-version" content="1.0">\n')
            f.write("    <title>Simple Index</title>\n")
            f.write("  </head>\n")
            f.write("  <body>\n")
            # This will either be the simple dir, or if we are using index
            # directory hashing, a list of subdirs to process.
            for pkg in local_names:
                # We're really trusty that this is all encoded in UTF-8. :/
                f.write(f'    <a href="{pkg}/">{pkg}</a><br/>\n')
            f.write("  </body>\n</html>")
        self.local_db.dump_json()


def download(
    session: requests.Session, url: str, dest: Path
) -> tuple[bool, Optional[requests.Response]]:
    try:
        resp = session.get(url, allow_redirects=True)
    except requests.RequestException:
        logger.warning("download %s failed with exception", exc_info=True)
        return False, None
    if resp.status_code >= 400:
        logger.warning(
            "download %s failed with status %s, skipping this package",
            url,
            resp.status_code,
        )
        return False, resp
    with overwrite(dest, "wb") as f:
        f.write(resp.content)
    return True, resp


def filter_release_from_meta(
    meta: dict, patterns: list[re.Pattern[str]] | tuple[re.Pattern[str], ...]
) -> None:
    for release in list(meta["releases"].keys()):
        if match_patterns(release, patterns):
            del meta["releases"][release]


class SyncPyPI(SyncBase):
    def __init__(
        self, basedir: Path, local_db: LocalVersionKV, sync_packages: bool = False
    ) -> None:
        self.pypi = PyPI()
        self.session = create_requests_session()
        super().__init__(basedir, local_db, sync_packages)

    def fetch_remote_versions(self) -> dict[str, int]:
        ret = self.pypi.list_packages_with_serial()
        logger.info("Remote has %s packages", len(ret))
        with overwrite(self.basedir / "remote.json") as f:
            json.dump(ret, f)
            logger.info("File saved to remote.json.")
        return ret

    def do_update(
        self,
        package_name: str,
        prerelease_excludes: list[re.Pattern[str]],
        use_db: bool = True,
    ) -> Optional[int]:
        logger.info("updating %s", package_name)
        package_simple_path = self.simple_dir / package_name
        package_simple_path.mkdir(exist_ok=True)
        try:
            meta = self.pypi.get_package_metadata(package_name)
            meta_original = deepcopy(meta)
            logger.debug("%s meta: %s", package_name, meta)
        except PackageNotFoundError:
            logger.warning(
                "%s missing from upstream, remove and ignore in the future.",
                package_name,
            )
            # try remove it locally, if it does not exist upstream
            self.do_remove(package_name, use_db=False)
            if not use_db:
                return -1
            self.local_db.set(package_name, -1)
            return None

        # filter prerelease, if necessary
        if match_patterns(package_name, prerelease_excludes):
            filter_release_from_meta(meta, PRERELEASE_PATTERNS)

        if self.sync_packages:
            # sync packages first, then sync index
            existing_hrefs = get_existing_hrefs(package_simple_path)
            existing_hrefs = [] if existing_hrefs is None else existing_hrefs
            release_files = PyPI.get_release_files_from_meta(meta)
            # remove packages that no longer exist remotely
            remote_hrefs = [
                self.pypi.file_url_to_local_url(i["url"]) for i in release_files
            ]
            should_remove = list(set(existing_hrefs) - set(remote_hrefs))
            for p in should_remove:
                logger.info("removing file %s (if exists)", p)
                package_path = Path(normpath(package_simple_path / p))
                package_path.unlink(missing_ok=True)
            for i in release_files:
                url = i["url"]
                dest = Path(
                    normpath(
                        package_simple_path / self.pypi.file_url_to_local_url(i["url"])
                    )
                )
                logger.info("downloading file %s -> %s", url, dest)
                if dest.exists():
                    continue
                dest.parent.mkdir(parents=True, exist_ok=True)
                success, _resp = download(self.session, url, dest)
                if not success:
                    logger.warning("skipping %s as it fails downloading", package_name)
                    return None

        last_serial: int = meta["last_serial"]

        self.write_meta_to_simple(package_simple_path, meta)
        json_meta_path = self.jsonmeta_dir / package_name
        with overwrite(json_meta_path) as f:
            # Note that we're writing meta_original here!
            json.dump(meta_original, f)

        if use_db:
            self.local_db.set(package_name, last_serial)

        return last_serial


class SyncPlainHTTP(SyncBase):
    def __init__(
        self,
        upstream: str,
        basedir: Path,
        local_db: LocalVersionKV,
        sync_packages: bool = False,
        use_pypi_index: bool = False,
    ) -> None:
        self.upstream = upstream
        self.session = create_requests_session()
        self.pypi: Optional[PyPI]
        if use_pypi_index:
            self.pypi = PyPI()
        else:
            self.pypi = None
        super().__init__(basedir, local_db, sync_packages)

    def fetch_remote_versions(self) -> dict[str, int]:
        remote: dict[str, int]
        if not self.pypi:
            remote_url = urljoin(self.upstream, "local.json")
            resp = self.session.get(remote_url)
            resp.raise_for_status()
            remote = resp.json()
        else:
            remote = self.pypi.list_packages_with_serial()
        logger.info("Remote has %s packages", len(remote))
        with overwrite(self.basedir / "remote.json") as f:
            json.dump(remote, f)
            logger.info("File saved to remote.json.")
        return remote

    def do_update(
        self,
        package_name: str,
        prerelease_excludes: list[re.Pattern[str]],
        use_db: bool = True,
    ) -> Optional[int]:
        logger.info("updating %s", package_name)
        package_simple_path = self.simple_dir / package_name
        package_simple_path.mkdir(exist_ok=True)
        if self.sync_packages:
            hrefs = get_existing_hrefs(package_simple_path)
            existing_hrefs = [] if hrefs is None else hrefs
        # Download JSON meta
        file_url = urljoin(self.upstream, f"json/{package_name}")
        success, resp = download(
            self.session, file_url, self.jsonmeta_dir / (package_name + ".new")
        )
        if not success:
            logger.error(
                "download %s JSON meta fails with code %s",
                package_name,
                resp.status_code if resp else None,
            )
            return None
        assert resp
        meta = resp.json()
        # filter prerelease, if necessary
        if match_patterns(package_name, prerelease_excludes):
            filter_release_from_meta(meta, PRERELEASE_PATTERNS)

        if self.sync_packages:
            release_files = PyPI.get_release_files_from_meta(meta)
            remote_hrefs = [PyPI.file_url_to_local_url(i["url"]) for i in release_files]
            should_remove = list(set(existing_hrefs) - set(remote_hrefs))
            for p in should_remove:
                logger.info("removing file %s (if exists)", p)
                package_path = Path(normpath(package_simple_path / p))
                package_path.unlink(missing_ok=True)
            package_simple_url = urljoin(self.upstream, f"simple/{package_name}/")
            for href in remote_hrefs:
                url = urljoin(package_simple_url, href)
                dest = Path(normpath(package_simple_path / href))
                logger.info("downloading file %s -> %s", url, dest)
                if dest.exists():
                    continue
                dest.parent.mkdir(parents=True, exist_ok=True)
                success, resp = download(self.session, url, dest)
                if not success:
                    logger.warning("skipping %s as it fails downloading", package_name)
                    return None

        # OK, now it's safe to rename
        (self.jsonmeta_dir / (package_name + ".new")).rename(
            self.jsonmeta_dir / package_name
        )
        # generate indexes
        self.write_meta_to_simple(package_simple_path, meta)

        last_serial: int = meta["last_serial"]
        if use_db:
            self.local_db.set(package_name, last_serial)

        return last_serial


def get_local_serial(package_meta_path: Path) -> Optional[int]:
    """
    Accepts /json/<package_name> as package_meta_path
    """
    package_name = package_meta_path.name
    try:
        with open(package_meta_path) as f:
            contents = f.read()
    except FileNotFoundError:
        logger.warning("%s does not have JSON metadata, skipping", package_name)
        return None
    try:
        meta = json.loads(contents)
        return meta["last_serial"]  # type: ignore
    except Exception:
        logger.warning("cannot parse %s's JSON metadata", package_name, exc_info=True)
        return None


def sync_shared_args(func: Callable[..., Any]) -> Callable[..., Any]:
    shared_options = [
        click.option(
            "--sync-packages/--no-sync-packages",
            default=False,
            help="Sync packages instead of just indexes, by default it's --no-sync-packages",
        ),
        click.option(
            "--shadowmire-upstream",
            required=False,
            type=str,
            help="Use another upstream using shadowmire instead of PyPI",
        ),
        click.option(
            "--use-pypi-index/--no-use-pypi-index",
            default=False,
            help="Always use PyPI index metadata (via XMLRPC). It's no-op without --shadowmire-upstream. Some packages might not be downloaded successfully.",
        ),
        click.option(
            "--exclude", multiple=True, help="Remote package names to exclude. Regex."
        ),
        click.option(
            "--prerelease-exclude",
            multiple=True,
            help="Package names of which prereleases will be excluded. Regex.",
        ),
    ]
    for option in shared_options[::-1]:
        func = option(func)
    return func


def read_config(
    ctx: click.Context, param: click.Option, filename: Optional[str]
) -> None:
    # Set default repo as cwd
    ctx.default_map = {}
    ctx.default_map["repo"] = "."

    if filename is None:
        return
    with open(filename, "rb") as f:
        data = tomllib.load(f)
    try:
        options = dict(data["options"])
    except KeyError:
        options = {}
    if options.get("repo"):
        ctx.default_map["repo"] = options["repo"]
        del options["repo"]

    logger.info("Read options from %s: %s", filename, options)

    ctx.default_map["sync"] = options
    ctx.default_map["verify"] = options
    ctx.default_map["do-update"] = options
    ctx.default_map["do-remove"] = options


@click.group()
@click.option(
    "--config",
    type=click.Path(dir_okay=False),
    help="Read option defaults from specified TOML file",
    callback=read_config,
    expose_value=False,
)
@click.option("--repo", type=click.Path(file_okay=False), help="Repo (basedir) path")
@click.pass_context
def cli(ctx: click.Context, repo: str) -> None:
    log_level = logging.DEBUG if os.environ.get("DEBUG") else logging.INFO
    logging.basicConfig(level=log_level, format=LOG_FORMAT)
    ctx.ensure_object(dict)

    if WORKERS > 10:
        logger.warning(
            "You have set a worker value larger than 10, which is forbidden by PyPI maintainers."
        )
        logger.warning("Don't blame me if you were banned!")

    # Make sure basedir is absolute
    basedir = Path(repo).resolve()
    local_db = LocalVersionKV(basedir / "local.db", basedir / "local.json")

    ctx.obj["basedir"] = basedir
    ctx.obj["local_db"] = local_db


def exclude_to_excludes(exclude: tuple[str]) -> list[re.Pattern[str]]:
    return [re.compile(i) for i in exclude]


def get_syncer(
    basedir: Path,
    local_db: LocalVersionKV,
    sync_packages: bool,
    shadowmire_upstream: Optional[str],
    use_pypi_index: bool,
) -> SyncBase:
    syncer: SyncBase
    if shadowmire_upstream:
        syncer = SyncPlainHTTP(
            upstream=shadowmire_upstream,
            basedir=basedir,
            local_db=local_db,
            sync_packages=sync_packages,
            use_pypi_index=use_pypi_index,
        )
    else:
        syncer = SyncPyPI(
            basedir=basedir, local_db=local_db, sync_packages=sync_packages
        )
    return syncer


@cli.command(help="Sync from upstream")
@click.pass_context
@sync_shared_args
def sync(
    ctx: click.Context,
    sync_packages: bool,
    shadowmire_upstream: Optional[str],
    exclude: tuple[str],
    prerelease_exclude: tuple[str],
    use_pypi_index: bool,
) -> None:
    basedir: Path = ctx.obj["basedir"]
    local_db: LocalVersionKV = ctx.obj["local_db"]
    excludes = exclude_to_excludes(exclude)
    prerelease_excludes = exclude_to_excludes(prerelease_exclude)
    syncer = get_syncer(
        basedir, local_db, sync_packages, shadowmire_upstream, use_pypi_index
    )
    local = local_db.dump(skip_invalid=False)
    plan = syncer.determine_sync_plan(local, excludes)
    # save plan for debugging
    with overwrite(basedir / "plan.json") as f:
        json.dump(plan, f, default=vars, indent=2)
    success = syncer.do_sync_plan(plan, prerelease_excludes)
    syncer.finalize()

    logger.info("Synchronization finished. Success: %s", success)

    if not success:
        sys.exit(1)


@cli.command(help="(Re)generate local db and json from json/")
@click.pass_context
def genlocal(ctx: click.Context) -> None:
    basedir: Path = ctx.obj["basedir"]
    local_db: LocalVersionKV = ctx.obj["local_db"]
    local = {}
    json_dir = basedir / "json"
    logger.info("Iterating all items under %s", json_dir)
    dir_items = [d for d in json_dir.iterdir() if d.is_file()]
    logger.info("Detected %s packages in %s in total", len(dir_items), json_dir)
    for package_metapath in tqdm(dir_items, desc="Reading packages from json/"):
        package_name = package_metapath.name
        serial = get_local_serial(package_metapath)
        if serial:
            local[package_name] = serial
    logger.info(
        "%d out of %d packages have valid serial number", len(local), len(dir_items)
    )
    local_db.nuke(commit=False)
    local_db.batch_set(local)
    local_db.dump_json()


@cli.command(
    help="Verify existing sync from local db, download missing things, remove unreferenced packages"
)
@click.pass_context
@sync_shared_args
@click.option(
    "--remove-not-in-local", is_flag=True, help="Do step 1 instead of skipping"
)
@click.option(
    "--compare-size",
    is_flag=True,
    help="Instead of just check if it exists, also compare local package size when possible, to decide if local package file is valid",
)
def verify(
    ctx: click.Context,
    sync_packages: bool,
    shadowmire_upstream: Optional[str],
    exclude: tuple[str],
    prerelease_exclude: tuple[str],
    remove_not_in_local: bool,
    compare_size: bool,
    use_pypi_index: bool,
) -> None:
    basedir: Path = ctx.obj["basedir"]
    local_db: LocalVersionKV = ctx.obj["local_db"]
    excludes = exclude_to_excludes(exclude)
    prerelease_excludes = exclude_to_excludes(prerelease_exclude)
    syncer = get_syncer(
        basedir, local_db, sync_packages, shadowmire_upstream, use_pypi_index
    )

    logger.info("====== Step 1. Remove packages NOT in local db ======")
    local_names = set(local_db.keys())
    simple_dirs = {i.name for i in (basedir / "simple").iterdir() if i.is_dir()}
    json_files = {i.name for i in (basedir / "json").iterdir() if i.is_file()}
    not_in_local = (simple_dirs | json_files) - local_names
    logger.info(
        "%d out of %d local packages NOT in local db",
        len(not_in_local),
        len(local_names),
    )
    for package_name in not_in_local:
        logger.info("package %s not in local db", package_name)
        if remove_not_in_local:
            # Old bandersnatch would download packages without normalization,
            # in which case one package file could have multiple "packages"
            # with different names, but normalized to the same one.
            # So, when in verify, we always set remove_packages=False
            # In step 4 unreferenced files would be removed, anyway.
            syncer.do_remove(package_name, remove_packages=False)

    logger.info("====== Step 2. Remove packages NOT in remote index ======")
    local = local_db.dump(skip_invalid=False)
    plan = syncer.determine_sync_plan(local, excludes)
    logger.info(
        "%s packages NOT in remote index -- this might contain packages that also do not exist locally",
        len(plan.remove),
    )
    for package_name in plan.remove:
        # We only take the plan.remove part here
        logger.info("package %s not in remote index", package_name)
        syncer.do_remove(package_name, remove_packages=False)

    # After some removal, local_names is changed.
    local_names = set(local_db.keys())

    logger.info(
        "====== Step 3. Make sure all local indexes are valid, and (if --sync-packages) have valid local package files ======"
    )
    success = syncer.check_and_update(
        list(local_names), prerelease_excludes, compare_size
    )
    syncer.finalize()

    logger.info(
        "====== Step 4. Remove any unreferenced files in `packages` folder ======"
    )
    ref_set = set()
    for sname in tqdm(simple_dirs, desc="Iterating simple/ directory"):
        sd = basedir / "simple" / sname
        hrefs = get_existing_hrefs(sd)
        hrefs = [] if hrefs is None else hrefs
        for i in hrefs:
            # use normpath, which is much faster than pathlib resolve(), as it does not need to access fs
            # we could make sure no symlinks could affect this here
            np = normpath(sd / i)
            logger.debug("add to ref_set: %s", np)
            ref_set.add(np)
    for file in tqdm(
        (basedir / "packages").glob("*/*/*/*"), desc="Iterating packages/*/*/*/*"
    ):
        # basedir is absolute, so file is also absolute
        # just convert to str to match normpath result
        logger.debug("find file %s", file)
        if str(file) not in ref_set:
            logger.info("removing unreferenced file %s", file)
            file.unlink()

    logger.info("Verification finished. Success: %s", success)

    if not success:
        sys.exit(1)


@cli.command(help="Manual update given package for debugging purpose")
@click.pass_context
@sync_shared_args
@click.argument("package_name")
def do_update(
    ctx: click.Context,
    sync_packages: bool,
    shadowmire_upstream: Optional[str],
    exclude: tuple[str],
    prerelease_exclude: tuple[str],
    use_pypi_index: bool,
    package_name: str,
) -> None:
    basedir: Path = ctx.obj["basedir"]
    local_db: LocalVersionKV = ctx.obj["local_db"]
    excludes = exclude_to_excludes(exclude)
    if excludes:
        logger.warning("--exclude is ignored in do_update()")
    prerelease_excludes = exclude_to_excludes(prerelease_exclude)
    syncer = get_syncer(
        basedir, local_db, sync_packages, shadowmire_upstream, use_pypi_index
    )
    syncer.do_update(package_name, prerelease_excludes)


@cli.command(help="Manual remove given package for debugging purpose")
@click.pass_context
@sync_shared_args
@click.argument("package_name")
def do_remove(
    ctx: click.Context,
    sync_packages: bool,
    shadowmire_upstream: Optional[str],
    exclude: tuple[str],
    prerelease_exclude: tuple[str],
    use_pypi_index: bool,
    package_name: str,
) -> None:
    basedir = ctx.obj["basedir"]
    local_db = ctx.obj["local_db"]
    if exclude or prerelease_exclude:
        logger.warning("exclusion rules are ignored in do_remove()")
    syncer = get_syncer(
        basedir, local_db, sync_packages, shadowmire_upstream, use_pypi_index
    )
    syncer.do_remove(package_name)


@cli.command(help="Call pypi list_packages_with_serial() for debugging")
@click.pass_context
def list_packages_with_serial(ctx: click.Context) -> None:
    basedir = ctx.obj["basedir"]
    local_db = ctx.obj["local_db"]
    syncer = SyncPyPI(basedir, local_db)
    syncer.fetch_remote_versions()


if __name__ == "__main__":
    cli(obj={})