#
# Copyright (C) 2026-present ScyllaDB
#
# SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.1
#

import boto3
import urllib.error
import urllib.request
from botocore import UNSIGNED
from botocore.config import Config
from packaging.version import Version
from pathlib import Path
import time
import re
import subprocess
import fcntl
import shutil
import tarfile
import os
from contextlib import contextmanager

from typing import Optional, List, Iterator

def _list_scylla_release_entries(bucket: str, prefix: str, pack: str = "") -> list[str]:
    """
    List Scylla release entries directly under an S3 prefix.
    The S3 listing is paginated and limited to one prefix level. Returned entries
    have the requested prefix and trailing slash removed, and are filtered to
    Scylla/ScyllaDB release names matching the requested package type (`pack`).
    """
    if not prefix.endswith("/"):
        prefix = f"{prefix}/"

    pack_part = rf"{re.escape(pack)}-" if pack else ""    
    pattern = re.compile(rf"^scylla(?:db)?-{pack_part}\d{{4}}\.\d+(?:\.\d+)?(?:/|$|[~.-])")

    s3 = boto3.client("s3", region_name="us-east-1", config=Config(signature_version=UNSIGNED))

    files = []
    folders = []
    continuation_token = None
    while True:
        kwargs = {"Bucket": bucket, "Prefix": prefix, "Delimiter": "/"}
        if continuation_token:
            kwargs["ContinuationToken"] = continuation_token
        resp = s3.list_objects_v2(**kwargs)
        files += resp.get("Contents", [])
        folders += resp.get("CommonPrefixes", [])
        if not resp.get("IsTruncated"):
            break
        continuation_token = resp.get("NextContinuationToken")
        if not continuation_token:
            break

    objs = [f["Key"].removeprefix(prefix) for f in files] if files else [f["Prefix"].removeprefix(prefix) for f in folders]
    return [o.rstrip("/") for o in objs if pattern.match(o)]


def _version_key(v: str, pack: str = "") -> str:
    """
    Extract the sortable version component from a Scylla release entry or archive name.
    The `pack` argument identifies the archive-name structure, so the function knows
    where to find the version component: after `scylla-` for default archives, or
    after `scylla-<pack>-` for package variants such as `dev` and `debug`.
    For example:
    `scylla-2026.1.0-...` with `pack=""` returns `2026.1.0-...`.
    `scylla-dev-2026.1.0-...` with `pack="dev"` returns `2026.1.0-...`.
    `scylla-debug-2026.1.0-...` with `pack="debug"` returns `2026.1.0-...`.
    The returned version is normalized for `packaging.version.Version` sorting by
    converting release-candidate versions from `~rc` to `rc`.
    """
    if not pack:
        v = v.rstrip("/").split("-", 2)[1]  # name-version-postfix or name-version
    else:
        v = v.rstrip("/").split("-", 3)[2]  # name-pack-postfix    
    v = v.replace("~rc", "rc")
    return v


def _version_matches(v: str, match_pattern: str) -> bool:
    return v == match_pattern or v.startswith(f"{match_pattern}.") or v.startswith(f"{match_pattern}rc")


def _get_latest_ver(objs: List[str], match_pattern: Optional[str] = None, pack: str = None) -> Optional[str]:
    sorted_vers = [_version_key(o, pack) for o in objs]
    if match_pattern:
        sorted_vers = [v for v in sorted_vers if _version_matches(v, match_pattern)]
    sorted_vers.sort(key=Version)
    return sorted_vers[-1] if sorted_vers else None


def _get_version_url(major: Optional[int] = None, minor: Optional[int] = None,
                     patch: Optional[int] = None, rc: Optional[int] = None, 
                     arch: str = "x86_64", pack: str = "") -> Optional[str]:
    """
    Resolve the download URL for a Scylla relocatable package.
    The lookup walks the Scylla downloads S3 bucket in two stages: first selecting
    the matching release directory from `major` and `minor`, then selecting the
    matching package artifact from `patch`, `rc`, `arch`, and `pack`. Missing version
    components are resolved to the latest available match. Returns the full HTTPS URL
    for the selected artifact, or `None` if no matching package is found.
    """

    bucket_url = "downloads.scylladb.com"
    prefix_url = "downloads/scylla/relocatable"

    if major is None:
        ver = _get_latest_ver(_list_scylla_release_entries(bucket_url, prefix_url))
    elif minor is None:
        ver = _get_latest_ver(_list_scylla_release_entries(bucket_url, prefix_url), f"{major}")
    else:
        ver = f"{major}.{minor}"

    if ver is None:
        return None

    prefix_url = f"{prefix_url}/scylladb-{ver}/"
    objs = _list_scylla_release_entries(bucket_url, prefix_url, pack)
    if patch is None:
        ver = _get_latest_ver(objs, ver, pack)
    elif rc is None:
        ver = _get_latest_ver(objs, f"{ver}.{patch}", pack)
    else:
        ver = f"{ver}.{patch}rc{rc}"

    if ver is None:
        return None

    filtered = [o for o in objs if _version_key(o, pack) == ver and f".{arch}." in o]

    return f"https://{bucket_url}/{prefix_url}{filtered[0]}" if filtered else None


def get_file_name_and_url_from_url(major: Optional[int] = None, minor: Optional[int] = None,
                                   patch: Optional[int] = None, rc: Optional[int] = None, 
                                   arch: str = "x86_64", pack: str = "", url: str = None):
    """
    Resolve the download URL and file name for a Scylla package.
    If `url` is provided, it is used directly. Otherwise, the URL is resolved from
    the requested `major`, `minor`, `patch`, `rc`, `arch`, and `pack` values, using
    the latest available value for any missing version component. If `rc` is
    provided, `patch` is treated as 0. Returns `(url, file_name)` on success, or
    `(None, None)` if no matching URL can be resolved.
    Args:
        major: ScyllaDB major version to fetch.
        minor: ScyllaDB minor version to fetch.
        patch: ScyllaDB patch version to fetch.
        rc: Release-candidate number, if fetching an RC build.
        arch: Target architecture of the archive.
        pack: Package/build variant to resolve. Use an empty string for the default
              archive name (`scylla-<version>-...`), or a variant such as `"dev"` or
              `"debug"` for archive names like `scylla-dev-<version>-...` and
              `scylla-debug-<version>-...`.
        url: Direct archive URL to fetch instead of resolving one from version parts.
             If `url` is provided, it is downloaded directly. Otherwise, the version URL is
             resolved from the requested `major`, `minor`, `patch`, `rc`, `arch`, and `pack`
             components, using the latest available value for any missing component.
    """

    if rc is not None:
        patch = 0

    if not url:
        url = _get_version_url(major, minor, patch, rc, arch, pack)
    
    return (url, url.rsplit("/", 1)[-1]) if url else (None, None)


def download_scylla_version(major: Optional[int] = None, minor: Optional[int] = None,
                            patch: Optional[int] = None, rc: Optional[int] = None,
                            arch: str = "x86_64", pack: str = "", 
                            output_dir: str | Path = ".", url: str = None, 
                            retry: int = 1) -> Optional[Path]:
    """
    Download a Scylla package matching the requested version components.
    If `url` is provided, it is downloaded directly. Otherwise, the version URL is
    resolved from the requested `major`, `minor`, `patch`, and `rc` components,
    using the latest available value for any missing component. If `rc` is provided,
    `patch` is treated as 0. Returns the path to the downloaded file on success, or
    `None` if no matching version is found or the download fails after all retries.
    Args:
        major: ScyllaDB major version to fetch.
        minor: ScyllaDB minor version to fetch.
        patch: ScyllaDB patch version to fetch.
        rc: Release-candidate number, if fetching an RC build.
        arch: Target architecture of the archive.
        pack: Package/build variant to resolve. Use an empty string for the default
              archive name (`scylla-<version>-...`), or a variant such as `"dev"` or
              `"debug"` for archive names like `scylla-dev-<version>-...` and
              `scylla-debug-<version>-...`.
        url: Direct archive URL to fetch instead of resolving one from version parts.
             If `url` is provided, it is downloaded directly. Otherwise, the version URL is
             resolved from the requested `major`, `minor`, `patch`, `rc`, `arch`, and `pack`
             components, using the latest available value for any missing component.
    """

    KB = 1024 * 1024

    if rc is not None:
        patch = 0

    if not url:
        url = _get_version_url(major, minor, patch, rc, arch, pack)
        if url is None:
            return None

    output_path = Path(output_dir) / url.rsplit("/", 1)[-1]

    for i in range(retry):
        try:
            with urllib.request.urlopen(url, timeout=60) as response:
                if response.status == 200:
                    with output_path.open("wb") as f:
                        while chunk := response.read(KB):
                            f.write(chunk)
                    return output_path
                if i == retry - 1:
                    return None
                time.sleep(1)
        except (urllib.error.HTTPError, urllib.error.URLError, TimeoutError, OSError):
            if i == retry - 1:
                return None
            time.sleep(1)
    return None


@contextmanager
def with_file_lock(lock_path: Path) -> Iterator[None]:
    lock_path.parent.mkdir(parents=True, exist_ok=True)
    with lock_path.open("a") as f:
        fcntl.flock(f, fcntl.LOCK_EX)
        try:
            yield
        finally:
            fcntl.flock(f, fcntl.LOCK_UN)


def extract_tar_no_same_owner(archive_path: Path, unpack_dir: Path) -> None:
    with tarfile.open(archive_path, "r:*") as archive:
        archive.extractall(path=unpack_dir, filter="data")            


def fetch_and_install_scylla_version(major: Optional[int] = None, minor: Optional[int] = None,
                                     patch: Optional[int] = None, rc: Optional[int] = None,
                                     arch: str = "x86_64", pack: str = "", 
                                     url: str = None) -> Path:
    """Fetch, cache, unpack, and install a ScyllaDB release archive.
    The archive is resolved from either the supplied version components or a direct
    URL, then cached under XDG_CACHE_HOME, or ~/.cache if XDG_CACHE_HOME is unset.
    Download, unpack, and install steps are guarded by marker files so repeated
    calls reuse the existing installation. A file lock prevents concurrent callers
    from modifying the same cached archive directory at the same time.
    Args:
        major: ScyllaDB major version to fetch.
        minor: ScyllaDB minor version to fetch.
        patch: ScyllaDB patch version to fetch.
        rc: Release-candidate number, if fetching an RC build.
        arch: Target architecture of the archive.
        pack: Package/build variant to resolve. Use an empty string for the default
              archive name (`scylla-<version>-...`), or a variant such as `"dev"` or
              `"debug"` for archive names like `scylla-dev-<version>-...` and
              `scylla-debug-<version>-...`.
        url: Direct archive URL to fetch instead of resolving one from version parts.
             If `url` is provided, it is downloaded directly. Otherwise, the version URL is
             resolved from the requested `major`, `minor`, `patch`, `rc`, `arch`, and `pack`
             components, using the latest available value for any missing component.
    Returns:
        Path to the installed ScyllaDB binary.
    Raises:
        RuntimeError: If the archive name cannot be resolved or the archive cannot be downloaded.
        subprocess.CalledProcessError: If the ScyllaDB install script fails.
    """
    xdg_cache_dir = Path(os.getenv("XDG_CACHE_HOME", str(Path.home() / ".cache")))
    archive_url, archive_name = get_file_name_and_url_from_url(major, minor, patch, rc, arch, pack, url)
    if not archive_name: 
        raise RuntimeError(f"couldnt get archive name for major: {major}, minor: {minor}," 
                           f" patch: {patch}, rc: {rc}, arch: {arch}, pack: {pack}, url: {url}")
    cache_dir = (xdg_cache_dir / "scylladb" / "test.py" / archive_name)
    cache_dir.mkdir(exist_ok=True, parents=True)

    archive_path = cache_dir/archive_name
    unpack_dir = cache_dir/"unpacked"
    install_dir = cache_dir/"installed"

    lock_file = cache_dir / "lock"
    downloaded_marker = cache_dir / "downloaded.success"
    unpacked_marker = cache_dir / "unpacked.success"
    installed_marker = cache_dir / "installed.success"

    with with_file_lock(lock_file):
        if not installed_marker.exists():
            if not unpacked_marker.exists():
                if not downloaded_marker.exists():
                    archive_path.unlink(missing_ok=True)
                    archive_path = download_scylla_version(url=archive_url, output_dir=cache_dir, retry=40)
                    if archive_path is None:
                        raise RuntimeError(f"Couldnt download Scylla archive: {archive_url}")
                    downloaded_marker.touch()
                shutil.rmtree(unpack_dir, ignore_errors=True)
                unpack_dir.mkdir(exist_ok=True, parents=True)
                extract_tar_no_same_owner(archive_path, unpack_dir)
                unpacked_marker.touch()
            shutil.rmtree(install_dir, ignore_errors=True)
            install_dir.mkdir(exist_ok=True, parents=True)
            subprocess.run(["bash", "./install.sh", "--without-systemd", "--nonroot", "--prefix", str(install_dir)], cwd=unpack_dir/"scylla", check=True)
            installed_marker.touch()

    return install_dir/"bin"/"scylla"