pobsync/src/pobsync_backend/config_checks.py

from __future__ import annotations

import os
import shutil
from pathlib import Path

from django.conf import settings

from .models import GlobalConfig, HostConfig, SshCredential
from .self_check import SelfCheck
from .ssh_keys import identity_path


CRITICAL_ROOT_EXCLUDES = ("/proc/***", "/sys/***", "/dev/***", "/run/***", "/tmp/***")


def collect_global_config_checks(global_config: GlobalConfig) -> list[SelfCheck]:
    checks = [
        _absolute_path_check("Global backup root", global_config.backup_root),
        _absolute_path_check("Runtime state root", settings.POBSYNC_HOME),
        _runtime_backup_root_check(global_config),
        _rsync_binary_check(global_config.rsync_binary),
        _rsync_recursion_check(
            "Global rsync recursion",
            [*list(global_config.rsync_args or []), *list(global_config.rsync_extra_args or [])],
        ),
        _source_root_check("Global source root", global_config.default_source_root),
        _root_excludes_check(global_config.default_source_root, list(global_config.excludes_default or [])),
        _retention_check(
            "Global retention",
            global_config.retention_daily,
            global_config.retention_weekly,
            global_config.retention_monthly,
            global_config.retention_yearly,
        ),
        _ssh_port_check("Global SSH port", global_config.ssh_port),
        _credential_check("Global SSH credential", global_config.default_ssh_credential),
    ]
    return checks


def collect_effective_host_config_checks(host: HostConfig, global_config: GlobalConfig) -> list[SelfCheck]:
    source_root = host.source_root or global_config.default_source_root
    ssh_user = host.ssh_user or global_config.ssh_user
    ssh_port = host.ssh_port or global_config.ssh_port
    credential = host.ssh_credential or global_config.default_ssh_credential
    if host.excludes_replace is not None:
        excludes = list(host.excludes_replace)
    else:
        excludes = [*list(global_config.excludes_default or []), *list(host.excludes_add or [])]
    rsync_args = [
        *list(global_config.rsync_args or []),
        *list(global_config.rsync_extra_args or []),
        *list(host.rsync_extra_args or []),
    ]

    checks = [
        _source_root_check("Host effective source root", source_root),
        _ssh_user_check(ssh_user),
        _ssh_port_check("Host effective SSH port", ssh_port),
        _credential_check("Host effective SSH credential", credential),
        _rsync_recursion_check("Host effective rsync recursion", rsync_args),
        _root_excludes_check(source_root, excludes, host=host),
        _includes_check(host),
        _retention_check(
            "Host retention",
            host.retention_daily,
            host.retention_weekly,
            host.retention_monthly,
            host.retention_yearly,
        ),
    ]
    return checks


def has_recursive_rsync_arg(args: list[str]) -> bool:
    for arg in args:
        if arg in {"--archive", "--recursive"}:
            return True
        if arg.startswith("-") and not arg.startswith("--") and any(flag in arg for flag in ("a", "r")):
            return True
    return False


def _absolute_path_check(name: str, value: str) -> SelfCheck:
    path = Path(value)
    if not value:
        return SelfCheck(name, "failed", "Path is empty.")
    if not path.is_absolute():
        return SelfCheck(name, "failed", f"{value} is not absolute.")
    return SelfCheck(name, "ok", value)


def _runtime_backup_root_check(global_config: GlobalConfig) -> SelfCheck:
    if global_config.backup_root == settings.POBSYNC_BACKUP_ROOT:
        return SelfCheck("Runtime backup root", "ok", global_config.backup_root)
    return SelfCheck(
        "Runtime backup root",
        "warning",
        "Database backup root differs from the runtime backup root.",
        f"database={global_config.backup_root} runtime={settings.POBSYNC_BACKUP_ROOT}",
    )


def _rsync_binary_check(binary: str) -> SelfCheck:
    if not binary:
        return SelfCheck("Global rsync binary", "failed", "Rsync binary is empty.")
    if Path(binary).is_absolute():
        exists = Path(binary).exists()
        message = binary if exists else f"{binary} does not exist."
        return SelfCheck("Global rsync binary", "ok" if exists else "failed", message)
    path = shutil.which(binary)
    return SelfCheck("Global rsync binary", "ok" if path else "failed", path or f"{binary} was not found in PATH.")


def _rsync_recursion_check(name: str, args: list[str]) -> SelfCheck:
    if has_recursive_rsync_arg(args):
        return SelfCheck(name, "ok", "Rsync args include archive or recursive transfer.", " ".join(args))
    return SelfCheck(
        name,
        "failed",
        "Rsync args do not include archive or recursive transfer.",
        "Add --archive or --recursive before running a real backup.",
    )


def _source_root_check(name: str, source_root: str) -> SelfCheck:
    if not source_root:
        return SelfCheck(name, "failed", "Source root is empty.")
    if not source_root.startswith("/"):
        return SelfCheck(name, "failed", f"{source_root} is not absolute.")
    return SelfCheck(name, "ok", source_root)


def _root_excludes_check(source_root: str, excludes: list[str], host: HostConfig | None = None) -> SelfCheck:
    if source_root != "/":
        return SelfCheck("Effective root excludes", "ok", "Source root is not /, critical OS excludes are less important.")
    missing = [pattern for pattern in CRITICAL_ROOT_EXCLUDES if pattern not in excludes]
    if missing:
        detail = ", ".join(missing)
        if host and host.excludes_replace is not None:
            detail = f"excludes_replace is active; missing {detail}"
        return SelfCheck(
            "Effective root excludes",
            "warning",
            "Source root is / but some critical default excludes are missing.",
            detail,
        )
    return SelfCheck("Effective root excludes", "ok", "Critical root excludes are present.")


def _includes_check(host: HostConfig) -> SelfCheck:
    includes = list(host.includes or [])
    if not includes:
        return SelfCheck("Host includes", "ok", "No host include rules are configured.")
    return SelfCheck(
        "Host includes",
        "warning",
        "Includes are passed to rsync as raw --include rules.",
        "Verify matching exclude rules if you intend to limit the backup scope.",
    )


def _retention_check(name: str, daily: int, weekly: int, monthly: int, yearly: int) -> SelfCheck:
    if any(value > 0 for value in (daily, weekly, monthly, yearly)):
        return SelfCheck(name, "ok", f"d{daily} w{weekly} m{monthly} y{yearly}")
    return SelfCheck(name, "warning", "All retention windows are zero.")


def _ssh_user_check(user: str) -> SelfCheck:
    if user.strip():
        return SelfCheck("Host effective SSH user", "ok", user.strip())
    return SelfCheck("Host effective SSH user", "failed", "SSH user is empty.")


def _ssh_port_check(name: str, port: int | None) -> SelfCheck:
    if port is None:
        return SelfCheck(name, "failed", "SSH port is empty.")
    if 1 <= int(port) <= 65535:
        return SelfCheck(name, "ok", str(port))
    return SelfCheck(name, "failed", f"{port} is outside the valid TCP port range.")


def _credential_check(name: str, credential: SshCredential | None) -> SelfCheck:
    if credential is None:
        return SelfCheck(name, "warning", "No SSH credential selected.")
    if credential.key_path:
        key_path = identity_path(credential)
        if not key_path.exists():
            return SelfCheck(name, "failed", f"{key_path} does not exist.")
        if not os.access(key_path, os.R_OK):
            return SelfCheck(name, "failed", f"{key_path} is not readable by this process.")
        return SelfCheck(name, "ok", str(credential), str(key_path))
    if credential.private_key:
        return SelfCheck(
            name,
            "warning",
            f"{credential} stores private key material in the database.",
            "Generated filesystem keys are recommended for native installs.",
        )
    return SelfCheck(name, "failed", f"{credential} has no private key material or key path.")