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"""SDK configuration parser that extends the shared parser."""

from __future__ import annotations

import logging
import os
import pathlib
from configparser import ConfigParser
from io import StringIO
from typing import Any

from airflow.sdk import yaml
from airflow.sdk._shared.configuration.parser import (
    AirflowConfigParser as _SharedAirflowConfigParser,
    configure_parser_from_configuration_description,
    expand_env_var,
)
from airflow.sdk.execution_time.secrets import _SERVER_DEFAULT_SECRETS_SEARCH_PATH

log = logging.getLogger(__name__)


def _default_config_file_path(file_name: str) -> str:
    """Get path to airflow core config.yml file."""
    # TODO: Task SDK will have its own config.yml
    # Temporary: SDK uses Core's config files during development

    # Option 1: For installed packages
    config_path = pathlib.Path(__file__).parent.parent / "config_templates" / file_name
    if config_path.exists():
        return str(config_path)

    # Option 2: Monorepo structure
    config_path = (
        pathlib.Path(__file__).parent.parent.parent.parent.parent
        / "airflow-core"
        / "src"
        / "airflow"
        / "config_templates"
        / file_name
    )
    if config_path.exists():
        return str(config_path)

    raise FileNotFoundError(f"Could not find '{file_name}' in config_templates. ")


def retrieve_configuration_description() -> dict[str, dict[str, Any]]:
    """
    Read Airflow configuration description from Core's YAML file.

    SDK reads airflow core config.yml. Eventually SDK will have its own config.yml
    with only authoring related configs.

    :return: Python dictionary containing configs & their info
    """
    base_configuration_description: dict[str, dict[str, Any]] = {}
    with open(_default_config_file_path("config.yml")) as config_file:
        base_configuration_description.update(yaml.safe_load(config_file))
    return base_configuration_description


def create_default_config_parser(configuration_description: dict[str, dict[str, Any]]) -> ConfigParser:
    """
    Create default config parser based on configuration description.

    This version expands {AIRFLOW_HOME} in default values but not other
    Core-specific expansion variables (SECRET_KEY, FERNET_KEY, etc.).

    :param configuration_description: configuration description from config.yml
    :return: Default Config Parser with default values
    """
    parser = ConfigParser()
    all_vars = get_sdk_expansion_variables()
    configure_parser_from_configuration_description(parser, configuration_description, all_vars)
    return parser


def get_sdk_expansion_variables() -> dict[str, Any]:
    """
    Get variables available for config value expansion in SDK.

    SDK only needs AIRFLOW_HOME for expansion. Core specific variables
    (FERNET_KEY, JWT_SECRET_KEY, etc.) are not needed in the SDK.
    """
    airflow_home = expand_env_var(os.environ.get("AIRFLOW_HOME", os.path.expanduser("~/airflow")))
    return {
        "AIRFLOW_HOME": airflow_home,
    }


def get_airflow_config() -> str:
    """Get path to airflow.cfg file."""
    airflow_config_var = os.environ.get("AIRFLOW_CONFIG")
    if airflow_config_var is None:
        airflow_home: str = os.environ.get("AIRFLOW_HOME", os.path.expanduser("~/airflow"))
        return os.path.join(expand_env_var(airflow_home), "airflow.cfg")
    return expand_env_var(airflow_config_var)


class AirflowSDKConfigParser(_SharedAirflowConfigParser):
    """
    SDK configuration parser that extends the shared parser.

    In Phase 1, this reads Core's config.yml and can optionally read airflow.cfg.
    Eventually SDK will have its own config.yml with only authoring-related configs.
    """

    def __init__(
        self,
        default_config: str | None = None,
        *args,
        **kwargs,
    ):
        # Imported lazily to preserve the module-level lazy ``conf`` initialization and avoid a
        # configuration/providers_manager_runtime import cycle.
        from airflow.sdk.providers_manager_runtime import ProvidersManagerTaskRuntime

        # Read Core's config.yml (Phase 1: shared config.yml)
        _configuration_description = retrieve_configuration_description()
        # Create default values parser
        _default_values = create_default_config_parser(_configuration_description)
        super().__init__(
            _configuration_description,
            _default_values,
            ProvidersManagerTaskRuntime,
            create_default_config_parser,
            _default_config_file_path("provider_config_fallback_defaults.cfg"),
            *args,
            **kwargs,
        )
        self._configuration_description = _configuration_description
        self._default_values = _default_values
        self._suppress_future_warnings = False

        # Optionally load from airflow.cfg if it exists
        airflow_config = get_airflow_config()
        if os.path.exists(airflow_config):
            try:
                self.read(airflow_config)
            except Exception as e:
                log.warning("Could not read airflow.cfg from %s: %s", airflow_config, e)

        if default_config is not None:
            self._update_defaults_from_string(default_config)

    def _get_custom_secret_backend(self, worker_mode: bool | None = None) -> Any | None:
        return super()._get_custom_secret_backend(
            worker_mode=worker_mode if worker_mode is not None else True
        )

    def expand_all_configuration_values(self):
        """Expand all configuration values using SDK-specific expansion variables."""
        all_vars = get_sdk_expansion_variables()
        for section in self.sections():
            for key, value in self.items(section):
                if value is not None:
                    if self.has_option(section, key):
                        self.remove_option(section, key)
                    if self.is_template(section, key) or not isinstance(value, str):
                        self.set(section, key, value)
                    else:
                        try:
                            self.set(section, key, value.format(**all_vars))
                        except (KeyError, ValueError, IndexError):
                            # Leave unexpanded if variable not available
                            self.set(section, key, value)

    def load_test_config(self):
        """
        Use the test configuration instead of Airflow defaults.

        Unit tests load values from `unit_tests.cfg` to ensure consistent behavior. Realistically we should
        not have this needed but this is temporary to help fix the tests that use dag_maker and rely on few
        configurations.

        The SDK does not expand template variables (FERNET_KEY, JWT_SECRET_KEY, etc.) because it does not use
        the config fields that require expansion.
        """
        unit_test_config_file = pathlib.Path(_default_config_file_path("unit_tests.cfg"))
        unit_test_config = unit_test_config_file.read_text()
        self.remove_all_read_configurations()
        with StringIO(unit_test_config) as test_config_file:
            self.read_file(test_config_file)

        self.expand_all_configuration_values()

        log.info("Unit test configuration loaded from 'unit_tests.cfg'")

    def remove_all_read_configurations(self):
        """Remove all read configurations, leaving only default values in the config."""
        for section in self.sections():
            self.remove_section(section)


def get_custom_secret_backend(worker_mode: bool = False):
    """
    Get Secret Backend if defined in airflow.cfg.

    Conditionally selects the section, key and kwargs key based on whether it is called from worker or not.

    This is a convenience function that calls conf._get_custom_secret_backend().
    Uses SDK's conf instead of Core's conf.
    """
    # Lazy import to trigger __getattr__ and lazy initialization
    from airflow.sdk.configuration import conf

    return conf._get_custom_secret_backend(worker_mode=worker_mode)


def initialize_secrets_backends(
    default_backends: list[str] = _SERVER_DEFAULT_SECRETS_SEARCH_PATH,
):
    """
    Initialize secrets backend.

    * import secrets backend classes
    * instantiate them and return them in a list

    Uses SDK's conf instead of Core's conf.
    """
    from airflow.sdk._shared.module_loading import import_string

    backend_list = []
    worker_mode = False
    # Determine worker mode - if default_backends is not the server default, it's worker mode
    # This is a simplified check; in practice, worker mode is determined by the caller
    if default_backends != _SERVER_DEFAULT_SECRETS_SEARCH_PATH:
        worker_mode = True

    custom_secret_backend = get_custom_secret_backend(worker_mode)

    if custom_secret_backend is not None:
        from airflow.sdk.definitions.connection import Connection

        custom_secret_backend._set_connection_class(Connection)
        backend_list.append(custom_secret_backend)

    for class_name in default_backends:
        from airflow.sdk.definitions.connection import Connection

        secrets_backend_cls = import_string(class_name)
        backend = secrets_backend_cls()
        backend._set_connection_class(Connection)
        backend_list.append(backend)

    return backend_list


def ensure_secrets_loaded(
    default_backends: list[str] = _SERVER_DEFAULT_SECRETS_SEARCH_PATH,
) -> list:
    """
    Ensure that all secrets backends are loaded.

    If the secrets_backend_list contains only 2 default backends, reload it.
    """
    # Check if the secrets_backend_list contains only 2 default backends.

    # Check if we are loading the backends for worker too by checking if the default_backends is equal
    # to _SERVER_DEFAULT_SECRETS_SEARCH_PATH.
    secrets_backend_list = initialize_secrets_backends()
    if len(secrets_backend_list) == 2 or default_backends != _SERVER_DEFAULT_SECRETS_SEARCH_PATH:
        return initialize_secrets_backends(default_backends=default_backends)
    return secrets_backend_list


def initialize_config() -> AirflowSDKConfigParser:
    """
    Initialize SDK configuration parser.

    Called automatically when SDK is imported.
    """
    airflow_config_parser = AirflowSDKConfigParser()
    if airflow_config_parser.getboolean("core", "unit_test_mode", fallback=False):
        airflow_config_parser.load_test_config()
    return airflow_config_parser


def __getattr__(name: str):
    if name == "conf":
        val = initialize_config()
        globals()[name] = val
        return val
    raise AttributeError(f"module '{__name__}' has no attribute '{name}'")
