#
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from __future__ import annotations

import contextlib
import os
import sys
import textwrap
import warnings
from collections.abc import Generator
from datetime import datetime, timedelta
from pathlib import Path
from typing import TYPE_CHECKING, Any, NamedTuple

from tabulate import tabulate

from airflow import settings
from airflow._shared.timezones import timezone
from airflow.configuration import conf
from airflow.dag_processing.importers import get_importer_registry
from airflow.exceptions import (
    AirflowClusterPolicyError,
    AirflowClusterPolicySkipDag,
    AirflowClusterPolicyViolation,
    AirflowDagDuplicatedIdException,
    AirflowException,
    UnknownExecutorException,
)
from airflow.executors.executor_loader import ExecutorLoader
from airflow.listeners.listener import get_listener_manager
from airflow.serialization.definitions.notset import NOTSET, ArgNotSet, is_arg_set
from airflow.serialization.serialized_objects import LazyDeserializedDAG
from airflow.utils.file import correct_maybe_zipped
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.session import NEW_SESSION, provide_session

if TYPE_CHECKING:
    from sqlalchemy.orm import Session

    from airflow import DAG
    from airflow.models.dagwarning import DagWarning


@contextlib.contextmanager
def _capture_with_reraise() -> Generator[list[warnings.WarningMessage], None, None]:
    """Capture warnings in context and re-raise it on exit from the context manager."""
    captured_warnings = []
    try:
        with warnings.catch_warnings(record=True) as captured_warnings:
            yield captured_warnings
    finally:
        if captured_warnings:
            for cw in captured_warnings:
                warnings.warn_explicit(
                    message=cw.message,
                    category=cw.category,
                    filename=cw.filename,
                    lineno=cw.lineno,
                    source=cw.source,
                )


class FileLoadStat(NamedTuple):
    """
    Information about single file.

    :param file: Loaded file.
    :param duration: Time spent on process file.
    :param dag_num: Total number of DAGs loaded in this file.
    :param task_num: Total number of Tasks loaded in this file.
    :param dags: DAGs names loaded in this file.
    :param warning_num: Total number of warnings captured from processing this file.
    :param bundle_path: The bundle path from DagBag, if any.
    :param bundle_name: The bundle name from DagBag, if any.
    """

    file: str
    duration: timedelta
    dag_num: int
    task_num: int
    dags: str
    warning_num: int
    bundle_path: Path | None
    bundle_name: str | None


def _executor_exists(executor_name: str, team_name: str | None) -> bool:
    """Check if executor exists, with global fallback for teams."""
    try:
        # First pass check for team-specific executor or a global executor (i.e. team_name=None)
        ExecutorLoader.lookup_executor_name_by_str(executor_name, team_name=team_name, validate_teams=False)
        return True
    except UnknownExecutorException:
        if team_name:
            # If we had a team_name but didn't find an executor, check if there is a global executor that
            # satisfies the request.
            try:
                ExecutorLoader.lookup_executor_name_by_str(
                    executor_name, team_name=None, validate_teams=False
                )
                return True
            except UnknownExecutorException:
                pass
    return False


def _validate_executor_fields(dag: DAG, bundle_name: str | None = None) -> None:
    """Validate that executors specified in tasks are available and owned by the same team as the dag bundle."""
    import logging

    log = logging.getLogger(__name__)
    dag_team_name = None

    # Check if multi team is available by reading the multi_team configuration (which is boolean)
    if conf.getboolean("core", "multi_team"):
        # Get team name from bundle configuration if available
        if bundle_name:
            from airflow.dag_processing.bundles.manager import DagBundlesManager

            bundle_manager = DagBundlesManager()
            bundle_config = bundle_manager._bundle_config[bundle_name]

            dag_team_name = bundle_config.team_name
            if dag_team_name:
                log.debug(
                    "Found team '%s' for DAG '%s' via bundle '%s'", dag_team_name, dag.dag_id, bundle_name
                )

    for task in dag.tasks:
        if not task.executor:
            continue

        if not _executor_exists(task.executor, dag_team_name):
            if dag_team_name:
                raise UnknownExecutorException(
                    f"Task '{task.task_id}' specifies executor '{task.executor}', which is not available "
                    f"for team '{dag_team_name}' (the team associated with DAG '{dag.dag_id}') or as a global executor. "
                    f"Make sure '{task.executor}' is configured for team '{dag_team_name}' or globally in your "
                    "[core] executors configuration, or update the task's executor to use one of the "
                    f"configured executors for team '{dag_team_name}' or available global executors."
                )
            raise UnknownExecutorException(
                f"Task '{task.task_id}' specifies executor '{task.executor}', which is not available. "
                "Make sure it is listed in your [core] executors configuration, or update the task's "
                "executor to use one of the configured executors."
            )


class DagBag(LoggingMixin):
    """
    A dagbag is a collection of dags, parsed out of a folder tree and has high level configuration settings.

    Some possible setting are database to use as a backend and what executor
    to use to fire off tasks. This makes it easier to run distinct environments
    for say production and development, tests, or for different teams or security
    profiles. What would have been system level settings are now dagbag level so
    that one system can run multiple, independent settings sets.

    :param dag_folder: the folder to scan to find DAGs
    :param safe_mode: when ``False``, scans all python modules for dags.
        When ``True`` uses heuristics (files containing ``DAG`` and ``airflow`` strings)
        to filter python modules to scan for dags.
    :param load_op_links: Should the extra operator link be loaded via plugins when
        de-serializing the DAG? This flag is set to False in Scheduler so that Extra Operator links
        are not loaded to not run User code in Scheduler.
    :param collect_dags: when True, collects dags during class initialization.
    :param known_pools: If not none, then generate warnings if a Task attempts to use an unknown pool.
    """

    def __init__(
        self,
        dag_folder: str | Path | None = None,  # todo AIP-66: rename this to path
        safe_mode: bool | ArgNotSet = NOTSET,
        load_op_links: bool = True,
        collect_dags: bool = True,
        known_pools: set[str] | None = None,
        bundle_path: Path | None = None,
        bundle_name: str | None = None,
    ):
        super().__init__()
        self.bundle_path = bundle_path
        self.bundle_name = bundle_name

        dag_folder = dag_folder or settings.DAGS_FOLDER
        self.dag_folder = dag_folder
        self.dags: dict[str, DAG] = {}
        # the file's last modified timestamp when we last read it
        self.file_last_changed: dict[str, datetime] = {}
        # Store import errors with relative file paths as keys (relative to bundle_path)
        self.import_errors: dict[str, str] = {}
        self.captured_warnings: dict[str, tuple[str, ...]] = {}
        self.has_logged = False
        # Only used by SchedulerJob to compare the dag_hash to identify change in DAGs
        self.dags_hash: dict[str, str] = {}

        self.known_pools = known_pools

        self.dagbag_import_error_tracebacks = conf.getboolean("core", "dagbag_import_error_tracebacks")
        self.dagbag_import_error_traceback_depth = conf.getint("core", "dagbag_import_error_traceback_depth")
        if collect_dags:
            self.collect_dags(
                dag_folder=dag_folder,
                safe_mode=(
                    safe_mode if is_arg_set(safe_mode) else conf.getboolean("core", "DAG_DISCOVERY_SAFE_MODE")
                ),
            )
        # Should the extra operator link be loaded via plugins?
        # This flag is set to False in Scheduler so that Extra Operator links are not loaded
        self.load_op_links = load_op_links

    def size(self) -> int:
        """:return: the amount of dags contained in this dagbag"""
        return len(self.dags)

    @property
    def dag_ids(self) -> list[str]:
        """
        Get DAG ids.

        :return: a list of DAG IDs in this bag
        """
        return list(self.dags)

    @provide_session
    def get_dag(self, dag_id, *, session: Session = NEW_SESSION):
        """
        Get the DAG out of the dictionary, and refreshes it if expired.

        :param dag_id: DAG ID
        """
        # Avoid circular import
        from airflow.models.dag import DagModel

        dag = self.dags.get(dag_id)

        # If DAG Model is absent, we can't check last_expired property. Is the DAG not yet synchronized?
        if (orm_dag := DagModel.get_current(dag_id, session=session)) is None:
            return dag

        is_expired = (
            orm_dag.last_expired and dag and dag.last_loaded and dag.last_loaded < orm_dag.last_expired
        )
        if is_expired:
            # Remove associated dags so we can re-add them.
            self.dags.pop(dag_id, None)
        if dag is None or is_expired:
            # Reprocess source file.
            found_dags = self.process_file(
                filepath=correct_maybe_zipped(orm_dag.fileloc), only_if_updated=False
            )

            # If the source file no longer exports `dag_id`, delete it from self.dags
            if found_dags and dag_id in [found_dag.dag_id for found_dag in found_dags]:
                return self.dags[dag_id]
            self.dags.pop(dag_id, None)
        return self.dags.get(dag_id)

    def process_file(self, filepath, only_if_updated=True, safe_mode=True):
        """Process a DAG file and return found DAGs."""
        if filepath is None or not os.path.isfile(filepath):
            return []

        try:
            file_last_changed_on_disk = datetime.fromtimestamp(os.path.getmtime(filepath))
            if (
                only_if_updated
                and filepath in self.file_last_changed
                and file_last_changed_on_disk == self.file_last_changed[filepath]
            ):
                return []
        except Exception as e:
            self.log.exception(e)
            return []

        self.captured_warnings.pop(filepath, None)

        registry = get_importer_registry()
        importer = registry.get_importer(filepath)

        if importer is None:
            self.log.debug("No importer found for file: %s", filepath)
            return []

        result = importer.import_file(
            file_path=filepath,
            bundle_path=self.bundle_path,
            bundle_name=self.bundle_name,
            safe_mode=safe_mode,
        )

        if result.skipped_files:
            for skipped in result.skipped_files:
                if not self.has_logged:
                    self.has_logged = True
                    self.log.info("File %s assumed to contain no DAGs. Skipping.", skipped)

        if result.errors:
            for error in result.errors:
                # Use the relative file path from error (importer provides relative paths)
                # Fall back to converting filepath to relative if error.file_path is not set
                error_path = error.file_path if error.file_path else self._get_relative_fileloc(filepath)
                error_msg = error.stacktrace if error.stacktrace else error.message
                self.import_errors[error_path] = error_msg
                self.log.error("Error loading DAG from %s: %s", error_path, error.message)

        if result.warnings:
            formatted_warnings = [
                f"{w.file_path}:{w.line_number}: {w.warning_type}: {w.message}" for w in result.warnings
            ]
            self.captured_warnings[filepath] = tuple(formatted_warnings)
            # Re-emit warnings so they can be handled by Python's warning system
            for w in result.warnings:
                warnings.warn_explicit(
                    message=w.message,
                    category=UserWarning,
                    filename=w.file_path,
                    lineno=w.line_number or 0,
                )

        bagged_dags = []
        for dag in result.dags:
            try:
                if dag.fileloc is None:
                    dag.fileloc = filepath
                # Validate before adding to bag (matches original _process_modules behavior)
                dag.validate()
                _validate_executor_fields(dag, self.bundle_name)
                self.bag_dag(dag=dag)
                bagged_dags.append(dag)
            except AirflowClusterPolicySkipDag:
                self.log.debug("DAG %s skipped by cluster policy", dag.dag_id)
            except Exception as e:
                self.log.exception("Error bagging DAG from %s", filepath)
                relative_path = self._get_relative_fileloc(filepath)
                self.import_errors[relative_path] = f"{type(e).__name__}: {e}"

        self.file_last_changed[filepath] = file_last_changed_on_disk
        return bagged_dags

    @property
    def dag_warnings(self) -> set[DagWarning]:
        """Get the set of DagWarnings for the bagged dags."""
        from airflow.models.dagwarning import DagWarning, DagWarningType

        # None means this feature is not enabled. Empty set means we don't know about any pools at all!
        if self.known_pools is None:
            return set()

        def get_pools(dag) -> dict[str, set[str]]:
            return {dag.dag_id: {task.pool for task in dag.tasks}}

        pool_dict: dict[str, set[str]] = {}
        for dag in self.dags.values():
            pool_dict.update(get_pools(dag))

        warnings: set[DagWarning] = set()
        for dag_id, dag_pools in pool_dict.items():
            nonexistent_pools = dag_pools - self.known_pools
            if nonexistent_pools:
                warnings.add(
                    DagWarning(
                        dag_id,
                        DagWarningType.NONEXISTENT_POOL,
                        f"Dag '{dag_id}' references non-existent pools: {sorted(nonexistent_pools)!r}",
                    )
                )
        return warnings

    def _get_relative_fileloc(self, filepath: str) -> str:
        """
        Get the relative file location for a given filepath.

        :param filepath: Absolute path to the file
        :return: Relative path from bundle_path, or original filepath if no bundle_path
        """
        if self.bundle_path:
            return str(Path(filepath).relative_to(self.bundle_path))
        return filepath

    def bag_dag(self, dag: DAG):
        """
        Add the DAG into the bag.

        :raises: AirflowDagCycleException if a cycle is detected.
        :raises: AirflowDagDuplicatedIdException if this dag already exists in the bag.
        """
        dag.check_cycle()
        dag.resolve_template_files()
        dag.last_loaded = timezone.utcnow()

        try:
            settings.dag_policy(dag)

            for task in dag.tasks:
                if getattr(task, "end_from_trigger", False) and get_listener_manager().has_listeners:
                    raise AirflowException(
                        "Listeners are not supported with end_from_trigger=True for deferrable operators. "
                        "Task %s in DAG %s has end_from_trigger=True with listeners from plugins. "
                        "Set end_from_trigger=False to use listeners.",
                        task.task_id,
                        dag.dag_id,
                    )

                settings.task_policy(task)
        except (AirflowClusterPolicyViolation, AirflowClusterPolicySkipDag):
            raise
        except Exception as e:
            self.log.exception(e)
            raise AirflowClusterPolicyError(e)
        from airflow.sdk.exceptions import AirflowDagCycleException

        try:
            prev_dag = self.dags.get(dag.dag_id)
            if prev_dag and prev_dag.fileloc != dag.fileloc:
                raise AirflowDagDuplicatedIdException(
                    dag_id=dag.dag_id,
                    incoming=dag.fileloc,
                    existing=self.dags[dag.dag_id].fileloc,
                )
            self.dags[dag.dag_id] = dag
            self.log.debug("Loaded DAG %s", dag)
        except (AirflowDagCycleException, AirflowDagDuplicatedIdException):
            # There was an error in bagging the dag. Remove it from the list of dags
            self.log.exception("Exception bagging dag: %s", dag.dag_id)
            raise

    def collect_dags(
        self,
        dag_folder: str | Path | None = None,
        only_if_updated: bool = True,
        safe_mode: bool = conf.getboolean("core", "DAG_DISCOVERY_SAFE_MODE"),
    ):
        """
        Look for python modules in a given path, import them, and add them to the dagbag collection.

        Note that if a ``.airflowignore`` file is found while processing
        the directory, it will behave much like a ``.gitignore``,
        ignoring files that match any of the patterns specified
        in the file.

        **Note**: The patterns in ``.airflowignore`` are interpreted as either
        un-anchored regexes or gitignore-like glob expressions, depending on
        the ``DAG_IGNORE_FILE_SYNTAX`` configuration parameter.
        """
        self.log.info("Filling up the DagBag from %s", dag_folder)
        dag_folder = dag_folder or self.dag_folder
        # Used to store stats around DagBag processing
        stats = []

        # Ensure dag_folder is a str -- it may have been a pathlib.Path
        dag_folder = correct_maybe_zipped(str(dag_folder))

        registry = get_importer_registry()
        files_to_parse = registry.list_dag_files(dag_folder, safe_mode=safe_mode)

        for filepath in files_to_parse:
            try:
                file_parse_start_dttm = timezone.utcnow()
                found_dags = self.process_file(filepath, only_if_updated=only_if_updated, safe_mode=safe_mode)

                file_parse_end_dttm = timezone.utcnow()
                try:
                    relative_file = Path(filepath).relative_to(Path(self.dag_folder)).as_posix()
                except ValueError:
                    # filepath is not under dag_folder (e.g., example DAGs from a different location)
                    relative_file = Path(filepath).as_posix()
                stats.append(
                    FileLoadStat(
                        file=relative_file,
                        duration=file_parse_end_dttm - file_parse_start_dttm,
                        dag_num=len(found_dags),
                        task_num=sum(len(dag.tasks) for dag in found_dags),
                        dags=str([dag.dag_id for dag in found_dags]),
                        warning_num=len(self.captured_warnings.get(filepath, [])),
                        bundle_path=self.bundle_path,
                        bundle_name=self.bundle_name,
                    )
                )
            except Exception as e:
                self.log.exception(e)

        self.dagbag_stats = sorted(stats, key=lambda x: x.duration, reverse=True)

    def dagbag_report(self):
        """Print a report around DagBag loading stats."""
        stats = self.dagbag_stats
        dag_folder = self.dag_folder
        duration = sum((o.duration for o in stats), timedelta()).total_seconds()
        dag_num = sum(o.dag_num for o in stats)
        task_num = sum(o.task_num for o in stats)
        table = tabulate(stats, headers="keys")

        report = textwrap.dedent(
            f"""\n
        -------------------------------------------------------------------
        DagBag loading stats for {dag_folder}
        -------------------------------------------------------------------
        Number of DAGs: {dag_num}
        Total task number: {task_num}
        DagBag parsing time: {duration}\n{table}
        """
        )
        return report


class BundleDagBag(DagBag):
    """
    Bundle-aware DagBag that permanently modifies sys.path.

    This class adds the bundle_path to sys.path permanently to allow DAG files
    to import modules from their bundle directory. No cleanup is performed.

    WARNING: Only use for one-off usages like CLI commands. Using this in long-running
    processes will cause sys.path to accumulate entries.

    Same parameters as DagBag, but bundle_path is required and examples are not loaded.
    """

    def __init__(self, *args, bundle_path: Path | None = None, **kwargs):
        if not bundle_path:
            raise ValueError("bundle_path is required for BundleDagBag")

        if str(bundle_path) not in sys.path:
            sys.path.append(str(bundle_path))

        kwargs["bundle_path"] = bundle_path
        super().__init__(*args, **kwargs)


@provide_session
def sync_bag_to_db(
    dagbag: DagBag,
    bundle_name: str,
    bundle_version: str | None,
    *,
    version_data: dict[str, Any] | None = None,
    session: Session = NEW_SESSION,
) -> None:
    """Save attributes about list of DAG to the DB."""
    from airflow.dag_processing.collection import update_dag_parsing_results_in_db

    import_errors = {(bundle_name, rel_path): error for rel_path, error in dagbag.import_errors.items()}

    # Build the set of all files that were parsed and include files with import errors
    # in case they are not in file_last_changed
    files_parsed = set(import_errors)
    if dagbag.bundle_path:
        files_parsed.update(
            (bundle_name, dagbag._get_relative_fileloc(abs_filepath))
            for abs_filepath in dagbag.file_last_changed
        )

    update_dag_parsing_results_in_db(
        bundle_name,
        bundle_version,
        [LazyDeserializedDAG.from_dag(dag) for dag in dagbag.dags.values()],
        import_errors,
        None,  # file parsing duration is not well defined when parsing multiple files / multiple DAGs.
        dagbag.dag_warnings,
        session=session,
        version_data=version_data,
        files_parsed=files_parsed,
    )
