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from __future__ import annotations

import os
import shutil
import tempfile
from collections.abc import Callable, Container, Sequence
from functools import cached_property
from typing import TYPE_CHECKING, Any, cast

from airflow.providers.common.compat.sdk import (
    AirflowException,
    AirflowSkipException,
    context_to_airflow_vars,
)
from airflow.providers.standard.hooks.subprocess import SubprocessHook, SubprocessResult, working_directory
from airflow.providers.standard.version_compat import BaseOperator

if TYPE_CHECKING:
    from airflow.providers.common.compat.sdk import Context
    from airflow.providers.standard.version_compat import ArgNotSet


class BashOperator(BaseOperator):
    r"""
    Execute a Bash script, command or set of commands.

    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:BashOperator`

    If BaseOperator.do_xcom_push is True, the last line written to stdout
    will also be pushed to an XCom when the bash command completes

    :param bash_command: The command, set of commands or reference to a
        Bash script (must be '.sh' or '.bash') to be executed. (templated)
    :param env: If env is not None, it must be a dict that defines the
        environment variables for the new process; these are used instead
        of inheriting the current process environment, which is the default
        behavior. (templated)
    :param append_env: If False(default) uses the environment variables passed in env params
        and does not inherit the current process environment. If True, inherits the environment variables
        from current passes and then environment variable passed by the user will either update the existing
        inherited environment variables or the new variables gets appended to it
    :param output_encoding: Output encoding of Bash command
    :param skip_on_exit_code: If task exits with this exit code, leave the task
        in ``skipped`` state (default: 99). If set to ``None``, any non-zero
        exit code will be treated as a failure.
    :param cwd: Working directory to execute the command in (templated).
        If None (default), the command is run in a temporary directory.
        To use current DAG folder as the working directory,
        you might set template ``{{ task.dag.folder }}``.
        When bash_command is a '.sh' or '.bash' file, Airflow must have write
        access to the working directory. The script will be rendered (Jinja
        template) into a new temporary file in this directory.
    :param output_processor: Function to further process the output of the bash script
        (default is lambda output: output).

    Airflow will evaluate the exit code of the Bash command. In general, a non-zero exit code will result in
    task failure and zero will result in task success.
    Exit code ``99`` (or another set in ``skip_on_exit_code``)
    will throw an :class:`airflow.exceptions.AirflowSkipException`, which will leave the task in ``skipped``
    state. You can have all non-zero exit codes be treated as a failure by setting ``skip_on_exit_code=None``.

    .. list-table::
       :widths: 25 25
       :header-rows: 1

       * - Exit code
         - Behavior
       * - 0
         - success
       * - `skip_on_exit_code` (default: 99)
         - raise :class:`airflow.exceptions.AirflowSkipException`
       * - otherwise
         - raise :class:`airflow.exceptions.AirflowException`

    .. note::

        Airflow will not recognize a non-zero exit code unless the whole shell exit with a non-zero exit
        code.  This can be an issue if the non-zero exit arises from a sub-command.  The easiest way of
        addressing this is to prefix the command with ``set -e;``

        .. code-block:: python

            bash_command = "set -e; python3 script.py '{{ data_interval_end }}'"

    .. note::

        To simply execute a ``.sh`` or ``.bash`` script (without any Jinja template), add a space after the
        script name ``bash_command`` argument -- for example ``bash_command="my_script.sh "``. This
        is because Airflow tries to load this file and process it as a Jinja template when
        it ends with ``.sh`` or ``.bash``.

        If you have Jinja template in your script, do not put any blank space. And add the script's directory
        in the DAG's ``template_searchpath``. If you specify a ``cwd``, Airflow must have write access to
        this directory. The script will be rendered (Jinja template) into a new temporary file in this directory.

    .. warning::

        Care should be taken with "user" input or when using Jinja templates in the
        ``bash_command``, as this bash operator does not perform any escaping or
        sanitization of the command.

        This applies mostly to using "dag_run" conf, as that can be submitted via
        users in the Web UI. Most of the default template variables are not at
        risk.

    For example, do **not** do this:

    .. code-block:: python

        bash_task = BashOperator(
            task_id="bash_task",
            bash_command='echo "Here is the message: \'{{ dag_run.conf["message"] if dag_run else "" }}\'"',
        )

    Instead, you should pass this via the ``env`` kwarg and use double-quotes
    inside the bash_command, as below:

    .. code-block:: python

        bash_task = BashOperator(
            task_id="bash_task",
            bash_command="echo \"here is the message: '$message'\"",
            env={"message": '{{ dag_run.conf["message"] if dag_run else "" }}'},
        )

    .. versionadded:: 2.10.0
       The `output_processor` parameter.

    """

    template_fields: Sequence[str] = ("bash_command", "env", "cwd")
    template_fields_renderers = {"bash_command": "bash", "env": "json"}
    template_ext: Sequence[str] = (".sh", ".bash")
    ui_color = "#f0ede4"

    def __init__(
        self,
        *,
        bash_command: str | ArgNotSet,
        env: dict[str, str] | None = None,
        append_env: bool = False,
        output_encoding: str = "utf-8",
        skip_on_exit_code: int | Container[int] | None = 99,
        cwd: str | None = None,
        output_processor: Callable[[str], Any] = lambda result: result,
        **kwargs,
    ) -> None:
        super().__init__(**kwargs)
        self.bash_command = bash_command
        self.env = env
        self.output_encoding = output_encoding
        self.skip_on_exit_code = (
            skip_on_exit_code
            if isinstance(skip_on_exit_code, Container)
            else [skip_on_exit_code]
            if skip_on_exit_code is not None
            else []
        )
        self.cwd = cwd
        self.append_env = append_env
        self.output_processor = output_processor
        self._is_inline_cmd = None
        if isinstance(bash_command, str):
            self._is_inline_cmd = self._is_inline_command(bash_command=bash_command)

    @cached_property
    def subprocess_hook(self):
        """Returns hook for running the bash command."""
        return SubprocessHook()

    def get_env(self, context) -> dict:
        """Build the set of environment variables to be exposed for the bash command."""
        system_env = os.environ.copy()
        env = self.env
        if env is None:
            env = system_env
        else:
            if self.append_env:
                system_env.update(env)
                env = system_env

        airflow_context_vars = context_to_airflow_vars(context, in_env_var_format=True)
        self.log.debug(
            "Exporting env vars: %s",
            " ".join(f"{k}={v!r}" for k, v in airflow_context_vars.items()),
        )
        env.update(airflow_context_vars)
        return env

    def execute(self, context: Context):
        bash_path: str = shutil.which("bash") or "bash"
        if self.cwd is not None:
            if not os.path.exists(self.cwd):
                raise AirflowException(f"Can not find the cwd: {self.cwd}")
            if not os.path.isdir(self.cwd):
                raise AirflowException(f"The cwd {self.cwd} must be a directory")
        env = self.get_env(context)

        if self._is_inline_cmd:
            result = self._run_inline_command(bash_path=bash_path, env=env)
        else:
            result = self._run_rendered_script_file(bash_path=bash_path, env=env)

        if result.exit_code in self.skip_on_exit_code:
            raise AirflowSkipException(f"Bash command returned exit code {result.exit_code}. Skipping.")
        if result.exit_code != 0:
            raise AirflowException(
                f"Bash command failed. The command returned a non-zero exit code {result.exit_code}."
            )

        return self.output_processor(result.output)

    def _run_inline_command(self, bash_path: str, env: dict) -> SubprocessResult:
        """Pass the bash command as string directly in the subprocess."""
        return self.subprocess_hook.run_command(
            command=[bash_path, "-c", self.bash_command],
            env=env,
            output_encoding=self.output_encoding,
            cwd=self.cwd,
        )

    def _run_rendered_script_file(self, bash_path: str, env: dict) -> SubprocessResult:
        """
        Save the bash command into a file and execute this file.

        This allows for longer commands, and prevents "Argument list too long error".
        """
        with working_directory(cwd=self.cwd) as cwd:
            with tempfile.NamedTemporaryFile(mode="w", dir=cwd, suffix=".sh") as file:
                file.write(cast("str", self.bash_command))
                file.flush()

                bash_script = os.path.basename(file.name)
                return self.subprocess_hook.run_command(
                    command=[bash_path, bash_script],
                    env=env,
                    output_encoding=self.output_encoding,
                    cwd=cwd,
                )

    @classmethod
    def _is_inline_command(cls, bash_command: str) -> bool:
        """Return True if the bash command is an inline string. False if it's a bash script file."""
        return not bash_command.endswith(tuple(cls.template_ext))

    def on_kill(self) -> None:
        self.subprocess_hook.send_sigterm()
