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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
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#
#   http://www.apache.org/licenses/LICENSE-2.0
#
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"""Custom logging formatter for Airflow"""

import logging
from typing import TYPE_CHECKING, Optional

from airflow.configuration import conf
from airflow.utils.helpers import parse_template_string, render_template_to_string

if TYPE_CHECKING:
    from jinja2 import Template

    from airflow.models.taskinstance import TaskInstance


class TaskHandlerWithCustomFormatter(logging.StreamHandler):
    """Custom implementation of StreamHandler, a class which writes logging records for Airflow"""

    prefix_jinja_template: Optional["Template"] = None

    def set_context(self, ti) -> None:
        """
        Accept the run-time context (i.e. the current task) and configure the formatter accordingly.

        :param ti:
        :return:
        """
        if ti.raw or self.formatter is None:
            return
        prefix = conf.get('logging', 'task_log_prefix_template')

        if prefix:
            _, self.prefix_jinja_template = parse_template_string(prefix)
            rendered_prefix = self._render_prefix(ti)
        else:
            rendered_prefix = ""
        formatter = logging.Formatter(f"{rendered_prefix}:{self.formatter._fmt}")
        self.setFormatter(formatter)
        self.setLevel(self.level)

    def _render_prefix(self, ti: "TaskInstance") -> str:
        if self.prefix_jinja_template:
            jinja_context = ti.get_template_context()
            return render_template_to_string(self.prefix_jinja_template, jinja_context)
        logging.warning("'task_log_prefix_template' is in invalid format, ignoring the variable value")
        return ""
