#
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
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# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
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"""Save Rendered Template Fields."""

from __future__ import annotations

import os
from typing import TYPE_CHECKING, Any

import sqlalchemy as sa
from sqlalchemy import (
    ForeignKeyConstraint,
    Integer,
    PrimaryKeyConstraint,
    delete,
    select,
)
from sqlalchemy.ext.associationproxy import association_proxy
from sqlalchemy.orm import Mapped, mapped_column, relationship

from airflow.configuration import conf
from airflow.models.base import StringID, TaskInstanceDependencies
from airflow.serialization.helpers import serialize_template_field
from airflow.utils.retries import retry_db_transaction
from airflow.utils.session import NEW_SESSION, provide_session
from airflow.utils.sqlalchemy import build_upsert_stmt, get_dialect_name

if TYPE_CHECKING:
    from sqlalchemy.orm import Session
    from sqlalchemy.sql.selectable import ScalarSelect

    from airflow.models.taskinstance import TaskInstance, TaskInstanceKey
    from airflow.serialization.definitions.baseoperator import SerializedBaseOperator


def _get_nested_value(obj: Any, path: str) -> Any:
    """
    Get a nested value from an object using a dot-separated path.

    :param obj: The object to extract the value from
    :param path: A dot-separated path (e.g., "configuration.query.sql")
    :return: The value at the nested path, or None if the path doesn't exist
    """
    keys = path.split(".")
    current = obj
    for key in keys:
        if isinstance(current, dict):
            current = current.get(key)
        elif hasattr(current, key):
            current = getattr(current, key)
        else:
            return None
        if current is None:
            return None
    return current


def get_serialized_template_fields(task: SerializedBaseOperator):
    """
    Get and serialize the template fields for a task.

    Used in preparing to store them in RTIF table.

    :param task: Operator instance with rendered template fields

    :meta private:
    """
    rendered_fields = {}

    for field in task.template_fields:
        rendered_fields[field] = serialize_template_field(getattr(task, field), field)

    renderers = getattr(task, "template_fields_renderers", {})
    for renderer_path in renderers:
        if "." in renderer_path:
            base_field = renderer_path.split(".", 1)[0]

            if base_field in task.template_fields:
                base_value = getattr(task, base_field)
                nested_value = _get_nested_value(base_value, renderer_path[len(base_field) + 1 :])

                if nested_value is not None:
                    rendered_fields[renderer_path] = serialize_template_field(nested_value, renderer_path)

    return rendered_fields


class RenderedTaskInstanceFields(TaskInstanceDependencies):
    """Save Rendered Template Fields."""

    __tablename__ = "rendered_task_instance_fields"

    dag_id: Mapped[str] = mapped_column(StringID(), primary_key=True)
    task_id: Mapped[str] = mapped_column(StringID(), primary_key=True)
    run_id: Mapped[str] = mapped_column(StringID(), primary_key=True)
    map_index: Mapped[int] = mapped_column(Integer, primary_key=True, server_default="-1")
    rendered_fields: Mapped[dict] = mapped_column(sa.JSON(), nullable=False)
    k8s_pod_yaml: Mapped[dict | None] = mapped_column(sa.JSON(), nullable=True)

    __table_args__ = (
        PrimaryKeyConstraint(
            "dag_id",
            "task_id",
            "run_id",
            "map_index",
            name="rendered_task_instance_fields_pkey",
        ),
        ForeignKeyConstraint(
            [dag_id, task_id, run_id, map_index],
            [
                "task_instance.dag_id",
                "task_instance.task_id",
                "task_instance.run_id",
                "task_instance.map_index",
            ],
            name="rtif_ti_fkey",
            ondelete="CASCADE",
        ),
    )
    task_instance = relationship(
        "TaskInstance",
        lazy="joined",
        back_populates="rendered_task_instance_fields",
    )

    # We don't need a DB level FK here, as we already have that to TI (which has one to DR) but by defining
    # the relationship we can more easily find the logical date for these rows
    dag_run = relationship(
        "DagRun",
        primaryjoin="""and_(
            RenderedTaskInstanceFields.dag_id == foreign(DagRun.dag_id),
            RenderedTaskInstanceFields.run_id == foreign(DagRun.run_id),
        )""",
        viewonly=True,
    )

    logical_date = association_proxy("dag_run", "logical_date")

    def __init__(self, ti: TaskInstance, render_templates=True, rendered_fields=None):
        self.dag_id = ti.dag_id
        self.task_id = ti.task_id
        self.run_id = ti.run_id
        self.map_index = ti.map_index
        self.ti = ti
        if render_templates:
            raise ValueError("render_templates=True is no longer supported")

        if TYPE_CHECKING:
            assert isinstance(ti.task, SerializedBaseOperator)

        self.task = ti.task
        if os.environ.get("AIRFLOW_IS_K8S_EXECUTOR_POD", None):
            # we can safely import it here from provider. In Airflow 2.7.0+ you need to have new version
            # of kubernetes provider installed to reach this place
            from airflow.providers.cncf.kubernetes.template_rendering import render_k8s_pod_yaml

            self.k8s_pod_yaml = render_k8s_pod_yaml(ti)
        self.rendered_fields = rendered_fields or get_serialized_template_fields(task=ti.task)

        self._redact()

    def __repr__(self):
        prefix = f"<{self.__class__.__name__}: {self.dag_id}.{self.task_id} {self.run_id}"
        if self.map_index != -1:
            prefix += f" map_index={self.map_index}"
        return prefix + ">"

    def _redact(self):
        from airflow._shared.secrets_masker import redact

        if self.k8s_pod_yaml:
            self.k8s_pod_yaml = redact(self.k8s_pod_yaml)

        for field, rendered in self.rendered_fields.items():
            self.rendered_fields[field] = redact(rendered, field)

    @classmethod
    @provide_session
    def get_templated_fields(
        cls,
        ti: TaskInstance | TaskInstanceKey,
        *,
        session: Session = NEW_SESSION,
    ) -> dict | None:
        """
        Get templated field for a TaskInstance from the RenderedTaskInstanceFields table.

        :param ti: Task Instance
        :param session: SqlAlchemy Session
        :return: Rendered Templated TI field
        """
        result = session.scalar(
            select(cls).where(
                cls.dag_id == ti.dag_id,
                cls.task_id == ti.task_id,
                cls.run_id == ti.run_id,
                cls.map_index == ti.map_index,
            )
        )

        if result:
            rendered_fields = result.rendered_fields
            return rendered_fields
        return None

    @classmethod
    @provide_session
    def get_k8s_pod_yaml(cls, ti: TaskInstance, *, session: Session = NEW_SESSION) -> dict | None:
        """
        Get rendered Kubernetes Pod Yaml for a TaskInstance from the RenderedTaskInstanceFields table.

        :param ti: Task Instance
        :param session: SqlAlchemy Session
        :return: Kubernetes Pod Yaml
        """
        result = session.scalar(
            select(cls).where(
                cls.dag_id == ti.dag_id,
                cls.task_id == ti.task_id,
                cls.run_id == ti.run_id,
                cls.map_index == ti.map_index,
            )
        )
        return result.k8s_pod_yaml if result else None

    @provide_session
    @retry_db_transaction
    def write(self, *, session: Session = NEW_SESSION) -> None:
        """
        Write instance to database.

        Uses a database-level upsert (INSERT ... ON CONFLICT DO UPDATE) to
        atomically insert or update the record, avoiding race conditions that
        can occur with session.merge() when concurrent requests (e.g. from
        client-side timeout retries) target the same primary key.

        :param session: SqlAlchemy Session
        """
        values = {
            "dag_id": self.dag_id,
            "task_id": self.task_id,
            "run_id": self.run_id,
            "map_index": self.map_index,
            "rendered_fields": self.rendered_fields,
            "k8s_pod_yaml": self.k8s_pod_yaml,
        }
        update_on_conflict = {
            "rendered_fields": self.rendered_fields,
            "k8s_pod_yaml": self.k8s_pod_yaml,
        }

        stmt = build_upsert_stmt(
            get_dialect_name(session),
            RenderedTaskInstanceFields,
            ["dag_id", "task_id", "run_id", "map_index"],
            values,
            update_on_conflict,
        )
        session.execute(stmt)

    @classmethod
    @provide_session
    def delete_old_records(
        cls,
        task_id: str,
        dag_id: str,
        num_to_keep: int = conf.getint("core", "num_dag_runs_to_retain_rendered_fields", fallback=0),
        *,
        session: Session = NEW_SESSION,
    ) -> None:
        """
        Keep RTIF records from the most recent dag runs, deleting records from older runs.

        Records are retained for the N most recent dag runs (ordered by run_after timestamp).
        All mapped task instance records for a given run are kept or deleted together,
        ensuring no partial data remains.

        :param task_id: Task ID
        :param dag_id: Dag ID
        :param num_to_keep: Number of recent dag runs to retain RTIF records for
        :param session: SqlAlchemy Session
        """
        if num_to_keep <= 0:
            return

        from airflow.models.dagrun import DagRun

        # Find run_ids from the N most recent dag runs (no RTIF table scan needed).
        # Use run_after instead of logical_date since logical_date can be NULL for manual runs.
        run_ids_to_keep_query = (
            select(DagRun.run_id)
            .where(DagRun.dag_id == dag_id)
            .order_by(DagRun.run_after.desc())
            .limit(num_to_keep)
        )

        if get_dialect_name(session) == "mysql":
            # MySQL doesn't support LIMIT in IN/NOT IN subqueries, so fetch IDs first
            run_ids_to_keep: list[str] | ScalarSelect[str] = list(
                session.scalars(run_ids_to_keep_query).all()
            )
        else:
            run_ids_to_keep = run_ids_to_keep_query.scalar_subquery()

        cls._do_delete_old_records(
            dag_id=dag_id,
            task_id=task_id,
            run_ids_to_keep=run_ids_to_keep,
            session=session,
        )
        session.flush()

    @classmethod
    @retry_db_transaction
    def _do_delete_old_records(
        cls,
        *,
        task_id: str,
        dag_id: str,
        run_ids_to_keep: list[str] | ScalarSelect[str],
        session: Session,
    ) -> None:
        # This query might deadlock occasionally and it should be retried if fails (see decorator)
        stmt = (
            delete(cls)
            .where(
                cls.dag_id == dag_id,
                cls.task_id == task_id,
                cls.run_id.not_in(run_ids_to_keep),
            )
            .execution_options(synchronize_session=False)
        )

        session.execute(stmt)
