import asyncio
import threading
import warnings
from collections.abc import AsyncIterator, Iterator, Sequence
from contextlib import asynccontextmanager, contextmanager
from typing import Any

from langchain_core.runnables import RunnableConfig
from langgraph.checkpoint.base import (
    WRITES_IDX_MAP,
    ChannelVersions,
    Checkpoint,
    CheckpointMetadata,
    CheckpointTuple,
    get_serializable_checkpoint_metadata,
)
from langgraph.checkpoint.serde.base import SerializerProtocol
from langgraph.checkpoint.serde.types import TASKS
from psycopg import (
    AsyncConnection,
    AsyncCursor,
    AsyncPipeline,
    Capabilities,
    Connection,
    Cursor,
    Pipeline,
)
from psycopg.rows import DictRow, dict_row
from psycopg.types.json import Jsonb
from psycopg_pool import AsyncConnectionPool, ConnectionPool

from langgraph.checkpoint.postgres import _ainternal, _internal
from langgraph.checkpoint.postgres.base import BasePostgresSaver

"""
To add a new migration, add a new string to the MIGRATIONS list.
The position of the migration in the list is the version number.
"""
MIGRATIONS = [
    """CREATE TABLE IF NOT EXISTS checkpoint_migrations (
    v INTEGER PRIMARY KEY
);""",
    """CREATE TABLE IF NOT EXISTS checkpoints (
    thread_id TEXT NOT NULL,
    checkpoint_ns TEXT NOT NULL DEFAULT '',
    type TEXT,
    checkpoint JSONB NOT NULL,
    metadata JSONB NOT NULL DEFAULT '{}',
    PRIMARY KEY (thread_id, checkpoint_ns)
);""",
    """CREATE TABLE IF NOT EXISTS checkpoint_blobs (
    thread_id TEXT NOT NULL,
    checkpoint_ns TEXT NOT NULL DEFAULT '',
    channel TEXT NOT NULL,
    type TEXT NOT NULL,
    blob BYTEA,
    PRIMARY KEY (thread_id, checkpoint_ns, channel)
);""",
    """CREATE TABLE IF NOT EXISTS checkpoint_writes (
    thread_id TEXT NOT NULL,
    checkpoint_ns TEXT NOT NULL DEFAULT '',
    checkpoint_id TEXT NOT NULL,
    task_id TEXT NOT NULL,
    idx INTEGER NOT NULL,
    channel TEXT NOT NULL,
    type TEXT,
    blob BYTEA NOT NULL,
    PRIMARY KEY (thread_id, checkpoint_ns, checkpoint_id, task_id, idx)
);""",
    """
    CREATE INDEX CONCURRENTLY IF NOT EXISTS checkpoints_thread_id_idx ON checkpoints(thread_id);
    """,
    """
    CREATE INDEX CONCURRENTLY IF NOT EXISTS checkpoint_blobs_thread_id_idx ON checkpoint_blobs(thread_id);
    """,
    """
    CREATE INDEX CONCURRENTLY IF NOT EXISTS checkpoint_writes_thread_id_idx ON checkpoint_writes(thread_id);
    """,
    """
    ALTER TABLE checkpoint_writes ADD COLUMN IF NOT EXISTS task_path TEXT NOT NULL DEFAULT '';
    """,
]

SELECT_SQL = f"""
select
    thread_id,
    checkpoint,
    checkpoint_ns,
    metadata,
    (
        select array_agg(array[bl.channel::bytea, bl.type::bytea, bl.blob])
        from jsonb_each_text(checkpoint -> 'channel_versions')
        inner join checkpoint_blobs bl
            on bl.thread_id = checkpoints.thread_id
            and bl.checkpoint_ns = checkpoints.checkpoint_ns
            and bl.channel = jsonb_each_text.key
    ) as channel_values,
    (
        select
        array_agg(array[cw.task_id::text::bytea, cw.channel::bytea, cw.type::bytea, cw.blob] order by cw.task_id, cw.idx)
        from checkpoint_writes cw
        where cw.thread_id = checkpoints.thread_id
            and cw.checkpoint_ns = checkpoints.checkpoint_ns
            and cw.checkpoint_id = (checkpoint->>'id')
    ) as pending_writes,
    (
        select array_agg(array[cw.type::bytea, cw.blob] order by cw.task_path, cw.task_id, cw.idx)
        from checkpoint_writes cw
        where cw.thread_id = checkpoints.thread_id
            and cw.checkpoint_ns = checkpoints.checkpoint_ns
            and cw.channel = '{TASKS}'
    ) as pending_sends
from checkpoints """

UPSERT_CHECKPOINT_BLOBS_SQL = """
    INSERT INTO checkpoint_blobs (thread_id, checkpoint_ns, channel, type, blob)
    VALUES (%s, %s, %s, %s, %s)
    ON CONFLICT (thread_id, checkpoint_ns, channel) DO UPDATE SET
        type = EXCLUDED.type,
        blob = EXCLUDED.blob;
"""

UPSERT_CHECKPOINTS_SQL = """
    INSERT INTO checkpoints (thread_id, checkpoint_ns, checkpoint, metadata)
    VALUES (%s, %s, %s, %s)
    ON CONFLICT (thread_id, checkpoint_ns)
    DO UPDATE SET
        checkpoint = EXCLUDED.checkpoint,
        metadata = EXCLUDED.metadata;
"""

UPSERT_CHECKPOINT_WRITES_SQL = """
    INSERT INTO checkpoint_writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, blob)
    VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)
    ON CONFLICT (thread_id, checkpoint_ns, checkpoint_id, task_id, idx) DO UPDATE SET
        channel = EXCLUDED.channel,
        type = EXCLUDED.type,
        blob = EXCLUDED.blob;
"""

INSERT_CHECKPOINT_WRITES_SQL = """
    INSERT INTO checkpoint_writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, blob)
    VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)
    ON CONFLICT (thread_id, checkpoint_ns, checkpoint_id, task_id, idx) DO NOTHING
"""


def _dump_blobs(
    serde: SerializerProtocol,
    thread_id: str,
    checkpoint_ns: str,
    values: dict[str, Any],
    versions: ChannelVersions,
) -> list[tuple[str, str, str, str, bytes | None]]:
    if not versions:
        return []

    return [
        (
            thread_id,
            checkpoint_ns,
            k,
            *(serde.dumps_typed(values[k]) if k in values else ("empty", None)),
        )
        for k in versions
    ]


class ShallowPostgresSaver(BasePostgresSaver):
    """A checkpoint saver that uses Postgres to store checkpoints.

    This checkpointer ONLY stores the most recent checkpoint and does NOT retain any history.
    It is meant to be a light-weight drop-in replacement for the PostgresSaver that
    supports most of the LangGraph persistence functionality with the exception of time travel.
    """

    SELECT_SQL = SELECT_SQL
    MIGRATIONS = MIGRATIONS
    UPSERT_CHECKPOINT_BLOBS_SQL = UPSERT_CHECKPOINT_BLOBS_SQL
    UPSERT_CHECKPOINTS_SQL = UPSERT_CHECKPOINTS_SQL
    UPSERT_CHECKPOINT_WRITES_SQL = UPSERT_CHECKPOINT_WRITES_SQL
    INSERT_CHECKPOINT_WRITES_SQL = INSERT_CHECKPOINT_WRITES_SQL

    lock: threading.Lock

    def __init__(
        self,
        conn: _internal.Conn,
        pipe: Pipeline | None = None,
        serde: SerializerProtocol | None = None,
    ) -> None:
        warnings.warn(
            "ShallowPostgresSaver is deprecated as of version 2.0.20 and will be removed in 3.0.0. "
            "Use PostgresSaver instead, and invoke the graph with `graph.invoke(..., durability='exit')`.",
            DeprecationWarning,
            stacklevel=2,
        )
        super().__init__(serde=serde)
        if isinstance(conn, ConnectionPool) and pipe is not None:
            raise ValueError(
                "Pipeline should be used only with a single Connection, not ConnectionPool."
            )

        self.conn = conn
        self.pipe = pipe
        self.lock = threading.Lock()
        self.supports_pipeline = Capabilities().has_pipeline()

    @classmethod
    @contextmanager
    def from_conn_string(
        cls, conn_string: str, *, pipeline: bool = False
    ) -> Iterator["ShallowPostgresSaver"]:
        """Create a new ShallowPostgresSaver instance from a connection string.

        Args:
            conn_string: The Postgres connection info string.
            pipeline: whether to use Pipeline

        Returns:
            ShallowPostgresSaver: A new ShallowPostgresSaver instance.
        """
        with Connection.connect(
            conn_string, autocommit=True, prepare_threshold=0, row_factory=dict_row
        ) as conn:
            if pipeline:
                with conn.pipeline() as pipe:
                    yield cls(conn, pipe)
            else:
                yield cls(conn)

    def setup(self) -> None:
        """Set up the checkpoint database asynchronously.

        This method creates the necessary tables in the Postgres database if they don't
        already exist and runs database migrations. It MUST be called directly by the user
        the first time checkpointer is used.
        """
        with self._cursor() as cur:
            cur.execute(self.MIGRATIONS[0])
            results = cur.execute(
                "SELECT v FROM checkpoint_migrations ORDER BY v DESC LIMIT 1"
            )
            row = results.fetchone()
            if row is None:
                version = -1
            else:
                version = row["v"]
            for v, migration in zip(
                range(version + 1, len(self.MIGRATIONS)),
                self.MIGRATIONS[version + 1 :],
                strict=False,
            ):
                cur.execute(migration)
                cur.execute("INSERT INTO checkpoint_migrations (v) VALUES (%s)", (v,))
        if self.pipe:
            self.pipe.sync()

    def list(
        self,
        config: RunnableConfig | None,
        *,
        filter: dict[str, Any] | None = None,
        before: RunnableConfig | None = None,
        limit: int | None = None,
    ) -> Iterator[CheckpointTuple]:
        """List checkpoints from the database.

        This method retrieves a list of checkpoint tuples from the Postgres database based
        on the provided config. For ShallowPostgresSaver, this method returns a list with
        ONLY the most recent checkpoint.
        """
        where, args = self._search_where(config, filter, before)
        query = self.SELECT_SQL + where
        params = list(args)
        if limit is not None:
            query += " LIMIT %s"
            params.append(int(limit))
        with self._cursor() as cur:
            cur.execute(query, params, binary=True)
            for value in cur:
                checkpoint: Checkpoint = {
                    **value["checkpoint"],
                    "channel_values": self._load_blobs(value["channel_values"]),
                    "pending_sends": [
                        self.serde.loads_typed((t.decode(), v))
                        for t, v in value["pending_sends"]
                    ]
                    if value["pending_sends"]
                    else [],
                }
                yield CheckpointTuple(
                    config={
                        "configurable": {
                            "thread_id": value["thread_id"],
                            "checkpoint_ns": value["checkpoint_ns"],
                            "checkpoint_id": checkpoint["id"],
                        }
                    },
                    checkpoint=checkpoint,
                    metadata=value["metadata"],
                    pending_writes=self._load_writes(value["pending_writes"]),
                )

    def get_tuple(self, config: RunnableConfig) -> CheckpointTuple | None:
        """Get a checkpoint tuple from the database.

        This method retrieves a checkpoint tuple from the Postgres database based on the
        provided config (matching the thread ID in the config).

        Args:
            config: The config to use for retrieving the checkpoint.

        Returns:
            The retrieved checkpoint tuple, or None if no matching checkpoint was found.

        Examples:

            Basic:
            >>> config = {"configurable": {"thread_id": "1"}}
            >>> checkpoint_tuple = memory.get_tuple(config)
            >>> print(checkpoint_tuple)
            CheckpointTuple(...)

            With timestamp:

            >>> config = {
            ...    "configurable": {
            ...        "thread_id": "1",
            ...        "checkpoint_ns": "",
            ...        "checkpoint_id": "1ef4f797-8335-6428-8001-8a1503f9b875",
            ...    }
            ... }
            >>> checkpoint_tuple = memory.get_tuple(config)
            >>> print(checkpoint_tuple)
            CheckpointTuple(...)
        """
        thread_id = config["configurable"]["thread_id"]
        checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
        args = (thread_id, checkpoint_ns)
        where = "WHERE thread_id = %s AND checkpoint_ns = %s"

        with self._cursor() as cur:
            cur.execute(
                self.SELECT_SQL + where,
                args,
                binary=True,
            )

            for value in cur:
                checkpoint: Checkpoint = {
                    **value["checkpoint"],
                    "channel_values": self._load_blobs(value["channel_values"]),
                    "pending_sends": [
                        self.serde.loads_typed((t.decode(), v))
                        for t, v in value["pending_sends"]
                    ]
                    if value["pending_sends"]
                    else [],
                }
                return CheckpointTuple(
                    config={
                        "configurable": {
                            "thread_id": thread_id,
                            "checkpoint_ns": checkpoint_ns,
                            "checkpoint_id": checkpoint["id"],
                        }
                    },
                    checkpoint=checkpoint,
                    metadata=value["metadata"],
                    pending_writes=self._load_writes(value["pending_writes"]),
                )

    def put(
        self,
        config: RunnableConfig,
        checkpoint: Checkpoint,
        metadata: CheckpointMetadata,
        new_versions: ChannelVersions,
    ) -> RunnableConfig:
        """Save a checkpoint to the database.

        This method saves a checkpoint to the Postgres database. The checkpoint is associated
        with the provided config. For ShallowPostgresSaver, this method saves ONLY the most recent
        checkpoint and overwrites a previous checkpoint, if it exists.

        Args:
            config: The config to associate with the checkpoint.
            checkpoint: The checkpoint to save.
            metadata: Additional metadata to save with the checkpoint.
            new_versions: New channel versions as of this write.

        Returns:
            RunnableConfig: Updated configuration after storing the checkpoint.

        Examples:

            >>> from langgraph.checkpoint.postgres import ShallowPostgresSaver
            >>> DB_URI = "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable"
            >>> with ShallowPostgresSaver.from_conn_string(DB_URI) as memory:
            >>>     config = {"configurable": {"thread_id": "1", "checkpoint_ns": ""}}
            >>>     checkpoint = {"ts": "2024-05-04T06:32:42.235444+00:00", "id": "1ef4f797-8335-6428-8001-8a1503f9b875", "channel_values": {"key": "value"}}
            >>>     saved_config = memory.put(config, checkpoint, {"source": "input", "step": 1, "writes": {"key": "value"}}, {})
            >>> print(saved_config)
            {'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1ef4f797-8335-6428-8001-8a1503f9b875'}}
        """
        configurable = config["configurable"].copy()
        thread_id = configurable.pop("thread_id")
        checkpoint_ns = configurable.pop("checkpoint_ns")

        copy = checkpoint.copy()
        next_config = {
            "configurable": {
                "thread_id": thread_id,
                "checkpoint_ns": checkpoint_ns,
                "checkpoint_id": checkpoint["id"],
            }
        }

        with self._cursor(pipeline=True) as cur:
            cur.execute(
                """DELETE FROM checkpoint_writes
                WHERE thread_id = %s AND checkpoint_ns = %s AND checkpoint_id NOT IN (%s, %s)""",
                (
                    thread_id,
                    checkpoint_ns,
                    checkpoint["id"],
                    configurable.get("checkpoint_id", ""),
                ),
            )
            cur.executemany(
                self.UPSERT_CHECKPOINT_BLOBS_SQL,
                _dump_blobs(
                    self.serde,
                    thread_id,
                    checkpoint_ns,
                    copy.pop("channel_values"),  # type: ignore[misc]
                    new_versions,
                ),
            )
            cur.execute(
                self.UPSERT_CHECKPOINTS_SQL,
                (
                    thread_id,
                    checkpoint_ns,
                    Jsonb(copy),
                    Jsonb(get_serializable_checkpoint_metadata(config, metadata)),
                ),
            )
        return next_config

    def put_writes(
        self,
        config: RunnableConfig,
        writes: Sequence[tuple[str, Any]],
        task_id: str,
        task_path: str = "",
    ) -> None:
        """Store intermediate writes linked to a checkpoint.

        This method saves intermediate writes associated with a checkpoint to the Postgres database.

        Args:
            config: Configuration of the related checkpoint.
            writes: List of writes to store.
            task_id: Identifier for the task creating the writes.
        """
        query = (
            self.UPSERT_CHECKPOINT_WRITES_SQL
            if all(w[0] in WRITES_IDX_MAP for w in writes)
            else self.INSERT_CHECKPOINT_WRITES_SQL
        )
        with self._cursor(pipeline=True) as cur:
            cur.executemany(
                query,
                self._dump_writes(
                    config["configurable"]["thread_id"],
                    config["configurable"]["checkpoint_ns"],
                    config["configurable"]["checkpoint_id"],
                    task_id,
                    task_path,
                    writes,
                ),
            )

    @contextmanager
    def _cursor(self, *, pipeline: bool = False) -> Iterator[Cursor[DictRow]]:
        """Create a database cursor as a context manager.

        Args:
            pipeline: whether to use pipeline for the DB operations inside the context manager.
                Will be applied regardless of whether the ShallowPostgresSaver instance was initialized with a pipeline.
                If pipeline mode is not supported, will fall back to using transaction context manager.
        """
        with _internal.get_connection(self.conn) as conn:
            if self.pipe:
                # a connection in pipeline mode can be used concurrently
                # in multiple threads/coroutines, but only one cursor can be
                # used at a time
                try:
                    with conn.cursor(binary=True, row_factory=dict_row) as cur:
                        yield cur
                finally:
                    if pipeline:
                        self.pipe.sync()
            elif pipeline:
                # a connection not in pipeline mode can only be used by one
                # thread/coroutine at a time, so we acquire a lock
                if self.supports_pipeline:
                    with (
                        self.lock,
                        conn.pipeline(),
                        conn.cursor(binary=True, row_factory=dict_row) as cur,
                    ):
                        yield cur
                else:
                    # Use connection's transaction context manager when pipeline mode not supported
                    with (
                        self.lock,
                        conn.transaction(),
                        conn.cursor(binary=True, row_factory=dict_row) as cur,
                    ):
                        yield cur
            else:
                with self.lock, conn.cursor(binary=True, row_factory=dict_row) as cur:
                    yield cur


class AsyncShallowPostgresSaver(BasePostgresSaver):
    """A checkpoint saver that uses Postgres to store checkpoints asynchronously.

    This checkpointer ONLY stores the most recent checkpoint and does NOT retain any history.
    It is meant to be a light-weight drop-in replacement for the AsyncPostgresSaver that
    supports most of the LangGraph persistence functionality with the exception of time travel.
    """

    SELECT_SQL = SELECT_SQL
    MIGRATIONS = MIGRATIONS
    UPSERT_CHECKPOINT_BLOBS_SQL = UPSERT_CHECKPOINT_BLOBS_SQL
    UPSERT_CHECKPOINTS_SQL = UPSERT_CHECKPOINTS_SQL
    UPSERT_CHECKPOINT_WRITES_SQL = UPSERT_CHECKPOINT_WRITES_SQL
    INSERT_CHECKPOINT_WRITES_SQL = INSERT_CHECKPOINT_WRITES_SQL
    lock: asyncio.Lock

    def __init__(
        self,
        conn: _ainternal.Conn,
        pipe: AsyncPipeline | None = None,
        serde: SerializerProtocol | None = None,
    ) -> None:
        warnings.warn(
            "AsyncShallowPostgresSaver is deprecated as of version 2.0.20 and will be removed in 3.0.0. "
            "Use AsyncPostgresSaver instead, and invoke the graph with `await graph.ainvoke(..., durability='exit')`.",
            DeprecationWarning,
            stacklevel=2,
        )
        super().__init__(serde=serde)
        if isinstance(conn, AsyncConnectionPool) and pipe is not None:
            raise ValueError(
                "Pipeline should be used only with a single AsyncConnection, not AsyncConnectionPool."
            )

        self.conn = conn
        self.pipe = pipe
        self.lock = asyncio.Lock()
        self.loop = asyncio.get_running_loop()
        self.supports_pipeline = Capabilities().has_pipeline()

    @classmethod
    @asynccontextmanager
    async def from_conn_string(
        cls,
        conn_string: str,
        *,
        pipeline: bool = False,
        serde: SerializerProtocol | None = None,
    ) -> AsyncIterator["AsyncShallowPostgresSaver"]:
        """Create a new AsyncShallowPostgresSaver instance from a connection string.

        Args:
            conn_string: The Postgres connection info string.
            pipeline: whether to use AsyncPipeline

        Returns:
            AsyncShallowPostgresSaver: A new AsyncShallowPostgresSaver instance.
        """
        async with await AsyncConnection.connect(
            conn_string, autocommit=True, prepare_threshold=0, row_factory=dict_row
        ) as conn:
            if pipeline:
                async with conn.pipeline() as pipe:
                    yield cls(conn=conn, pipe=pipe, serde=serde)
            else:
                yield cls(conn=conn, serde=serde)

    async def setup(self) -> None:
        """Set up the checkpoint database asynchronously.

        This method creates the necessary tables in the Postgres database if they don't
        already exist and runs database migrations. It MUST be called directly by the user
        the first time checkpointer is used.
        """
        async with self._cursor() as cur:
            await cur.execute(self.MIGRATIONS[0])
            results = await cur.execute(
                "SELECT v FROM checkpoint_migrations ORDER BY v DESC LIMIT 1"
            )
            row = await results.fetchone()
            if row is None:
                version = -1
            else:
                version = row["v"]
            for v, migration in zip(
                range(version + 1, len(self.MIGRATIONS)),
                self.MIGRATIONS[version + 1 :],
                strict=False,
            ):
                await cur.execute(migration)
                await cur.execute(
                    "INSERT INTO checkpoint_migrations (v) VALUES (%s)", (v,)
                )
        if self.pipe:
            await self.pipe.sync()

    async def alist(
        self,
        config: RunnableConfig | None,
        *,
        filter: dict[str, Any] | None = None,
        before: RunnableConfig | None = None,
        limit: int | None = None,
    ) -> AsyncIterator[CheckpointTuple]:
        """List checkpoints from the database asynchronously.

        This method retrieves a list of checkpoint tuples from the Postgres database based
        on the provided config. For ShallowPostgresSaver, this method returns a list with
        ONLY the most recent checkpoint.
        """
        where, args = self._search_where(config, filter, before)
        query = self.SELECT_SQL + where
        params = list(args)
        if limit is not None:
            query += " LIMIT %s"
            params.append(int(limit))
        async with self._cursor() as cur:
            await cur.execute(query, params, binary=True)
            async for value in cur:
                checkpoint: Checkpoint = {
                    **value["checkpoint"],
                    "channel_values": self._load_blobs(value["channel_values"]),
                    "pending_sends": [
                        self.serde.loads_typed((t.decode(), v))
                        for t, v in value["pending_sends"]
                    ]
                    if value["pending_sends"]
                    else [],
                }
                yield CheckpointTuple(
                    config={
                        "configurable": {
                            "thread_id": value["thread_id"],
                            "checkpoint_ns": value["checkpoint_ns"],
                            "checkpoint_id": checkpoint["id"],
                        }
                    },
                    checkpoint=checkpoint,
                    metadata=value["metadata"],
                    pending_writes=await asyncio.to_thread(
                        self._load_writes, value["pending_writes"]
                    ),
                )

    async def aget_tuple(self, config: RunnableConfig) -> CheckpointTuple | None:
        """Get a checkpoint tuple from the database asynchronously.

        This method retrieves a checkpoint tuple from the Postgres database based on the
        provided config (matching the thread ID in the config).

        Args:
            config: The config to use for retrieving the checkpoint.

        Returns:
            The retrieved checkpoint tuple, or None if no matching checkpoint was found.
        """
        thread_id = config["configurable"]["thread_id"]
        checkpoint_ns = config["configurable"].get("checkpoint_ns", "")
        args = (thread_id, checkpoint_ns)
        where = "WHERE thread_id = %s AND checkpoint_ns = %s"

        async with self._cursor() as cur:
            await cur.execute(
                self.SELECT_SQL + where,
                args,
                binary=True,
            )

            async for value in cur:
                checkpoint: Checkpoint = {
                    **value["checkpoint"],
                    "channel_values": self._load_blobs(value["channel_values"]),
                    "pending_sends": [
                        self.serde.loads_typed((t.decode(), v))
                        for t, v in value["pending_sends"]
                    ]
                    if value["pending_sends"]
                    else [],
                }
                return CheckpointTuple(
                    config={
                        "configurable": {
                            "thread_id": thread_id,
                            "checkpoint_ns": checkpoint_ns,
                            "checkpoint_id": checkpoint["id"],
                        }
                    },
                    checkpoint=checkpoint,
                    metadata=value["metadata"],
                    pending_writes=await asyncio.to_thread(
                        self._load_writes, value["pending_writes"]
                    ),
                )

    async def aput(
        self,
        config: RunnableConfig,
        checkpoint: Checkpoint,
        metadata: CheckpointMetadata,
        new_versions: ChannelVersions,
    ) -> RunnableConfig:
        """Save a checkpoint to the database asynchronously.

        This method saves a checkpoint to the Postgres database. The checkpoint is associated
        with the provided config. For AsyncShallowPostgresSaver, this method saves ONLY the most recent
        checkpoint and overwrites a previous checkpoint, if it exists.

        Args:
            config: The config to associate with the checkpoint.
            checkpoint: The checkpoint to save.
            metadata: Additional metadata to save with the checkpoint.
            new_versions: New channel versions as of this write.

        Returns:
            RunnableConfig: Updated configuration after storing the checkpoint.
        """
        configurable = config["configurable"].copy()
        thread_id = configurable.pop("thread_id")
        checkpoint_ns = configurable.pop("checkpoint_ns")

        copy = checkpoint.copy()
        next_config = {
            "configurable": {
                "thread_id": thread_id,
                "checkpoint_ns": checkpoint_ns,
                "checkpoint_id": checkpoint["id"],
            }
        }

        async with self._cursor(pipeline=True) as cur:
            await cur.execute(
                """DELETE FROM checkpoint_writes
                WHERE thread_id = %s AND checkpoint_ns = %s AND checkpoint_id NOT IN (%s, %s)""",
                (
                    thread_id,
                    checkpoint_ns,
                    checkpoint["id"],
                    configurable.get("checkpoint_id", ""),
                ),
            )
            await cur.executemany(
                self.UPSERT_CHECKPOINT_BLOBS_SQL,
                _dump_blobs(
                    self.serde,
                    thread_id,
                    checkpoint_ns,
                    copy.pop("channel_values"),  # type: ignore[misc]
                    new_versions,
                ),
            )
            await cur.execute(
                self.UPSERT_CHECKPOINTS_SQL,
                (
                    thread_id,
                    checkpoint_ns,
                    Jsonb(copy),
                    Jsonb(get_serializable_checkpoint_metadata(config, metadata)),
                ),
            )
        return next_config

    async def aput_writes(
        self,
        config: RunnableConfig,
        writes: Sequence[tuple[str, Any]],
        task_id: str,
        task_path: str = "",
    ) -> None:
        """Store intermediate writes linked to a checkpoint asynchronously.

        This method saves intermediate writes associated with a checkpoint to the database.

        Args:
            config: Configuration of the related checkpoint.
            writes: List of writes to store, each as (channel, value) pair.
            task_id: Identifier for the task creating the writes.
        """
        query = (
            self.UPSERT_CHECKPOINT_WRITES_SQL
            if all(w[0] in WRITES_IDX_MAP for w in writes)
            else self.INSERT_CHECKPOINT_WRITES_SQL
        )
        params = await asyncio.to_thread(
            self._dump_writes,
            config["configurable"]["thread_id"],
            config["configurable"]["checkpoint_ns"],
            config["configurable"]["checkpoint_id"],
            task_id,
            task_path,
            writes,
        )
        async with self._cursor(pipeline=True) as cur:
            await cur.executemany(query, params)

    @asynccontextmanager
    async def _cursor(
        self, *, pipeline: bool = False
    ) -> AsyncIterator[AsyncCursor[DictRow]]:
        """Create a database cursor as a context manager.

        Args:
            pipeline: whether to use pipeline for the DB operations inside the context manager.
                Will be applied regardless of whether the AsyncShallowPostgresSaver instance was initialized with a pipeline.
                If pipeline mode is not supported, will fall back to using transaction context manager.
        """
        async with _ainternal.get_connection(self.conn) as conn:
            if self.pipe:
                # a connection in pipeline mode can be used concurrently
                # in multiple threads/coroutines, but only one cursor can be
                # used at a time
                try:
                    async with conn.cursor(binary=True, row_factory=dict_row) as cur:
                        yield cur
                finally:
                    if pipeline:
                        await self.pipe.sync()
            elif pipeline:
                # a connection not in pipeline mode can only be used by one
                # thread/coroutine at a time, so we acquire a lock
                if self.supports_pipeline:
                    async with (
                        self.lock,
                        conn.pipeline(),
                        conn.cursor(binary=True, row_factory=dict_row) as cur,
                    ):
                        yield cur
                else:
                    # Use connection's transaction context manager when pipeline mode not supported
                    async with (
                        self.lock,
                        conn.transaction(),
                        conn.cursor(binary=True, row_factory=dict_row) as cur,
                    ):
                        yield cur
            else:
                async with (
                    self.lock,
                    conn.cursor(binary=True, row_factory=dict_row) as cur,
                ):
                    yield cur

    def list(
        self,
        config: RunnableConfig | None,
        *,
        filter: dict[str, Any] | None = None,
        before: RunnableConfig | None = None,
        limit: int | None = None,
    ) -> Iterator[CheckpointTuple]:
        """List checkpoints from the database.

        This method retrieves a list of checkpoint tuples from the Postgres database based
        on the provided config. For ShallowPostgresSaver, this method returns a list with
        ONLY the most recent checkpoint.
        """
        aiter_ = self.alist(config, filter=filter, before=before, limit=limit)
        while True:
            try:
                yield asyncio.run_coroutine_threadsafe(
                    anext(aiter_),  # type: ignore[arg-type]
                    self.loop,
                ).result()
            except StopAsyncIteration:
                break

    def get_tuple(self, config: RunnableConfig) -> CheckpointTuple | None:
        """Get a checkpoint tuple from the database.

        This method retrieves a checkpoint tuple from the Postgres database based on the
        provided config (matching the thread ID in the config).

        Args:
            config: The config to use for retrieving the checkpoint.

        Returns:
            The retrieved checkpoint tuple, or None if no matching checkpoint was found.
        """
        try:
            # check if we are in the main thread, only bg threads can block
            # we don't check in other methods to avoid the overhead
            if asyncio.get_running_loop() is self.loop:
                raise asyncio.InvalidStateError(
                    "Synchronous calls to AsyncShallowPostgresSaver are only allowed from a "
                    "different thread. From the main thread, use the async interface."
                    "For example, use `await checkpointer.aget_tuple(...)` or `await "
                    "graph.ainvoke(...)`."
                )
        except RuntimeError:
            pass
        return asyncio.run_coroutine_threadsafe(
            self.aget_tuple(config), self.loop
        ).result()

    def put(
        self,
        config: RunnableConfig,
        checkpoint: Checkpoint,
        metadata: CheckpointMetadata,
        new_versions: ChannelVersions,
    ) -> RunnableConfig:
        """Save a checkpoint to the database.

        This method saves a checkpoint to the Postgres database. The checkpoint is associated
        with the provided config. For AsyncShallowPostgresSaver, this method saves ONLY the most recent
        checkpoint and overwrites a previous checkpoint, if it exists.

        Args:
            config: The config to associate with the checkpoint.
            checkpoint: The checkpoint to save.
            metadata: Additional metadata to save with the checkpoint.
            new_versions: New channel versions as of this write.

        Returns:
            RunnableConfig: Updated configuration after storing the checkpoint.
        """
        return asyncio.run_coroutine_threadsafe(
            self.aput(config, checkpoint, metadata, new_versions), self.loop
        ).result()

    def put_writes(
        self,
        config: RunnableConfig,
        writes: Sequence[tuple[str, Any]],
        task_id: str,
        task_path: str = "",
    ) -> None:
        """Store intermediate writes linked to a checkpoint.

        This method saves intermediate writes associated with a checkpoint to the database.

        Args:
            config: Configuration of the related checkpoint.
            writes: List of writes to store, each as (channel, value) pair.
            task_id: Identifier for the task creating the writes.
            task_path: Path of the task creating the writes.
        """
        return asyncio.run_coroutine_threadsafe(
            self.aput_writes(config, writes, task_id, task_path), self.loop
        ).result()
