dify/api/services/message_service.py

from collections.abc import Sequence

from sqlalchemy import select
from sqlalchemy.orm import Session, sessionmaker

from extensions.ext_database import db
from libs.infinite_scroll_pagination import InfiniteScrollPagination
from models import Account
from models.model import (
    App,
    EndUser,
    Message,
)
from repositories.execution_extra_content_repository import ExecutionExtraContentRepository
from repositories.sqlalchemy_execution_extra_content_repository import (
    SQLAlchemyExecutionExtraContentRepository,
)
from services.conversation_service import ConversationService
from services.errors.message import (
    FirstMessageNotExistsError,
    LastMessageNotExistsError,
    MessageNotExistsError,
)


def _create_execution_extra_content_repository() -> ExecutionExtraContentRepository:
    session_maker = sessionmaker(bind=db.engine, expire_on_commit=False)
    return SQLAlchemyExecutionExtraContentRepository(session_maker=session_maker)


def attach_message_extra_contents(messages: Sequence[Message]) -> None:
    if not messages:
        return

    repository = _create_execution_extra_content_repository()
    extra_contents_lists = repository.get_by_message_ids([message.id for message in messages])

    for index, message in enumerate(messages):
        contents = extra_contents_lists[index] if index < len(extra_contents_lists) else []
        message.set_extra_contents([content.model_dump(mode="json", exclude_none=True) for content in contents])


class MessageService:
    @classmethod
    def pagination_by_first_id(
        cls,
        app_model: App,
        user: Account | EndUser | None,
        conversation_id: str,
        first_id: str | None,
        limit: int,
        order: str = "asc",
        *,
        session: Session,
    ) -> InfiniteScrollPagination:
        if not user:
            return InfiniteScrollPagination(data=[], limit=limit, has_more=False)

        if not conversation_id:
            return InfiniteScrollPagination(data=[], limit=limit, has_more=False)

        conversation = ConversationService.get_conversation(
            app_model=app_model, user=user, conversation_id=conversation_id, session=session
        )

        fetch_limit = limit + 1

        if first_id:
            first_message = session.scalar(
                select(Message).where(Message.conversation_id == conversation.id, Message.id == first_id).limit(1)
            )

            if not first_message:
                raise FirstMessageNotExistsError()

            history_messages = session.scalars(
                select(Message)
                .where(
                    Message.conversation_id == conversation.id,
                    Message.created_at < first_message.created_at,
                    Message.id != first_message.id,
                )
                .order_by(Message.created_at.desc())
                .limit(fetch_limit)
            ).all()
        else:
            history_messages = session.scalars(
                select(Message)
                .where(Message.conversation_id == conversation.id)
                .order_by(Message.created_at.desc())
                .limit(fetch_limit)
            ).all()

        has_more = False
        if len(history_messages) > limit:
            has_more = True
            history_messages = history_messages[:-1]

        if order == "asc":
            history_messages = list(reversed(history_messages))

        attach_message_extra_contents(history_messages)

        return InfiniteScrollPagination(data=history_messages, limit=limit, has_more=has_more)

    @classmethod
    def pagination_by_last_id(
        cls,
        app_model: App,
        user: Account | EndUser | None,
        last_id: str | None,
        limit: int,
        conversation_id: str | None = None,
        include_ids: list | None = None,
        *,
        session: Session,
    ) -> InfiniteScrollPagination:
        if not user:
            return InfiniteScrollPagination(data=[], limit=limit, has_more=False)

        stmt = select(Message)

        fetch_limit = limit + 1

        if conversation_id is not None:
            conversation = ConversationService.get_conversation(
                app_model=app_model, user=user, conversation_id=conversation_id, session=session
            )

            stmt = stmt.where(Message.conversation_id == conversation.id)

        # Check if include_ids is not None and not empty to avoid WHERE false condition
        if include_ids is not None:
            if len(include_ids) == 0:
                return InfiniteScrollPagination(data=[], limit=limit, has_more=False)
            stmt = stmt.where(Message.id.in_(include_ids))

        if last_id:
            last_message = session.scalar(stmt.where(Message.id == last_id).limit(1))

            if not last_message:
                raise LastMessageNotExistsError()

            history_messages = session.scalars(
                stmt.where(Message.created_at < last_message.created_at, Message.id != last_message.id)
                .order_by(Message.created_at.desc())
                .limit(fetch_limit)
            ).all()
        else:
            history_messages = session.scalars(stmt.order_by(Message.created_at.desc()).limit(fetch_limit)).all()

        has_more = False
        if len(history_messages) > limit:
            has_more = True
            history_messages = history_messages[:-1]

        return InfiniteScrollPagination(data=history_messages, limit=limit, has_more=has_more)

    @classmethod
    def get_message(cls, app_model: App, user: Account | EndUser | None, message_id: str, *, session: Session):
        message = session.scalar(
            select(Message)
            .where(
                Message.id == message_id,
                Message.app_id == app_model.id,
                Message.from_source == ("api" if isinstance(user, EndUser) else "console"),
                Message.from_end_user_id == (user.id if isinstance(user, EndUser) else None),
                Message.from_account_id == (user.id if isinstance(user, Account) else None),
            )
            .limit(1)
        )

        if not message:
            raise MessageNotExistsError()

        return message