"""设置服务：生成偏好。

生成偏好为本地单用户单行，无则返回默认值；模型网关状态由神识承接（用户面见神识阁）。
"""

from app.core.config import settings
from app.core.time import utc_now
from app.db.session import AsyncSessionLocal
from app.models.governance import GenerationPreferences
from app.repositories import preferences as preferences_repo
from app.schemas.preferences import (
    GenerationPreferencesResponse,
    UpdateGenerationPreferencesRequest,
)
from app.services.serializers import generation_preferences_to_response


def _default_preferences() -> GenerationPreferences:
    return GenerationPreferences(
        owner_scope=settings.default_owner_scope,
        default_model_hint=settings.default_model_hint,
        temperature=0.7,
        top_p=1.0,
        max_output_tokens=4096,
        streaming=True,
    )


async def get_generation_preferences(
    owner_scope: str = settings.default_owner_scope,
) -> GenerationPreferencesResponse:
    async with AsyncSessionLocal() as session:
        prefs = await preferences_repo.get_preferences(session, owner_scope)
        if prefs is None:
            prefs = _default_preferences()
        return generation_preferences_to_response(prefs)


async def update_generation_preferences(
    payload: UpdateGenerationPreferencesRequest,
    owner_scope: str = settings.default_owner_scope,
) -> GenerationPreferencesResponse:
    async with AsyncSessionLocal() as session:
        prefs = await preferences_repo.get_preferences(session, owner_scope)
        if prefs is None:
            prefs = _default_preferences()
            for key, value in payload.model_dump(exclude_unset=True).items():
                setattr(prefs, key, value)
            prefs.updated_at = utc_now()
            session.add(prefs)
            try:
                await session.commit()
            except Exception:
                await session.rollback()
                prefs = await preferences_repo.get_preferences(session, owner_scope)
                if prefs is None:
                    raise
                for key, value in payload.model_dump(exclude_unset=True).items():
                    setattr(prefs, key, value)
                prefs.updated_at = utc_now()
                await session.commit()
        else:
            for key, value in payload.model_dump(exclude_unset=True).items():
                setattr(prefs, key, value)
            prefs.updated_at = utc_now()
            await session.commit()
        await session.refresh(prefs)
        return generation_preferences_to_response(prefs)