"""Persistent projections of native jobs; this is not another scheduler."""

from dataclasses import asdict, dataclass, field
from datetime import UTC, datetime
from uuid import uuid4

from sqlalchemy import select
from pydantic.alias_generators import to_camel
from db.models import BackgroundTask, BackgroundTaskEvent
from db.session import SessionLocal

TERMINAL = {"succeeded", "failed", "cancelled"}
ACTIVE = {"queued", "submitted", "running", "waiting_input", "cancel_requested", "unknown"}


@dataclass
class TaskRecord:
    id: str
    assistant_id: str
    conversation_id: str
    tool_id: str
    instruction: str
    origin_key: str
    connection: dict
    secrets: dict
    status: str = "queued"
    summary: str = "任务已排队"
    result: str = ""
    remote_handle: dict = field(default_factory=dict)
    input_request: dict = field(default_factory=dict)
    job_id: str = ""
    sequence: int = 0
    created_at: str = field(default_factory=lambda: datetime.now(UTC).isoformat())
    updated_at: str = field(default_factory=lambda: datetime.now(UTC).isoformat())

    def public(self):
        hidden = {"connection", "secrets", "origin_key", "remote_handle"}
        return {to_camel(key): value for key, value in asdict(self).items() if key not in hidden}


def from_row(row) -> TaskRecord:
    return TaskRecord(**{key: getattr(row, key) for key in TaskRecord.__dataclass_fields__})


class TaskRepository:
    async def create(self, record: TaskRecord) -> TaskRecord:
        async with SessionLocal() as db:
            # All calls are serialized by the application entry point; unique
            # origin_key also protects against duplicate tool delivery.
            existing = (await db.execute(select(BackgroundTask).where(BackgroundTask.origin_key == record.origin_key))).scalar_one_or_none()
            if existing:
                return from_row(existing)
            db.add(BackgroundTask(**asdict(record)))
            await db.commit()
        return record

    async def get(self, task_id: str) -> TaskRecord | None:
        async with SessionLocal() as db:
            row = await db.get(BackgroundTask, task_id)
            return from_row(row) if row else None

    async def list(self, assistant_id: str | None = None, *, active=False) -> list[TaskRecord]:
        statement = select(BackgroundTask).order_by(BackgroundTask.created_at.desc())
        if not active:
            statement = statement.limit(100)
        if assistant_id:
            statement = statement.where(BackgroundTask.assistant_id == assistant_id)
        if active:
            statement = statement.where(BackgroundTask.status.in_(ACTIVE))
        async with SessionLocal() as db:
            return [from_row(row) for row in (await db.execute(statement)).scalars().all()]

    async def patch(self, task_id: str, **changes) -> TaskRecord:
        async with SessionLocal() as db:
            row = (await db.execute(select(BackgroundTask).where(BackgroundTask.id == task_id).with_for_update())).scalar_one()
            if row.status in TERMINAL:
                return from_row(row)
            for key, value in changes.items():
                setattr(row, key, value)
            row.sequence += 1
            row.updated_at = datetime.now(UTC).isoformat()
            record = from_row(row)
            db.add(BackgroundTaskEvent(id="te_" + uuid4().hex, task_id=task_id, sequence=row.sequence, data=record.public()))
            await db.commit()
            return record