"""
回忆录状态服务：get_or_create_state、update_slot、mark_stage_complete 等。
供 memoir service、conversation ws 使用；Celery 任务内使用同步版本（见 tasks/memoir_tasks）。
"""
import uuid
from typing import Dict, List

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.agents.state_schema import MemoirStateSchema, SlotData, default_state
from app.features.memoir.models import MemoirState as MemoirStateModel


def _coerce_state(model: MemoirStateModel) -> MemoirStateSchema:
    return MemoirStateSchema.model_validate(
        {
            "stage_order": model.stage_order or default_state().stage_order,
            "current_stage": model.current_stage,
            "covered_stages": model.covered_stages or [],
            "slots": model.slots if isinstance(model.slots, dict) else default_state().slots,
        }
    )


async def get_or_create_state(user_id: str, db: AsyncSession) -> MemoirStateSchema:
    stmt = select(MemoirStateModel).where(MemoirStateModel.user_id == user_id)
    result = await db.execute(stmt)
    state = result.scalar_one_or_none()
    if state:
        return _coerce_state(state)

    default = default_state()
    state = MemoirStateModel(
        id=str(uuid.uuid4()),
        user_id=user_id,
        stage_order=default.stage_order,
        current_stage=default.current_stage,
        covered_stages=default.covered_stages,
        slots={k: {sk: sv.model_dump() for sk, sv in v.items()} for k, v in default.slots.items()},
    )
    db.add(state)
    await db.commit()
    await db.refresh(state)
    return _coerce_state(state)


async def update_slot(
    user_id: str,
    stage: str,
    slot_name: str,
    snippet: str,
    segment_ids: List[str],
    db: AsyncSession,
) -> MemoirStateSchema:
    stmt = select(MemoirStateModel).where(MemoirStateModel.user_id == user_id)
    result = await db.execute(stmt)
    state = result.scalar_one_or_none()
    if not state:
        await get_or_create_state(user_id, db)
        result = await db.execute(stmt)
        state = result.scalar_one()

    slots: Dict[str, Dict] = state.slots or {}
    stage_slots = slots.get(stage, {})
    existing = stage_slots.get(slot_name, {})

    merged_segment_ids = list({*(existing.get("segment_ids") or []), *segment_ids})
    stage_slots[slot_name] = SlotData(snippet=snippet, segment_ids=merged_segment_ids).model_dump()
    slots[stage] = stage_slots
    state.slots = slots
    state.current_stage = state.current_stage or stage
    await db.commit()
    await db.refresh(state)
    return _coerce_state(state)


async def mark_stage_complete(user_id: str, stage: str, db: AsyncSession) -> MemoirStateSchema:
    stmt = select(MemoirStateModel).where(MemoirStateModel.user_id == user_id)
    result = await db.execute(stmt)
    state = result.scalar_one_or_none()
    if not state:
        return await get_or_create_state(user_id, db)

    covered = state.covered_stages or []
    if stage not in covered:
        covered.append(stage)
    state.covered_stages = covered

    stage_order = state.stage_order or default_state().stage_order
    if state.current_stage == stage:
        try:
            idx = stage_order.index(stage)
            state.current_stage = stage_order[min(idx + 1, len(stage_order) - 1)]
        except ValueError:
            state.current_stage = default_state().current_stage
    await db.commit()
    await db.refresh(state)
    return _coerce_state(state)


async def get_empty_slots(user_id: str, db: AsyncSession) -> List[str]:
    state = await get_or_create_state(user_id, db)
    return state.empty_slots_for_current_stage()


async def switch_stage(user_id: str, new_stage: str, db: AsyncSession) -> MemoirStateSchema:
    stmt = select(MemoirStateModel).where(MemoirStateModel.user_id == user_id)
    result = await db.execute(stmt)
    state = result.scalar_one_or_none()
    if not state:
        return await get_or_create_state(user_id, db)

    state.current_stage = new_stage
    await db.commit()
    await db.refresh(state)
    return _coerce_state(state)