"""Шаги state machine внутри ветки: сид, чтение, правка (Спринт 6a).

Шаги живут в БД (`intent_steps`), сид при старте читает файлы промптов из
`prompts/intents/{intent_code}/steps/{step_code}.md`. Список шагов и переходы
описаны в словаре `SEED_INTENT_STEPS` ниже — новые state-machine-ветки
добавляются сюда + соответствующие файлы.
"""
import json
import logging
from datetime import datetime, timezone
from pathlib import Path

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

from db.models import Intent, IntentStep

logger = logging.getLogger(__name__)

PROMPTS_INTENTS_DIR = Path(__file__).resolve().parent.parent / "prompts" / "intents"


# Стартовая описание шагов для state-machine-веток. Ключ — code ветки; значение —
# список шагов в порядке следования. `allowed_next` описывает граф переходов.
SEED_INTENT_STEPS: dict[str, list[dict]] = {
    "new_booking": [
        {
            "code": "intro",
            "name": "Приветствие",
            "allowed_next": ["intro", "qualify"],
        },
        {
            "code": "qualify",
            "name": "Повод и специалист",
            "allowed_next": ["qualify", "present"],
        },
        {
            "code": "present",
            "name": "Презентация плана",
            "allowed_next": ["present", "qualify", "offer_time"],
        },
        {
            "code": "offer_time",
            "name": "Удобное время",
            "allowed_next": ["offer_time", "book"],
        },
        {
            "code": "book",
            "name": "Подтверждение записи",
            "allowed_next": ["book", "qualify", "offer_time", "close"],
        },
        {
            "code": "close",
            "name": "Завершение",
            "allowed_next": ["close"],
        },
    ],
}


def _step_prompt_path(intent_code: str, step_code: str) -> Path:
    return PROMPTS_INTENTS_DIR / intent_code / "steps" / f"{step_code}.md"


def load_seed_step_prompt(intent_code: str, step_code: str) -> str:
    path = _step_prompt_path(intent_code, step_code)
    try:
        return path.read_text(encoding="utf-8").strip()
    except FileNotFoundError:
        logger.warning("Seed prompt for step %s/%s not found at %s", intent_code, step_code, path)
        return ""


def has_state_machine(intent_code: str) -> bool:
    return intent_code in SEED_INTENT_STEPS


def parse_allowed_next(step: IntentStep) -> list[str]:
    try:
        value = json.loads(step.allowed_next_json)
    except (json.JSONDecodeError, TypeError):
        return []
    return value if isinstance(value, list) else []


def parse_guards(step: IntentStep) -> dict:
    try:
        value = json.loads(step.guards_json)
    except (json.JSONDecodeError, TypeError):
        return {}
    return value if isinstance(value, dict) else {}


async def list_steps_for_intent(session: AsyncSession, intent_id: int) -> list[IntentStep]:
    stmt = select(IntentStep).where(IntentStep.intent_id == intent_id).order_by(IntentStep.order_index, IntentStep.id)
    return list((await session.execute(stmt)).scalars().all())


async def get_step_by_code(
    session: AsyncSession, intent_id: int, step_code: str
) -> IntentStep | None:
    stmt = select(IntentStep).where(
        IntentStep.intent_id == intent_id, IntentStep.code == step_code
    )
    return (await session.execute(stmt)).scalar_one_or_none()


async def get_first_step(session: AsyncSession, intent_id: int) -> IntentStep | None:
    stmt = (
        select(IntentStep)
        .where(IntentStep.intent_id == intent_id)
        .order_by(IntentStep.order_index, IntentStep.id)
        .limit(1)
    )
    return (await session.execute(stmt)).scalar_one_or_none()


async def update_step(
    session: AsyncSession,
    step: IntentStep,
    *,
    name: str | None = None,
    system_prompt: str | None = None,
    allowed_next: list[str] | None = None,
    guards: dict | None = None,
) -> IntentStep:
    if name is not None:
        step.name = name
    if system_prompt is not None:
        step.system_prompt = system_prompt
    if allowed_next is not None:
        step.allowed_next_json = json.dumps(allowed_next, ensure_ascii=False)
    if guards is not None:
        step.guards_json = json.dumps(guards, ensure_ascii=False)
    step.updated_at = datetime.now(timezone.utc)
    await session.commit()
    await session.refresh(step)
    return step


async def ensure_seed_steps(session: AsyncSession) -> None:
    """Досиживает недостающие шаги для state-machine-веток. Существующие не трогаются."""
    added = 0
    for intent_code, steps_def in SEED_INTENT_STEPS.items():
        intent = (await session.execute(
            select(Intent).where(Intent.code == intent_code)
        )).scalar_one_or_none()
        if intent is None:
            logger.warning("Cannot seed steps for %s: intent not found", intent_code)
            continue

        existing = set((await session.execute(
            select(IntentStep.code).where(IntentStep.intent_id == intent.id)
        )).scalars().all())

        for order, data in enumerate(steps_def):
            if data["code"] in existing:
                continue
            prompt = load_seed_step_prompt(intent_code, data["code"])
            session.add(IntentStep(
                intent_id=intent.id,
                code=data["code"],
                name=data["name"],
                order_index=order,
                system_prompt=prompt,
                allowed_next_json=json.dumps(data["allowed_next"], ensure_ascii=False),
                guards_json="{}",
            ))
            added += 1

    if added:
        await session.commit()
        logger.info("Seeded %d missing intent_steps", added)