"""投保领域异步任务边界。

第一阶段使用进程内调度器保证本地一键运行；接口可以在后续替换为 RabbitMQ
发布器和独立 Worker，支付回调与保单签发规则无需改写。
"""

from collections.abc import Callable
from dataclasses import replace
from datetime import datetime, timedelta
from typing import Protocol

from app.core.errors import AppError
from app.core.identifiers import new_ulid
from app.domains.enrollment.models import AsyncTask, Policy
from app.domains.enrollment.repository import EnrollmentRepository


class TaskDispatcher(Protocol):
    def dispatch(self, task: AsyncTask) -> Policy: ...


class InlinePolicyTaskDispatcher:
    """本地运行适配器：真实记录任务生命周期，然后在当前进程执行。"""

    def __init__(
        self,
        repository: EnrollmentRepository,
        clock: Callable[[], datetime],
    ) -> None:
        self._repository = repository
        self._clock = clock

    def dispatch(self, task: AsyncTask) -> Policy:
        existing = self._repository.get_policy_by_order(task.business_key)
        if existing is not None:
            self._repository.save_task(
                replace(task, status="SUCCEEDED", attempt_count=task.attempt_count + 1)
            )
            return existing

        running = replace(
            task,
            status="RUNNING",
            attempt_count=task.attempt_count + 1,
        )
        self._repository.save_task(running)
        try:
            policy = self._issue_policy(task.business_key)
        except Exception:
            self._repository.save_task(replace(running, status="FAILED"))
            raise
        self._repository.save_task(replace(running, status="SUCCEEDED"))
        return policy

    def _issue_policy(self, order_id: str) -> Policy:
        order = self._repository.get_order(order_id)
        if order is None:
            raise AppError("ORDER_NOT_FOUND", "未找到待签发保单的订单", 404)
        if order.status not in {"PAID", "ISSUED"}:
            raise AppError("ORDER_NOT_PAID", "订单尚未支付，不能签发保单", 409)
        existing = self._repository.get_policy_by_order(order.id)
        if existing is not None:
            return existing

        now = self._clock()
        policy = Policy(
            id=new_ulid(),
            policy_no=f"POL-{now:%Y%m%d}-{new_ulid()[-8:]}",
            order_id=order.id,
            user_id=order.user_id,
            product_id=order.product_id,
            product_version_id=order.product_version_id,
            plan_id=order.plan_id,
            premium_cents=order.amount_cents,
            currency=order.currency,
            coverage_start=now.date() + timedelta(days=1),
            coverage_end=now.date() + timedelta(days=365),
            status="ACTIVE",
            issued_at=now,
        )
        self._repository.save_policy(policy)
        self._repository.save_order(replace(order, status="ISSUED"))
        return policy