"""短生命周期状态存储：验证码、幂等键。

dev/test 用进程内实现（不依赖 Redis 也能跑测试），prod 强制走 Redis。
接口刻意做小，将来换实现不影响调用方。
"""

from __future__ import annotations

import json
import time
from typing import Protocol

from .config import get_settings

settings = get_settings()


class KVStore(Protocol):
    async def set(self, key: str, value: str, ttl_seconds: int) -> None: ...

    async def get(self, key: str) -> str | None: ...

    async def delete(self, key: str) -> None: ...

    async def incr(self, key: str, ttl_seconds: int) -> int: ...


class MemoryStore:
    """进程内 TTL 字典。仅限单进程 dev/test——多 worker 下不共享，别在生产用。"""

    def __init__(self) -> None:
        self._data: dict[str, tuple[str, float]] = {}

    def _purge(self, key: str) -> None:
        item = self._data.get(key)
        if item and item[1] < time.time():
            self._data.pop(key, None)

    async def set(self, key: str, value: str, ttl_seconds: int) -> None:
        self._data[key] = (value, time.time() + ttl_seconds)

    async def get(self, key: str) -> str | None:
        self._purge(key)
        item = self._data.get(key)
        return item[0] if item else None

    async def delete(self, key: str) -> None:
        self._data.pop(key, None)

    async def incr(self, key: str, ttl_seconds: int) -> int:
        self._purge(key)
        current = int(self._data[key][0]) if key in self._data else 0
        current += 1
        expire_at = self._data[key][1] if key in self._data else time.time() + ttl_seconds
        self._data[key] = (str(current), expire_at)
        return current


class RedisStore:
    def __init__(self, url: str) -> None:
        from redis.asyncio import Redis  # 延迟导入：dev 环境没有 redis 包也能起

        self._client = Redis.from_url(url, decode_responses=True)

    async def set(self, key: str, value: str, ttl_seconds: int) -> None:
        await self._client.set(key, value, ex=ttl_seconds)

    async def get(self, key: str) -> str | None:
        return await self._client.get(key)

    async def delete(self, key: str) -> None:
        await self._client.delete(key)

    async def incr(self, key: str, ttl_seconds: int) -> int:
        value = await self._client.incr(key)
        if value == 1:
            await self._client.expire(key, ttl_seconds)
        return int(value)


_store: KVStore | None = None


def get_store() -> KVStore:
    global _store
    if _store is None:
        _store = RedisStore(settings.redis_url) if settings.env == "prod" else MemoryStore()
    return _store


def reset_store_for_tests() -> None:
    """测试夹具用：清掉进程内状态。"""
    global _store
    _store = None


def dumps(value: object) -> str:
    return json.dumps(value, ensure_ascii=False, separators=(",", ":"))


# ── 业务键约定 ──────────────────────────────────────────
def sms_code_key(phone: str) -> str:
    return f"sms:login:{phone}"


def sms_throttle_key(phone: str) -> str:
    return f"sms:throttle:{phone}"


# ── 邮箱注册 ────────────────────────────────────────────
def email_code_key(email: str) -> str:
    return f"email:code:{email}"


def email_tries_key(email: str) -> str:
    """试错计数：错一次算一次，超过上限就把验证码作废，别让人拿 6 位数当彩票刮。"""
    return f"email:tries:{email}"


def email_throttle_key(email: str) -> str:
    return f"email:throttle:{email}"


def idempotency_key(user_id: str, key: str) -> str:
    return f"idem:{user_id}:{key}"