import json
import uuid
from contextlib import asynccontextmanager
from typing import Annotated, AsyncContextManager

import redis.asyncio as redis
from fastapi import Depends

from app.config.env import env


class RedisUtils():
  def __init__(self):
    self.redis_pool = None

  # 检查 Redis 连接，先创建连接池管理对象
  async def check_redis_connection(self):
    self.redis_pool = redis.ConnectionPool(
      host=env.redis_host,
      port=env.redis_port,
      password=env.redis_password,
      db=env.redis_db,
      encoding="utf-8",
      decode_responses=True
    )
    # 立即对redis做一次读写测试
    async with self.get_redis_connection() as redis_client:
      try:
        await redis_client.ping()
        random_id = str(uuid.uuid4())
        await redis_client.set("__init__setup__", random_id)
        cache_random_id = await  redis_client.get("__init__setup__")
        if cache_random_id != random_id:
          raise Exception("Redis 连接失败，读写测试不一致")
        print("✅ Redis connection successful：", f"redis://{env.redis_password}@${env.redis_host}:{env.redis_port}/{env.redis_db}")
      except Exception as e:
        print(f"❌ Database connection failed")
        raise e

  # 获取一个Redis连接客户端
  @asynccontextmanager
  async def get_redis_connection(self) -> AsyncContextManager[redis.Redis]:
    if not self.redis_pool:
      raise Exception("Redis 连接池未初始化")
    redis_client = redis.Redis(connection_pool=self.redis_pool)
    try:
      yield redis_client
    finally:
      await redis_client.close()

  # 清理Redis连接池
  async def close_redis_connection(self):
    if self.redis_pool:
      await self.redis_pool.disconnect()


redis_utils = RedisUtils()


# 作用：用于在接口中注入得到会话实例对象session，在接口执行完毕之后，自动执行close动作关闭会话
async def get_redis_client() -> redis.Redis:
  async with redis_utils.get_redis_connection() as redis_client:
    yield redis_client


RedisClientDep = Annotated[redis.Redis, Depends(get_redis_client)]


# 从redis中获取key的缓存，如果没有值则执行默认值获取函数，并保存到redis中
async def get_redis_cache(key: str, default_value_getter):
  async with redis_utils.get_redis_connection() as redis_client:
    # default_value_getter返回的字段可能嵌套多层对象，这里改成用json字符串缓存
    json_string = await redis_client.get(key)
    exists = bool(json_string)
    if exists:
      return json.loads(json_string)
    else:
      value = await default_value_getter()
      print("value", value)
      if value is not None:
        new_value = {k: v for k, v in value.items() if v is not None}
        await redis_client.set(key, json.dumps(new_value, ensure_ascii=False))
      return value


# 删除redis缓存
async def remove_redis_cache(key: str):
  async with redis_utils.get_redis_connection() as redis_client:
    result = await redis_client.delete(key)
    return result > 0  # 返回是否删除成功