"""
系统监控模块 - 提供性能指标和健康检查
"""
from prometheus_client import Counter, Gauge, Histogram, Summary
import time

# 定义指标
QUERY_COUNTER = Counter('student_grade_queries_total', '成绩查询总次数')
QUERY_ERRORS = Counter('student_grade_query_errors_total', '成绩查询错误次数', ['error_type'])
WAITING_ROOM_SIZE = Gauge('waiting_room_current_size', '等待室当前大小')
CONCURRENT_QUERIES_GAUGE = Gauge('concurrent_queries_current', '当前并发查询数')
CACHE_HIT_COUNTER = Counter('cache_hits_total', '缓存命中次数')
CACHE_MISS_COUNTER = Counter('cache_misses_total', '缓存未命中次数')
QUERY_LATENCY = Histogram('query_latency_seconds', '查询延迟', 
                         buckets=[0.05, 0.1, 0.5, 1.0, 2.5, 5.0, 10.0])
DB_CONNECTION_LATENCY = Summary('db_connection_latency_seconds', '数据库连接延迟')

# 连接池指标
DB_POOL_SIZE = Gauge('db_pool_size', '数据库连接池大小')
DB_POOL_FREE = Gauge('db_pool_free', '数据库连接池空闲连接数')
REDIS_POOL_SIZE = Gauge('redis_pool_size', 'Redis连接池大小')

class Timer:
    """计时器上下文管理器"""
    def __init__(self, metric):
        self.metric = metric
        
    def __enter__(self):
        self.start = time.time()
        return self
        
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.metric.observe(time.time() - self.start)

def record_query_attempt():
    """记录查询尝试"""
    QUERY_COUNTER.inc()
    
def record_query_error(error_type):
    """记录查询错误"""
    QUERY_ERRORS.labels(error_type=error_type).inc()
    
def update_waiting_room_size(size):
    """更新等待室大小"""
    WAITING_ROOM_SIZE.set(size)
    
def update_concurrent_queries(count):
    """更新当前并发查询数"""
    CONCURRENT_QUERIES_GAUGE.set(count)
    
def record_cache_hit():
    """记录缓存命中"""
    CACHE_HIT_COUNTER.inc()
    
def record_cache_miss():
    """记录缓存未命中"""
    CACHE_MISS_COUNTER.inc()
    
def query_timer():
    """查询计时器"""
    return Timer(QUERY_LATENCY)
    
def connection_timer():
    """连接计时器"""
    return Timer(DB_CONNECTION_LATENCY)

def update_pool_metrics(db_pool, redis_client):
    """更新连接池指标"""
    if db_pool:
        DB_POOL_SIZE.set(db_pool.maxsize)
        DB_POOL_FREE.set(db_pool.freesize)
    
    if hasattr(redis_client, 'connection_pool'):
        REDIS_POOL_SIZE.set(redis_client.connection_pool.max_connections)