from django.db.models import Count, Case, When, Q, Subquery, OuterRef
from .models import ServiceGroup, Service, ServiceCheckRecord

# 引入loguru库用于日志记录
try:
    from loguru import logger
except ImportError:
    import logging
    logger = logging.getLogger(__name__)

# 工具函数：获取或创建服务
def get_or_create_service(data):
    """当客户端上报一个不存在的服务时，自动创建"""
    service, created = Service.objects.get_or_create(
        name=data['service_name'],
        host=data['host'],
        port=data.get('port'),
        defaults={
            'group': ServiceGroup.objects.get_or_create(name="Default")[0],
            'check_type': data['check_type'],
            'description': f"Auto-created from client checkin: {data['service_name']}"
        }
    )
    if created:
        logger.info(f"自动创建新服务: {service.name} ({service.host})")
    return service

# 工具函数：获取状态摘要
def get_status_summary():
    """获取全局状态摘要（如：总共服务数、正常数、异常数）"""
    # 获取每个服务的最新状态
    latest_records = ServiceCheckRecord.objects.filter(
        service=OuterRef('pk')
    ).order_by('-checked_at')
    
    services_with_status = Service.objects.annotate(
        latest_status=Subquery(latest_records.values('status')[:1])
    )
    
    total = services_with_status.count()
    up_count = services_with_status.filter(latest_status='UP').count()
    down_count = services_with_status.filter(latest_status='DOWN').count()
    unknown_count = services_with_status.filter(latest_status='UNKNOWN').count()
    
    return {
        'total': total,
        'up': up_count,
        'down': down_count,
        'unknown': unknown_count
    }

# 工具函数：获取服务的最新状态
def get_service_latest_status(service):
    """获取服务的最新状态"""
    latest_record = service.records.order_by('-checked_at').first()
    if latest_record:
        return {
            'status': latest_record.status,
            'check_time': latest_record.checked_at,
            'response_time': latest_record.response_time,
            'message': latest_record.message
        }
    return {
        'status': 'UNKNOWN',
        'check_time': None,
        'response_time': None,
        'message': None
    }

# 工具函数：获取服务的状态变化时间轴
def get_service_status_timeline(service, limit=20):
    """获取服务的状态变化时间轴"""
    status_changes = []
    prev_status = None
    
    for record in service.records.all().order_by('-checked_at'):
        if prev_status is None or record.status != prev_status:
            status_changes.append(record)
            prev_status = record.status
            
            if len(status_changes) >= limit:
                break
    
    return status_changes

# 工具函数：获取服务的响应时间趋势数据
def get_service_response_time_chart_data(service, hours=24):
    """获取服务的响应时间趋势数据"""
    from django.utils import timezone
    import datetime
    
    end_time = timezone.now()
    start_time = end_time - datetime.timedelta(hours=hours)
    
    # 获取指定时间范围内的记录
    chart_records = service.records.filter(
        checked_at__gte=start_time,
        checked_at__lte=end_time,
        response_time__isnull=False
    ).order_by('checked_at')
    
    # 准备图表数据
    chart_labels = []
    chart_data = []
    
    for record in chart_records:
        chart_labels.append(record.checked_at.strftime('%H:%M'))
        chart_data.append(record.response_time)
    
    return {
        'labels': chart_labels,
        'data': chart_data
    }