"""
Health Check Blueprint
Provides API health monitoring and system status endpoints.
"""

import os
import time
import logging
from flask import Blueprint, request

from ..app import Config, stats_collector
from ..shared import task_status, TASK_STATUS_PENDING, TASK_STATUS_PROCESSING
from ..shared import _format_response, log_performance, logger

# Create blueprint
health_bp = Blueprint('health', __name__, url_prefix='/health')


@health_bp.route('', methods=['GET'])
@log_performance
def health_check():
    """API Health Check"""
    logger.debug("Health check requested")

    try:
        # Check storage accessibility
        uploads_writable = os.access(Config.UPLOAD_FOLDER, os.W_OK)
        outputs_writable = os.access(Config.OUTPUT_FOLDER, os.W_OK)

        # Check active tasks
        active_tasks = len([t for t in task_status.values() if t.get("status") in [TASK_STATUS_PENDING, TASK_STATUS_PROCESSING]])

        # Get basic stats for health check
        stats_summary = stats_collector.get_summary()

        health_data = {
            "status": "healthy",
            "version": "1.0.0",
            "timestamp": time.time(),
            "uptime": stats_summary['summary']['uptime_formatted'],
            "storage": {
                "uploads_writable": uploads_writable,
                "outputs_writable": outputs_writable
            },
            "tasks": {
                "active_count": active_tasks,
                "total_tracked": len(task_status),
                "total_processed": stats_summary['tasks']['total_completed'] + stats_summary['tasks']['total_failed'],
                "success_rate_percent": stats_summary['tasks']['success_rate_percent']
            },
            "performance": {
                "requests_per_second": stats_summary['summary']['requests_per_second'],
                "avg_response_time_ms": stats_summary['performance']['avg_response_time_ms'],
                "error_rate_percent": stats_summary['summary']['error_rate_percent']
            }
        }

        # Determine health status based on metrics
        is_healthy = True
        issues = []

        if not uploads_writable:
            issues.append("上传文件夹不可写")
            is_healthy = False
        if not outputs_writable:
            issues.append("输出文件夹不可写")
            is_healthy = False
        if active_tasks > 20:  # High load threshold
            issues.append(f"活跃任务数量过多 ({active_tasks})")
        if stats_summary['summary']['error_rate_percent'] > 10:  # High error rate
            issues.append(f"错误率过高 ({stats_summary['summary']['error_rate_percent']:.1f}%)")
            is_healthy = False

        health_data["status"] = "healthy" if is_healthy else "degraded"
        if issues:
            health_data["issues"] = issues

        # Log warnings for potential issues
        for issue in issues:
            logger.warning(f"Health check issue: {issue}")

        status_level = logging.DEBUG if is_healthy else logging.WARNING
        logger.log(status_level, f"Health check: {health_data['status']} (active tasks: {active_tasks})")

        status_code = 200 if is_healthy else 503  # 503 Service Unavailable for degraded
        return _format_response(status_code, "健康检查完成" if is_healthy else "服务不可用", health_data)

    except Exception as e:
        logger.error(f"Health check failed: {str(e)}", exc_info=True)
        return _format_response(500, "健康检查失败", {
            "status": "unhealthy",
            "error": str(e),
            "timestamp": time.time()
        })