import os
import psutil
import time
from datetime import datetime
from flask import jsonify
from sqlalchemy import text
from . import db

def check_database():
    """Check database connection and response time."""
    try:
        start_time = time.time()
        # Execute a simple query
        db.session.execute(text('SELECT 1'))
        response_time = (time.time() - start_time) * 1000  # Convert to milliseconds
        
        return {
            'status': 'healthy',
            'response_time_ms': round(response_time, 2)
        }
    except Exception as e:
        return {
            'status': 'unhealthy',
            'error': str(e)
        }

def check_disk_space():
    """Check available disk space."""
    try:
        disk = psutil.disk_usage('/')
        return {
            'status': 'healthy' if disk.percent < 90 else 'warning',
            'total_gb': round(disk.total / (1024**3), 2),
            'used_gb': round(disk.used / (1024**3), 2),
            'free_gb': round(disk.free / (1024**3), 2),
            'percent_used': disk.percent
        }
    except Exception as e:
        return {
            'status': 'unhealthy',
            'error': str(e)
        }

def check_memory():
    """Check memory usage."""
    try:
        memory = psutil.virtual_memory()
        return {
            'status': 'healthy' if memory.percent < 90 else 'warning',
            'total_gb': round(memory.total / (1024**3), 2),
            'used_gb': round(memory.used / (1024**3), 2),
            'free_gb': round(memory.available / (1024**3), 2),
            'percent_used': memory.percent
        }
    except Exception as e:
        return {
            'status': 'unhealthy',
            'error': str(e)
        }

def check_cpu():
    """Check CPU usage."""
    try:
        cpu_percent = psutil.cpu_percent(interval=1)
        return {
            'status': 'healthy' if cpu_percent < 90 else 'warning',
            'usage_percent': cpu_percent,
            'core_count': psutil.cpu_count()
        }
    except Exception as e:
        return {
            'status': 'unhealthy',
            'error': str(e)
        }

def check_application():
    """Check application-specific metrics."""
    try:
        # Check if required directories exist
        required_dirs = ['instance', 'logs', 'backups']
        dir_status = {}
        for dir_name in required_dirs:
            dir_status[dir_name] = os.path.exists(dir_name)

        # Check if log files are writable
        log_status = {}
        log_files = ['logs/mold_cost_calculator.log', 'logs/error.log', 'logs/access.log']
        for log_file in log_files:
            log_status[log_file] = os.access(os.path.dirname(log_file), os.W_OK)

        return {
            'status': 'healthy' if all(dir_status.values()) and all(log_status.values()) else 'warning',
            'directories': dir_status,
            'log_files': log_status,
            'startup_time': datetime.utcnow().isoformat()
        }
    except Exception as e:
        return {
            'status': 'unhealthy',
            'error': str(e)
        }

def get_health_status():
    """Get comprehensive health status of the application."""
    checks = {
        'database': check_database(),
        'disk_space': check_disk_space(),
        'memory': check_memory(),
        'cpu': check_cpu(),
        'application': check_application()
    }
    
    # Determine overall status
    statuses = [check['status'] for check in checks.values()]
    if 'unhealthy' in statuses:
        overall_status = 'unhealthy'
    elif 'warning' in statuses:
        overall_status = 'warning'
    else:
        overall_status = 'healthy'
    
    return {
        'status': overall_status,
        'timestamp': datetime.utcnow().isoformat(),
        'checks': checks
    }