"""Health check endpoint for WealthWise API.

This module provides a comprehensive health check endpoint that verifies:
- Application is running
- Database connectivity
- Overall system status
"""

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy import text
from sqlmodel.ext.asyncio.session import AsyncSession

from app.api.deps import SessionDep
from app.core.config import get_settings
from app.core.db import check_db_connection

router = APIRouter()
settings = get_settings()


@router.get(
    "/health",
    summary="Health check endpoint",
    description="Performs comprehensive health checks including database connectivity.",
    response_description="Health status with version and database state",
    tags=["Health"],
)
async def health_check(session: AsyncSession = SessionDep) -> dict:
    """Check application and database health.
    
    This endpoint performs an actual database query (SELECT 1) to verify
    that the database connection is working properly. It returns a detailed
    health status including:
    - Overall application status
    - Database connectivity state
    - Application version
    
    Returns:
        dict: Health status object with the following structure:
            {
                "status": "healthy" | "degraded",
                "database": "connected" | "disconnected",
                "version": "1.0.0",
                "timestamp": "2024-01-01T00:00:00Z"
            }
    
    Raises:
        HTTPException: 503 if database is unreachable
    """
    health_status = {
        "status": "healthy",
        "database": "connected",
        "version": settings.VERSION,
    }
    
    try:
        # Perform actual database query to verify connectivity
        result = await session.execute(text("SELECT 1"))
        db_response = result.scalar()
        
        if db_response != 1:
            raise Exception("Unexpected database response")
            
    except Exception as e:
        health_status.update({
            "status": "degraded",
            "database": "disconnected",
            "error": str(e),
        })
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail=health_status,
        )
    
    return health_status


@router.get(
    "/health/ready",
    summary="Readiness probe",
    description="Kubernetes-style readiness probe endpoint.",
    tags=["Health"],
)
async def readiness_probe() -> dict:
    """Kubernetes readiness probe.
    
    Returns 200 if the application is ready to receive traffic.
    Used by container orchestrators to determine when to route traffic.
    
    Returns:
        dict: Simple status object
    """
    return {"ready": True}


@router.get(
    "/health/live",
    summary="Liveness probe",
    description="Kubernetes-style liveness probe endpoint.",
    tags=["Health"],
)
async def liveness_probe() -> dict:
    """Kubernetes liveness probe.
    
    Returns 200 if the application is alive and should not be restarted.
    Used by container orchestrators to detect deadlocks or stuck processes.
    
    Returns:
        dict: Simple status object
    """
    return {"alive": True}