"""
Monitoring endpoints for token usage, performance metrics, and health checks.

Endpoints:
- GET /metrics/tokens - Token usage statistics
- GET /metrics/tokens/recent - Recent token usage records
- GET /metrics/performance - Performance metrics
- GET /metrics/health - Detailed health status
"""

from fastapi import APIRouter, Depends, Query
from datetime import datetime, timedelta
from typing import Optional
from app.utils.token_tracker import token_tracker
from app.utils.logging_config import get_owner_id
from app.conversation.store import conversation_store
from app.config.settings import settings
import psutil
import os

router = APIRouter(prefix="/metrics", tags=["monitoring"])


@router.get("/tokens")
async def get_token_stats(
    owner_id: Optional[str] = Query(None),
):
    """
    Get token usage statistics.
    
    **Query Parameters:**
    - `owner_id` (optional): Filter stats for specific user (defaults to current user from header)
    
    **Headers:**
    - `owner-id`: User identifier (required)
    
    **Response:**
    ```json
    {
      "total_requests": 150,
      "total_tokens": 45000,
      "total_cost_usd": 0.85,
      "average_tokens_per_request": 300,
      "average_cost_per_request": 0.0057,
      "by_feature": {
        "text_triage": {
          "requests": 100,
          "tokens": 30000,
          "cost_usd": 0.60
        }
      },
      "by_status": {
        "success": {
          "count": 148,
          "total_tokens": 44000,
          "total_cost_usd": 0.84
        }
      }
    }
    ```
    """
    # Get user from context (set by middleware)
    current_user = get_owner_id()
    
    # Allow query param to override (for admin viewing other users)
    target_user = owner_id or current_user
    
    if not target_user:
        return {
            "error": "owner-id header required",
            "total_requests": 0,
            "total_tokens": 0,
            "total_cost_usd": 0
        }
    
    return token_tracker.get_stats(target_user)


@router.get("/tokens/recent")
async def get_recent_token_records(limit: int = Query(50, le=500)):
    """
    Get recent token usage records.
    
    **Query Parameters:**
    - `limit` (optional): Number of records to return, max 500 (default: 50)
    
    **Headers:**
    - `owner-id`: User identifier (required)
    
    **Response:**
    ```json
    [
      {
        "timestamp": "2026-01-25T12:30:45.123456",
        "feature": "text_triage",
        "input_tokens": 250,
        "output_tokens": 150,
        "total_tokens": 400,
        "cost_usd": 0.007,
        "owner_id": "user_123",
        "model": "gemini-1.5-flash",
        "status": "success",
        "latency_ms": 2345.6
      }
    ]
    ```
    """
    # Get user from context
    current_user = get_owner_id()
    
    if not current_user:
        return {"error": "owner-id header required", "records": []}
    
    records = token_tracker.get_recent_records(limit)
    
    # Filter to only show user's own records
    filtered = [r for r in records if r["owner_id"] == current_user]
    
    return filtered


@router.get("/performance")
async def get_performance_metrics():
    """
    Get system performance metrics.
    
    **Response:**
    ```json
    {
      "cpu_percent": 12.5,
      "memory_percent": 45.2,
      "memory_mb": 1234,
      "disk_percent": 67.8,
      "process_threads": 8,
      "uptime_hours": 24.5
    }
    ```
    """
    process = psutil.Process(os.getpid())
    
    return {
        "timestamp": datetime.utcnow().isoformat(),
        "cpu_percent": process.cpu_percent(interval=1),
        "memory_mb": process.memory_info().rss / 1024 / 1024,
        "memory_percent": process.memory_percent(),
        "disk_percent": psutil.disk_usage('/').percent,
        "process_threads": process.num_threads(),
        "conversation_store_size": len(conversation_store.conversations),
        "total_token_records": len(token_tracker.records)
    }


@router.get("/health/detailed")
async def get_detailed_health():
    """
    Get detailed health status with all subsystems.
    
    **Response:**
    ```json
    {
      "status": "healthy",
      "timestamp": "2026-01-25T12:30:45.123456",
      "components": {
        "api": {
          "status": "healthy",
          "response_time_ms": 1.2
        },
        "conversation_store": {
          "status": "healthy",
          "conversations": 45,
          "memory_mb": 12.5
        },
        "logging": {
          "status": "healthy",
          "records": 1234
        },
        "rate_limiter": {
          "status": "healthy",
          "active_users": 12
        }
      },
      "uptime": {
        "hours": 24.5,
        "requests_processed": 5000,
        "errors": 2
      }
    }
    ```
    """
    process = psutil.Process(os.getpid())
    
    return {
        "status": "healthy",
        "timestamp": datetime.utcnow().isoformat(),
        "components": {
            "api": {
                "status": "healthy",
                "version": settings.api_version
            },
            "conversation_store": {
                "status": "healthy",
                "conversations": len(conversation_store.conversations),
                "conversations_by_user": len(set(
                    state.user_id for state in conversation_store.conversations.values()
                )),
                "stats": conversation_store.get_stats()
            },
            "token_tracking": {
                "status": "healthy",
                "records": len(token_tracker.records),
                "current_month_cost_usd": token_tracker.get_stats().get("total_cost_usd", 0)
            },
            "performance": {
                "cpu_percent": process.cpu_percent(interval=0.5),
                "memory_percent": process.memory_percent(),
                "memory_mb": process.memory_info().rss / 1024 / 1024,
                "disk_percent": psutil.disk_usage('/').percent
            }
        }
    }


@router.get("/tokens/export")
async def export_token_records(
    owner_id: Optional[str] = Query(None)
):
    """
    Export token records as CSV.
    
    **Query Parameters:**
    - `owner_id` (optional): Filter export for specific user (defaults to current user from header)
    
    **Headers:**
    - `owner-id`: User identifier (required if owner_id not provided)
    
    **Returns:** CSV file download
    """
    import tempfile
    from fastapi.responses import FileResponse
    
    current_user = get_owner_id()
    target_user = owner_id or current_user
    
    if not target_user:
        return {"error": "owner-id header required"}
    
    # Create temporary file
    with tempfile.NamedTemporaryFile(mode='w', suffix='.csv', delete=False) as f:
        temp_path = f.name
    
    token_tracker.export_csv(temp_path, target_user)
    
    return FileResponse(
        path=temp_path,
        filename=f"token_usage_{target_user}_{datetime.utcnow().strftime('%Y%m%d')}.csv",
        media_type="text/csv"
    )