#!/usr/bin/env python3
"""
Node Registry Service
Central registry for DAGI network nodes (Node #1, Node #2, Node #N)

This is a stub implementation - full API will be implemented by Cursor.
"""

import os
import time
from datetime import datetime
from typing import Dict, Any

from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse
from pydantic import BaseModel
import uvicorn


# Environment configuration
HTTP_PORT = int(os.getenv("NODE_REGISTRY_HTTP_PORT", "9205"))
ENV = os.getenv("NODE_REGISTRY_ENV", "development")
LOG_LEVEL = os.getenv("NODE_REGISTRY_LOG_LEVEL", "info")
DB_HOST = os.getenv("NODE_REGISTRY_DB_HOST", "postgres")
DB_PORT = int(os.getenv("NODE_REGISTRY_DB_PORT", "5432"))
DB_NAME = os.getenv("NODE_REGISTRY_DB_NAME", "node_registry")
DB_USER = os.getenv("NODE_REGISTRY_DB_USER", "node_registry_user")
DB_PASSWORD = os.getenv("NODE_REGISTRY_DB_PASSWORD", "")

# Service metadata
SERVICE_NAME = "node-registry"
VERSION = "0.1.0-stub"
START_TIME = time.time()


app = FastAPI(
    title="Node Registry Service",
    description="Central registry for DAGI network nodes",
    version=VERSION,
    docs_url="/docs" if ENV == "development" else None,
    redoc_url="/redoc" if ENV == "development" else None,
)


# Models (stub - will be expanded by Cursor)
class HealthResponse(BaseModel):
    status: str
    service: str
    version: str
    environment: str
    uptime_seconds: float
    timestamp: str
    database: Dict[str, Any]


class MetricsResponse(BaseModel):
    service: str
    uptime_seconds: float
    total_nodes: int
    active_nodes: int
    timestamp: str


# Health check endpoint
@app.get("/health", response_model=HealthResponse)
async def health_check():
    """
    Health check endpoint for monitoring systems.
    
    Returns service status, version, and database connectivity.
    """
    uptime = time.time() - START_TIME
    
    # TODO: Implement actual DB health check
    db_status = {
        "connected": False,
        "host": DB_HOST,
        "port": DB_PORT,
        "database": DB_NAME,
        "message": "Not implemented (stub)"
    }
    
    return HealthResponse(
        status="healthy",
        service=SERVICE_NAME,
        version=VERSION,
        environment=ENV,
        uptime_seconds=uptime,
        timestamp=datetime.utcnow().isoformat() + "Z",
        database=db_status
    )


# Metrics endpoint (Prometheus-compatible format will be added by Cursor)
@app.get("/metrics", response_model=MetricsResponse)
async def metrics():
    """
    Metrics endpoint for Prometheus scraping.
    
    TODO: Add proper Prometheus format (prometheus_client library)
    """
    uptime = time.time() - START_TIME
    
    # TODO: Implement actual metrics from database
    return MetricsResponse(
        service=SERVICE_NAME,
        uptime_seconds=uptime,
        total_nodes=0,
        active_nodes=0,
        timestamp=datetime.utcnow().isoformat() + "Z"
    )


# Root endpoint
@app.get("/")
async def root():
    """Root endpoint - service information"""
    return {
        "service": SERVICE_NAME,
        "version": VERSION,
        "status": "running",
        "environment": ENV,
        "message": "Node Registry Service (stub implementation)",
        "endpoints": {
            "health": "/health",
            "metrics": "/metrics",
            "docs": "/docs" if ENV == "development" else "disabled",
        }
    }


# Stub API endpoints (to be implemented by Cursor)
@app.post("/api/v1/nodes/register")
async def register_node():
    """
    Register a new node in the registry.
    
    TODO: Implement by Cursor
    """
    raise HTTPException(status_code=501, detail="Not implemented - stub endpoint")


@app.post("/api/v1/nodes/{node_id}/heartbeat")
async def update_heartbeat(node_id: str):
    """
    Update node heartbeat (keep-alive).
    
    TODO: Implement by Cursor
    """
    raise HTTPException(status_code=501, detail="Not implemented - stub endpoint")


@app.get("/api/v1/nodes")
async def list_nodes():
    """
    List all registered nodes.
    
    TODO: Implement by Cursor
    """
    raise HTTPException(status_code=501, detail="Not implemented - stub endpoint")


@app.get("/api/v1/nodes/{node_id}")
async def get_node(node_id: str):
    """
    Get specific node information.
    
    TODO: Implement by Cursor
    """
    raise HTTPException(status_code=501, detail="Not implemented - stub endpoint")


if __name__ == "__main__":
    print(f"🚀 Starting {SERVICE_NAME} v{VERSION}")
    print(f"📊 Environment: {ENV}")
    print(f"🔌 Port: {HTTP_PORT}")
    print(f"🗄️  Database: {DB_USER}@{DB_HOST}:{DB_PORT}/{DB_NAME}")
    print(f"📝 Log level: {LOG_LEVEL}")
    print()
    
    uvicorn.run(
        app,
        host="0.0.0.0",
        port=HTTP_PORT,
        log_level=LOG_LEVEL.lower(),
        access_log=True,
    )