from datetime import datetime
from typing import Optional, Dict, Any
from pydantic import BaseModel, Field, ConfigDict
from bson import ObjectId
from pydantic_core import core_schema


class PyObjectId(str):
    """Custom ObjectId type for Pydantic v2"""

    @classmethod
    def __get_pydantic_core_schema__(cls, source_type, handler):
        return core_schema.union_schema([
            core_schema.is_instance_schema(ObjectId),
            core_schema.chain_schema([
                core_schema.str_schema(),
                core_schema.no_info_plain_validator_function(cls.validate),
            ])
        ],
        serialization=core_schema.plain_serializer_function_ser_schema(
            lambda x: str(x)
        ))

    @classmethod
    def validate(cls, v):
        if not ObjectId.is_valid(v):
            raise ValueError("Invalid ObjectId")
        return ObjectId(v)


class ServiceStatus:
    """Service status constants"""
    HEALTHY = "healthy"
    UNHEALTHY = "unhealthy"
    UNKNOWN = "unknown"


class ServiceType:
    """Service type constants"""
    BACKEND = "backend"
    FRONTEND = "frontend"
    DATABASE = "database"
    CACHE = "cache"
    MESSAGE_QUEUE = "message_queue"
    OTHER = "other"


class Service(BaseModel):
    """Service model for MongoDB"""
    id: Optional[PyObjectId] = Field(alias="_id", default=None)
    name: str = Field(..., min_length=1, max_length=100)
    description: Optional[str] = Field(default=None, max_length=500)
    service_type: str = Field(default=ServiceType.BACKEND)
    url: str = Field(..., min_length=1)
    health_endpoint: Optional[str] = Field(default="/health")
    status: str = Field(default=ServiceStatus.UNKNOWN)
    last_health_check: Optional[datetime] = None
    response_time_ms: Optional[float] = None
    created_at: datetime = Field(default_factory=datetime.utcnow)
    updated_at: datetime = Field(default_factory=datetime.utcnow)
    metadata: Dict[str, Any] = Field(default_factory=dict)

    model_config = ConfigDict(
        populate_by_name=True,
        arbitrary_types_allowed=True,
        json_encoders={ObjectId: str},
        json_schema_extra={
            "example": {
                "name": "News API",
                "description": "News generation and management API",
                "service_type": "backend",
                "url": "http://news-api:8050",
                "health_endpoint": "/health",
                "status": "healthy",
                "metadata": {
                    "version": "1.0.0",
                    "port": 8050
                }
            }
        }
    )