"""
Pydantic schemas for defining health check responses, following IETF standards.
"""

from datetime import datetime
from enum import Enum

# Import ConfigDict from pydantic to resolve the deprecation warning
from pydantic import BaseModel, Field, ConfigDict

# Define acceptable statuses as an Enum for robust validation
class HealthStatusEnum(str, Enum):
    """Enumeration for standard health check statuses."""
    passed = "pass"
    warned = "warn"
    failed = "fail"

class ComponentCheck(BaseModel):
    """
    Represents the status and metrics for a single internal component or dependency.
    """
    # Use ConfigDict instead of the class Config approach
    model_config = ConfigDict(
        populate_by_name=True  # Allows instantiation using either 'observed_value' or 'observedValue'
    )

    name: str = Field(description="The unique name of the component being checked (e.g., 'postgres', 'redis').")
    status: HealthStatusEnum = Field(description="The status of the check: 'pass', 'warn', or 'fail'.")
    time: datetime | None = Field(default=None, description="The time at which the check was performed in ISO 8601 format.")
    output: str | None = Field(default=None, description="Additional details, error messages, or logs if the status is 'fail' or 'warn'.")
    
    # Python uses snake_case internally, JSON uses camelCase for the alias
    observed_value: float | int | None = Field(
        default=None, 
        alias="observedValue", 
        description="The value observed during the check (e.g., latency in ms)."
    )
    # Python uses snake_case internally, JSON uses camelCase for the alias
    observed_unit: str | None = Field(
        default=None, 
        alias="observedUnit", 
        description="The unit of the observed value (e.g., 'ms', 'count', 'bytes')."
    )

class HealthStatus(BaseModel):
    """
    The overall system health response model, aggregating all individual component checks.
    """
    # Use ConfigDict instead of the class Config approach
    model_config = ConfigDict(
        populate_by_name=True
    )

    status: HealthStatusEnum = Field(description="The aggregate status of the entire service: 'pass', 'warn', or 'fail'.")
    version: str | None = Field(default=None, description="The application version (e.g., Git SHA or semantic version number).")
    environment: str | None = Field(default=None, description="The deployment environment (e.g., 'production', 'staging').")
    
    # Python uses snake_case internally, JSON uses camelCase for the alias
    service_name: str | None = Field(
        default=None, 
        alias="serviceName", 
        description="The name of the service."
    )
    description: str | None = Field(default=None, description="A brief description of the service.")
    checks: dict[str, ComponentCheck] = Field(description="A dictionary mapping check keys (e.g., 'Database') to their detailed ComponentCheck results.")