"""
AETERNA AI — Base Data Source Architecture

Defines the abstract interface that all data connectors must implement.
Every record returned must include provenance metadata so the system
can transparently communicate data origin to users and stakeholders.
"""

from abc import ABC, abstractmethod
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional
from enum import Enum
from datetime import datetime


class ProvenanceType(str, Enum):
    """
    Formal classification of data provenance.

    OBSERVED        — Directly measured by an authoritative body
    DERIVED         — Mathematically computed from observed sources
    SYNTHETIC       — Procedurally generated by simulation
    EXTERNAL_REALTIME — Fetched from a live third-party public API
    MODEL_OUTPUT    — Produced by an ML or simulation model
    UNVERIFIED      — Origin unclear or not yet validated
    """
    OBSERVED = "OBSERVED"
    DERIVED = "DERIVED"
    SYNTHETIC = "SYNTHETIC"
    EXTERNAL_REALTIME = "EXTERNAL_REALTIME"
    MODEL_OUTPUT = "MODEL_OUTPUT"
    UNVERIFIED = "UNVERIFIED"


@dataclass
class DataRecord:
    """
    A single normalized data record with full provenance metadata.
    """
    value: Any
    field_name: str
    provenance: ProvenanceType
    source_name: str
    source_url: Optional[str] = None
    geographic_granularity: Optional[str] = None
    temporal_granularity: Optional[str] = None
    observation_date: Optional[str] = None
    fetched_at: str = field(default_factory=lambda: datetime.utcnow().isoformat() + "Z")
    limitations: Optional[str] = None
    validation_status: str = "UNVALIDATED"
    extra: Dict[str, Any] = field(default_factory=dict)

    def to_dict(self) -> Dict[str, Any]:
        return {
            "value": self.value,
            "field_name": self.field_name,
            "provenance": self.provenance.value,
            "source_name": self.source_name,
            "source_url": self.source_url,
            "geographic_granularity": self.geographic_granularity,
            "temporal_granularity": self.temporal_granularity,
            "observation_date": self.observation_date,
            "fetched_at": self.fetched_at,
            "limitations": self.limitations,
            "validation_status": self.validation_status,
            **self.extra,
        }


class BaseDataSource(ABC):
    """
    Abstract base class for all AETERNA AI data connectors.

    Every connector must implement:
    - is_available(): Check if the source is accessible
    - fetch(): Return normalized DataRecord list with provenance
    """

    SOURCE_NAME: str = "Unknown"
    SOURCE_URL: Optional[str] = None
    IS_STUB: bool = True  # True if not yet connected to live data

    @abstractmethod
    def is_available(self) -> bool:
        """
        Returns True if the data source is currently accessible.
        NEVER fabricate data if the source is unavailable — return False.
        """
        ...

    @abstractmethod
    def fetch(self, **kwargs) -> List[DataRecord]:
        """
        Fetch data from the source and return normalized DataRecord objects.
        NEVER return fabricated records — raise NotImplementedError or return empty list
        if the source is unavailable or credentials are missing.
        """
        ...

    def get_status(self) -> Dict[str, Any]:
        """Return connection status metadata for diagnostics."""
        return {
            "source_name": self.SOURCE_NAME,
            "source_url": self.SOURCE_URL,
            "is_stub": self.IS_STUB,
            "is_available": self.is_available(),
        }