from __future__ import annotations

from dataclasses import dataclass
from typing import Literal, Optional

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from domain.property.site_notes import SiteNotes

SourcePath = Literal["site_notes", "epc_with_overlay"]


@dataclass(frozen=True)
class PropertyIdentity:
    """Identifies a single Property within a portfolio.

    Keyed by `(portfolio_id, uprn)` or `(portfolio_id, landlord_property_id)` —
    a UPRN is permanent but each portfolio gets its own Property against it
    (CONTEXT.md: UPRN).
    """

    portfolio_id: int
    postcode: str
    address: str
    uprn: Optional[int] = None
    landlord_property_id: Optional[str] = None


@dataclass
class Property:
    """The Ara modelling aggregate root for a single dwelling (ADR-0002).

    Holds identity plus the source data the pipeline reasons about. Enrichments
    (geospatial, solar) and modelling outputs (baseline performance, plans) are
    added by later slices — this is the minimal-and-growing shape for First Run.
    """

    identity: PropertyIdentity
    epc: Optional[EpcPropertyData] = None
    site_notes: Optional[SiteNotes] = None

    @property
    def source_path(self) -> SourcePath:
        """Which of the two disjoint source paths models this Property (ADR-0001).

        Site Notes alone, or the public EPC (with Landlord Overrides, once that
        slice lands). When both exist the newer wins (Recency Tie-Break); on an
        equal date the survey wins, as it reflects on-site observation.
        """
        if self.site_notes is not None and self.epc is not None:
            epc_date = self.epc.registration_date or self.epc.inspection_date
            if self.site_notes.surveyed_at >= epc_date:
                return "site_notes"
            return "epc_with_overlay"
        if self.site_notes is not None:
            return "site_notes"
        if self.epc is not None:
            return "epc_with_overlay"
        raise ValueError(
            "Property has neither Site Notes nor an EPC; no source path to model from"
        )

    @property
    def effective_epc(self) -> EpcPropertyData:
        """The EpcPropertyData the modelling pipeline scores against.

        Path 1: the Site Notes' surveyed data. Path 2: the public EPC (Landlord
        Overrides overlay is a later slice — returned as-is for now).
        """
        if self.source_path == "site_notes":
            assert self.site_notes is not None
            return self.site_notes.to_epc_property_data()
        assert self.epc is not None
        return self.epc