from __future__ import annotations

from dataclasses import dataclass, field
from typing import Literal, Optional, Sequence

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from domain.geospatial.planning_restrictions import PlanningRestrictions
from domain.modelling.scoring.overlay_applicator import apply_simulations
from domain.modelling.simulation import EpcSimulation
from domain.property.site_notes import SiteNotes

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


@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
    # A neighbour-synthesised EpcPropertyData (EPC Prediction gap-fill, ADR-0031),
    # held in its own slot so it coexists with any lodged `epc` (provenance is
    # structural). Used as the Effective EPC only as a last resort — when there is
    # neither a lodged EPC nor Site Notes; a real source always wins.
    predicted_epc: Optional[EpcPropertyData] = None
    # Resolved Landlord Overrides as Simulation Overlays, folded onto the lodged
    # OR neighbour-synthesised EPC to form the Effective EPC (ADR-0032). Empty
    # when the Property has no overrides — the EPC is then returned unchanged.
    # Applied on the `epc_with_overlay` and `predicted` paths; never when Site
    # Notes are the source.
    landlord_overrides: Sequence[EpcSimulation] = field(default_factory=tuple)
    # The current open-market value (a Property Valuation) — externally sourced
    # and mostly absent; feeds the Plan's Valuation Uplift £ forms (ADR-0018).
    current_market_value: Optional[float] = None
    # Planning protections resolved from the geospatial layer (ADR-0020); gate
    # wall insulation (ADR-0019). Defaults to unrestricted when unknown.
    planning_restrictions: PlanningRestrictions = PlanningRestrictions()

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

        Site Notes, or the public EPC (with Landlord Overrides folded on), or —
        as a last resort when neither real source exists — a neighbour-synthesised
        EPC (EPC Prediction, ADR-0031). When both Site Notes and an EPC exist the
        newer wins (Recency Tie-Break); on an equal date the survey wins, as it
        reflects on-site observation. A real source always beats the prediction.
        """
        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"
        if self.predicted_epc is not None:
            return "predicted"
        raise ValueError(
            "Property has neither Site Notes, an EPC, nor a predicted 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 with any Landlord Overrides folded on as Simulation Overlays (ADR-0032) — returned
        as-is when there are none.
        Path 3: a neighbour-synthesised EPC (EPC Prediction gap-fill, ADR-0031), likewise with any Landlord Overrides
        folded on: the cohort fills the unknown fields, the landlord's known
        facts (wall/roof/glazing/heating/age) correct them. Used only when
        neither real source is present.
        """
        if self.source_path == "site_notes":
            assert self.site_notes is not None
            return self.site_notes.to_epc_property_data()
        if self.source_path == "predicted":
            assert self.predicted_epc is not None
            return self._with_overrides(self.predicted_epc)
        assert self.epc is not None
        return self._with_overrides(self.epc)

    def _with_overrides(self, epc: EpcPropertyData) -> EpcPropertyData:
        """``epc`` with any Landlord Overrides folded on as Simulation Overlays,
        or unchanged when there are none (ADR-0032)."""
        if self.landlord_overrides:
            return apply_simulations(epc, self.landlord_overrides)
        return epc