"""TechniqueEntity — pure domain object for a MITRE ATT&CK technique.

Owns the status recalculation logic that was previously in
``status_service.py``.  Has **no** dependency on FastAPI, SQLAlchemy,
or any infrastructure concern.

Usage::

    entity = TechniqueEntity.from_orm(technique_orm_model)
    entity.recalculate_status(test_states_and_results)
    entity.mark_reviewed()
    entity.apply_to(technique_orm_model)
"""

from __future__ import annotations

import uuid
from dataclasses import dataclass, field
from datetime import datetime
from typing import Any

from app.domain.enums import TechniqueStatus, TestResult, TestState
from app.domain.value_objects.mitre_id import MitreId


@dataclass(frozen=True)
class _TestSnapshot:
    """Minimal read-only view of a test for status calculation."""

    state: TestState
    detection_result: str | None


@dataclass
class TechniqueEntity:
    """Pure domain representation of a MITRE ATT&CK technique."""

    id: uuid.UUID
    mitre_id: str
    name: str
    tactic: str | None = None
    description: str | None = None
    platforms: list[str] = field(default_factory=list)
    is_subtechnique: bool = False
    parent_mitre_id: str | None = None
    status_global: TechniqueStatus = TechniqueStatus.not_evaluated
    review_required: bool = False
    last_review_date: datetime | None = None

    # -- Factory -----------------------------------------------------------

    @classmethod
    def create(
        cls,
        *,
        mitre_id: str,
        name: str,
        tactic: str | None = None,
        description: str | None = None,
        platforms: list[str] | None = None,
    ) -> TechniqueEntity:
        """Create a new technique, validating the MITRE ID format."""
        validated_id = MitreId(mitre_id)
        return cls(
            id=uuid.uuid4(),
            mitre_id=validated_id.value,
            name=name,
            tactic=tactic,
            description=description,
            platforms=platforms or [],
            is_subtechnique=validated_id.is_subtechnique,
            parent_mitre_id=validated_id.parent_id,
            status_global=TechniqueStatus.not_evaluated,
        )

    @classmethod
    def from_orm(cls, model: Any) -> TechniqueEntity:
        """Build a TechniqueEntity from a SQLAlchemy Technique model."""
        raw_status = model.status_global
        status = (
            raw_status
            if isinstance(raw_status, TechniqueStatus)
            else TechniqueStatus(raw_status)
        )
        return cls(
            id=model.id,
            mitre_id=model.mitre_id,
            name=model.name,
            tactic=model.tactic,
            description=model.description,
            platforms=model.platforms or [],
            is_subtechnique=model.is_subtechnique or False,
            parent_mitre_id=model.parent_mitre_id,
            status_global=status,
            review_required=model.review_required or False,
            last_review_date=model.last_review_date,
        )

    def apply_to(self, model: Any) -> None:
        """Copy mutable fields back onto the ORM model."""
        model.status_global = self.status_global
        model.review_required = self.review_required
        model.last_review_date = self.last_review_date

    # -- Business logic ----------------------------------------------------

    def recalculate_status(
        self,
        test_snapshots: list[tuple[str, str | None]],
    ) -> TechniqueStatus:
        """Recompute ``status_global`` from a list of (state, detection_result) pairs.

        Rules (v2):
          1. No tests -> not_evaluated
          2. All validated -> inspect detection results:
             - All detected -> validated
             - Any partially_detected -> partial
             - Otherwise -> not_covered
          3. Some validated, others in progress -> partial
          4. All in intermediate states -> in_progress

        Returns the new status (also set on the entity).
        """
        tests = [
            _TestSnapshot(
                state=s if isinstance(s, TestState) else TestState(s),
                detection_result=dr,
            )
            for s, dr in test_snapshots
        ]

        if not tests:
            self.status_global = TechniqueStatus.not_evaluated
        elif all(t.state == TestState.validated for t in tests):
            results = [t.detection_result for t in tests if t.detection_result]
            if results and all(r == TestResult.detected or r == "detected" for r in results):
                self.status_global = TechniqueStatus.validated
            elif any(
                r == TestResult.partially_detected or r == "partially_detected"
                for r in results
            ):
                self.status_global = TechniqueStatus.partial
            else:
                self.status_global = TechniqueStatus.not_covered
        elif any(t.state == TestState.validated for t in tests):
            self.status_global = TechniqueStatus.partial
        else:
            self.status_global = TechniqueStatus.in_progress

        return self.status_global

    def mark_reviewed(self) -> None:
        """Mark the technique as reviewed, clearing the review flag."""
        self.review_required = False
        self.last_review_date = datetime.utcnow()

    def flag_for_review(self) -> None:
        """Flag the technique as needing review."""
        self.review_required = True