"""Rule-based rubric scorer — deterministic (SLICE-03 TASK-03-02, REQ-NFR-MAST-01).

No LLM. Maps evidence signals to rubric level anchors: for each criterion, pick
the highest level whose `signals[]` are all present in the matched evidence,
fallback to level 1 if no level matches. The output is reproducible given the
same (evidence, rubric) pair.
"""

from __future__ import annotations

from pydantic import BaseModel, Field

from server.mastery.evidence_extractor import Evidence
from server.mastery.rubric_schema import Rubric, RubricCriterion


class CriterionScore(BaseModel):
    criterion_id: str
    level: int = Field(ge=1, le=5)
    weight: float
    evidence_quote: str = ""
    matched_signals: list[str] = Field(default_factory=list)


def _evidence_for(evidence: list[Evidence], criterion_id: str) -> Evidence | None:
    for ev in evidence:
        if ev.criterion_id == criterion_id:
            return ev
    return None


def _level_for_criterion(criterion: RubricCriterion, ev: Evidence | None) -> tuple[int, list[str]]:
    if ev is None or not ev.signals:
        return 1, []
    ev_signals = set(ev.signals)
    best_level = 1
    best_signals: list[str] = []
    for lvl in sorted(criterion.levels, key=lambda l: l.level):
        if all(s in ev_signals for s in lvl.signals):
            best_level = lvl.level
            best_signals = list(lvl.signals)
    return best_level, best_signals


def score(evidence: list[Evidence], rubric: Rubric) -> list[CriterionScore]:
    """Score evidence against the rubric — deterministic, no LLM.

    Returns one CriterionScore per rubric criterion, in rubric order. Criteria
    with no matching evidence get level 1 (the "Fail" anchor).
    """
    out: list[CriterionScore] = []
    for c in rubric.criteria:
        ev = _evidence_for(evidence, c.id)
        level, matched = _level_for_criterion(c, ev)
        out.append(
            CriterionScore(
                criterion_id=c.id,
                level=level,
                weight=c.weight,
                evidence_quote=ev.quote if ev else "",
                matched_signals=matched,
            )
        )
    return out


__all__ = ["CriterionScore", "score"]