"""Load case YAML into typed dataclasses."""
from __future__ import annotations
from dataclasses import dataclass, field
from pathlib import Path
import yaml


@dataclass(frozen=True)
class Witness:
    id: str
    name: str
    portrait_ref: str
    persona: str
    secret_knowledge: str
    reliability: float
    independence_group: str | None
    cost_days: int
    is_physical_evidence: bool
    target_mass: dict[frozenset[str], float]


@dataclass(frozen=True)
class GroundTruth:
    culprit: str
    accomplice: str | None


@dataclass(frozen=True)
class CaseData:
    case_id: str
    title: str
    setting_blurb: str
    victim: str
    dock: list[str]
    court_days: int
    threshold: float
    methods_available: list[str]
    witnesses: list[Witness]
    ground_truth: GroundTruth
    intended_path: str
    reveal_expectations: dict


def _parse_mass(raw: dict | None, dock: list[str]) -> dict[frozenset[str], float]:
    if not raw:
        return {}
    dock_set = set(dock)
    out: dict[frozenset[str], float] = {}
    for key, val in raw.items():
        # keys are comma-separated suspect names, e.g. "Gardener,Maid"
        names = [s.strip() for s in str(key).split(",")]
        for n in names:
            if n not in dock_set:
                raise ValueError(f"unknown suspect in target_mass: {n!r}")
        out[frozenset(names)] = float(val)
    return out


def load_case(path: str | Path) -> CaseData:
    raw = yaml.safe_load(Path(path).read_text())
    dock = list(raw["dock"])
    witnesses = [
        Witness(
            id=w["id"],
            name=w["name"],
            portrait_ref=w.get("portrait_ref", ""),
            persona=w["persona"],
            secret_knowledge=w["secret_knowledge"],
            reliability=float(w.get("reliability", 1.0)),
            independence_group=w.get("independence_group"),
            cost_days=int(w.get("cost_days", 1)),
            is_physical_evidence=bool(w.get("is_physical_evidence", False)),
            target_mass=_parse_mass(w.get("target_mass"), dock),
        )
        for w in raw["witnesses"]
    ]
    gt = raw["ground_truth"]
    return CaseData(
        case_id=raw["case_id"],
        title=raw["title"],
        setting_blurb=raw["setting_blurb"],
        victim=raw["victim"],
        dock=dock,
        court_days=int(raw["court_days"]),
        threshold=float(raw["threshold"]),
        methods_available=list(raw["methods_available"]),
        witnesses=witnesses,
        ground_truth=GroundTruth(culprit=gt["culprit"], accomplice=gt.get("accomplice")),
        intended_path=raw.get("intended_path", ""),
        reveal_expectations=raw.get("reveal_expectations", {}),
    )