"""Night diary line picker from fixed pool (not NLG)."""
from __future__ import annotations

import json
import random
from pathlib import Path
from typing import List, Optional, Sequence

class DiaryPool:
    def __init__(self, lines: List[dict], rng: Optional[random.Random] = None):
        self.lines = lines
        self.rng = rng or random.Random()

    @classmethod
    def load(cls, path: Path, rng: Optional[random.Random] = None) -> "DiaryPool":
        data = json.loads(path.read_text(encoding="utf-8"))
        return cls(list(data.get("lines") or []), rng=rng)

    def pick(self, tags: Sequence[str]) -> str:
        tagset = set(tags)
        scored = []
        for line in self.lines:
            lt = set(line.get("tags") or [])
            score = len(lt & tagset)
            if "default" in lt:
                score = max(score, 0)
            scored.append((score, line.get("text", "")))
        scored.sort(key=lambda x: x[0], reverse=True)
        best = scored[0][0] if scored else 0
        top = [t for s, t in scored if s == best and t]
        if not top:
            return "巷子很安静。店也是。"
        return self.rng.choice(top)