"""感慨触发判定（辰正设计 §7.2）。

纯函数：消费 ``TemporalSnapshot`` + 对话/记忆信号，返回 ``sentiment_trigger`` 或 None。
触发类型对齐契约字典 §11.4.7。v1 实时判定（流 A/C 入口）；``season_resonance`` 留 v2。
"""

from __future__ import annotations

from pydantic import BaseModel

from app.modules.time_sense.snapshot import TemporalSnapshot


class SentimentInput(BaseModel):
    """detect_sentiment 的对话/记忆信号输入（service 层收集）。"""

    duration_days: int  # 认识天数
    next_milestone_days: int | None = None  # 距下一周年/里程碑天数；None=无下一里程碑
    has_active_milestone: bool = False  # 今日是否命中里程碑
    is_reunion: bool = False  # 是否处于重逢档
    has_reunion_memory: bool = False  # 是否存在临别前最后一批记忆线索
    strong_solar_terms: set[str] = set()  # 强节气名集合（来自 TimeConfig）
    prewarm_days: int = 7  # 周年预热窗口（来自 TimeConfig）
    duration_nodes: set[int] = set()  # 有感天数节点（来自 TimeConfig）


def detect_sentiment(snapshot: TemporalSnapshot, signals: SentimentInput) -> str | None:
    """按设计 §7.2 判定感慨触发，返回 ``sentiment_trigger`` 或 None。

    优先级（v1）：duration_node > anniversary_prewarm > reunion_memory >
    late_night_overlay > solar_term。season_resonance 留 v2。
    """
    # 1. duration_node：认识天数命中节点
    if signals.duration_days in signals.duration_nodes:
        return "duration_node"

    # 2. anniversary_prewarm：距周年 ≤ prewarm_days
    if (
        signals.next_milestone_days is not None
        and 0 < signals.next_milestone_days <= signals.prewarm_days
    ):
        return "anniversary_prewarm"

    # 3. reunion_memory：久别重逢 + 存在临别记忆
    if signals.is_reunion and signals.has_reunion_memory:
        return "reunion_memory"

    # 4. late_night_overlay：凌晨 + 里程碑/重逢叠加
    if snapshot.day_period == "凌晨" and (signals.has_active_milestone or signals.is_reunion):
        return "late_night_overlay"

    # 5. solar_term：今日处于强节气
    term_name = snapshot.solar_term.current_name if snapshot.solar_term else None
    if term_name and term_name in signals.strong_solar_terms:
        return "solar_term"

    return None