"""风控事件引擎（B4 · 架构 §3.1 ④ / PRD FR-3）。

编排（网关 B5 在 core_trade 落库后**同步调用**，不用消息队列）：
当日流水上下文（core_ro）→ RISK-001~005 纯函数 → AML 姓名匹配 → 预警落库
（alert_service：聚合/去重/审计/推送）→ L3 upsert（profile_l3）。
审计 pass（未命中）与命中审计均由 alert_service 完成，本层不重复落审计。

RISK-004 窗口以 trade["traded_at"] 为事件时点（非墙钟 now）：rebuild_alerts
幂等重放可复现窗口判定，演示脚本不受执行时刻影响。

客户事件钩子 on_customer_created/on_customer_updated 为 FR-5 预留（本期 no-op，
模拟环境无开户流程）。
"""

from __future__ import annotations

from datetime import datetime, timedelta
from decimal import Decimal
from typing import Any

from app.repository.core_ro import CoreReadOnlyRepository
from app.repository.risk_repository import RiskRepository
from app.service.risk.alert_service import record_aml_alert, record_trade_alerts
from app.service.risk.aml_service import match_customer
from app.service.risk.profile_l3 import upsert_profile_l3
from app.service.risk.rules import RiskThresholds, run_rules
from app.utils.trace import ensure_trace


def _as_datetime(value: Any) -> datetime:
    if isinstance(value, datetime):
        return value
    if isinstance(value, str):
        return datetime.fromisoformat(value)
    raise TypeError(f"traded_at must be datetime/str, got {type(value)!r}")


def _normalize_trades(trades: list[dict[str, Any]]) -> list[dict[str, Any]]:
    """驱动差异防御：sqlite text 查询返回 str 时间，统一转 datetime（MySQL 驱动本就返回 datetime）。"""
    for t in trades:
        if isinstance(t.get("traded_at"), str):
            t["traded_at"] = datetime.fromisoformat(t["traded_at"])
    return trades


def _build_customer_context(
    core: CoreReadOnlyRepository, customer_id: str, day_start: datetime
) -> dict[str, Any]:
    """预警 payload 客户上下文（PRD FR-4：L0 事实 + 近 30 天交易统计；B4 评审 P1-1 补组装）。

    display_name 为脱敏展示名口径，可直存 payload；core_cash_flow 上下文一期
    未接（core_ro 无对应查询，挂账见开发计划 B4 行）。
    """
    l0 = core.get_customer_l0(customer_id) or {}
    month_ago = day_start - timedelta(days=30)
    day_end = day_start + timedelta(days=1)  # 近 30 天含当日（本笔在内）
    trades_30d = core.list_trades_range(customer_id, month_ago, day_end)
    total = sum((Decimal(str(t["amount"])) for t in trades_30d), Decimal(0))
    return {
        "l0": {
            k: l0[k]
            for k in ("customer_id", "display_name", "age", "risk_code")
            if l0.get(k) is not None
        },
        "trades_30d": {"count": len(trades_30d), "total_amount": str(total)},
    }


def process_trade_event(
    trade: dict[str, Any],
    core_ro: CoreReadOnlyRepository | None = None,
    risk_repo: RiskRepository | None = None,
    thresholds: RiskThresholds | None = None,
) -> dict[str, Any]:
    """处理一笔已落库交易（PRD FR-1 ②③b 之后）。

    返回 {"triggered_rules": [...], "alert_ids": [...], "aml_hit": bool}，
    网关据此拼装响应（FR-1 ⑤：blocked=false + trade_id + 触发规则列表）。
    """
    core = core_ro or CoreReadOnlyRepository()
    repo = risk_repo or RiskRepository()
    th = thresholds or RiskThresholds.from_settings()
    ensure_trace()  # 脚本/重放入口兜底归因（中间件场景保留现有 trace，评审 P3-8）

    event_at = _as_datetime(trade["traded_at"])
    day_start = event_at.replace(hour=0, minute=0, second=0, microsecond=0)
    day_end = day_start + timedelta(days=1)
    trades = _normalize_trades(
        core.list_trades_range(trade["customer_id"], day_start, day_end)
    )

    result: dict[str, Any] = {"triggered_rules": [], "alert_ids": [], "aml_hit": False}

    hits = run_rules(trades, th, now=event_at)
    if hits:
        alert = record_trade_alerts(
            trade,
            hits,
            risk_repo=repo,
            customer_context=_build_customer_context(core, trade["customer_id"], day_start),
        )
        result["triggered_rules"] = sorted({h.rule_id for h in hits})
        if alert:
            result["alert_ids"].append(alert["alert_id"])
        best = max(hits, key=lambda h: h.risk_score)
        upsert_profile_l3(
            trade["customer_id"],
            best.alert_type,
            last_alert_id=alert["alert_id"] if alert else None,
            risk_repo=repo,
        )
    else:
        # 未命中分支：pass 审计由 alert_service 统一落库（架构 §3.1 ④）
        record_trade_alerts(trade, [], risk_repo=repo)

    aml_hits = match_customer(trade["customer_id"], core_ro=core, risk_repo=repo)
    if aml_hits:
        result["aml_hit"] = True
        alert = record_aml_alert(
            trade["customer_id"],
            {
                "trigger": "trade",
                "trade_id": trade.get("trade_id"),
                "product_id": trade.get("product_id"),  # 评审 P3-6：payload/审计透传
                "matches": aml_hits,
            },
            risk_repo=repo,
        )
        result["alert_ids"].append(alert["alert_id"])
        upsert_profile_l3(
            trade["customer_id"], "aml", last_alert_id=alert["alert_id"], risk_repo=repo
        )

    return result


def on_customer_created(customer_id: str) -> None:
    """AML 开户触发预留（本期 no-op；模拟环境无开户流程，PRD FR-5）。"""

def on_customer_updated(customer_id: str) -> None:
    """客户信息变更触发预留（本期 no-op；PRD FR-5）。"""