# -*- coding: utf-8 -*-
from datetime import datetime, date
from pathlib import Path
from statistics import mean


class FishHistoryManager:
    """维护每日鱼类活动档案，并在指定时间生成报告。"""

    def __init__(self, report_dir: str = "reports", report_hour: int = 20):
        self.report_dir = Path(report_dir)
        self.report_dir.mkdir(parents=True, exist_ok=True)
        self.report_hour = report_hour
        self.records = {}  # fish_id -> metrics
        self.last_report_date: date | None = None

    def update(self, track_stats, ts: datetime):
        """用当前帧的跟踪统计更新档案。"""
        for stats in track_stats:
            fid = stats["id"]
            rec = self.records.setdefault(fid, {
                "frames": 0,
                "distance": 0.0,
                "bottom_frames": 0,
                "slow_frames": 0,
                "speed_samples": [],
                "first_seen": ts,
                "last_seen": ts,
            })
            rec["frames"] += 1
            rec["distance"] += float(stats.get("distance_delta", 0) or 0)
            if stats.get("is_bottom"):
                rec["bottom_frames"] += 1
            if stats.get("is_slow"):
                rec["slow_frames"] += 1
            speed = stats.get("speed")
            if speed is not None:
                rec["speed_samples"].append(float(speed))
            rec["last_seen"] = ts

    def _analyze_record(self, fid, rec):
        frames = rec.get("frames", 1)
        bottom_ratio = rec.get("bottom_frames", 0) / frames
        slow_ratio = rec.get("slow_frames", 0) / frames
        avg_speed = mean(rec["speed_samples"]) if rec["speed_samples"] else 0
        distance = rec.get("distance", 0)

        issues = []
        if avg_speed < 10 or slow_ratio > 0.5:
            issues.append("活动偏低")
        if bottom_ratio > 0.4:
            issues.append("长时间停留底部")

        health = "疑似异常" if issues else "正常"
        return {
            "fish_id": fid,
            "frames": frames,
            "distance": distance,
            "avg_speed": avg_speed,
            "bottom_ratio": bottom_ratio,
            "slow_ratio": slow_ratio,
            "health": health,
            "issues": issues,
            "active_period": f"{rec['first_seen'].strftime('%H:%M:%S')} - {rec['last_seen'].strftime('%H:%M:%S')}",
        }

    def generate_report(self, report_date: date | None = None):
        """生成报告文本并写入文件，返回文件路径。"""
        report_date = report_date or date.today()
        analyses = [self._analyze_record(fid, rec) for fid, rec in self.records.items()]
        analyses.sort(key=lambda x: x["fish_id"])

        lines = [f"鱼类日度报告 - {report_date.strftime('%Y-%m-%d')}"]
        if not analyses:
            lines.append("今日无检测数据。")
        else:
            for item in analyses:
                issues_text = "；".join(item["issues"]) if item["issues"] else "无"
                lines.append(
                    f"- 鱼 {item['fish_id']}: 状态={item['health']}，平均速度={item['avg_speed']:.1f}px/s，"
                    f"底部占比={item['bottom_ratio']:.2f}，慢速占比={item['slow_ratio']:.2f}，"
                    f"累计位移={item['distance']:.1f}px，时间段={item['active_period']}，问题={issues_text}"
                )

        report_path = self.report_dir / f"fish_report_{report_date.strftime('%Y%m%d')}.txt"
        report_path.write_text("\n".join(lines), encoding="utf-8")
        self.last_report_date = report_date
        # 每日报告后可选择清空记录，当前继续保留，次日将覆盖分析。
        return report_path

    def maybe_generate_report(self, now: datetime):
        """在到达指定时间且今日未生成报告时生成报告。"""
        if now.hour >= self.report_hour:
            today = now.date()
            if self.last_report_date != today:
                return self.generate_report(today)
        return None