from dataclasses import dataclass, field
from datetime import datetime, timezone
from enum import Enum
from typing import Optional
import asyncio
import logging

logger = logging.getLogger("report_distributor")


class DeliveryStatus(Enum):
    PENDING = "pending"
    SENT = "sent"
    FAILED = "failed"
    RETRYING = "retrying"


@dataclass
class Recipient:
    email: str
    name: str
    region: str
    role: str  # "rep" | "manager" | "admin"
    timezone: str = "Asia/Shanghai"


@dataclass
class DeliveryRecord:
    recipient: Recipient
    report_type: str  # "daily_region" | "weekly_summary"
    status: DeliveryStatus = DeliveryStatus.PENDING
    attempts: int = 0
    sent_at: Optional[datetime] = None
    error: Optional[str] = None
    email_size_kb: int = 0


class ReportDistributor:
    """销售报告分发引擎"""

    MAX_RETRIES = 3
    RETRY_DELAYS = [60, 300, 1800]  # 1分钟, 5分钟, 30分钟
    MAX_EMAIL_SIZE_KB = 10 * 1024  # 10MB

    def __init__(self, smtp_client, report_generator, recipient_store):
        self.smtp = smtp_client
        self.reports = report_generator
        self.recipients = recipient_store
        self.delivery_log: list[DeliveryRecord] = []

    async def distribute_daily_reports(self):
        """每日区域报告分发"""
        regions = await self.recipients.get_active_regions()
        tasks = []

        for region in regions:
            reps = await self.recipients.get_region_recipients(region)
            report_html = await self.reports.generate_region_report(region)

            for rep in reps:
                tasks.append(self._deliver_with_retry(
                    recipient=rep,
                    report_type="daily_region",
                    subject=f"【日报】{region}区销售报告 - {self._today()}",
                    html_body=report_html,
                ))

        # 管理层汇总
        managers = await self.recipients.get_managers()
        summary_html = await self.reports.generate_company_summary()
        for mgr in managers:
            tasks.append(self._deliver_with_retry(
                recipient=mgr,
                report_type="daily_summary",
                subject=f"【日报】全公司销售汇总 - {self._today()}",
                html_body=summary_html,
            ))

        # 并发发送，互不阻塞
        results = await asyncio.gather(*tasks, return_exceptions=True)
        return self._build_distribution_summary(results)

    async def _deliver_with_retry(self, recipient: Recipient,
                                   report_type: str, subject: str,
                                   html_body: str):
        """带重试的投递"""
        record = DeliveryRecord(
            recipient=recipient,
            report_type=report_type,
            email_size_kb=len(html_body.encode()) // 1024,
        )
        self.delivery_log.append(record)

        # 检查邮件大小
        if record.email_size_kb > self.MAX_EMAIL_SIZE_KB:
            logger.warning(f"邮件过大 ({record.email_size_kb}KB)，"
                          f"转为下载链接模式")
            html_body = await self._convert_to_download_link(html_body)

        for attempt in range(self.MAX_RETRIES):
            record.attempts = attempt + 1
            try:
                await self.smtp.send(
                    to=recipient.email,
                    subject=subject,
                    html=html_body,
                )
                record.status = DeliveryStatus.SENT
                record.sent_at = datetime.now(timezone.utc)
                logger.info(f"已发送: {recipient.email} ({report_type})")
                return record

            except Exception as e:
                record.error = str(e)
                record.status = DeliveryStatus.RETRYING
                logger.warning(
                    f"发送失败 (第{attempt+1}次): {recipient.email} - {e}"
                )
                if attempt < self.MAX_RETRIES - 1:
                    await asyncio.sleep(self.RETRY_DELAYS[attempt])

        # 全部重试失败
        record.status = DeliveryStatus.FAILED
        logger.error(f"发送最终失败: {recipient.email}, "
                    f"共尝试 {self.MAX_RETRIES} 次")
        await self._alert_admin(record)
        return record

    async def _alert_admin(self, record: DeliveryRecord):
        """向管理员发送告警"""
        logger.critical(
            f"告警: 报告投递失败 - "
            f"收件人: {record.recipient.email}, "
            f"区域: {record.recipient.region}, "
            f"错误: {record.error}"
        )

    def _build_distribution_summary(self, results) -> dict:
        """构建分发摘要"""
        sent = sum(1 for r in self.delivery_log
                   if r.status == DeliveryStatus.SENT)
        failed = sum(1 for r in self.delivery_log
                     if r.status == DeliveryStatus.FAILED)
        return {
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "total": len(self.delivery_log),
            "sent": sent,
            "failed": failed,
            "success_rate": f"{sent/(sent+failed)*100:.1f}%" if (sent+failed) > 0 else "N/A",
            "failures": [
                {
                    "email": r.recipient.email,
                    "region": r.recipient.region,
                    "error": r.error,
                    "attempts": r.attempts,
                }
                for r in self.delivery_log
                if r.status == DeliveryStatus.FAILED
            ],
        }

    def _today(self) -> str:
        return datetime.now().strftime("%Y-%m-%d")

    async def _convert_to_download_link(self, html: str) -> str:
        """将大报告上传到文件服务，返回包含下载链接的邮件"""
        # 实际实现中上传到 S3/OSS
        return "<p>报告内容过大，请点击链接下载完整报告。</p>"

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from apscheduler.triggers.cron import CronTrigger


def setup_scheduler(distributor: ReportDistributor):
    """配置定时分发任务"""
    scheduler = AsyncIOScheduler()

    # 每日区域报告 —— 工作日 8:00 AM
    scheduler.add_job(
        distributor.distribute_daily_reports,
        CronTrigger(
            day_of_week="mon-fri",
            hour=8,
            minute=0,
            timezone="Asia/Shanghai",
        ),
        id="daily_region_report",
        name="每日区域销售报告",
        misfire_grace_time=300,  # 5分钟内补发
        max_instances=1,  # 防止重复执行
    )

    # 每周全公司汇总 —— 周一 7:00 AM
    scheduler.add_job(
        distributor.distribute_weekly_summary,
        CronTrigger(
            day_of_week="mon",
            hour=7,
            minute=0,
            timezone="Asia/Shanghai",
        ),
        id="weekly_summary_report",
        name="每周全公司销售汇总",
        misfire_grace_time=600,
    )

    scheduler.start()
    return scheduler

class DistributionAuditLog:
    """分发审计日志"""

    def __init__(self, db):
        self.db = db

    async def query_history(self, filters: dict) -> list[dict]:
        """
        查询分发历史
        filters: region, recipient_email, date_from, date_to, status
        """
        query = "SELECT * FROM distribution_log WHERE 1=1"
        params = []

        if "region" in filters:
            query += " AND region = %s"
            params.append(filters["region"])
        if "status" in filters:
            query += " AND status = %s"
            params.append(filters["status"])
        if "date_from" in filters:
            query += " AND sent_at >= %s"
            params.append(filters["date_from"])

        query += " ORDER BY sent_at DESC LIMIT 200"
        return await self.db.fetch_all(query, params)

    async def get_failure_summary(self, days: int = 7) -> dict:
        """最近 N 天的失败统计"""
        rows = await self.db.fetch_all("""
            SELECT recipient_email, region, COUNT(*) as fail_count,
                   MAX(error) as last_error
            FROM distribution_log
            WHERE status = 'failed'
              AND sent_at >= NOW() - INTERVAL %s DAY
            GROUP BY recipient_email, region
            ORDER BY fail_count DESC
        """, [days])

        return {
            "period_days": days,
            "total_failures": sum(r["fail_count"] for r in rows),
            "by_recipient": rows,
        }