import smtplib
import ssl
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.utils import formataddr
from email.header import Header
from models import SMTPConfig
import random

class EmailService:
    """邮件服务类"""

    @staticmethod
    def get_smtp_config():
        """获取可用的SMTP配置（负载均衡）"""
        configs = SMTPConfig.query.filter_by(is_enabled=True).all()

        if not configs:
            raise Exception("没有可用的SMTP配置")

        # 加权随机选择
        total_weight = sum(c.weight for c in configs)
        if total_weight == 0:
            return random.choice(configs)

        rand = random.uniform(0, total_weight)
        current = 0

        for config in configs:
            current += config.weight
            if rand <= current:
                return config

        return configs[-1]

    @staticmethod
    def _do_send(smtp_config, to_email: str, subject: str, content: str, html: bool = True):
        """实际发送邮件的内部方法"""
        server = None
        try:
            print(f"[SMTP调试] 开始发送邮件")
            print(f"[SMTP调试] 服务器: {smtp_config.host}:{smtp_config.port}")
            print(f"[SMTP调试] 用户名: {smtp_config.username}")
            print(f"[SMTP调试] 使用TLS: {smtp_config.use_tls}")
            print(f"[SMTP调试] 发件人: {smtp_config.from_email}")

            msg = MIMEMultipart('alternative')
            from_email = smtp_config.from_email or smtp_config.username
            from_name = smtp_config.from_name or smtp_config.username
            msg['From'] = formataddr((str(Header(from_name, 'utf-8')), from_email))
            msg['To'] = to_email
            msg['Subject'] = Header(subject, 'utf-8')

            if html:
                msg.attach(MIMEText(content, 'html', 'utf-8'))
            else:
                msg.attach(MIMEText(content, 'plain', 'utf-8'))

            print(f"[SMTP调试] 开始连接服务器...")
            if smtp_config.port == 465:
                print(f"[SMTP调试] 使用 SSL 模式（端口 465）")
                server = smtplib.SMTP_SSL(smtp_config.host, smtp_config.port, timeout=30)
            elif smtp_config.use_tls:
                print(f"[SMTP调试] 使用 STARTTLS 模式（端口 {smtp_config.port}）")
                server = smtplib.SMTP(smtp_config.host, smtp_config.port, timeout=30)
                server.ehlo()
                context = ssl.create_default_context()
                server.starttls(context=context)
                server.ehlo()
            else:
                print(f"[SMTP调试] 使用普通 SMTP 模式（端口 {smtp_config.port}）")
                server = smtplib.SMTP(smtp_config.host, smtp_config.port, timeout=30)

            print(f"[SMTP调试] 连接成功，开始登录...")
            server.login(smtp_config.username, smtp_config.password)
            print(f"[SMTP调试] 登录成功，开始发送邮件...")
            server.sendmail(from_email, [to_email], msg.as_string())
            print(f"[SMTP调试] 邮件发送成功！")

            # 更新发送统计
            smtp_config.send_count += 1
            from models import db
            db.session.commit()

            return True
        finally:
            if server:
                try:
                    server.quit()
                except:
                    pass

    @staticmethod
    def send_email(to_email: str, subject: str, content: str, html: bool = True):
        """发送邮件（支持故障自动转移）"""
        configs = SMTPConfig.query.filter_by(is_enabled=True).all()

        if not configs:
            raise Exception("没有可用的SMTP配置")

        # 按权重排序，优先尝试高权重的配置
        configs.sort(key=lambda x: x.weight, reverse=True)

        last_error = None
        tried_ids = []

        for smtp_config in configs:
            tried_ids.append(smtp_config.id)
            try:
                return EmailService._do_send(smtp_config, to_email, subject, content, html)
            except Exception as e:
                last_error = str(e)
                print(f"[SMTP调试] {smtp_config.name} 发送失败: {last_error}")
                # 更新失败统计
                smtp_config.fail_count += 1
                from models import db
                db.session.commit()

                # 如果还有其他配置，继续尝试
                remaining = len(configs) - len(tried_ids)
                if remaining > 0:
                    print(f"[SMTP调试] 尝试下一个SMTP配置，剩余 {remaining} 个")
                continue

        # 所有配置都失败了
        raise Exception(f"所有SMTP配置均发送失败，最后错误: {last_error}")

    @staticmethod
    def send_verification_code(to_email: str, code: str, purpose: str):
        """发送验证码邮件"""
        purpose_text = {
            'register': '注册账号',
            'reset_password': '重置密码',
            'forgot_password': '找回密码'
        }.get(purpose, '验证')

        subject = f"【短视频解析平台】{purpose_text}验证码"

        content = f"""
        <html>
        <body style="font-family: Arial, sans-serif; padding: 20px;">
            <h2>验证码</h2>
            <p>您正在进行<strong>{purpose_text}</strong>操作，验证码为：</p>
            <h1 style="color: #4CAF50; letter-spacing: 5px;">{code}</h1>
            <p>验证码有效期为10分钟，请勿泄露给他人。</p>
            <hr>
            <p style="color: #999; font-size: 12px;">如果这不是您的操作，请忽略此邮件。</p>
        </body>
        </html>
        """

        return EmailService.send_email(to_email, subject, content, html=True)